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Showing posts with label PAK1. Show all posts
Showing posts with label PAK1. Show all posts

Thursday 27 July 2017

Targeting Dendritic Spines to Improve Cognitive Function and Behavior in Autism; plus Hair Loss/Graying



I have written several posts about dendritic spines and their varying shapes (morphology).  This sounds like a rather obscure subject, but it looks like it may be a key area where both behavior and cognition can be modified, even later in life.



Homer Simson after using a Wnt Activator 

Dendritic spines

In a typical neuron (brain cell) you have dendrites at one end and so-called axon terminals at the other. When neurons connect with each other, an axon terminal connects with a dendritic spine from another close by neuron.  Axons transmit electrochemical signals from one neuron to the dendrites of other neurons.  The junction formed between a dendritic spine and an axon terminal is called a synapse.







One neuron can have as many as 15,000 spines, some of which are picking up signals from axon terminals of other neurons.
The number and shape of these spines is constantly changing and not surprisingly defects in this process affect both cognition and behavior.
The other end of the neuron, with the axon terminals is much less studied.  The myelin sheath deserves a mention. This protective coating is constantly being repaired in a process called remyelination. MS (Multiple Sclerosis) is caused by damage to the myelin coating that does not self repair. A newly identified feature of autism is an abnormally thin layer of myelin. A lack of insulation along the axon will affect the flow of electrical signals.
Many factors are involved in dendritic spine morphology and plasticity. Many of the same factors are known to be disturbed in autism and other related dysfunctions (schizophrenia, bipolar, ADHD etc).
Recall that within autism there are two broad groups; the larger group has “too many” dendritic spines and the smaller group has “too few”. I am writing about the larger group. My post is a simplification of a complex subject.
Factors that influence dendritic spine morphology and plasticity include:- 

·        BDNF  (want less)

·        Estrogen  (want more)

·        Reelin (want more)

·        BCL2 (want more)

·        PAK1 (want less)

·        GSK3 beta (want more)

·        PTEN (want more)

All the above seem to work via

·        Wnt signaling (want less) 

BDNF is a growth factor within the brain, which tends to be elevated in most autism.
The female hormone estrogen seems to be reduced in male autism and this will have many effects via something called ROR alpha. There is also reduced expression of estrogen receptor beta.
Reelin is a protein that is critical in brain development and maintenance. Reelin is implicated in most brain diseases, including autism. It stimulates dendritic spine development. Reelin is found to be reduced in autism.
BCl2 is a very well-known cancer gene/protein. BCL2 is part of a broader family of genes/proteins that control cell growth/death. BCL2 is anti-apoptotic, meaning it encourages growth rather than cell death. You will find elevated BCL2 in cancers.  BCL2 is implicated in both schizophrenia and autism.
Bax is another key member of the BCL2 family. The BCL2 protein duels with Bax, its counteracting twin. When Bax is in excess, cells execute a death command. When BCL2 dominates, the program is inhibited and cells survive. In cancer you want more Bax.
Modulating BCL2/Bax has been proposed as an autism therapy in Japan.
BCL2 is found to be reduced in autism.
The Japanese proposed the use of Navitoclax, a drug responsible for inhibiting BCL2 production for the treatment of cancer. I think they want to activate BCL2 production. 
I covered PAK1 in some lengthy posts. This was what the Japanese Nobel Laureate at MIT was working on. In summary, a PAK1 inhibitor should be helpful in autism, schizophrenia and some cancer.  Some people with a condition called neurofibromatosis, where non-cancerous tumors grow, use a special kind of bee propolis that contains a substance called CAPE (caffeic acid phenethyl ester), that is a mild PAK1 inhibitor.


