Taurine for subgroups of Autism? Plus, vitamin B5 and L Carnitine for KAT6A syndrome?

 

   A Red Bull Formula 1 racing car

 

Today’s post should be of wide interest because it concerns the potential benefit from the OTC supplement taurine. There is a section at the end answering a query about mutations in the KAT6A gene.

Taurine is an amino acid and it is found in abundance in both mother’s milk and formula milk.  It has long been used as a supplement by some people with autism. It is finally going to be the subject of a clinical trial in autism and not surprisingly that will be in China - nowadays home to much autism research.

Taurine is also a key ingredient in energy drinks like Red Bull.

 

In a study of children with autism a third had low levels of taurine. Since taurine has anti-oxidant activity, children with ASD with low taurine concentrations were then examined for abnormal mitochondrial function. That study suggests that taurine may be a valid biomarker in a subgroup of ASD.

Taurine has several potential benefits to those with autism and it is already used to treat a wide variety of other conditions, some of which are relevant to autism. One example is its use in Japan to improve mitochondrial function in a conditional called MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes).

The effects that are suggested to relate to some types of autism include:-

 

·        Activating GABA_A receptors, in the short term

·        Down regulating GABA_A receptors, after long term use

·        Enhancing the PTEN/mTOR/AKT pathway

·        Reverse autophagy impairment caused by microglial activation

·        Reduce NMDA mediated activation of calcium channels

·        Protective effect on mitochondria and upregulating Complex 1

·        Improving the quality of the gut microbiota

 

If you have a pet you may know that taurine is widely given to cats and dogs. All cat food has taurine added and some breeds of dog need supplementation.

Taurine is crucial for several bodily functions in pets, including: 

Heart Health: Taurine helps regulate heart rhythm and improves heart muscle function. It can help prevent a type of heart disease called dilated cardiomyopathy (DCM) in both cats and dogs.

Vision: Taurine plays a role in maintaining healthy vision and can prevent retinal degeneration, a serious eye disease.

Immune System Function: Taurine may help boost the immune system and fight off infections.

 

From China we have the following recent study showing a benefit in the BTBR model of autism:

Taurine Improved Autism-Like Behaviours and Defective Neurogenesis of the Hippocampus in BTBR Mice through the PTEN/mTOR/AKT Signalling Pathway

Effective treatment of patients with autism spectrum disorder (ASD) is still absent so far. Taurine exhibits therapeutic effects towards the autism-like behaviour in ASD model animals. Here, we determined the mechanism of taurine effect on hippocampal neurogenesis in genetically inbred BTBR T⁺ tf/J (BTBR) mice, a proposed model of ASD. In this ASD mouse model, we explored the effect of oral taurine supplementation on ASD-like behaviours in an open field test, elevated plus maze, marble burying test, self-grooming test, and three-chamber test. The mice were divided into four groups of normal controls (WT) and models (BTBR), who did or did not receive 6-week taurine supplementation in water (WT, WT+ Taurine, BTBR, and BTBR+Taurine). Neurogenesis-related effects were determined by Ki67 immunofluorescence staining. Western blot analysis was performed to detect the expression of phosphatase and tensin homologue deleted from chromosome 10 (PTEN)/mTOR/AKT pathway-associated proteins. Our results showed that taurine improved the autism-like behaviour, increased the proliferation of hippocampal cells, promoted PTEN expression, and reduced phosphorylation of mTOR and AKT in hippocampal tissue of the BTBR mice. In conclusion, taurine reduced the autism-like behaviour in partially inherited autism model mice, which may be associa­ted with improving the defective neural precursor cell proliferation and enhancing the PTEN-associated pathway in hippocampal tissue.

 

A trial in humans with autism is scheduled in Guizhou, China. In this trial they seem to believe the benefit may come from modification to the gut microbiota.

 

Study on the Treatment of Taurine in Children With Autism

In the treatment of autism spectrum disorders (ASD), medication is only an adjunct, and the main treatment modalities are education and behavioral therapy. People with autism incur huge medical and educational costs, which puts a great financial burden on families. Taurine is one of the abundant amino acids in tissues and organs, and plays a variety of physiological and pharmacological functions in nervous, cardiovascular, renal, endocrine and immune systems. A large number of studies have shown that taurine can improve cognitive function impairment under various physiological or pathological conditions through a variety of mechanisms, taurine can increase the abundance of beneficial bacteria in the intestine, inhibit the growth of harmful bacteria, and have a positive effect on intestinal homeostasis. This study intends to analyze the effect of taurine supplementation on ASD, and explore the possible mechanism by detecting intestinal symptoms, intestinal flora, markers of oxidative stress and clinical symptoms of ASD.

Taurine granules mixed with corn starch and white sugar, 0.4g in 1 bag, taken orally. One time dosage: 1 bag each time for 1-2 years old, 3 times a day, 1.5 bags each time for 3-5 years old, 3 times a day, 2 bags each time for 6-8 years old, 3 times a day, 2.5-3 bags each time for 9-13 years old, 3 to 4 bags each time for children and adults over 14 years old, 3 times a day. The use of taurine is strictly in accordance with the specifications of Chinese Pharmacopoeia. 

 

Roles of taurine in cognitive function of physiology, pathologies and toxication

Taurine is a key functional amino acid with many functions in the nervous system. The effects of taurine on cognitive function have aroused increasing attention. First, the fluctuations of taurine and its transporters are associated with cognitive impairments in physiology and pathology. This may help diagnose and treat cognitive impairment though mechanisms are not fully uncovered in existing studies. Then, taurine supplements in cognitive impairment of different physiologies, pathologies and toxicologies have been demonstrated to significantly improve and restore cognition in most cases. However, elevated taurine level in cerebrospinal fluid (CSF) by exogenous administration causes cognition retardations only in physiologically sensitive period between the perinatal to early postnatal period. In this review, taurine levels are summarized in different types of cognitive impairments. Subsequently, the effects of taurine supplements on cognitions in physiology, different pathologies and toxication of cognitive impairments (e.g. aging, Alzheimer' disease, streptozotocin (STZ)-induced brain damage, ischemia model, mental disorder, genetic diseases and cognitive injuries of pharmaceuticals and toxins) are analyzed. These data suggest that taurine can improve cognition function through multiple potential mechanisms (e.g. restoring functions of taurine transporters and γ-aminobutyric acid (GABA) A receptors subunit; mitigating neuroinflammation; up-regulating Nrf2 expression and antioxidant capacities; activating Akt/CREB/PGC1α pathway, and further enhancing mitochondria biogenesis, synaptic function and reducing oxidative stress; increasing neurogenesis and synaptic function by pERK; activating PKA pathway). However, more mechanisms still need explorations.

 

Effects and Mechanisms of Taurine as a Therapeutic Agent

Taurine as an inhibitory neuromodulator

Although ER stress assumes an important role in the cytoprotective actions of taurine in the central nervous system (CNS), another important mechanism affecting the CNS is the neuromodulatory activity of taurine. Toxicity in the CNS commonly occurs when an imbalance develops between excitatory and inhibitory neurotransmitters. GABA is one of the dominant inhibitory neurotransmitters, therefore, reductions in either the CNS levels of GABA or the activity of the GABA receptors can favor neuronal hyperexcitability. Taurine serves as a weak agonist of the GABA_A, glycine and NMDA receptors Therefore, taurine can partially substitute for GABA by causing inhibition of neuronal excitability. However, the regulation of the GABA_A receptor by taurine is complex. While acute taurine administration activates the GABA_A receptor, chronic taurine feeding promotes the downregulation of the GABA_A receptor  and the upregulation of glutamate decarboxylase, the rate-limiting step in GABA biosynthesis. Therefore, complex interactions within the GABAeric system, as well as in the glycine and NMDA receptors, largely define the actions of taurine in the CNS.

