Having read
the literature, it looked to me that anyone over 50 years old is likely to benefit
from a little extra Taurine, but it certainly was not clear whether it would
make my 21 year old’s autism better or worse. I went ahead and ordered some to
investigate.
In theory
one of the many effects of Taurine is negative. Taurine does affect the KCC2 transporter
that takes chloride out of neurons the “wrong” way. The other effects include
on calcium homeostasis, which we know is disturbed in most autism.
N = 2 Trial
Subject
#1 (Peter)
I took 2g a
day for a month and noticed no effect at all, other than some mild GI
irritation.
In adults
the long-term effects are numerous and varied throughout the body. Even the
cells that remodel your bones (osteoblasts and osteoclasts) have special
taurine transporters, whose sole role is to let taurine inside – taurine makes the
osteoblasts work harder, while encouraging osteoclasts to take a break. The net
effect should be stronger bones. As you get
older your natural levels of taurine fall substantially. There are taurine-rich
foods you can eat and if you engage in strenuous exercise your liver starts making
more taurine.
Subject
#2 (Monty)
There is a
clear contradiction when it comes to Taurine and sleep. Many energy drinks
contain Taurine to keep you alert, but in theory Taurine should be calming and
many people take it add bedtime to improve sleep.
Monty, aged
21 with ASD, likes getting up early and going to bed early.
Adding 2g a
day of Taurine at breakfast shifted his circadian rhythms, so that he now goes
to bed at a time typical for a 21 year old, but still wants to get up at 7am. Monty even fell asleep on the sofa watching TV late one night, something big brother often does. Indeed, Monty received a nod of approval when big brother discovered him in the early hours.
The most
beneficial change has been on his spring and summertime aggression. This has
been controlled for years using an L-type calcium channel blocker. This does
not resolve the allergy at all, but it “switches off” the consequential
anxiety/aggression. With the addition of allergy therapies and the
immunomodulation of Pioglitazone (in peak allergy season) the problem behaviors
are controlled.
It appears
that Taurine has a similar anti-anxiety/aggression effect. Maybe its effect
on calcium channels and broader calcium homeostasis is the reason why. Anyway,
it works – simple, cheap, OTC and effective.It has no effect on allergy, in case you are wondering.
Conclusion
Taurine can
be bought as a bulk powder for very little money. It is not like those numerous
expensive supplements that would cost you several hundred dollars/euros/pounds
a year.
If you have your
own “healthspan polytherapy”, to ward off high blood pressure, high cholesterol,
type 2 diabetes, dementia, arthritis, osteoporosis etc, consider spending a few
pennies more and add a scoop of taurine.
The people who
write to me and tell me how Verapamil has transformed life at home, by banishing
aggression and self-injurious behaviors, should seriously consider a trial of
Taurine.
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 GABAA
receptors, in the short term
·Down regulating
GABAA receptors, after long term use
·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:
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.
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.
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.
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 GABAA, glycine and
NMDA receptors Therefore, taurine can partially substitute for GABA by
causing inhibition of neuronal excitability. However, the regulation of the
GABAA receptor by taurine is complex. While acute taurine administration activates the
GABAA receptor, chronic taurine feeding promotes the
downregulation of the GABAA receptorand 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.
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)
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.
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.
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.
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.
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 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.
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.
-------
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.
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.
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.
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.
Today’s post is really for the regular readers of this blog who are interested in the GABA switch and Bumetanide. It is not light reading. We see how advanced some Taiwanese researchers are in their understanding of GABAA dysfunctions in Huntington’s Disease.
Taipei 101, briefly the world’s tallest building
It is an excellent paper and much of it is applicable to autism. There are some omissions, but you will struggle to find a more complete paper.
They even go into the detail of altered the sub-unit expression of GABAA receptors that occurs as the disease progresses. I think that correcting sub-unit miss-expression has great potential in treating some autism.
Huntington’s is an inherited brain disorder that first manifests itself around the age of 40 and then progresses for the next 15 to 20 years.