GSK3 beta plays a role in several key signaling pathways. Abnormal expression of GSK3 beta is associated with Bipolar disorder. One role played by GSK3 beta is in Wnt signaling, which then affects dendritic spines. A GSK3 beta inhibitor, like lithium, is a Wnt activator which will increase the number of dendritic spines.
PTEN is a tumor suppressor gene/protein that is also an autism gene.
PTEN deficiency results in abnormal arborization and myelination in humans. PTEN-deficient neurons in brains of animal models have increased synaptic spine density.
People with autism and PTEN mutations have large heads because they lacked enough PTEN to reign in cell growth (and head growth).  You would expect them to have increased synaptic spine density.
Note than in both autism/cancer genes (BCL2 and PTEN) the balance is shifted towards growth, which fits in with the broad concept of autism as a growth dysfunction.
Wnt signaling is a complex and only partially understood subject, that has been previously discussed in this blog.  The short version is that most people with autism and particularly the ones with large heads will likely have too much Wnt signaling as the result of their various metabolic “disturbances”. The best way to inhibit their Wnt signaling might be to counter their particular metabolic disturbances, so if you are one of the 2% of autism with a PTEN mutation, then increase your PTEN levels.  If this is not possible than any other way to inhibit Wnt might be effective.
In Bipolar, where GSK3 beta is a known risk gene, you want more dendritic spines and so you want a GSK3 beta inhibitor like lithium. 
I think lithium will have a negative effect on most autism. Within children diagnosed with autism, a minority may well better fit a diagnosis of bipolar.

OBJECTIVE:


Children with autism spectrum disorder (ASD) have higher rates of comorbid psychiatric disorders, including mood disorders, than the general child population. Although children with ASD may experience irritability (aggression, self-injury, and tantrums), a portion also experience symptoms that are typical of a mood disorder, such as euphoria/elevated mood, mania, hypersexuality, paranoia, or decreased need for sleep. Despite lithium's established efficacy in controlling mood disorder symptoms in the neurotypical population, lithium has been rarely studied in children with ASD.

METHODS:


We performed a retrospective chart review of 30 children and adolescents diagnosed with ASD by the Diagnostic and Statistical Manual of Mental Disorders, 4th ed., Text Revision (DSM-IV-TR) criteria who were prescribed lithium in order to assess target symptoms, safety, and tolerability. Clinical Global Impressions - Improvement (CGI-I) ratings were performed by two board-certified child psychiatrists with expertise in ASD. CGI-I scores were dichotomized into "improved" (CGI-I score of 1 or 2) or "not improved" (CGI-I score ≥3).

RESULTS:


Forty-three percent of patients who received lithium were rated as "improved" on the CGI-I. Seventy-one percent of patients who had two or more pretreatment mood disorder symptoms were rated as "improved." The presence of mania (p=0.033) or euphoria/elevated mood (p=0.041) were the pretreatment symptoms significantly associated with an "improved" rating. The mean lithium blood level was 0.70 mEq/L (SD=0.26), and the average length of lithium treatment was 29.7 days (SD=23.9). Forty-seven percent of patients were reported to have at least one side effect, most commonly vomiting (13%), tremor (10%), fatigue (10%), irritability (7%), and enuresis (7%).

CONCLUSIONS:


This preliminary assessment of lithium in children and adolescents with ASD suggests that lithium may be a medication of interest for those who exhibit two or more mood disorder symptoms, particularly mania or euphoria/elevated mood. A relatively high side effect rate merits caution, and these results are limited by the retrospective, uncontrolled study design. Future study of lithium in a prospective trial with treatment-sensitive outcome measures may be indicated.


Hair Growth and Graying 
One surprising observation is the apparent connection between dendritic spine modification and modifying growth/color of human hair.
The same pathway is involved in signaling growth and coloring in the hair on your head and growing the dendritic spines on the neurons inside your head. I have mentioned this once before in a previous post. It is relevant because if a substance is potent enough to affect your dendritic spines you would expect it also to have a visible effect on the hair, of at least some people.
For example one reader of this blog uses a PAK1 inhibitor to treat her case of autism and she found that it has a hair graying effect.

EdnrB Governs Regenerative Response of Melanocyte Stem Cells by Crosstalk with Wnt Signaling

Pigmented hair regeneration requires epithelial stem cells (EpSCs) and melanocyte stem cells (McSCs) in the hair follicle.