Pharmacological characterization of GABA_A receptors in taurine-fed mice

Background

Taurine is one of the most abundant free amino acids especially in excitable tissues, with wide physiological actions. Chronic supplementation of taurine in drinking water to mice increases brain excitability mainly through alterations in the inhibitory GABAergic system. These changes include elevated expression level of glutamic acid decarboxylase (GAD) and increased levels of GABA. Additionally we reported that GABAA receptors were down regulated with chronic administration of taurine. Here, we investigated pharmacologically the functional significance of decreased / or change in subunit composition of the GABAA receptors by determining the threshold for picrotoxin-induced seizures. Picrotoxin, an antagonist of GABAA receptors that blocks the channels while in the open state, binds within the pore of the channel between the β2 and β3 subunits. These are the same subunits to which GABA and presumably taurine binds.

Methods

Two-month-old male FVB/NJ mice were subcutaneously injected with picrotoxin (5 mg kg-1) and observed for a) latency until seizures began, b) duration of seizures, and c) frequency of seizures. For taurine treatment, mice were either fed taurine in drinking water (0.05%) or injected (43 mg/kg) 15 min prior to picrotoxin injection. 

Results

We found that taurine-fed mice are resistant to picrotoxin-induced seizures when compared to age-matched controls, as measured by increased latency to seizure, decreased occurrence of seizures and reduced mortality rate. In the picrotoxin-treated animals, latency and duration were significantly shorter than in taurine-treated animas. Injection of taurine 15 min before picrotoxin significantly delayed seizure onset, as did chronic administration of taurine in the diet. Further, taurine treatment significantly increased survival rates compared to the picrotoxin-treated mice. 

Conclusions

We suggest that the elevated threshold for picrotoxin-induced seizures in taurine-fed mice is due to the reduced binding sites available for picrotoxin binding due to the reduced expression of the beta subunits of the GABAA receptor. The delayed effects of picrotoxin after acute taurine injection may indicate that the two molecules are competing for the same binding site on the GABAA receptor. Thus, taurine-fed mice have a functional alteration in the GABAergic system. These include: increased GAD expression, increased GABA levels, and changes in subunit composition of the GABAA receptors. Such a finding is relevant in conditions where agonists of GABAA receptors, such as anesthetics, are administered.

 

Taurine as used in Japan to treat MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes)

Taurine powder 98% "Taisho" [Prevention of stroke-like episodes of MELAS]

Effects of this medicine

This medicine improves mitochondrial dysfunction related to cell energy production etc., and suppresses stroke-like episodes.
It is usually used for prevention of stroke-like episodes of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes).

·         Your dosing schedule prescribed by your doctor is ((        to be written by a healthcare professional))

·         In general, take as following dose according to your weight, 3 times a day after meals. If you weigh less than 15 kg, take 1.02 g (1 g of the active ingredient) at a time. If your weight ranges 15 kg to less than 25 kg, take 2.04 g (2 g) at a time. If your weight ranges 25 kg to less than 40 kg, take 3.06 g (3 g) at a time. If you weigh 40 kg and more, take 4.08 g (4 g) at a time. Strictly follow the instructions.

·         If you miss a dose, take the missed a dose as soon as possible. However, if it is almost time for the next dose, skip the missed a dose and continue your regular dosing schedule. You should never take two doses at one time.

·         If you accidentally take more than your prescribed dose, consult with your doctor or pharmacist.

·         Do not stop taking this medicine unless your doctor instructs you to do so.

 

On the Potential Therapeutic Roles of Taurine in Autism Spectrum Disorder

 

Contemporary research has found that people with autism spectrum disorder (ASD) exhibit aberrant immunological function, with a shift toward increased cytokine production and unusual cell function. Microglia and astroglia were found to be significantly activated in immuno-cytochemical studies, and cytokine analysis revealed that the macrophage chemoattractant protein-1 (MCP-1), interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and transforming growth factor β-1 (TGFB-1), all generated in the neuroglia, constituted the most predominant cytokines in the brain. Taurine (2-aminoethanesulfonic acid) is a promising therapeutic molecule able to increase the activity of antioxidant enzymes and ATPase, which may be protective against aluminum-induced neurotoxicity. It can also stimulate neurogenesis, synaptogenesis, and reprogramming of proinflammatory M1 macrophage polarization by decreasing mitophagy (mitochondrial autophagy) and raising the expression of the markers of the anti-inflammatory and pro-healing M2 macrophages, such as macrophage mannose receptor (MMR, CD206) and interleukin 10 (IL-10), while lowering the expression of the M1 inflammatory factor genes. Taurine also induces autophagy, which is a mechanism that is impaired in microglia cells and is critically associated with the pathophysiology of ASD. We hypothesize here that taurine could reprogram the metabolism of M1 macrophages that are overstimulated in the nervous system of people suffering from ASD, thereby decreasing the neuroinflammatory process characterized by autophagy impairment (due to excessive microglia activation), neuronal death, and improving cognitive functions. Therefore, we suggest that taurine can serve as an important lead for the development of novel drugs for ASD treatment.

  

Taurine as a potential therapeutic agent interacting with multiple signaling pathways implicated in autism spectrum disorder (ASD): An in-silico analysis

  

Autism spectrum disorders (ASD) are a complex sequelae of neurodevelopmental disorders which manifest in the form of communication and social deficits. Currently, only two agents, namely risperidone and aripiprazole have been approved for the treatment of ASD, and there is a dearth of more drugs for the disorder. The exact pathophysiology of autism is not understood clearly, but research has implicated multiple pathways at different points in the neuronal circuitry, suggesting their role in ASD. Among these, the role played by neuroinflammatory cascades like the NF-KB and Nrf2 pathways, and the excitotoxic glutamatergic system, are said to have a bearing on the development of ASD. Similarly, the GPR40 receptor, present in both the gut and the blood brain barrier, has also been said to be involved in the disorder. Consequently, molecules which can act by interacting with one or multiple of these targets might have a potential in the therapy of the disorder, and for this reason, this study was designed to assess the binding affinity of taurine, a naturally-occurring amino acid, with these target molecules. The same was scored against these targets using in-silico docking studies, with Risperidone and Aripiprazole being used as standard comparators. Encouraging docking scores were obtained for taurine across all the selected targets, indicating promising target interaction. But the affinity for targets actually varied in the order NRF-KEAP > NF-κB > NMDA > Calcium channel > GPR 40. Given the potential implication of these targets in the pathogenesis of ASD, the drug might show promising results in the therapy of the disorder if subjected to further evaluations.

 

Is Taurine a Biomarker in Autistic Spectrum Disorder?