Much autism is present prior to birth but there is a progression that occurs as the brain develops in early childhood. Some people do seem to be entirely typical at birth and only around 2 years old develop symptoms. After 5 years old you cannot really develop “autism”, just the symptoms might not get noticed till later in life.
Schizophrenia only develops in early to mid-adulthood.
It is surprising to many people that such varied disorders share some similar aspects of biology.
In terms of practical interventions, in today’s paper these include:
·Inhibition of NKCC1 (bumetanide)
·Activation of KCC2 (N-Ethylmaleimide)
·Enhancer of CKB (creatine)
·Inhibitor of WNK/SPAK
·Activation of extra-synaptic GABAa receptors (taurine, progesterone)
·Activation of synaptic GABAa receptors (zolpidem, alprazolam)
·Inhibition of GABA transport mechanism (Tiagabine)
One thing to note is that activating GABAa receptors may well have a negative effect in some people.
Sub-unit specific therapies, like very low dose clonazepam targeting α3, are not mentioned in this paper, nor is the role of GABAb on NKCC1/KCC2 expression.
We are familiar with Bumetanide as an NKCC1 blocker intervention in autism, but looking at the list there are other common autism therapies (creatine and taurine) and the female hormone progesterone. We come upon the beneficial effect of female hormones on a regular basis in this blog (estradiol, pregnenalone, progesterone …).We even saw how a sub-SSRI dose of Prozac increases the amount of the neurosteroid 3α-hydroxy-5α-pregnan-20-one (Allo) that potently, positively, and allosterically modulates GABA action at GABAA receptors. Progesterone is converted to Allo in the body.
An overview of the g-aminobutyric acid (GABA) signalling system. (a) GABA homeostasis is regulated by neurons and astrocytes. GABA is synthesized by GAD65/67 from glutamate in neurons, while astrocytic GABA is synthesized through MAOB. The release of GABA is mediated by membrane depolarization in neurons and Best1 in astrocytes. The reuptake of GABA is mediated through GAT1 in neurons and GAT3 in astrocytes. The metabolism of GABA is mediated by GABA-T in neurons and astrocytes. The reuptake of GABA in astrocytes is further transformed into glutamine via the TCA cycle and glutamine synthetase (GS). The glutamine is then transported to neurons and converted to glutamate for regeneration of GABA.
(b) GABAA receptors are heteropentameric complexes assembled from 19 different subunits. The compositions of different subunits determines the subcellular distributions and functional properties of the receptors. Phasic inhibition is mediated via the activation of synaptic GABAA receptors following brief exposure to a high concentration of extracellular GABA. Tonic inhibition is mediated via the activation of extrasynaptic GABAA receptors by a low concentration of ambient GABA.
c) The excitatory inhibitory response of GABA is driven by the chloride gradient across cell membranes, which can be determined via two cation–chloride cotransporters (NKCC1 and KCC2). The high expression of NKCC1 during the developmental stage maintains higher intracellular [Cl2] via chloride influx to the cell. The activation of GABAA receptors at an early developmental stage results in an outward flow of chloride and an excitatory GABAergic response. As neurons mature, the high expression of KCC2 maintains lower intracellular [Cl2] via chloride efflux out of the cell. The activation of GABAA receptors on mature neurons results in the inward flow of chloride and an inhibitory GABAergic response.