Thus far, only a handful of signals that regulate McSCs have been identified, including extrinsic signals, such as transforming growth factor beta (TGFB) and Wnts, which are provided by the epithelial niche. Wnt signaling induces activation of EpSCs to drive epithelial regeneration while coordinately inducing McSCs to proliferate and differentiate to pigment regenerating hair follicle


One known but uncommon side effect of my current favourite Wnt inhibitor, Mebendazole, is hair loss. Hair follicles require Wnt signaling and if there is too little Wnt signaling you will lose some hair.
BCL2 is a very important cancer gene/protein but it also plays a role in autism and in dendritic spine morphology.  Low levels of the protein BCl2 leads to premature graying.

The team then looked at what would happen if they 'knocked out' a gene in mice that is known to be important for cell survival.
Mice lacking this Bcl2 gene went grey shortly after birth.

The scientists believe the same principle might apply in humans, which would explain why some people - such as TV presenter Philip Schofield - go grey in their 20s, while others keep their dark locks into retirement.
  

BCL2 is known to be reduced in the reduced in the brains of people with autism, as is another substance called Reelin.  Both Reelin and Bcl-2 are needed for dendritic spines to develop correctly.  

Autism is a severe neurodevelopmental disorder with potential genetic and environmental causes. Cerebellar pathology including Purkinje cell atrophy has been demonstrated previously. We hypothesized that cell migration and apoptotic mechanisms may account for observed Purkinje cell abnormalities. Reelin is an important secretory glycoprotein responsible for normal layering of the brain. Bcl-2 is a regulatory protein responsible for control of programmed cell death in the brain. Autistic and normal control cerebellar corteces matched for age, sex, and post-mortem interval (PMI) were prepared for SDS-gel electrophoresis and Western blotting using specific anti-Reelin and anti-Bcl-2 antibodies. Quantification of Reelin bands showed 43%, 44%, and 44% reductions in autistic cerebellum (mean optical density +/- SD per 30 microg protein 4.05 +/- 4.0, 1.98 +/- 2.0, 13.88 +/- 11.9 for 410 kDa, 330 kDa, and 180 kDa bands, respectively; N = 5) compared with controls (mean optical density +/- SD per 30 microg protein, 7.1 +/- 1.6, 3.5 +/- 1.0, 24.7 +/- 5.0; N = 8, p < 0.0402 for 180 kDa band). Quantification of Bcl-2 levels showed a 34% to 51% reduction in autistic cerebellum (M +/- SD per 75 microg protein 0.29 +/- 0.08; N = 5) compared with controls (M +/- SD per 75 microg protein 0.59 +/- 0.31; N = 8, p < 0.0451). Measurement of beta-actin (M +/- SD for controls 7.3 +/- 2.9; for autistics 6.77 +/- 0.66) in the same homogenates did not differ significantly between groups. These results demonstrate for the first time that dysregulation of Reelin and Bcl-2 may be responsible for some of the brain structural and behavioral abnormalities observed in autism.  

Abstract

The development of distinct cellular layers and precise synaptic circuits is essential for the formation of well-functioning cortical structures in the mammalian brain. The extracellular protein Reelin through the activation of a core signaling pathway including the ApoER2 and VLDLR receptors and the adapter protein Dab1, controls the positioning of radially migrating principal neurons, promotes the extension of dendritic processes in immature forebrain neurons, and affects synaptic transmission. Here we report for the first time that the Reelin signaling pathway promotes the development of postsynaptic structures such as dendritic spines in hippocampal pyramidal neurons. Our data underscore the importance of Reelin as a factor that promotes the maturation of target neuronal populations and the development of excitatory circuits in the postnatal hippocampus. These findings may have implications for understanding the origin of cognitive disorders associated with Reelin deficiency.