Taurine is a sulfur-containing amino acid which is not incorporated into protein. However, taurine has various critical physiological functions including development of the eye and brain, reproduction, osmoregulation, and immune functions including anti-inflammatory as well as anti-oxidant activity. The causes of autistic spectrum disorder (ASD) are not clear but a high heritability implicates an important role for genetic factors. Reports also implicate oxidative stress and inflammation in the etiology of ASD. Thus, taurine, a well-known antioxidant and regulator of inflammation, was investigated here using the sera from both girls and boys with ASD as well as their siblings and parents. Previous reports regarding taurine serum concentrations in ASD from various laboratories have been controversial. To address the potential role of taurine in ASD, we collected sera from 66 children with ASD (males: 45; females: 21, age 1.5-11.5 years, average age 5.2 ± 1.6) as well as their unaffected siblings (brothers: 24; sisters: 32, age 1.5-17 years, average age 7.0 ± 2.0) as controls of the children with ASD along with parents (fathers: 49; mothers: 54, age 28-45 years). The sera from normal adult controls (males: 47; females: 51, age 28-48 years) were used as controls for the parents. Taurine concentrations in all sera samples were measured using high performance liquid chromatography (HPLC) using a phenylisothiocyanate labeling technique. Taurine concentrations from female and male children with ASD were 123.8 ± 15.2 and 145.8 ± 8.1 μM, respectively, and those from their unaffected brothers and sisters were 142.6 ± 10.4 and 150.8 ± 8.4 μM, respectively. There was no significant difference in taurine concentration between autistic children and their unaffected siblings. Taurine concentrations in children with ASD were also not significantly different from their parents (mothers: 139.6 ± 7.7 μM, fathers: 147.4 ± 7.5 μM). No significant difference was observed between adult controls and parents of ASD children (control females: 164.8 ± 4.8 μM, control males: 163.0 ± 7.0 μM). However, 21 out of 66 children with ASD had low taurine concentrations (<106 μM). Since taurine has anti-oxidant activity, children with ASD with low taurine concentrations will be examined for abnormal mitochondrial function. Our data imply that taurine may be a valid biomarker in a subgroup of ASD.

  

The Role of Taurine in Mitochondria Health: More Than Just an Antioxidant

Taurine is a naturally occurring sulfur-containing amino acid that is found abundantly in excitatory tissues, such as the heart, brain, retina and skeletal muscles. Taurine was first isolated in the 1800s, but not much was known about this molecule until the 1990s. In 1985, taurine was first approved as the treatment among heart failure patients in Japan. Accumulating studies have shown that taurine supplementation also protects against pathologies associated with mitochondrial defects, such as aging, mitochondrial diseases, metabolic syndrome, cancer, cardiovascular diseases and neurological disorders. In this review, we will provide a general overview on the mitochondria biology and the consequence of mitochondrial defects in pathologies. Then, we will discuss the antioxidant action of taurine, particularly in relation to the maintenance of mitochondria function. We will also describe several reported studies on the current use of taurine supplementation in several mitochondria-associated pathologies in humans.

 

Taurine is known not as a radical scavenger. Several potential mechanisms by which taurine exerts its antioxidant activity in maintaining mitochondria health include: taurine conjugates with uridine on mitochondrial tRNA to form a 5-taurinomethyluridine for proper synthesis of mitochondrial proteins (mechanism 1), which regulates the stability and functionality of respiratory chain complexes; taurine reduces superoxide generation by enhancing the activity of intracellular antioxidants (mechanism 2); taurine prevents calcium overload and prevents reduction in energy production and the collapse of mitochondrial membrane potential (mechanism 3); taurine directly scavenges HOCl to form N-chlorotaurine in inhibiting a pro-inflammatory response (mechanism 4); and taurine inhibits mitochondria-mediated apoptosis by preventing caspase activation or by restoring the Bax/Bcl-2 ratio and preventing Bax translocation to the mitochondria to promote apoptosis (mechanism 5).

Taurine Forms a Complex with Mitochondrial tRNA

Taurine Reduces Superoxide Generation in the Mitochondria

Taurine Regulates Intracellular Calcium Homeostasis

Taurine Inhibits Mitochondria-Mediated Apoptosis

 

Taurine therapy, therefore, could potentially improve mitochondrial health, particularly in mitochondria-targeted pathologies, such as cardiovascular diseases, metabolic diseases, mitochondrial diseases and neurological disorders. Whether the protective mechanism on mitochondria primarily relies on the taurine modification of mitochondrial tRNA requires further investigation.

 

Taurine and the gut microbiota 

We now regularly in the research see that you can make changes in the gut microbiota to treat medical conditions. I think the most interesting was the discovery that the ketogenic diet, used for a century to treat epilepsy, actually works via the high fat diet changing the bacteria that live in your gut; it has nothing at all to do with ketones. UCLA are developing a bacteria product that will mimic the effect of this diet.

We should not be surprised to see that one mode of action put forward for Taurine is changes it makes in the gut microbiota.  It is this very mechanism that the Chinese researchers think is relevant to its benefit in autism.

The paper below is not about autism, but it is about Taurine’s effect on the gut microbiota.

Effects of Taurine on Gut Microbiota Homeostasis: An Evaluation Based on Two Models of Gut Dysbiosis

Taurine, an abundant free amino acid, plays multiple roles in the body, including bile acid conjugation, osmoregulation, oxidative stress, and inflammation prevention. Although the relationship between taurine and the gut has been briefly described, the effects of taurine on the reconstitution of intestinal flora homeostasis under conditions of gut dysbiosis and underlying mechanisms remain unclear. This study examined the effects of taurine on the intestinal flora and homeostasis of healthy mice and mice with dysbiosis caused by antibiotic treatment and pathogenic bacterial infections. The results showed that taurine supplementation could significantly regulate intestinal microflora, alter fecal bile acid composition, reverse the decrease in Lactobacillus abundance, boost intestinal immunity in response to antibiotic exposure, resist colonization by Citrobacter rodentium, and enhance the diversity of flora during infection. Our results indicate that taurine has the potential to shape the gut microbiota of mice and positively affect the restoration of intestinal homeostasis. Thus, taurine can be utilized as a targeted regulator to re-establish a normal microenvironment and to treat or prevent gut dysbiosis.

  

Conclusion

Your body can synthesize taurine from other amino acids, particularly cysteine, with the help of vitamin B6. In most cases, this internal production is enough to meet your daily needs for basic bodily functions.

Infants and some adults may need taurine added to their diet.

Based on the small study in humans, about a third of children with autism have low levels of taurine in their blood.

Is extra taurine going to provide a benefit to the other two thirds?

Taurine looks easy to trial. It is normally taken three times a day after a meal. Each dose would be 0.4g to 4g depending on weight and what the purpose was. The 2 year olds in the Chinese autism trial will be taking 0.4g three times a day. Japanese adults with mitochondrial disease (MELAS) are taking 4g three times a day.

One can oF Red Bull contains 1g of taurine. Most supplements contain 0.5 to 1g. This is a similar dose to what is given to pet cats and dogs. Just like Red Bull contains B vitamins, so do the taurine products for cats and dogs. 

Some of the effects will be immediate, while others will take time to show effect. For example there can potentially be an increase in mitochondrial biogenesis. I expect any changes in gut bacteria would also take a long time to get established.

The effect via GABA on increasing brain excitability is an interesting one for people taking bumetanide for autism, where the GABA developmental switch did not take place. Based on the research you could argue that it will be beneficial or indeed harmful.