An excerpt showing data on sub-unit misexpression in different parts of the brain at different stages of the disease
5.2. Modulation of chloride homeostasis via cation – chloride cotransporters
Emerging evidence suggests that chloride homeostasis is a therapeutic target for HD. Pharmacological agents that target cation–chloride cotransporters (i.e. NKCC1 or KCC2) therefore might be used to treat HD (figure 3b). Of note, dysregulation of cation–chloride cotransporters and GABA polarity was associated with several neuropsychiatric disorders [70,134–139] (reviewed in [27,140]). Such abnormal excitatory GABAA receptor neurotransmission can be rescued by bumetanide, an NKCC1 inhibitor that decreases intracellular chloride concentration. Bumetanide is an FDA-approved diuretic agent that has been used in the clinic. It attenuates many neurological and psychiatric disorders in preclinical studies and some clinical trials for traumatic brain injury, seizure, chronic pain, cerebral infarction, Down syndrome, schizophrenia, fragile X syndrome and autism (reviewed in [141]). Daily intraperitoneal injections of bumetanide also restored the impaired motor function of HD mice. The effect of bumetanide is likely to be mediated by NKCC1 because genetic ablation of NKCC1 in the striatum also rescued the motor deficits in R6/2 mice. This study uncovered a previously unrecognized depolarizing or excitatory action of GABA in the aberrant motor control in HD. In addition, chronic treatment with bumetanide also improved the impaired memory in R6/2 mice [69], supporting the importance of NKCC1 in HD pathogenesis.Owing to the poor ability of bumetanide to pass through the blood–brain barrier, further optimization of bumetanide and other NKCC1 inhibitors is warranted [142,143]. Disruption of KCC2 function is detrimental to inhibitory transmission and agents to activate KCC2 function would be beneficial in HD. However, no agonist of KCC2 has been described until very recently [144,145]. A new KCC2 agonist (CLP290) has been shown to facilitate functional recovery after spinal cord injury [145]. It would be of great interest to evaluate the effect of KCC2 agonists on HD progression. Another KCC2 activator, CLP257, was found to increase the cell surface expression of KCC2 in a rat model of neuropathic pain [146]. Post-translational modification of KCC2 by kinases may modulate the function of KCC2. The WNK/ SPAK kinase complex, composed of WNK (with no lysine) and SPAK (SPS1-related proline/alanine-rich kinase), is known to phosphorylate and stimulate NKCC1 or inhibit KCC2 [147]. Thus, compounds that inhibit WNK/SPAK kinases will result in KCC2 activation and NKCC1 inhibition. Some compounds have been noted as potential inhibitors of WNK/SPAK kinases and need to be further tested for their effects on cation –chloride cotransporters [148–150]. An alternative mechanism to activate KCC2 is manipulation of its interacting proteins (e.g. CKB [65,66]). Because CKB could activate the function of KCC2 [65,66], CKB enhancers may increase the function of KCC2. In HD, reduced expression and activity of CKB is associated with motor deficits and hearing impairment [68,88]. Enhancing CKB activity by creatine supplements ameliorated the motor deficits and hearing impairment of HD mice. It is worthwhile to further investigate the interaction of KCC2 and CKB in GABAergic neurotransmission and motor deficits in HD. The depolarizing GABA action with altered expression levels of NKCC1 or KCC2 is associated with neuroinflammation in HD brains [32,69]. Blockade of TNF-a using Xpro1595 (a dominant negative inhibitor of soluble TNF-a) [151] in vivo led to significant beneficial effects on disease progression in HD mice [152] and reduced the expression of NKCC1. It would be of great interest to test the effect of other anti-inflammatory agents [153] on the function and expression of NKCC1 and GABAergic inhibition. Neuroinflammation is implicated in most neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease [154,155], and the interaction of cation–chloride cotransporters and neuroinflammation in GABAergic neurotransmission may also play a critical role in other neurodegenerative diseases.
Figure 2. Molecular mechanism(s) underlying the abnormal GABAAergic system in HD. (a) In the normal condition, adult neurons express high KCC2 and few NKCC1 to maintain the lower intracellular chloride concentration, which results in an inward flow of chloride when GABAA receptors are activated. Astrocytes function normally for the homeostasis of glutamate, potassium and glutamate/GABA-glutamine cycle. (b) In Huntington’s disease, reduced GABAA receptor-mediated neuronal inhibition is associated with enhanced NKCC1 expression and a decreased expression in KCC2 and membrane localized GABAA receptors.The dysregulated GABAAergic system might be caused by mutant HTT, excitotoxicity, neuroinflammation or other factors. Mutant HTT in neurons alters the transcription of genes (GABAAR and KCC2) through interactions with transcriptional activators (SP1) and repressors (REST/NRSF). Mutant HTT in neurons also disrupts the intracellular trafficking of GABAARs to the cellular membrane. HD astrocytes have impaired homeostasis of extracellular potassium/glutamate (due to deficits of astrocytic Kir4.1 channel and glutamate transporters, Glt-1) and cause neuronal excitability, which might be related to the changes of KCC2, NKCC1 and GABAAR. The activity of KCC2 could be affected through its interacting proteins, such as CKB and mHTT. Neuroinflammation, which is evoked by the interaction of HD astrocyte and microglia, enhances NKCC1 expression in neurons at the transcriptional level through an NF-kB-dependent pathway. HD astrocytes also have compromised astrocytic metabolism of glutamate/GABA–glutamine cycle that contributes to lower GABA synthesis.