While not everything relating to dendritic spines is variable, and hence potentially can be modified, much seems to be.
Rather like in this blog it took a few years to get a comprehensive view of the factors involved in neuronal chloride and extend the list of potential therapies, getting to the bottom of fine tuning dendritic spin morphology for improved behavior and cognition will be a complex task.
Much is already known.
Our reader AJ is busy looking at GSK3 beta inhibitors.
GSK3 beta is best known as a bipolar gene/protein, but it is becoming seen as an autism gene.


GSK3 is one of the few signaling mediators that play central roles in a diverse range of signaling pathways, including those activated by Wnts, hedgehog, growth factors, cytokines, and G protein-coupled ligands. Although the inhibition of GSK3-mediated β-catenin phosphorylation is known to be the key event in Wnt-β-catenin signaling, the mechanisms which underlie this event remain incompletely understood. The recent demonstration of GSK3 involvement in Wnt receptor phosphorylation illustrates the multifaceted roles that GSK3 plays in Wnt-β-catenin signaling. In this review, we will summarize these recent results and offer explanations, hypotheses, and models to reconcile some of these observations.
Recent advances indicate that GSK3 also plays a positive role in Wnt signal transduction by phosphorylating the Wnt receptors low density lipoprotein receptor-related protein (LRP5/6) and provide new mechanisms for the suppression of GSK3 activity by Wnt in β-catenin stabilization. Furthermore, GSK3 mediates crosstalk between signaling pathways and β-catenin-independent downstream signaling from Wnt.


it is known that glycogen synthase kinase 3β (GSK-3β) regulates both synaptic plasticity and memory. 
GSK-3β overexpression led to a general reduction in the number of dendritic spines. In addition, it caused a slight reduction in the percentage, head diameter and length of thin spines, whereas the head diameter of mushroom spines was increased.


Over the past 2 decades, neuroscientists have built a body of evidence that links not only bipolar disease, but other psychiatric disorders including autism and schizophrenia to abnormal brain development. In particular, they have found abnormalities in the numbers of synapses and in the shape of neurons at the points where they form synapses. Their studies have often implicated abnormal signaling in a brain pathway called Wnt, which is involved both in early brain development and later, more complex, refining of brain connections. The role of Wnt could help explain why lithium is effective: It blocks an enzyme called GSK-3 β, which is an inhibitor on the Wnt pathway. By boosting Wnt signaling, lithium could produce a therapeutic effect in psychiatric diseases in which the Wnt pathway is underpowered.

They then treated the mutant mice with lithium. Although the researchers acknowledge that rodents are an imperfect proxy for human mood disorders, they did observe that the animals’ symptoms markedly improved; studies of their brains also revealed normal numbers of spines. “That’s the key finding,” Cheyette says. “It suggests that lithium could have its well-known therapeutic effect on patients with bipolar disorder by changing the stability of spines in the brain.”







GSK3 has numerous effects.

Glycogen synthase kinase-3 (GSK-3) is a cytoplasmic serine/threonine protein kinase that phosphorylates and inhibits glycogen synthase, thereby inhibiting glycogen synthesis from glucose. However, this serine/threonine kinase is now known to regulate numerous cellular processes through a number of signaling pathways important for cell proliferation, stem cell renewal, apoptosis and development. Because of these diverse roles, malfunction of this kinase is also known to be involved in the pathogenesis of human diseases, such as nervous system disorders, diabetes, bone formation, inflammation, cancer and heart failure. Therefore, GSK-3 is recognized as an attractive target for the development of new drugs. The present review summarizes the roles of GSK-3 in the insulin, Wnt/β-catenin and hedgehog signaling pathways including the regulation of their activities. The roles of GSK-3 in the development of human diseases within the context of its participation in various signaling pathways are also summarized. Finally, the possibility of new drug development targeting this kinase is discussed with recent information about inhibitors and activators of GSK-3.  

Estradiol


The present study demonstrates that estradiol may trigger formation of new dendritic spines by activation of a cAMPregulated CREB phosphorylation. Induction of the CREB response requires activation of NMDA receptors, increased intracellularcalciumconcentrationsandcAMP-activatedPKA.These systems together then contribute to the CREB response, which in turn leads to the morphological changes seen with estradiol—i.e., spine formation. The biochemical and cellular routes leading from activated CREB to the morphological change in dendritic spine density are still uncharted.