What I can say is that in Monty, aged 20 with ASD and taking bumetanide for 12 years, he responded very well on the rare occasions he drank Red Bull.

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Vitamin B5 and L carnitine for KATA6A Syndrome

I was asked about KATA6A syndrome recently.  This syndrome is researched by Dr Kelley, the same doctor who coined the term Autism secondary to mitochondrial dysfunction (AMD).

KAT6A Research and Treatment An Update by Richard I Kelley , MD, PHD

Some kids with KATA6A, like Peter below, respond very well to Dr Kelley’s mito cocktail.

 

Peter’s Experience with a Mitochondrial Cocktail

 

Here’s my experience with the mitochondrial cocktail:

– At 4 weeks after the start of the cocktail, Peter became potty-trained during the day without any training. He pulled his pull up off, refused to put it back on.

-At 2 months, Peter started riding his bike with no training wheels and playing soccer. He became able to kick the ball and run after it till he scores.

-At 2.5 months, he started skiing independently. I used to try to teach how to ski since he was 3yo. I used to spend hours and hours picking him up off the snow with no result. I tried different kind of reinforcers (food,..) with no result. After the cocktail, he just went down the hill by himself, He can ski independently now and knows how to make turns.

-At 2-3 months, I started noticing an increased strength in playing ice hockey and street hockey with a better understanding of the game. His typing ability improved too, he used to have severe apraxia while typing (type the letter next to the letter he wants to type…).

-At 3-4 months, Peter’s fingers on the piano became stronger, he became able to play harder songs with less training and less frustration. I also noticed an increase in “common sense” like for example putting his backpack in the car instead of throwing it on the floor next to the car and riding the car without his backpack. Another example, when we go to the public library, he knows by himself that he has to go to the children section, and walks independently without showing him directions to the play area inside the children section. In the past, he used to grab books the time he enters the library, throw a tantrum on the floor. The most important milestone is that Peter started to say few words that I can understand.

-At 11 months, Peter became potty-trained at night. His speech is slowly getting clearer. His fine and gross motor skills are still getting better.

 

Some readers of this blog have been in touch with Dr Kelley and he does give very thorough replies.

Generally speaking, the therapies for mitochondrial diseases/dysfunctions seem to be about avoiding it getting worse, rather than making dramatic improvements. In the case of Peter (above) the effects do look dramatic. There are many other ideas in the research that do not seem to have been translated into therapy.

A study from two years ago does suggest that vitamin B5 and L carnitine should be trialed. 

Pantothenate and L-Carnitine Supplementation Improves Pathological Alterations in Cellular Models of KAT6A Syndrome

Mutations in several genes involved in the epigenetic regulation of gene expression have been considered risk alterations to different intellectual disability (ID) syndromes associated with features of autism spectrum disorder (ASD). Among them are the pathogenic variants of the lysine-acetyltransferase 6A (KAT6A) gene, which causes KAT6A syndrome. The KAT6A enzyme participates in a wide range of critical cellular functions, such as chromatin remodeling, gene expression, protein synthesis, cell metabolism, and replication. In this manuscript, we examined the pathophysiological alterations in fibroblasts derived from three patients harboring KAT6A mutations. We addressed survival in a stress medium, histone acetylation, protein expression patterns, and transcriptome analysis, as well as cell bioenergetics. In addition, we evaluated the therapeutic effectiveness of epigenetic modulators and mitochondrial boosting agents, such as pantothenate and L-carnitine, in correcting the mutant phenotype. Pantothenate and L-carnitine treatment increased histone acetylation and partially corrected protein and transcriptomic expression patterns in mutant KAT6A cells. Furthermore, the cell bioenergetics of mutant cells was significantly improved. Our results suggest that pantothenate and L-carnitine can significantly improve the mutant phenotype in cellular models of KAT6A syndrome.

Next, we analyzed the expression changes of specific genes in treated and untreated conditions. We found that the expression levels of downregulated genes in the mutant KAT6A fibroblasts, such as KAT6A, SIRT1, SIRT3, NAMPT1, Mt-ND6, NDUFA9, PANK2, mtACP, PDH (E1 subunit α2), KGDH (E2 subunit), SOD1, SOD2, and GPX4 were significantly restored after pantothenate and L-carnitine treatment. The proteins encoded by these genes are involved in acetylation-deacetylation pathways, CoA metabolism, mitochondria, and antioxidant enzymes, all of which are critical for intracellular processes in embryonic and childhood development.

 

KAT6A acts as a master regulator by fine-tuning gene expression through chromatin modifications, so we should expect it to have wide ranging effects. All the closest interactions are will other genes that modify gene expression.

 

https://string-db.org/cgi/network?taskId=b9YRZJrlHtMF&sessionId=b1EyJebcKvBK

A useful site is genecards:

https://www.genecards.org/cgi-bin/carddisp.pl?gene=KAT6A

 

KAT6A mutations are indeed linked to microcephaly, a condition characterized by a smaller than average head circumference.

Most autism is associated with hyperactive pro-growth signalling pathways; only a minority is associated with the opposite and this would fit with microcephaly, which is typical in KAT6A.

Microcephaly is a very common feature of Rett syndrome.

Among the features of KAT6A syndrome there will be overlaps with other syndromes.

Dr Kelley analyses amino acids looking for mitochondrial dysfunction. He has found this present in KAT6A, but this is only one treatable feature of the syndrome.

Targeting growth signaling pathways might well be worth pursuing. You would be looking a what works in other people with smaller heads.

I wrote quite a lot about IGF-1 previously in this blog.

It would be highly plausible that these related therapies might be of benefit. The easy one to try is cGPMax, because it is sold OTC. IGF-1 itself might be beneficial, you would have to find a helpful endocrinologist to trial it.

All the therapies of idiopathic autism could be trialed.

If the child has a paradoxical reaction to any benzodiazepine drug, then you know that bumetanide is likely to be beneficial.

Since mitochondrial function is impaired in KAT6A, taurine is another thing to trial.

GABAa receptor trafficking, Migraine, Pain, Light Sensitivity, Autophagy, Jacobsen Syndrome, Angelman Syndrome, GABARAP, TRPV1, PX-RICS, CaMKII and CGRP ... Oh and the "fever effect"

The mechanism controlling transporting just the “right” number of GABA_A receptors

Today’s post is not for the faint-hearted.  It is another one that could just keep on rolling.  Ling will like it.

It again shows that GABA_A receptors are at the centre of much autism, whether single gene or idiopathic. Today we highlight what can go wrong as these receptors are “transported”.

Today’s post also draws on several quite recent papers. It seeks to tie together some previous things mentioned in this blog like the symptoms of pain, particularly felt in the head, sensory sensitivity with dysfunction processes like autophagy and linking it all back to the GABA_A receptor.  There is even a link at the end to the "fever effect", which occurs when a high temperature in some people causes a marked improvement in their autism symptoms.

We will come across some expensive drugs like Erenumab, the medical food PEA (Palmitoylethanolamide) and indeed Natasa’s favourite, CBD (Cannabidiol) and a newcomer CBDV (Cannabidivarin).   

We come across a protein called GABARAP (GABA_A receptor associated protein) for the first time in this blog.  There is a vast amount in this blog about the GABA_A receptor, how and why to modulate it. 

