Modulation of IP3 receptors in Autism – Pancreatitis and Caffeine?

This post stems from our Greek reader Petra's original observations about the combined effects of coffee and bumetanide.

In earlier posts we learned that one likely nexus in autism is the IP3 receptor that releases calcium from a store within each cell.

It turns out that too little/too much activity from IP3 receptors is a feature of a wide range of disease, some of which you may not have heard of, including:-

·      Gillespie syndrome, a genetic condition leading to MR/ID, ataxia and notably part of the iris to be missing

·      Spinocerebellar ataxias, genetic conditions that cause loss of movement control

·      Glioblastoma, an aggressive and “untreatable” brain cancer

·      Alzheimer’s disease

·      Huntington’s disease

·      Pancreatitis, inflammation of the pancreas where your body makes its digestive enzymes and insulin 

For detail, refer to this Japanese paper:- 

IP3 receptor mutations and brain diseases in human and rodents

Of the three types of IP₃Rs, the type 1 receptor (IP₃R1) is dominantly expressed in the brain and is important for brain function. Recent emerging evidence suggests that abnormal Ca²⁺ signals from the IP₃R1 are closely associated with human brain pathology. In this review, we focus on the recent advances in our knowledge of the regulation of IP₃R1 and its functional implication in human brain diseases, as revealed by IP₃R mutation studies and analysis of human disease‐associated genes. 

I suspect that both hyper and hypo-active IP3 receptors will be found in different types of autism. I assume the variant I deal with in my son is more likely to be hyperactive. The research by Gargus suggested “dysregulated IP3R” in autism in 3 single gene autisms; he found depressed Ca²⁺ release through inositol trisphosphate receptors (IP₃Rs) in patient-derived fibroblasts.

Shared functional defect in IP3R-mediated calcium signaling in diverse monogenic autism syndromes

Your body contains a lot of calcium, but almost all of it is in your bones, as calcium phosphate.  Only the residual amount (about 1%) of calcium is present in solution as the ion Ca²⁺. Ca²⁺ plays an important role in many physiological functions.  An excessive elevation of Ca²⁺ inside cells will kill them. Cells must maintain the intracellular Ca²⁺ concentration at the low level of ~10⁻⁷ mol/L, against the much higher extracellular Ca²⁺ concentration (~10⁻³ mol/L).

Cells must be able to rapidly and dynamically change the intracellular Ca²⁺ concentration in response to extracellular stimuli to regulate physiological functions such as cell proliferation, fertilization, immune response, and brain functioning.

To dynamically change the intracellular Ca²⁺ level, cells use two sources of Ca²⁺:

·      Ca²⁺ influx from outside (the extracellular space)

·      Ca²⁺ release from inside (the intracellular Ca²⁺ store, the endoplasmic reticulum – ER)

Many Ca²⁺ handling molecules (Ca²⁺ ion channels, Ca²⁺ pumps, Ca²⁺ sequester proteins) work to maintain the correct balance. The IP3 receptor is a key protein in the regulation of the intracellular Ca²⁺ dynamics, because it  controls the release of intracelluar Ca²⁺.

If IP3R is left open, Ca²⁺ levels inside cells become too high; if it is left shut Ca²⁺ becomes too low.

No medical therapy currently exists to inhibit/block IP3 receptors, but today’s post considers one potential therapy – caffeine. 

Caffeine

Caffeine is a drug, although it is not regulated as one.  At high doses caffeine is toxic, but at non-toxic doses caffeine does have some potent medical effects and it does protect against certain diseases.

It protects against pancreatitis, for example.

It would be very hard to drink yourself to death with coffee. Just like eating numerous bananas does not cause death by having too much potassium in your blood. Supplements have more risks than food. 

Pancreatitis IP3R and Caffeine 

Caffeine protects against experimental acute pancreatitis by inhibition of inositol 1,4,5-trisphosphatereceptor-mediated Ca2+ release 

Significance of this study

What is already known on this subject?

·       Acute pancreatitis is a major health problem without specific drug therapy.

·       Coffee consumption reduces the incidence of acute alcoholic pancreatitis.

·       Caffeine blocks physiological intracellular Ca²⁺ oscillations by inhibition of inositol 1,4,5-trisphosphate receptor-(IP₃R)-mediated signalling.

·       Sustained cytosolic Ca²⁺ overload from abnormal Ca²⁺ signalling is implicated as a critical trigger in the pathogenesis of acute pancreatitis.

What are the new findings?

·       Caffeine and its dimethylxanthine metabolites inhibit IP₃R-mediated, sustained cytosolic Ca²⁺ elevations, loss of mitochondrial membrane potential and necrotic cell death pathway activation in pancreatic acinar cells.

·       Neither specific phosphodiesterase inhibitors nor cyclic adenosine monophosphate and cyclic guanosine monophosphate inhibit sustained Ca²⁺ elevations in pancreatic acinar cells.

·       Serum levels of xanthines after 25 mg/kg caffeine administration are sufficient to inhibit IP₃R-mediated Ca²⁺ overload in experimental acute pancreatitis.

·       Caffeine but not theophylline or paraxanthine administered at 25 mg/kg significantly ameliorated pancreatic injury in experimental acute pancreatitis through IP₃R-mediated signalling inhibition.

How might it impact on clinical practice in the foreseeable future?

·       These findings support an approach of inhibition of Ca²⁺ overload and of its consequences as novel potential therapy for acute pancreatitis.

·       Methylxanthine-based structures are suitable starting points for drug discovery and development to treat acute pancreatitis. 