Dendritic spines of the medial amygdala: plasticity, density, shape, and subcellular modulation by sex steroids.

The medial nucleus of the amygdala (MeA) is a complex component of the "extended amygdala" in rats. Its posterodorsal subnucleus (MePD) has a remarkable expression of gonadal hormone receptors, is sexually dimorphic or affected by sex steroids, and modulates various social behaviors. Dendritic spines show remarkable changes relevant for synaptic strength and plasticity. Adult males have more spines than females, the density of dendritic spines changes in the course of hours to a few days and is lower in proestrous and estrous phases of the ovarian cycle, or is affected by both sex steroid withdrawal and hormonal replacement therapy in the MePD. Males also have more thin spines than mushroom-like or stubby/wide ones. The presence of dendritic fillopodia and axonal protrusions in the MePD neuropil of adult animals reinforces the evidence for local plasticity. Estrogen affects synaptic and cellular growth and neuroprotection in the MeA by regulating the activity of the cyclic AMP response element-binding protein (CREB)-related gene products, brain-derived neurotrophic factor (BDNF), the anti-apoptotic protein B-cell lymphoma-2 (Bcl-2) and the activity-regulated cytoskeleton-related protein (Arc). These effects on signal transduction cascades can also lead to local protein synthesis and/or rearrangement of the cytoskeleton and subsequent numerical/morphological alterations in dendritic spines. Various working hypotheses are raised from these experimental data and reveal the MePD as a relevant region to study the effects of sex steroids in the rat brain.

PTEN 


CNS deletion of Pten in the mouse has revealed its roles in controlling cell size and number, thus providing compelling etiology for macrocephaly and Lhermitte-Duclos disease. PTEN mutations in individuals with autism spectrum disorders (ASD) have also been reported, although a causal link between PTEN and ASD remains unclear. In the present study, we deleted Pten in limited differentiated neuronal populations in the cerebral cortex and hippocampus of mice. Resulting mutant mice showed abnormal social interaction and exaggerated responses to sensory stimuli. We observed macrocephaly and neuronal hypertrophy, including hypertrophic and ectopic dendrites and axonal tracts with increased synapses. This abnormal morphology was associated with activation of the Akt/mTor/S6k pathway and inactivation of Gsk3β. Thus, our data suggest that abnormal activation of the PI3K/AKT pathway in specific neuronal populations can underlie macrocephaly and behavioral abnormalities reminiscent of certain features of human ASD.  


Mutations in phosphatase and tensin homolog deleted on chromosome ten (PTEN) are implicated in neuropsychiatric disorders including autism. Previous studies report that PTEN knockdown in neurons in vivo leads to increased spine density and synaptic activity. To better characterize synaptic changes in neurons lacking PTEN, we examined the effects of shRNA knockdown of PTEN in basolateral amygdala neurons on synaptic spine density and morphology using fluorescent dye confocal imaging. Contrary to previous studies in dentate gyrus, we find that knockdown of PTEN in basolateral amygdala leads to a significant decrease in total spine density in distal dendrites. Curiously, this decreased spine density is associated with increased miniature excitatory post-synaptic current frequency and amplitude, suggesting an increase in number and function of mature spines. These seemingly contradictory findings were reconciled by spine morphology analysis demonstrating increased mushroom spine density and size with correspondingly decreased thin protrusion density at more distal segments. The same analysis of PTEN conditional deletion in dentate gyrus demonstrated that loss of PTEN does not significantly alter total density of dendritic protrusions in the dentate gyrus, but does decrease thin protrusion density and increases density of more mature mushroom spines. These findings suggest that, contrary to previous reports, PTEN knockdown may not induce de novo spinogenesis, but instead may increase synaptic activity by inducing morphological and functional maturation of spines. Furthermore, behavioral analysis of basolateral amygdala PTEN knockdown suggests that these changes limited only to the basolateral amygdala complex may not be sufficient to induce increased anxiety-related behaviors. 