CaMKII makes an appearance, this is a protein kinase that is miss-regulated in much neurological disease. It changes the effect of many other proteins, acting just like a switch, by chemically adding phosphate groups to them. We have previously seen how important the protein kinases PKA, PKB and PKC are to autism.  Today add CaMKII to the list.

We come across another distinctive “face” of autism, this time it is Jacobsen syndrome, which I think is easily spotted by the trained eye, or some facial recognition software.  Jacobsen syndrome is a rare chromosomal disorder resulting from deletion of genes from chromosome 11 that includes band 11q24. This may include the gene that encodes the protein PX-RICS and, if so, it will lead to “autism”. Loss of that gene should be treatable with a GABA agonist.     

We also come back to that happy puppet syndrome (Angelman syndrome) which usually involves loss of the gene UBE3A, from chromosome 15. What I found interesting was that both Jacobsen syndrome and Angelman syndrome should share impaired GABA_A receptor trafficking as a feature. They each have a different impediment that should reduce the number of functioning GABA_A receptors. In the case of Angelman the impediment is CaMKII inhibition, in Jacobsen it is lack of the protein PX-RICS. Angelman syndrome may well respond to the same therapy as Jacobsen syndrome – a GABA agonist, of just a PAM (positive allosteric modulator, to “turn up the volume”).

Back to GABARAP

GABARAP has multiple functions:

1.     Transport of freshly minted GABA_A receptors

In order for newly minted GABA_A receptors to get to their final destination it requires four “helpers”: GABARAP, PX-RICS, 14-3-3 and Dynactin.  In addition, you need a dose of CaMKII. If you lack any one of these four, you will end up with reduced expression of GABA_A receptors. If CaMKII is overactivated you get too many GABA_A receptors.

In Jacobsen Syndrome there is reduced GABA_A receptor trafficking/transport, leading to reduced surface expression. (in effect not enough functioning GABA_A receptors in situ).  In some people with this syndrome the part of their DNA which encodes PX-RICS is missing.  This lack of PX-RICS produces autism.  The autism-like behavioural abnormalities in PX-RICS-deficient mice are ameliorated by enhancing inhibitory synaptic transmission with a GABA_AR agonist.

2.     GABARAP modulates TRPV1 expression

GABARAP also does something totally different, it modulates TRPV1 ion channels, that we have previously touched on in this blog.  This then triggers a cascade of effects relating to pain, neuralgia, migraine headaches, microglial activation, epilepsy and indeed longevity.

The simple function of TRPV1 is detection and regulation of body temperature. In addition, TRPV1 provides a sensation of scalding heat and pain. TRPV1 is also known as the capsaicin receptor.  Capsaicin is the active component of chilli peppers.

TRPV1 not only plays a role in pain, but is suggested to play a role in migraine. In migraine TRPV1 plays a role along with calcitonin gene-related peptide receptor (CGRPR). TRPV1 determines how much of the CGRPR protein is produced. CGRPR affects your metabolism broadly and as such plays a key role in longevity.  Ablation of select pain sensory receptors (TRPV1) or the inhibition of CGRP are associated with increased metabolic health and longevity.

Erenumab/Aimovig is a medication which targets CGRPR for the prevention of migraine. It was the first of the group of CGRPR antagonists to be FDA approved in 2018. It is a form of monoclonal antibody therapy in which antibodies are used to block the receptors for the protein CGRP, thought to play a major role in starting migraines.

Recent evidence suggests that TRPV1 may contribute to the onset and progression of some forms of epilepsy;  Cannabidivarin  (CBDV) and cannabidiol (CBD), activate and desensitize TRPV1.

TRPV1 also plays a crucial role in the activation of microglia. As the researchers put it “TRPV1 channels are critical brain inflammation detectors … microglia shifted toward an anti-inflammatory phenotype when TRPV1 is lacking. “

So, if we jump a few steps forward we can see that desensitizing TRPV1 might be helpful for people with: -

·        Some epilepsy

·        Some neuralgia

·        Perhaps some with chronic migraine

·        People with activated microglia, which is most autism

We also can see that a dysfunction in GABARAP may itself contribute to worsening the above conditions via its effect on TRPV1.

Non-psychotropic plant cannabinoids, cannabidivarin (CBDV) and cannabidiol (CBD), activate and desensitize transient receptor potential vanilloid 1 (TRPV1) channels in vitro: potential for the treatment of neuronal hyperexcitability

Epilepsy is the most common neurological disorder, with over 50 million people worldwide affected. Recent evidence suggests that the transient receptor potential cation channel subfamily member 1 (TRPV1) may contribute to the onset and progression of some forms of epilepsy. V Since the two nonpsychotropic cannabinoids cannabidivarin (CBDV) and cannabidiol (CBD) exert anticonvulsant activity in vivo and produce TRPV1-mediated intracellular calcium elevation in vitro, we evaluated the effects of these two compounds on TRPV1 channel activation and desensitization and in an in vitro model of epileptiform activity. Patch clamp analysis in transfected HEK293 cells demonstrated that CBD and CBDV dose-dependently activate and rapidly desensitize TRPV1, as well as TRP channels of subfamily V type 2 (TRPV2) and subfamily A type 1 (TRPA1). TRPV1 and TRPV2 transcripts were shown to be expressed in rat hippocampal tissue. When tested on epileptiform neuronal spike activity in hippocampal brain slices exposed to a Mg2+-free solution using multielectrode arrays (MEAs), CBDV reduced both epileptiform burst amplitude and duration. The prototypical TRPV1 agonist, capsaicin, produced similar, although not identical effects. Capsaicin, but not CBDV, effects on burst amplitude were reversed by IRTX, a selective TRPV1 antagonist. These data suggest that CBDV antiepileptiform effects in the Mg2+-free model are not uniquely mediated via activation of TRPV1. However, TRPV1 was strongly phosphorylated (and hence likely sensitized) in Mg2+-free solution-treated hippocampal tissue, and both capsaicin and CBDV caused TRPV1 dephosphorylation, consistent with TRPV1 desensitization. We propose that CBDV effects on TRP channels should be studied further in different in vitro and in vivo models of epilepsy.

TRPV1 channels are critical brain inflammation detectors and neuropathic pain biomarkers in mice

The capsaicin receptor TRPV1 has been widely characterized in the sensory system as a key component of pain and inflammation. A large amount of evidence shows that TRPV1 is also functional in the brain although its role is still debated. Here we report that TRPV1 is highly expressed in microglial cells rather than neurons of the anterior cingulate cortex and other brain areas. We found that stimulation of microglial TRPV1 controls cortical microglia activation per se and indirectly enhances glutamatergic transmission in neurons by promoting extracellular microglial microvesicles shedding. Conversely, in the cortex of mice suffering from neuropathic pain, TRPV1 is also present in neurons affecting their intrinsic electrical properties and synaptic strength. Altogether, these findings identify brain TRPV1 as potential detector of harmful stimuli and a key player of microglia to neuron communication.

TRPV1 controls cortical microglia activation

In the healthy mature brain, microglial cells play a role in immune surveillance and ensure the maintenance of brain homeostasis. Upon injuries these cells shift to an activated state characterized by drastic changes in the cellular shape, functional behavior and by the release of different proinflammatory and immunoregulatory factors^58,59. Conforming to the capsaicin-mediated induction of microglial chemotaxis²⁹, we investigated whether TRPV1 stimulation regulates the morphology of microglial cells…. Thus, stimulation of TRPV1 induced a pro-inflammatory phenotype of microglia from WTs. Conversely, microglia shifted toward an anti-inflammatory phenotype when TRPV1 is lacking.