The Pancreas and Autism

The biomarker proposed by Joan Fallon/Curemark for her autism treatment (CM-AT) is low fecal chymotrypsin level. Chymotrypsin is a digestive enzyme produced in the pancreas and it can be used as a test for early cystic fibrosis. In adults low chymotrypsin indicates a pancreatic disease like pancreatitis.

Many people with autism have GI problems, but there are several distinct sub-groups. Some people have inflammatory bowel disease (IBD) potentially leading to ulcerative colitis, but most do not. Some people with autism have GI dysfunctions that remain undiagnosed, for some it is as if they do not digest food the same way as other people.

If IP3R hyperactivity is a feature of some autism and IP3R hyperactivity is inherent in pancreatitis, is it a surprise that some people with autism do not seem to digest their food properly? Or is it just a coincidence?

Brain Cancer

We did come across glioblastoma in a previous post that looked at off-label therapies for some cancers. In that post we came across an academic from San Diego, who decided to read the research and try and reverse his incurable aggressive brain cancer. This involved driving across the border to Mexico to freely acquire the prescription drugs he used to treat himself.  Two decades later he is still very much alive. 

More Wnt Modulation for Autism and More Inexpensive Potential Cancer Therapies

According to the study below, a hot cup of strong Greek coffee might be a good choice to maintain Professor Williams in good health.

Caffeine-mediated inhibition of calcium release channel inositol 1,4,5-trisphosphate receptor subtype 3 blocks glioblastoma invasion and extends survival.

IP₃Rs are known to be difficult to study especially due to the lack of suitable inhibitors and subtype specific blockers. We found that caffeine paradoxically inhibited IP₃R-mediated Ca²⁺ responses in a subtype 3 specific manner (Figure 5). Using caffeine as a tool to inhibit IP₃R3-mediate Ca²⁺ release, we have demonstrated that inhibiting IP₃R3 effectively reduced the migration, invasion, and survival of glioblastoma cells (Figure 2). The gene silencing of IP₃R3 by shRNA also effectively reduced the caffeine sensitivity of Ca²⁺ signaling and invasiveness in the Matrigel invasion assay (Figure 5). Our results are the first to demonstrate the involvement of IP₃R3 in glioblastoma Ca²⁺ signaling and invasion. Furthermore, we suggest that IP₃R3 can be specifically targeted for therapeutic intervention in glioblastoma patients with minimal influence on normal glial as well as neuronal functions.

Whether caffeine can directly affect the gating of IP₃R3 channels or not is still unknown. However, according to previous studies demonstrating that caffeine can compete with ATP binding to IP₃Rs (21) at millimolar concentrations (20), caffeine could selectively bind to IP₃R3 and affect the gating of IP₃R3. Further work is required to investigate the direct role of caffeine on IP₃R3 gating in comparison to other subtypes of IP₃R.

In summary our study provides IP₃R3 as a novel therapeutic target for glioblastoma treatment. Our study also provides new insights into the detailed molecular mechanism of caffeine action on migration and invasion of glioblastoma. The apparent beneficial effect of caffeine suggested by our study should trigger future investigations of the therapeutic potential for caffeine to treat this deadly disease that otherwise has no cure. 

Conclusion

Caffeine is the most obvious modulator of IP3R in your kitchen or at the local pharmacy.

cAMP plays a complex role in IP3R, PKA is involved so PDE4 should be. Parathyroid hormone (PTH) is also important. PTH is secreted to tell your bones to release Ca²⁺ into the bloodstream, but it has multiple roles. PTH causes the release of IP3 and DAG and hence release of calcium from the store within cells (the ER). PTH release is stimulated when Ca²⁺ is low but also by other things, such as notably by histamine. PTH also is reported to increase the sensitivity of IP3R receptors, so too much PTH would clearly be a bad idea.

Primary Hyperparathyroidism (PHPT) is characterized by hypercalcaemia and elevation of parathyroid hormone.  Children with PHPT may present with non-specific complaints such as behavioural change and deteriorating school performance.  As we know, behavioural change in the form of aggression sometimes occurs in autism, ADHD and various other mood disorders. It may also present as a psychiatric manifestation of an endocrine disorder such as Primary Hyperparathyroidism (PHPT).

It is not surprising that histamine can cause aggression in the same way that Primary Hyperparathyroidism does. Aggression in all psychiatric disorders very likely has a biological cause, you just have to look for it. 

Aggression and Homicidal Thoughts in a Patient with Primary Hyperparathyroidism: A Case Report.

How about checking kids with aggression/SIB for PHPT, or just high levels of calcium (hypercalcaemia). Or perhaps:-

Going Loco? Think histamine, calcium and hyper-parathyroidism, before taking antipsychotics.

Back to caffeine.

In people with hyperactive IP3 receptors, such as those who damaged their pancreas by drinking too much alcohol, caffeine looks a smart therapy. The same would apply to people with autism and hyperactive IP3 receptors. So for those people, drink coffee, preferably Greek coffee (or Turkish coffee, which is the same thing). Some Latin American countries also make potent coffee drinks. Your cup of instant coffee, or chain store coffee is not going to do much.

There are numerous interesting substances in less processed coffee, not just caffeine. The key is to process it as little as possible, as we saw cocoa. In instant coffee only the caffeine is going to have much effect.

Chlorogenic acid, an OAT3 inhibitor, that should enhance bumetanide, is there in coffee.