Notably, neuroinflammation and the GABA neurotransmitter system are reciprocally regulated in the brain (reviewed in [104,105]). Specifically, neuroinflammation induces changes in the GABA neurotransmitter system, such as reduced GABAA receptor subunit expression, while activation
of GABAA receptors likely antagonizes inflammation.
TNF-a, a proinflammatory cytokine, induces a downregulation of the surface expression of GABAARs containing a1, a2, b2/3 and g2 subunits and a decrease in inhibitory synaptic strength in a cellular model of hippocampal neuron culture [106]. The same group further demonstrated that protein phosphatase 1-dependent trafficking of GABAARs was involved in the TNF-a evoked downregulation of GABAergic neurotransmission [107]. Upregulation of TNF-a also negatively impacts the expression of GABAAR a2 subunit mRNA and thus decreases the presynaptic inhibition in the dorsal root ganglion in a rat experimental neuropathic painmodel [108]. Conversely, blockade of central GABAARs in mice by aGABAAR antagonist increased both the basal and restraint stress-induced plasma IL-6 levels [109]. Inhibition of GABAAR activation by picrotoxin increased the nuclear translocation of NF-kB in acute hippocampal slice preparations [110]. Collectively, neuroinflammation
weakens the inhibitory synaptic strength in neurons, at least partly, through the reduction of GABAARs.
The reduced expression and function of GABAARs may further increase inflammatory responses. It remains elusive whether the same mechanism occurs in the inflammatory environment in HD brains.
hyperexcitability resulting from deficiency of astrocytic Kir4.1 might have also contributed to neuronal NKCC1 upregulation and altered GABAergic signalling in HD brains.
Figure 3. Strategy to target (a) GABAAR and (b) cation–chloride cotransporters as potential therapeutic avenues. (a) The GABAergic system is influenced directly by agents that (1) target synaptic GABAAR, (2) increase tonic GABA current or interfere with synaptic GABA concentrations via a reduction of GABA reuptake (3), and (4) block GABA metabolism.
5.1. Modulating the GABAA receptor as a therapeutic target
In view of the presently discovered HD-related deficit in the GABA system, the question arises whether HD patients can benefit from drugs that stimulate the GABA system (figure 3a). HD patients suffer from motor abnormalities and
non-motor symptoms, including cognitive deficits, psychiatric symptoms, sleep disturbance, irritability, anxiety, depression and an increased incidence of seizures [74,77,116,117].
Seizures are a well-established part of juvenile HD but no more prevalent in adult-onset HD than in the general population [73,74,118]. Several pharmacological compounds can enhance inhibitory GABAergic neurotransmission by targeting GABAAR and thereby producing sedative, anxiolytic, anticonvulsant and muscle-relaxant effects. A recent study demonstrated that zolpidem, a GABAAR modulator that enhances GABA inhibition mainly via the a1-containing GABAA receptors, corrected sleep disturbance and electroencephalographic abnormalities in symptomatic HD mice (R6/2) [119].Alprazolam, a benzodiazepine-activating GABA receptor, reversed the dysregulated circadian rhythms and improved cognitive performance of HD mice (R6/2) [120].