Angelman syndrome

Angelman syndrome (Happy puppet syndrome) is a genetic disorder that mainly affects the nervous system. Symptoms include a small head and a specific facial appearance, severe intellectual disability, developmental disability, speaking problems, balance and movement problems, seizures, and sleep problems. Children usually have a happy personality and have a particular interest in water. The symptoms generally become noticeable by one year of age.  Angelman syndrome is typically due to a new mutation rather than one inherited from a person's parents. Angelman syndrome is due to a lack of function of part of chromosome 15 inherited from a person's mother. Most of the time, it is due to a deletion or mutation of the UBE3A gene.

CaMKII inhibition underlies Angelman Syndrome

CaMKII

CaMKII is a serine/threonine-specific protein kinase that is regulated by the Ca²⁺/calmodulin complex. CaMKII is involved in many signaling cascades and is thought to be an important mediator of learning and memory. CaMKII is also necessary for Ca²⁺ homeostasis and reuptake in cardiomyocytes, chloride transport in epithelia, positive T-cell selection, and CD8 T-cell activation.

Misregulation of CaMKII is linked to Alzheimer’s disease, Angelman syndrome, and heart arrhythmia.

Emerging role of CaMKII in neuropsychiatric disease

Recent evidence for CaMKII dysregulation in psychiatric diseases is reviewed.

Changes in postsynaptic structure and function appear to be central to multiple diseases.

Altered regulation of the CaMKIIα gene promoter may be a common mechanism among diseases.

CaMKII dysregulation in diverse brain regions may account for myriad disorders.

Although it has been known for decades that hippocampal calcium/calmodulin (CaM)-dependent protein kinase II (CaMKII) plays an essential role in learning and memory consolidation, the roles of CaMKII in other brain regions are only recently being explored in depth. A series of recent studies suggest that CaMKII dysfunction throughout the brain may underlie myriad neuropsychiatric disorders, including drug addiction, schizophrenia, depression, epilepsy, and multiple neurodevelopmental disorders, perhaps through maladaptations in glutamate signaling and neuroplasticity. I review here the structure, function, subcellular localization, and expression patterns of CaMKII isoforms, as well as recent advances demonstrating that disturbances in these properties may contribute to psychiatric disorders.

A Novel Human CAMK2A Mutation Disrupts Dendritic Morphology and Synaptic Transmission, and Causes ASD-Related Behaviors

Characterizing the functional impact of novel mutations linked to autism spectrum disorder (ASD) provides a deeper mechanistic understanding of the underlying pathophysiological mechanisms. Here we show that a de novo Glu183 to Val (E183V) mutation in the CaMKIIα catalytic domain, identified in a proband diagnosed with ASD, decreases both CaMKIIα substrate phosphorylation and regulatory autophosphorylation, and that the mutated kinase acts in a dominant-negative manner to reduce CaMKIIα-WT autophosphorylation. The E183V mutation also reduces CaMKIIα binding to established ASD-linked proteins, such as Shank3 and subunits of l-type calcium channels and NMDA receptors, and increases CaMKIIα turnover in intact cells. In cultured neurons, the E183V mutation reduces CaMKIIα targeting to dendritic spines. Moreover, neuronal expression of CaMKIIα-E183V increases dendritic arborization and decreases both dendritic spine density and excitatory synaptic transmission. Mice with a knock-in CaMKIIα-E183V mutation have lower total forebrain CaMKIIα levels, with reduced targeting to synaptic subcellular fractions. The CaMKIIα-E183V mice also display aberrant behavioral phenotypes, including hyperactivity, social interaction deficits, and increased repetitive behaviors. Together, these data suggest that CaMKIIα plays a previously unappreciated role in ASD-related synaptic and behavioral phenotypes.

SIGNIFICANCE STATEMENT Many autism spectrum disorder (ASD)-linked mutations disrupt the function of synaptic proteins, but no single gene accounts for >1% of total ASD cases. The molecular networks and mechanisms that couple the primary deficits caused by these individual mutations to core behavioral symptoms of ASD remain poorly understood. Here, we provide the first characterization of a mutation in the gene encoding CaMKIIα linked to a specific neuropsychiatric disorder. Our findings demonstrate that this ASD-linked de novo CAMK2A mutation disrupts multiple CaMKII functions, induces synaptic deficits, and causes ASD-related behavioral alterations, providing novel insights into the synaptic mechanisms contributing to ASD.

Jacobsen Sydrome

The signs and symptoms of Jacobsen syndrome can vary. Most affected people have delayed development of motor skills and speech; cognitive impairment; and learning difficulties. Behavioral features have been reported and may include compulsive behavior; a short attention span; and distractibility. Many people with the condition are diagnosed with attention deficit-hyperactivity disorder (ADHD). The vast majority of people with Jacobsen syndrome also have a bleeding disorder called Paris-Trousseau syndrome, which causes abnormal bleeding and easy bruising. 

People with Jacobsen syndrome typically have distinctive facial features, which include small and low-set ears; wide-set eyes (hypertelorism) with droopy eyelids (ptosis); skin folds covering the inner corner of the eyes; a broad nasal bridge; down-turned corners of the mouth; a thin upper lip; and a small lower jaw (micrognathia). Affected people often have a large head (macrocephaly) and a skull abnormality called trigonocephaly, giving the forehead a pointed appearance.

The Autism-Related Protein PX-RICS Mediates GABAergic Synaptic Plasticity in Hippocampal Neurons and Emotional Learning in Mice

GABAergic dysfunction underlies many neurodevelopmental and psychiatric disorders. GABAergic synapses exhibit several forms of plasticity at both pre- and postsynaptic levels. NMDA receptor (NMDAR)–dependent inhibitory long-term potentiation (iLTP) at GABAergic postsynapses requires an increase in surface GABA_ARs through promoted exocytosis; however, the regulatory mechanisms and the neuropathological significance remain unclear. Here we report that the autism-related protein PX-RICS is involved in GABA_AR transport driven during NMDAR–dependent GABAergic iLTP. Chemically induced iLTP elicited a rapid increase in surface GABA_ARs in wild-type mouse hippocampal neurons, but not in PX-RICS/RICS–deficient neurons. This increase in surface GABA_ARs required the PX-RICS/GABARAP/14–3-3 complex, as revealed by gene knockdown and rescue studies. iLTP induced CaMKII–dependent phosphorylation of PX-RICS to promote PX-RICS–14-3-3 assembly. Notably, PX-RICS/RICS–deficient mice showed impaired amygdala–dependent fear learning, which was ameliorated by potentiating GABAergic activity with clonazepam. Our results suggest that PX-RICS–mediated GABA_AR trafficking is a key target for GABAergic plasticity and its dysfunction leads to atypical emotional processing underlying autism.