Coffee contains small amounts of Caffeic acid. What we would really like is Caffeic Acid Phenethyl Ester (CAPE), which is a substance found in some bee propolis. CAPE acts as a PAK1 inhibitor, among other potentially beneficial effects.

Catechin, epicatechin, and surprisingly vanillin are present in coffee.

Roasting coffee makes big changes to its chemical composition and of course to its taste. Green coffee bean extract, used as a supplement for weight loss, is a rich source of chlorogenic acid.

Perhaps someone should do a study on adults with autism using 2 cups of Greek coffee a day.  Alternatively you could just use caffeine pills, with or without coffee bean extract for those interesting flavanols.

PAK inhibitors and potentially treating some Autism using Grandpa’s Medicine Cabinet

I wrote several posts about why PAK1 inhibitors should be beneficial in some autism and indeed some schizophrenia.

We also saw that PAK1-blocking drugs could be potentially useful for the treatment of neurofibromatosis type 2, in addition to RAS-induced cancers and neurofibromatosis type 1.

One problem with drugs developed for cancer is that, even if they finally get approved, they tend to be ultra-expensive.  Production volumes are low because even if they “work” they do not prolong life for so long and cancer has numerous sub-types.

Cheap drugs are ones used to treat common chronic conditions like high blood pressure, high cholesterol and indeed treatment of male lower urinary tract symptoms (LUTS), like benign prostatic hyperplasia (BPH).

A small number of readers of this blog have confirmed the beneficial effect of PAK inhibitors in their specific sub-types of autism.  The problem is that there are no potent PAK1 inhibitors suitable for long term use that are readily available.

The anti-parasite drug Ivermectin is an extremely cheap PAK1 inhibitor, but cannot be used long term, due to its other effects.

Propolis containing CAPE (Caffeic Acid Phenethyl Ester) is a natural PAK1 inhibitor, but may not be sufficiently potent as is reported by people with neurofibromatosis.

You would think somebody would just synthesize CAPE (Caffeic Acid Phenethyl Ester) artificially and then higher doses could be achieved.

PAK Inhibitors and Treatment of Prostate Enlargement

I was rather surprised that research has recently been published suggesting that PAK inhibitors could be used to treat the prostate enlargement, common in most older men. 

P21-Activated Kinase Inhibitors FRAX486 and IPA3: Inhibition of Prostate Stromal Cell Growth and Effects on Smooth Muscle Contraction in the Human Prostate

Abstract

Prostate smooth muscle tone and hyperplastic growth are involved in the pathophysiology and treatment of male lower urinary tract symptoms (LUTS). Available drugs are characterized by limited efficacy. Patients’ adherence is particularly low to combination therapies of 5α-reductase inhibitors and α₁-adrenoceptor antagonists, which are supposed to target contraction and growth simultaneously. Consequently, molecular etiology of benign prostatic hyperplasia (BPH) and new compounds interfering with smooth muscle contraction or growth in the prostate are of high interest. Here, we studied effects of p21-activated kinase (PAK) inhibitors (FRAX486, IPA3) in hyperplastic human prostate tissues, and in stromal cells (WPMY-1). In hyperplastic prostate tissues, PAK1, -2, -4, and -6 may be constitutively expressed in catecholaminergic neurons, while PAK1 was detected in smooth muscle and WPMY-1 cells. Neurogenic contractions of prostate strips by electric field stimulation were significantly inhibited by high concentrations of FRAX486 (30 μM) or IPA3 (300 μM), while noradrenaline- and phenylephrine-induced contractions were not affected. FRAX486 (30 μM) inhibited endothelin-1- and -2-induced contractions. In WPMY-1 cells, FRAX486 or IPA3 (24 h) induced concentration-dependent (1–10 μM) degeneration of actin filaments. This was paralleled by attenuation of proliferation rate, being observed from 1 to 10 μM FRAX486 or IPA3. Cytotoxicity of FRAX486 and IPA3 in WPMY-1 cells was time- and concentration-dependent. Stimulation of WPMY-1 cells with endothelin-1 or dihydrotestosterone, but not noradrenaline induced PAK phosphorylation, indicating PAK activation by endothelin-1. Thus, PAK inhibitors may inhibit neurogenic and endothelin-induced smooth muscle contractions in the hyperplastic human prostate, and growth of stromal cells. Targeting prostate smooth muscle contraction and stromal growth at once by a single compound is principally possible, at least under experimental conditions.

It looks like a PAK inhibitor could potentially solve both the key problems in BPH and so replace the current therapies.

Existing Drugs for LUTS/BPH

Undoubtedly someone is going to wonder whether existing drugs for LUTS/BPH might improve autism.  This is actually possible, but totally unrelated to PAK1 inhibition and RASopathies.

Existing drugs are in two classes, 5α-reductase inhibitors and α₁-adrenoceptor antagonists.

α-adrenoceptor antagonists

Alpha blockers relax certain muscles and help small blood vessels remain open. They work by keeping the hormone norepinephrine (noradrenaline) from tightening the muscles in the walls of smaller arteries and veins, which causes the vessels to remain open and relaxed. This improves blood flow and lowers blood pressure.

Because alpha blockers also relax other muscles throughout the body, these medications can help improve urine flow in older men with prostate problems.

Selective α₁-adrenergic receptor antagonists are often used in BPH because it is the α₁-adrenergic receptor that is present in the prostate.

 α ₂-adrenergic receptors are present elsewhere in the body

Alpha-2 blockers are used to treat anxiety and post-traumatic stress disorder (PTSD). They decrease sympathetic outflow from the central nervous system. Post-traumatic stress disorder is an anxiety disorder that is theorized to be related to a hyperactive sympathetic nervous system.