In addition, progesterone, a positive modulator of GABAAR, significantly reversed the behavioural impairment in a 3-nitropropionic acid (3-NP)-induced HD rat model [121]. Apart from modulating the activity of the GABAergic system by interfering directly with the receptor, pharmacological agents can also interfere with synaptic GABA concentrations. Tiagabine, a drug that specifically blocks the GABA transporter (GAT1) to increase synaptic GABA level,was found to improve motor performance and extend survival inN171-82Q and R6/2 mice [122].It is also worth evaluating whether vigabatrin, a GABA-T inhibitor that blocksGABAcatabolismin neurons and astrocytes [123], plays a role in the compromised astrocytic glutamate–GABA–glutamine cycling [56].Interestingly, taurine exerted GABAA agonistic and antioxidant activities in a 3-NP HD model and improved locomotor deficits and increased GABA levels[124]. However, several early studies failed to provide the expected benefits of GABA analogues in slowing disease progression in HD patients [125–127]. For example, gaboxadol, an agonist for the extrasynaptic d-containing GABAA receptor, failed to improve the decline in cognitive and motor functions of five HD patients during a short two-week trial, but it caused side effects at the maximal dose [125]. Interestingly, although treatment with muscimol (a potent agonist of GABA receptors) did not improve motor or cognitive deficits in 10HDpatients, it did ameliorate chorea in the most severely hyperkinetic patient [126]. The therapeutic failure of GABA stimulation in early clinical trials does not argue against the importance of GABAergic deficits in HD pathogenesis. The alteration of GABAergic circuits plays a primary role or is a compensatory response to excitotoxicity, and it may contribute to HD by disrupting the balance between the excitation and inhibition systems and the overall functions of neuronal circuits. Because the subunits of the GABAA receptor are brain region- or neuron subtypespecific, the choice of drugs may have distinct effects on the brain region or neuronal population targeted [128–130]. For example, the expression of GABAAR subunits is differentially altered in MSNs and other striatal interneurons in HD 54,60]. The early involvement of D2-expressing MSNs can cause chorea [131], while dysfunctional PV-expressing interneurons can cause dystonia in HD patients [132]. Specific alteration in neuronal populations and receptor subtypes during HD progression needs to be taken into consideration when treating the dysfunction of GABAergic circuitry.
Notably, striatal tonic inhibition mediated by the dcontaining GABAARs may have neuroprotective effects against excitotoxicity in the adult striatum [63]. Because the reductions in d-containing GABAARs and tonic GABA currents in D2-expressing MSNs have been observed in early HD [32,39,40,54,61], it would be of great interest to evaluate the effects of several available compounds, such as alphaxalone and ganaxolone [133], that target d-containing GABAARs, in animal models of HD.
(b) GABAAR-mediated signalling in HD neurons is depolarizing due to the high intracellular chloride concentration caused by high NKCC1 expression and low KCC2 expression. Rescuing the function of cation–chloride cotransporters can occur via (1) inhibition of NKCC1 activity using bumetanide, (2, 3) increase in KCC2 function using a KCC2 activator or CKB enhancer, and (4) inhibitors of WNK/SPAK kinases.