There is a growing consensus that autism arises from the atypical regulation of the excitation/inhibition balance within specific neural microcircuitry. In terms of neural inhibition, autism is closely related to dysfunctional inhibitory signaling mediated by the γ-aminobutyric acid (GABA) type A receptors (GABA_ARs). Impaired presynaptic release of GABA and postsynaptic trafficking of GABA_ARs lead to autistic-like social behavior in mouse models of autism. There is a significant reduction in the number of GABA_ARs and GABAergic activity in certain brain areas of autistic individuals. Genetic association studies have revealed that several GABA_AR subunits are linked to an increased risk for autism. GABA_AR–mediated signaling is thus essential for the proper regulation of the excitation/inhibition balance associated with socio-emotional cognition.

PX-RICS, GABARAP and 14-3-3ζ/θ are localized in the specific dendritic compartments that are immunopositive for organelle markers for the endoplasmic reticulum (ER), ER exit sites and the trans-Golgi network. This structure, termed the dendritic satellite secretory pathway, is comprised of the dendritic ER and the Golgi outposts and is involved in the local synthesis, processing and transport of membrane-integral or secretory proteins in dendrites. The rapid increase in surface-expressed GABA_ARs after NMDA stimulation could be explained by the localization of the PX-RICS–dependent trafficking machinery in the dendritic secretory compartments.

Several lines of evidence suggest that the dysregulation of GABA signaling underlies atypical social behavior in autism However, there has been no report describing deficits in GABAergic plasticity that contribute to autistic features. The present study has shown that PX-RICS is essential for GABAergic iLTP and that loss of the PX-RICS function in mice leads to impaired cued fear learning. Cued fear learning is closely associated with GABA_AR–mediated activity and plasticity in the amygdala and is inversely correlated with the severity of autistic symptoms. Considering all of these findings, we thus reason that PX-RICS–dependent GABA_AR transport may play critical roles in emotional learning in the amygdala through the control of GABAergic synaptic plasticity and that the impairment of this transport mechanism may lead to improper socio-emotional processing, resulting in autistic-like atypical social behavior (Supplementary Fig. 7). Further elucidation of the functional link between GABAergic plasticity and socio-emotional learning could lead to a better understanding of autism pathogenesis and treatment. 

We have previously identified and characterized two splicing isoforms of GTPase-activating proteins specific for Cdc42 predominantly expressed in neurons of the cerebral cortex, amygdala and hippocampus: RICS (ARHGAP32 isoform 2) and PX-RICS (ARHGAP32 isoform 1) . RICS regulates NMDAR–mediated signaling at the postsynaptic density and axonal elongation at the growth cone. In contrast, PX-RICS forms an adaptor complex with GABARAP and 14-3-3ζ/θ to facilitate steady-state trafficking of the N-cadherin/β-catenin complex and GABA_ARs. PX-RICS is also responsible for autistic-like features observed in more than half of the patients with Jacobsen syndrome (JBS) [3]. Mice lacking PX-RICS/RICS show marked decreases in surface-expressed GABA_ARs and GABA_AR–mediated inhibitory synaptic transmission, resulting in various autistic-like behaviors and autism-related comorbidities. Rare single-nucleotide variations in PX-RICS are also linked to non-syndromic autism, schizophrenia and alexithymia. These findings strongly suggest that dysfunction of PX-RICS–mediated GABA_AR trafficking has severe effects on socio-emotional processing of the brain.

Our previous study described above showed that PX-RICS and other components of the GABA_AR trafficking complex are required for constitutive transport of the receptor. In this study, we have focused on the role of PX-RICS in the activity–induced promotion of GABA_AR trafficking during iLTP. Here we show that PX-RICS–mediated GABA_AR trafficking is also involved in NMDAR activity–dependent trafficking of GABA_ARs and that PX-RICS is a key target of CaMKII for regulating GABAergic synaptic plasticity. Furthermore, we show that PX-RICS dysfunction in mice leads to impaired amygdala–dependent emotional learning, which manifests as autistic-like social behavior [3].

Supplementary Fig. 7. PX-RICS–mediated GABAAR trafficking underlies NMDAR–dependent GABAergic iLTP PX-RICS, GABARAP and 14-3-3s are assembled to form an adaptor complex that interconnects γ2-containing GABAARs (cargo) and dynein/dynactin (motor). Interaction

of PX-RICS with 14-3-3s depends on the phosphorylation activity of CaMKII, and this interaction is a critical regulatory point for GABAAR trafficking. When CaMKII activity is at a basal level, the PX-RICS–mediated trafficking complex has a role in steady-state transport of GABAARs to maintain the number of surface GABAARs as needed for proper synaptic inhibition.3 Neural activity that evokes moderate Ca2+ influx through NMDAR preferentially increases the activated form of CaMKII and elicits its translocation to inhibitory synapses, where it phosphorylates target proteins such as gephyrin and the GABAAR β3 subunit. Phosphorylated gephyrin and the GABAAR β3 subunit regulate the surface dynamics of GABAARs such as lateral diffusion and synaptic confinement. The present study has revealed that PXRICS

is a downstream CaMKII target associated with anterograde transport of

GABAARs. Enhanced PX-RICS phosphorylation increases the PX-RICS–14-3-3 complex and thereby drives de novo GABAAR surface expression, resulting in GABAergic iLTP. Dysfunction of this trafficking mechanism in the amygdala causes impaired GABAergic synaptic plasticity, which may contribute to deficits in socioemotional behavior as observed in PX-RICS/RICS–deficient mice and JBS patients with autism.

PX-RICS-deficient mice mimic autism spectrum disorder in Jacobsen syndrome through impaired GABA_A receptor trafficking

Jacobsen syndrome (JBS) is a rare congenital disorder caused by a terminal deletion of the long arm of chromosome 11. A subset of patients exhibit social behavioural problems that meet the diagnostic criteria for autism spectrum disorder (ASD); however, the underlying molecular pathogenesis remains poorly understood. PX-RICS is located in the chromosomal region commonly deleted in JBS patients with autistic-like behaviour. Here we report that PX-RICS-deficient mice exhibit ASD-like social behaviours and ASD-related comorbidities. PX-RICS-deficient neurons show reduced surface γ-aminobutyric acid type A receptor (GABAAR) levels and impaired GABAAR-mediated synaptic transmission. PX-RICS, GABARAP and 14-3-3ζ/θ form an adaptor complex that interconnects GABAAR and dynein/dynactin, thereby facilitating GABAAR surface expression. ASD-like behavioural abnormalities in PX-RICS-deficient mice are ameliorated by enhancing inhibitory synaptic transmission with a GABAAR agonist. Our findings demonstrate a critical role of PX-RICS in cognition and suggest a causal link between PX-RICS deletion and ASD-like behaviour in JBS patients.

TRPV1

We now come back to TRPV1, which we saw is modulated by GABARAP.

GABAA receptor associated protein (GABARAP) modulates TRPV1 expression and channel function and desensitization

Transient receptor potential vanilloid (TRPV1) transduces noxious chemical and physical stimuli in high-threshold nociceptors. The pivotal role of TRPV1 in the physiopathology of pain transduction has thrust the identification and characterization of interacting partners that modulate its cellular function. Here, we report that TRPV1 associates with γ-amino butyric acid A-type (GABA_A) receptor associated protein (GABARAP) in HEK293 cells and in neurons from dorsal root ganglia coexpressing both proteins. At variance with controls, GABARAP augmented TRPV1 expression in cotransfected cells and stimulated surface receptor clustering. Functionally, GABARAP expression attenuated voltage and capsaicin sensitivity of TRPV1 in the presence of extracellular calcium. Furthermore, the presence of the anchor protein GABARAP notably lengthened the kinetics of vanilloid-induced tachyphylaxia. Notably, the presence of GABARAP selectively increased the interaction of tubulin with the C-terminal domain of TRPV1. Disruption of tubulin cytoskeleton with nocodazole reduced capsaicin-evoked currents in cells expressing TRPV1 and GABARAP, without affecting the kinetics of vanilloid-induced desensitization. Taken together, these findings indicate that GABARAP is an important component of the TRPV1 signaling complex that contributes to increase the channel expression, to traffic and cluster it on the plasma membrane, and to modulate its functional activity at the level of channel gating and desensitization.