Alpha-2 receptor agonists for the treatment of post-traumatic stress disorder

So a nonselective alpha blocker, like one given to an older man with high blood pressure and BPH, might well have an effect on some kinds of anxiety.

You would think that a selective alpha 2 blocker might be interesting, how about Idazoxan?

Idazoxan is a drug which is used in research. It acts as both a selective α2 adrenergic receptor antagonist, and an antagonist for the imidazoline receptor. Idazoxan has been under investigation as an antidepressant, but it did not reach the market as such. More recently, it is under investigation as an adjunctive treatment in schizophrenia. Due to its alpha-2 receptor antagonism it is capable of enhancing therapeutic effects of antipsychotics, possibly by enhancing dopamine neurotransmission in the prefrontal cortex of the brain, a brain area thought to be involved in the pathogenesis of schizophrenia.

Mirtazapine is a cheap generic drug used at high doses for depression.  It happens to be a selective alpha 2 blocker, but it has numerous other effects as well.  One reader of this blog does respond very well to Mirtazapine.

So realistically in Grandpa’s medicine cabinet there might a selective alpha 1 agonist or a non-selective alpha agonist, it is the latter type that might have an effect on some kinds of autism.

5α-reductase inhibitors

The pharmacology of 5α-reductase inhibition involves the binding of NADPH to the enzyme followed by the substrate. Specific substrates include testosterone, progesterone, androstenedione, epitestosterone, cortisol, aldosterone, and deoxycorticosterone.

Beyond being a catalyst in testosterone reduction, 5α-reductase isoforms I and II reduce progesterone to 5α-dihydroprogesterone (5α-DHP) and deoxycorticosterone to dihydrodeoxycorticosterone (DHDOC).

In vitro and animal models suggest subsequent 3α-reduction of DHT, 5α-DHP and DHDOC lead to neurosteroid metabolites with effect on cerebral function.

These neurosteroids, which include allopregnanolone, tetrahydrodeoxycorticosterone (THDOC), and 5α-androstanediol, act as potent positive allosteric modulators of GABA_A receptors, and have anticonvulsant, antidepressant, anxiolytic, prosexual, and anticonvulsant effects.

Inhibition of 5α-reductase results in decreased conversion of testosterone to DHT.

This, in turn, results in slight elevations in testosterone and estradiol levels. 

In BPH, DHT acts as a potent cellular androgen and promotes prostate growth; therefore, it inhibits and alleviates symptoms of BPH. In alopecia, male and female-pattern baldness is an effect of androgenic receptor activation, so reducing levels of DHT also reduces hair loss.

A new look at the 5alpha-reductase inhibitor finasteride

Finasteride is the first 5alpha-reductase inhibitor that received clinical approval for the treatment of human benign prostatic hyperplasia (BPH) and androgenetic alopecia (male pattern hair loss). These clinical applications are based on the ability of finasteride to inhibit the Type II isoform of the 5alpha-reductase enzyme, which is the predominant form in human prostate and hair follicles, and the concomitant reduction of testosterone to dihydrotestosterone (DHT). In addition to catalyzing the rate-limiting step in the reduction of testosterone, both isoforms of the 5alpha-reductase enzyme are responsible for the reduction of progesterone and deoxycorticosterone to dihydroprogesterone (DHP) and dihydrodeoxycorticosterone (DHDOC), respectively. Recent preclinical data indicate that the subsequent 3alpha-reduction of DHT, DHP and DHDOC produces steroid metabolites with rapid non-genomic effects on brain function and behavior, primarily via an enhancement of gamma-aminobutyric acid (GABA)ergic inhibitory neurotransmission. Consistent with their ability to enhance the action of GABA at GABA(A) receptors, these steroid derivatives (termed neuroactive steroids) possess anticonvulsant, antidepressant and anxiolytic effects in addition to altering aspects of sexual- and alcohol-related behaviors. Thus, finasteride, which inhibits both isoforms of 5alpha-reductase in rodents, has been used as a tool to manipulate neuroactive steroid levels and determine the impact on behavior. Results of some preclinical studies and clinical observations with finasteride are described in this review article. The data suggest that endogenous neuroactive steroid levels may be inversely related to symptoms of premenstrual and postpartum dysphoric disorder, catamenial epilepsy, depression, and alcohol withdrawal.

This would suggest that a 5α-reductase inhibitor, like finasteride, that might be among Grandpa’s tablets might very well have an effect on someone with GABAa dysfunction, this includes very many people with autism, schizophrenia and Down Syndrome.

Whether the effect will be good or bad is hard to say, and may well depend on whether other drugs that target GABA or NMDA receptors are being used. Due to their other effects, 5α-reductase inhibitors are usually only used in adults.

Merck developed a lower dose form of finasteride, called Prospecia to treat baldness, usually in men.  It is 20% the normal potency used for BPH.

Side effects

The current BPH drugs cause side effects in some people.  PAK1 inhibitors may also have some side effects.

Conclusion

Going back in the days of living with your extended family might make treating many people’s autism much simpler.  It looks like many older people’s drugs can be repurposed for some types of autism (ion channel modifying diuretics, calcium channel blockers, statins, even potentially intranasal insulin in some).  Because older people’s drugs are so widely used they are well understood and inexpensive.  