5.2. Modulation of chloride homeostasis via cation–chloride cotransporters
Emerging evidence suggests that chloride homeostasis is a therapeutic target for HD. Pharmacological agents that target cation–chloride cotransporters (i.e.NKCC1 orKCC2) therefore might be used to treat HD (figure 3b). Of note, dysregulation of cation–chloride cotransporters and GABA polarity was associated with several neuropsychiatric disorders [70,134–139] (reviewed in [27,140]). Such abnormal receptor neurotransmission can be rescued by bumetanide, an NKCC1 inhibitor that decreases intracellular chloride concentration. Bumetanide is an FDA-approved diuretic agent that has been used in the clinic. It attenuates many neurological and psychiatric disorders in preclinical studies and some clinical trials for traumatic brain injury, seizure, chronic pain, cerebral infarction, Down syndrome, schizophrenia, fragile X syndrome and autism (reviewed in [141]). Daily intraperitoneal injections of bumetanide also restored the impaired motor function ofHDmice (R6/2, Y-T Hsu,Y-GChang, Y-CLi, K-YWang, H-MChen, D-J Lee, C-HTsai, C-C Lien,YChern 2018, personal communication). The effect of bumetanide is likely to be mediated by NKCC1 because genetic ablation of NKCC1 in the striatum also rescued the motor deficits in R6/2 mice (Y-T Hsu, Y-G Chang, Y-C Li, K-Y Wang, H-M Chen, D-J Lee, C-H Tsai, C-C Lien, Y Chern 2018, personal communication). This study uncovered a previously unrecognized depolarizing or excitatory action of GABA in the aberrant motor control in HD. In addition, chronic treatment with bumetanide also improved the impaired memory in R6/2 mice [69], supporting the importance of NKCC1 in HD pathogenesis. Owing to the poor ability of bumetanide to pass through the blood–brain barrier, further optimization of bumetanide and other NKCC1 inhibitors is warranted [142,143].
Disruption of KCC2 function is detrimental to inhibitory transmission and agents to activate KCC2 function would be beneficial in HD. However, no agonist of KCC2 has been described until very recently [144,145]. A new KCC2 agonist (CLP290) has been shown to facilitate functional recovery after spinal cord injury [145]. It would be of great interest to evaluate the effect of KCC2 agonists on HD progression. Another KCC2 activator, CLP257, was found to increase the cell surface expression of KCC2 in a rat model of neuropathic pain [146]. Post-translational modification of KCC2 by kinases may modulate the function of KCC2. The WNK/SPAK kinase complex, composed of WNK (with no lysine) and SPAK (SPS1-related proline/alanine-rich kinase), is known to phosphorylate and stimulate NKCC1 or inhibit KCC2 [147]. Thus, compounds that inhibit WNK/SPAK kinases will result in KCC2 activation and NKCC1 inhibition.
Some compounds have been noted as potential inhibitors of WNK/SPAK kinases and need to be further tested for their effects on cation–chloride cotransporters [148–150]. An alternative mechanism to activate KCC2 is manipulation of its interacting proteins (e.g. CKB [65,66]). Because CKB could activate the function of KCC2 [65,66], CKB enhancers may increase the function of KCC2. In HD, reduced expression and activity of CKB is associated with motor deficits and hearing impairment [68,88]. Enhancing CKB activity by creatine supplements ameliorated the motor deficits and hearing impairment of HD mice. It is worthwhile to further investigate the interaction of KCC2 and CKB in GABAergic neurotransmission and motor deficits in HD. The depolarizing GABA action with altered expression levels of NKCC1 or KCC2 is associated with neuroinflammation in HD brains [32,69]. Blockade of TNF-a using Xpro1595 (a dominant negative inhibitor of soluble TNF-a) [151] in vivo led to significant beneficial effects on disease progression in HD mice [152] and reduced the expression of NKCC1It would be of great interest to test the effect of other anti-inflammatory agents [153] on the function and expression of NKCC1 and GABAergic inhibition. Neuroinflammation is implicated in most neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease [154,155], and the interaction of cation–chloride cotransporters and neuroinflammation in GABAergic neurotransmission may also play a critical role in other neurodegenerative diseases.
Upon activation by with-no-lysine kinases, STE20/SPS1-related proline–alanine-rich protein kinase (SPAK) phosphorylates and activates SLC12A transporters such as the Na+-Cl− cotransporter (NCC) and Na+-K+-2Cl− cotransporter type 1 (NKCC1) and type 2 (NKCC2); these transporters have important roles in regulating BP through NaCl reabsorption and vasoconstriction. SPAK knockout mice are viable and display hypotension with decreased activity (phosphorylation) of NCC and NKCC1 in the kidneys and aorta, respectively. Therefore, agents that inhibit SPAK activity could be a new class of antihypertensive drugs with dual actions (i.e., NaCl diuresis and vasodilation). In this study, we developed a new ELISA-based screening system to find novel SPAK inhibitors and screened >20,000 small-molecule compounds. Furthermore, we used a drug repositioning strategy to identify existing drugs that inhibit SPAK activity. As a result, we discovered one small-molecule compound (Stock 1S-14279) and an antiparasitic agent (Closantel) that inhibited SPAK-regulated phosphorylation and activation of NCC and NKCC1 in vitro and in mice. Notably, these compounds had structural similarity and inhibited SPAK in an ATP-insensitive manner. We propose that the two compounds found in this study may have great potential as novel antihypertensive drugs.