‘Entourage’ effectsof N‐palmitoylethanolamide and N‐oleoylethanolamide on vasorelaxation to anandamide occur through TRPV1 receptors

Age-Dependent Anti-seizure and Neuroprotective Effect of Cannabidivarin in Neonatal Rats

Neonatal seizures and seizures of infancy represent a significant cause of morbidity. 30–40% of infants and children with seizures will fail to achieve seizure remission with current anti-epileptic drug (AED) treatment. Moreover, pharmacotherapy during critical periods of brain development can adversely affect nervous system function. We, and others, have shown that early life exposure to AEDs including phenobarbital, phenytoin, and valproate are associated with induction of enhanced neuronal apoptosis during a confined period of postnatal development in rats. Thus, identification of new therapies for neonatal/infantile epilepsy syndromes that provide seizure control without neuronal toxicity is a high priority.

Current clinical trials report that modulation of the cannabinoid system with the phytocannabinoid cannabidiol exerts anti-seizure effects in children with epilepsy. While cannabidiol and the propyl analog cannabidivarin (CBDV) display anti-seizure efficacy in adult animal models of seizures/epilepsy, they remained unexplored in neonatal models. Therefore, we investigated the therapeutic potential of CBDV in multiple neonatal rodent seizure models. To evaluate the therapeutic potential of CBDV, we tested its anti-seizure efficacy in five models of neonatal seizures: pentylenetetrazole (PTZ), DMCM, hypoxia, kainate and NMDA-evoked spasms, each representing a different clinical seizure phenotype. We also evaluated the preclinical safety profile in the developing brain.

Postnatal day (P) 10 or P20 male, Sprague-Dawley rat pups were pretreated with CBDV or vehicle prior to chemically or hypoxia induced seizures. CBDV only displayed anticonvulsant effects in the P20 rat pups in the PTZ and DMCM models, with no effect on seizure severity or latency in the P10 animals. Therefore, we next measured the relative expression of known targets for CBDV (TRPV1, TRPA1) to determine a mechanism for which CBDV is anticonvulsant in P20, but not P10 animals. The P20 animals show increased expression of TRPV1 in key brain regions implicated in epileptogenic activity.

Together, these results indicate that modulation of the cannabinoid system in a receptor independent manner can provide seizure control in developing animals, but in an age specific manner. Further, during a developmentally sensitive neonatal period, drugs targeting the cannabinoid system do not induce neuronal apoptosis characteristic of many other AEDs. These results provide some of the first systemic, preclinical data evaluating CBDV in pediatric models of epilepsy.

Cannabidivarin (CBDV) vs. Placebo in Children With Autism Spectrum Disorder (ASD)

Weight-based dosing of 10 mg/kg/day of CBDV for 12 weeks

Primary Outcome Measures  :

1.     Aberrant Behavior Checklist-Irritability Subscale (ABC-I) [ Time Frame: Change in ABC-I from Baseline to Week 12 (Change over 12 weeks) ]

Change in ABC-I from Baseline to Endpoint

Safety and Tolerability of Cannabidivarin (CBDV) in Children and Young Adults With Autism Spectrum Disorder

  

Lack of Autophagy will reduce the number of GABA_A receptors, by blocking GABARAP function

Regular readers will recall that one feature of autism and many other neurological diseases is a reduction in autophagy, which I likened to an intra-cellular garbage collection service. 

The very recent paper below shows that lack of autophagy blocks GABARAP from its job to transport freshly minted GABA_A receptors.

If correct, this actually has very wide implications.

Autophagy links MTOR and GABAsignaling in the brain

The disruption of MTOR-regulated macroautophagy/autophagy was previously shown to cause autistic-like abnormalities; however, the underlying molecular defects remained largely unresolved. In a recent study, we demonstrated that autophagy deficiency induced by conditional Atg7 deletion in either forebrain GABAergic inhibitory or excitatory neurons leads to a similar set of autistic-like behavioral abnormalities even when induced following the peak period of synaptic pruning during postnatal neurodevelopment. Our proteomic analysis and molecular dissection further revealed a mechanism in which the GABA_A receptor trafficking function of GABARAP (gamma-aminobutyric acid receptor associated protein) family proteins was compromised as they became sequestered by SQSTM1/p62-positive aggregates formed due to autophagy deficiency. Our discovery of autophagy as a link between MTOR and GABA signaling may have implications not limited to neurodevelopmental and neuropsychiatric disorders, but could potentially be involved in other human pathologies such as cancer and diabetes in which both pathways are implicated.

Conclusion

You may have skipped to the conclusion to avoid all the science.

The conclusion is simple, you need to keep your GABA_A receptors in tip top form if you want to avoid the symptoms of autism.

o   You need the right number of them

o   You need the right balance among the five constituent subunits

o   You need the correct level of chloride inside neurons so the receptors are not “working backwards”

All of the genes that encode proteins involved in the above are individually “autism genes”, because any one of them can disrupt the process.

Whether it is Dravet syndrome (GABA_A receptor α₂ subunit), Angelman syndrome, Jacobsen syndrome, Down syndrome or numerous other autism syndromes, not to mention idiopathic autism, check the above 3 bullet points.

Tune up/down your GABA_A receptors!

Desensitizing TRPV1 looks interesting and not just for epilepsy.  TRPV1 appears to be essential for microglia in the in brain to be activated.  We know that in autism microglia in the brain are permanently activated, as if there was a threat.

I do think there is cross-talk (feedback loops etc) going on here, for example you can treat the severe epilepsy in Dravet syndrome by any of the following:-

·        KBr, to lower intracellular chloride

·        Low dose clonazepam to affect α subunits of GABA_A receptors

·        CBD or CBDV to modify TRPV1

Note that Dravet syndrome is caused by a mutation in the gene that encodes the sodium ion channel Nav1.1, the dysfunction of GABA_A receptors is a secondary effect. Also of interest is that the seizures that occur in Dravet syndrome are often triggered by hot temperatures or fever, so you can see how TRPV1 is indeed likely involved.  More generally in idiopathic autism, we have the "fever effect" when high temperatures trigger a reduction in autistic behaviors, making it the opposite of Dravet syndrome. 

On the one hand the biology behind the various problems may look horribly complicated and interwoven, the solutions appear to be much simpler and you have multiple options.

I await the results of the autism clinical trial of CBDV (Cannabidivarin) with interest.

Just impaired autophagy may lead to a reduction in GABA_A receptors and the appearance of autistic features in an otherwise “normal” brain. This reminds us again of why autism is not a medical diagnosis, it is just a vague/subjective observation, which, in severe cases, should then trigger a thorough medical investigation.