Clearly the research on PAK inhibitors for LUTS/BPH is at an early stage, but there is a huge potential market.   A widely available PAK1 inhibitor might be a big help to some people with autism, neurofibromatosis, other RASopathies, not just Grandpa’s prostate.

In addition to FRAX486 and IPA3, why doesn’t someone try synthetic CAPE, i.e. without the bees, as a PAK inhibitor?

Bioactivity and chemical synthesis of caffeic acid phenethyl ester and its derivatives.

There is far more chance of a PAK1 inhibitor coming to market for LUTS/BPH, or certain cancers than for autism.  That is a fact of life.

As for 5α-reductase inhibitors, like finasteride, we know from Hardan’s study on Pregnenolone at Stanford that this hormone can have a positive effect and we know that various natural steroid metabolites will modulate GABA subunits.  So it is quite likely that finasteride is going have a behavioral effect.  Perhaps Hardan would like to trial finasteride 5mg and 1mg (Prospecia) in some adults with autism. I suspect it will make some people “worse” and others somewhat “better”; so please do not report the “average” response, highlight the nature of the positive responders.

Tuning Wnt Signaling for more/fewer hairs and to optimize Dendritic Spine Morphology in Autism

Today’s post is about another example of how evolution can play jokes on us.  It really is the case that a signaling pathway that controls hair growth is the same that determines the number and shape of dendritic spines in the brain.

This is good news not just for Homer Simpson but for people interesting in perking up behavior and cognitive function in autism.

The post also connects several subjects that we have previously encountered - dendritic spines which are abnormal in autism, Wnt signaling which is implicated in cancer (and autism), statins, Ivermectin, CAPE found in some propolis and verapamil.  There is plenty of research to back all these connections, but strangely nobody seems to be applying them to develop any practical therapies.

I introduced dendritic spines in an earlier post.  Each neuron in your brain has hundreds of protruding spines.

Dendritic Spines in Autism – Why, and potentially how, to modify them

In that post I reported that PAK1, the gene NrCAM and the protein MTOR were all implicated in the dysfunction in both shape and number of these spines.

It now seems that there may be one even more critical pathway involved – Wnt. There are links between Wnt and PAK1, that appeared in several earlier posts.

You may recall that dendritic spines are constantly changing shape.  Their shape affects their function.  In many disorders, both the number and shape of the spines is dysfunctional.  It appears that the morphology (shape) can be modified, which implies you could affect behavior, memory, and cognitive function.

My follow up post of dendritic spines has yet to materialize, but here is a sneak preview, showing the progression of autism, schizophrenia and Alzheimer’s in terms of the number of dendritic spines.

Dendritic Spines and Wnt Signaling

Dendritic spines are constantly changing their shape and certain psychiatric disorders are characterized by different morphologies (shapes) of these spines.  It is not just the number of spines, but their shape which affects cognitive function, memory and behavior.

The Wnt signaling pathway also lies behind hair growth.

What is more, we know that Wnt signaling is dysfunctional in autism and we even now which the genes are that likely trigger of this dysfunction.

Wnt dysfunction is also involved in many types of cancer and therefore has been subject of much research.

The surprise came when I read that attempts are underway to “tune” Wnt signaling to control hair growth.  Why not autism?

This post is about tuning Wnt signaling to improve cognitive function and behavior.  This appears just as plausible as controlling hair growth.

The Wnt Signaling Pathways

Here is the Wikipedia explanation.

Wnt signaling pathway

The Wnt signaling pathways are a group of signal transduction pathways made of proteins that pass signals from outside of a cell through cell surface receptors to the inside of the cell. Three Wnt signaling pathways have been characterized: the canonical Wnt pathway, the noncanonical planar cell polarity pathway, and the noncanonical Wnt/calcium pathway. All three Wnt signaling pathways are activated by the binding of a Wnt-protein ligand to a Frizzled family receptor, which passes the biological signal to the protein Dishevelled inside the cell. The canonical Wnt pathway leads to regulation of gene transcription, the noncanonical planar cell polarity pathway regulates the cytoskeleton that is responsible for the shape of the cell, and the noncanonical Wnt/calcium pathway regulates calcium inside the cell. Wnt signaling pathways use either nearby cell-cell communication (paracrine) or same-cell communication (autocrine). They are highly evolutionarily conserved, which means they are similar across many species from fruit flies to humans.^[1][2]
Wnt signaling was first identified for its role in carcinogenesis, but has since been recognized for its function in embryonic development. The embryonic processes it controls include body axis patterning, cell fate specification, cell proliferation, and cell migration. These processes are necessary for proper formation of important tissues including bone, heart, and muscle. Its role in embryonic development was discovered when genetic mutations in proteins in the Wnt pathway produced abnormal fruit fly embryos. Later research found that the genes responsible for these abnormalities also influenced breast cancer development in mice.
The clinical importance of this pathway has been demonstrated by mutations that lead to a variety of diseases, including breast and prostate cancer, glioblastoma, type II diabetes, and others.^[3][4]

The Canonical Wnt pathway is dysfunctional in Autism

It is the canonical Wnt pathway that is dysfunction in autism and it is this same pathway plays a role in dendrite growth and suboptimal Wnt activity negatively affects the dendritic arbor.

A very thorough review of all the genetic evidence is provided in the following study:

A review of the evidence for the canonical Wnt pathway in autism spectrum disorders

Notably, the available genetic information indicates that not only canonical Wnt pathway activation, but also inhibition seems to increase autism risk. The canonical Wnt pathway plays a role in dendrite growth and suboptimal activity negatively affects the dendritic arbor. In principle, this provides a logical explanation as to why both hypo- and hyperactivity may generate a similar set of behavioral and cognitive symptoms.