WNKs (with-no-lysine kinases) are the causative genes of a hereditary hypertensive disease, PHAII (pseudohypoaldosteronism type II), and form a signal cascade with OSR1 (oxidative stress-responsive 1)/SPAK (STE20/SPS1-related proline/alanine-rich protein kinase) and Slc12a (solute carrier family 12) transporters. We have shown that this signal cascade regulates blood pressure by controlling vascular tone as well as renal NaCl excretion. Therefore agents that inhibit this signal cascade could be a new class of antihypertensive drugs. Since the binding of WNK to OSR1/SPAK kinases was postulated to be important for signal transduction, we sought to discover inhibitors of WNK/SPAK binding by screening chemical compounds that disrupt the binding. For this purpose, we developed a high-throughput screening method using fluorescent correlation spectroscopy. As a result of screening 17000 compounds, we discovered two novel compounds that reproducibly disrupted the binding of WNK to SPAK. Both compounds mediated dose-dependent inhibition of hypotonicity-induced activation of WNK, namely the phosphorylation of SPAK and its downstream transporters NKCC1 (Na/K/Cl cotransporter 1) and NCC (NaCl cotransporter) in cultured cell lines. The two compounds could be the promising seeds of new types of antihypertensive drugs, and the method that we developed could be applied as a general screening method to identify compounds that disrupt the binding of two molecules.
K+/Cl− cotransporter 2 (KCC2) is selectively expressed in the adult nervous system and allows neurons to maintain low intracellular Cl− levels. Thus, KCC2 activity is an essential prerequisite for fast hyperpolarizing synaptic inhibition mediated by type A γ-aminobutyric acid (GABAA) receptors, which are Cl−-permeable, ligand-gated ion channels. Consistent with this, deficits in the activity of KCC2 lead to epilepsy and are also implicated in neurodevelopmental disorders, neuropathic pain, and schizophrenia. Accordingly, there is significant interest in developing activators of KCC2 as therapeutic agents. To provide insights into the cellular processes that determine KCC2 activity, we have investigated the mechanism by which N-ethylmaleimide (NEM) enhances transporter activity using a combination of biochemical and electrophysiological approaches. Our results revealed that, within 15 min, NEM increased cell surface levels of KCC2 and modulated the phosphorylation of key regulatory residues within the large cytoplasmic domain of KCC2 in neurons. More specifically, NEM increased the phosphorylation of serine 940 (Ser-940), whereas it decreased phosphorylation of threonine 1007 (Thr-1007). NEM also reduced with no lysine (WNK) kinase phosphorylation of Ste20-related proline/alanine-rich kinase (SPAK), a kinase that directly phosphorylates KCC2 at residue Thr-1007. Mutational analysis revealed that Thr-1007 dephosphorylation mediated the effects of NEM on KCC2 activity. Collectively, our results suggest that compounds that either increase the surface stability of KCC2 or reduce Thr-1007 phosphorylation may be of use as enhancers of KCC2 activity.
Today’s post shows how you need to read well beyond the autism research, not to miss something useful.
Some of today’s suggested therapies for Huntington’s are likely to help some types of autism, but some will certainly have a negative effect in some people.For example, increasing the amount of GABA in the CNS would do my son no good at all.
The emerging field of drugs that enhance KCC2 should be very beneficial to all those with autism who are bumetanide responders.
Enhancing CKB with creatine is interesting. Creatine is a muscle building supplement used by body builders and some DAN doctors. It does have interactions at high doses.