The review highlights that, as we have seen before, some people with autism are hypo and some people are hyper; this means some people need Wnt signaling to be inhibited and other people need the opposite therapy.  The author points out that you really need some test to check which way you need your Wnt “tuned”.  

It sounds a bit like tuning the timing of the sparks inside your car engine, in the days before it was all electronic and self-tuning.  In theory you needed to measure the timing of the sparks with a special strobe light; but if you knew what you were doing you could just use your ears.  So in the same vein, you could make a small change to inhibit Wnt and see the result, if it made matters worse you just stop and go the other way.  As you will see later in this post, some of us are already tuning Wnt without even realizing it.

We have exactly the same issue with mGluR5, where you might need a positive/negative allosteric modulator to optimize brain performance.  Different variants of “autism” would be located either left or right of “top dead center”.

In that post we learnt that at MIT they are suggesting that errors in synaptic protein synthesis are behind several types of autism and that these errors can be corrected using either positive or negative stimulators of the receptor mGluR5.

Ketamine, Memantine, D-Cycloserin, Magnesium, Fenobam and yet more as Glutamatergic Modulators in Autism (and Fragile X)

For a more detailed understanding of Wnt signaling, see the paper below:-

Wnt signal transduction pathways

For Homer Simpson and others wanting more hair

Tuning Wnt signals for more or fewer hairs

Abnormal hair development and regeneration has been implicated in diseases of the skin (ie., hirsutism, alopecia, etc) or in open wounds when hair follicles are completely eliminated. To manage these clinical conditions, it is important to understand molecular pathways which regulate the number, size, growth and regeneration of hair follicles. Wnt signaling plays a fundamental role in this process. We need a deeper understanding so we can reliably adjust Wnt levels in existing follicles. This studies reviewed here have future translational value for skin regeneration following severe wound injuries or in the context of tissue engineering. Tuning the levels of Wnt ligands can directly modulate the number and growth of hairs. Using this new knowledge, we now know that Wnt activity can be modulated by adjusting the secretion of Wnt ligands, altering binding of ligands to receptors, inhibiting β-catenin translocation, or by regulating extra-follicular dermal Wnt and Wnt inhibitors.

How to tune Dendritic Spine Morphology

We have already encounter Brain-Derived Neurotropic Factor  (BDNF) in an earlier post.  You could think of BDNF as brain fertilizer.

Human Growth Factors, Autism and the Centenarian Nobel Laureate

“Older people and anyone with Retts Syndrome are likely to benefit from more NGF (Nerve Growth Factor).  In autism it appears possible that there was too much NGF and BDNF at a very early age, with levels then changing.  High levels of NGF and BDNF look a bad idea.  A lot more research is needed to understand what determines  NGF and BDNF levels.  It appears that BDNF may stay high in autism, but NGF levels.”

It has been shown that BDNF and Wnt signaling together regulate dendritic spine formation.

So, since in autism we have excess BDNF as the brain is developing, this might explain there are too many dendritic spines in autistic brains.  Too many spines and the wrong morphology (shape) would explain very many issues that have gone “wrong” in autistic brains.

Neurotrophin and Wnt signaling cooperatively regulate dendritic spine formation

Here, we show that Wnt signaling inhibition in cultured cortical neurons disrupts dendritic spine development, reduces dendritic arbor size and complexity, and blocks BDNF-induced dendritic spine formation and maturation. Additionally, we show that BDNF regulates expression of Wnt2, and that Wnt2 is sufficient to promote cortical dendrite growth and dendritic spine formation. Together, these data suggest that BDNF and Wnt signaling cooperatively regulate dendritic spine formation.

BDNF overexpression rapidly and robustly increases primary dendrite formation in cortical neurons (Horch et al., 1999; McAllister et al., 1997; Wirth et al., 2003). We reproduced this finding, and found that this increase was not blocked by overexpression of the Wnt inhibitors (Fig. S2), indicating that some aspects of BDNF modulation of dendrites remain intact in the presence of Wnt inhibitors. To further assess whether expression of the Wnt inhibitors impaired the signaling ability of BDNF, we analyzed autocrine induction of c-Fos expression by BDNF overexpression. c-Fos is an immediate early gene whose transcription is rapidly upregulated by BDNF (Calella et al., 2007; Gaiddon et al., 1996). We found that BDNF induced c-Fos expression was not reduced in neurons overexpressing any of the four Wnt inhibitors, suggesting that the ability of the inhibitors to interfere with BDNF-induced spine formation and spine head width expansion was not a result of decreased levels of BDNF signaling (Fig. S3).

Fig. 5

Wnt2 overexpression is sufficient to increase cortical dendrite length. (A) Representative cortical neurons expressing either EV or Wnt2. Quantification of the total dendrite length per neuron (B) and the number of dendritic endpoints per neuron (C) for ...

Fig. 6

Wnt2 overexpression increases dendritic protrusion density and influences spine shape on cortical neurons. (A) Representative dendritic segments of cortical neurons expressing either EV or Wnt2. (B) Quantification of dendritic protrusion density. (C) ...

Wnt inhibition and dendritic spine maturation

We found that a series of different Wnt signaling inhibitors were able to block BDNF-induced increases in dendritic spine density and dendritic spine head width

I think all this existing science really tells us a lot.

Back in the slow lane

In cancer research, decades have already been spent investigating Wnt signaling.

Wnt Signaling Inhibition: Will Decades of Effort Be Fruitful at Last?

Drugs that Enhance Wnt Signaling

Back in my world, with a little help from Google scholar, I rapidly find that drugs already exist that affect Wnt signaling.  Some very familiar names pop up.

Simvastatin Promotes Adult Hippocampal Neurogenesis by Enhancing Wnt/β-Catenin Signaling

SummaryStatins improve recovery from traumatic brain injury and show promise in preventing Alzheimer disease. However, the mechanisms by which statins may be therapeutic for neurological conditions are not fully understood. In this study, we present the initial evidence that oral administration of simvastatin in mice enhances Wnt signaling in vivo. Concomitantly, simvastatin enhances neurogenesis in cultured adult neural progenitor cells as well as in the dentate gyrus of adult mice. Finally, we find that statins enhance Wnt signaling through regulation of isoprenoid synthesis and not through cholesterol. These findings provide direct evidence that Wnt signaling is enhanced in vivo by simvastatin and that this elevation of Wnt signaling is required for the neurogenic effects of simvastatin. Collectively, these data add to the growing body of evidence that statins may have therapeutic value for treating certain neurological disorders.Simvastatin rescues cerebrovascular and memory-related deficits in mouse models of Alzheimer disease (AD) (Li et al., 2006; Tong et al., 2009, 2012), and recent meta-analysis of clinical studies concluded that statins provide a slight benefit in the prevention of AD and all-type dementia (Wong et al., 2013). While these effects have been attributed to reduction of inflammation, reduced oxidative stress, upregulated PI3K/AKT signaling, and enhanced neurogenesis, the mechanisms by which statins are beneficial in neurological disorders are not fully understood.Simva is under investigation for its potential therapeutic effects outside of hyperlipidemia treatment. While statins have been reported to enhance Wnt signaling in vitro, it was heretofore not known whether statins can enhance this pathway in vivo and in the context of neurogenesis. Here we provide evidence that oral simva treatment enhances Wnt signaling in the mammalian adult hippocampus. This is significant in that aside from lithium, no other clinically approved compound has been demonstrated to enhance Wnt signaling in the brain

You will find the element Lithium in your smart phone battery, but it is also a drug.

Lithium is useful in the treatment of bipolar disorder. Lithium salts may also be helpful for related diagnoses, such as schizoaffective disorder and cyclic major depression. The active part of these salts is the lithium ion Li⁺.

But, not surprisingly, Lithium has other effects, like activating Wnt signaling.

Lithium activates the Wnt and phosphatidylinositol 3-kinase Akt signaling pathways to promote cell survival in the absence of soluble survival factors.

Drugs that inhibit Wnt Signaling

There are drugs with the opposite effect, inhibiting Wnt signaling.

Verapamil Protects against Cartilage Degradation in Osteoarthritis by Inhibiting Wnt/β-Catenin Signaling

Abstract

In past years, the canonical Wnt/β-catenin signaling pathway has emerged as a critical regulator of cartilage development and homeostasis. FRZB, a soluble antagonist of Wnt signaling, has been studied in osteoarthritis (OA) animal models and OA patients as a modulator of Wnt signaling. We screened for FDA-approved drugs that induce FRZB expression and suppress Wnt/β-catenin signaling. We found that verapamil, a widely prescribed L-type calcium channel blocker, elevated FRZB expression and suppressed Wnt/β-catenin signaling in human OA chondrocytes. Expression and nuclear translocation of β-catenin was attenuated by verapamil in OA chondrocytes. Lack of the verapamil effects in LiCl-treated and FRZB-downregulated OA chondrocytes also suggested that verpamil suppressed Wnt signaling by inducing FRZB. Verapamil enhanced gene expressions of chondrogenic markers of ACAN encoding aggrecan, COL2A1 encoding collagen type II α1, and SOX9, and suppressed Wnt-responsive AXIN2 and MMP3 in human OA chondrocytes. Verapamil ameliorated Wnt3A-induced proteoglycan loss in chondrogenically differentiated ATDC5 cells. Verapamil inhibited hypertrophic differentiation of chondrocytes in the explant culture of mouse tibiae. Intraarticular injection of verapamil inhibited OA progression as well as nuclear localizations of β-catenin in a rat OA model. We propose that verapamil holds promise as a potent therapeutic agent for OA by upregulating FRZB and subsequently downregulating Wnt/β-catenin signaling.

Repositioning verapamil—for Wnt of an OA treatment

The river blindness drug Ivermectin and related macrocyclic lactones inhibit WNT-TCF pathway responses in human cancer

AbstractConstitutive activation of canonical WNT-TCF signaling is implicated in multiple diseases, including intestine and lung cancers, but there are no WNT-TCF antagonists in clinical use. We have performed a repositioning screen for WNT-TCF response blockers aiming to recapitulate the genetic blockade afforded by dominant-negative TCF. We report that Ivermectin inhibits the expression of WNT-TCF targets, mimicking dnTCF, and that its low concentration effects are rescued by direct activation by TCF^VP16. Ivermectin inhibits the proliferation and increases apoptosis of various human cancer types. It represses the levels of C-terminal β-CATENIN phosphoforms and of CYCLIN D1 in an okadaic acid-sensitive manner, indicating its action involves protein phosphatases. In vivo, Ivermectin selectively inhibits TCF-dependent, but not TCF-independent, xenograft growth without obvious side effects. Analysis of single semi-synthetic derivatives highlights Selamectin, urging its clinical testing and the exploration of the macrocyclic lactone chemical space. Given that Ivermectin is a safe anti-parasitic agent used by > 200 million people against river blindness, our results suggest its additional use as a therapeutic WNT-TCF pathway response blocker to treat WNT-TCF-dependent diseases including multiple cancers.

Effects of Caffeic Acid Phenethyl Ester in Wnt/β-Catenin Signaling Pathway on Human Neuroglioma

Previous studies have revealed that its anti-tumor function could be attributed to its ability to suppress the abnormal Wnt/β-catenin signaling pathway

What about hair loss/gain?

To quote from  the previous study on hair loss gain:-

“Using this new knowledge, we now know that Wnt activity can be modulated by adjusting the secretion of Wnt ligands, altering binding of ligands to receptors, inhibiting β-catenin translocation, or by regulating extra-follicular dermal Wnt and Wnt inhibitors.”

We have now learnt that the drug Verapamil is thought to be a Wnt inhibitor.  So it would be fair to assume that hair loss would be reported as a side effect of using Verapamil.  Indeed it is.

Dermatologic

Dermatologic side effects have included rash (up to 1.4%). Diaphoresis has been reported with intravenous verapamil. Arthralgia and rash, exanthema, hair loss, hyperkeratosis, macules, sweating, urticaria, Stevens-Johnson syndrome, and erythema multiforme have been reported during open trials/postmarketing experience.

What about Statins and hair?

So many millions of people take statins, of course somebody would claim it causes hair loss (alopecia).  I think it should cause hair gain.  As with Verapamil the effect on the hair growth would be much greater if it was applied to the skin and not taken orally.  Maybe older people would not go to the doctor to complain about hair gain?

Do statins cause alopecia?

Summary

·        As hair loss is a generally accepted male characteristic, drug-induced alopecia may be mistaken as part of a natural process and therefore under reported.

·        There have been reports of alopecia associated with the use of all UK licensed statins but there is insufficient data to confidently attribute hair loss to statin use.

·        Case studies suggest an association but as yet there is insufficient information to suggest a mechanism, make comparisons of the individual incidence of alopecia between the various statins or propose a class effect.

·        The greatest number of reports of alopecia is for simvastatin but this may be related to a greater market share or length of time on market.

It would seem that enough people lose hair from Verapamil for it to be a published side effect.  The same is not true for statins and I think hair loss may be coincidental.

But, maybe too much and too little Wnt signaling cause hair loss ?

Recall earlier in this post that Hans Otto Kalkman suggested that both too much and too little Wnt might cause similar behavioral and cognitive symptoms.  Perhaps the same is true with hair growth.

The canonical Wnt pathway plays a role in dendrite growth and suboptimal activity negatively affects the dendritic arbor. In principle, this provides a logical explanation as to why both hypo- and hyperactivity may generate a similar set of behavioral and cognitive symptoms.

For optimal hair growth perhaps there is an optimal amount of Wnt signaling? 

That might explain why a small number of people find Wnt inhibitors (Verapamil) and drugs that enhance Wnt (statins) cause hair loss.

That might mean that people with very full hair have optimal Wnt signaling?

So advise Homer Simpson to find out whether his Wnt signaling is hyper or hypo.  Then he might find either simvastatin or verapamil brings back his full head of hair.

Wnt signaling and Diabetes

Yet again we find another connection between Diabetes and autism.

In the pancreas  β-cells produce insulin. In diabetics these β-cells get destroyed.  It appears that Wnt signaling is involved in controlling these β-cells.  It has been proposed that they could be protected via this pathway.

Role of Wnt signaling in the development of type 2 diabetes.

 

Abstract

Type 2 diabetes is characterized by insulin resistance, insulin deficiency, and hyperglycemia. Susceptibility to type 2 diabetes has been linked to Wnt signaling, which plays an important role in intestinal tumorigenesis. Carriers of variants of the transcription factor 7-like 2 gene, an important component of the Wnt pathway, are at enhanced risk for developing type 2 diabetes. The modulation of proglucagon expression by Wnt activity may partially explain the link between Wnt signaling and diabetes, and one of the transcriptional and processing products of the proglucagon gene, the glucagon-like peptide-1 (GLP-1), exhibits a wide variety of antidiabetogenic activities. GLP-1 stimulates Wnt signaling in pancreatic beta cells, enhancing cell proliferation; thus, positive feedback between GLP-1 and Wnt signaling may result in increased proliferation, and suppressed apoptosis, of pancreatic cells. Since beta-cell protection is a potential treatment for type 2 diabetes, stimulation of Wnt activity may represent a valid therapeutic approach.

Wnt signaling: relevance to β-cell biology and diabetes

Here, we review emerging new evidence that Wnt signaling influences endocrine pancreas development and modulates mature β-cell functions including insulin secretion, survival and proliferation. Alterations in Wnt signaling might also impact other metabolic tissues involved in the pathogenesis of diabetes, with TCF7L2 proposed to modulate adipogenesis and regulate GLP-1 production. Together, these studies point towards a role for Wnt signaling in the pathogenesis of type 2 diabetes, highlighting the importance of further investigation of this pathway to develop new therapies for this disease.

Future Prospects of Wnt-Targeted Therapy for Treatment of Type 2 Diabetes

As with autism and cancer, the people with diabetes are also perhaps not benefiting from the latest science.

Preventing β-Cell Loss and Diabetes With Calcium Channel Blockers

Oral verapamil administration prevents β-cell apoptosis and STZ-induced diabetes.

The End.