Aberrant regulation of WNT/β-catenin signaling has a crucial role in the onset and progression of cancers, where the effects are not always predictable depending on tumor context. In melanoma, for example, models of the disease predict differing effects of the WNT/β-catenin pathway on metastatic progression. Understanding the processes that underpin the highly context-dependent nature of WNT/β-catenin signaling in tumors is essential to achieve maximal therapeutic benefit from WNT inhibitory compounds. In this study, we have found that expression of the tumor suppressor, phosphatase and tensin homolog deleted on chromosome 10 (PTEN), alters the invasive potential of melanoma cells in response to WNT/β-catenin signaling, correlating with differing metabolic profiles. This alters the bioenergetic potential and mitochondrial activity of melanoma cells, triggered through regulation of pro-survival autophagy. Thus, WNT/β-catenin signaling is a regulator of catabolic processes in cancer cells, which varies depending on the metabolic requirements of tumors.

BDNF
A meta-analysis of blood BDNF in 887 patients with ASD and 901 control subjects demonstrated significantly higher BDNF levels in ASD compared to controls with the SMD of 0.47 (95% CI 0.07-0.86, p = 0.02). In addition subgroup meta-analyses were performed based on the BDNF specimen. The present meta-analysis study led to conclusion that BDNF might play role in autism initiation/ propagation and therefore it can be considered as a possible biomarker of ASD.

Dendritic spines are major sites of excitatory synaptic transmission and changes in their numbers and morphology have been associated with neurodevelopmental and neurodegenerative disorders. Brain-derived Neurotrophic Factor (BDNF) is a secreted growth factor that influences hippocampal, striatal and neocortical pyramidal neuron dendritic spine density. However, the mechanisms by which BDNF regulates dendritic spines and how BDNF interacts with other regulators of spines remain unclear. We propose that one mechanism by which BDNF promotes dendritic spine formation is through an interaction with Wnt signaling. 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.


Other Wnt inhibitors

Yet another anti-parasite drug, Niclosamide,  turns out to be a Wnt inhibitor. 


Not surprisingly, Niclosamide is now a candidate drug to treat several different types of cancer.  It is also thought to have great potential in suppressing the metastatic process of prostate cancer. Another extremely cheap drug, not available in the US.
Even the flavonoid quercetin can inhibit Wnt. 

Therapeutic Avenues

There certainly are many potential ways to fine tune dendritic spine morphology.
Some readers of this blog are already doing just that, perhaps not all realizing it. 
·        BDNF  (want less - TrkB inhibitor)

·        Estrogen 

·        Reelin (want more – statin via RAS activation)

·        BCL2 (want more – statin)

·        PAK1 (want less – PAK inhibitor, BIO30)

·        GSK3 beta (want more – GSK3 activator)

·        PTEN (want more – statin)

All the above seem to work via

·        Wnt signaling (want less – Mebendazole/Niclosamide etc)

If you inhibit GSK3 beta you activate Wnt. You need get things the right way around. 
Statins promote RAS signaling which appears to increase Reelin expression. 


Conclusion

Fine tuning dendritic spine morphology seems like a good target for those with MR/ID and also those with any kind of neurological disorder.
There appear to be many ways to achieve this.
It seems a plausible idea and in many ways seems more credible than the idea of a diuretic (bumetanide) raising some people’s IQ.
The big issue is which substances have sufficient potency, once they have crossed the blood brain barrier, to do anything at all.  This is an issue with all therapies targeting the brain, including bumetanide.
At least substances that can affect hair growth and color are making it through to the bloodstream, which is a start.
Does this mean that tuning your dendritic spines will inevitably make your hair turn grey or begin to thin?  I don’t think so. I think this will happen in people who have low to normal Wnt signaling to start with.
Do some people with naturally premature graying, or thinning, hair have low levels of Wnt signaling? Quite possibly. Are they more likely to have traits of bipolar/creativity? Look for actors with gray or thinning hair.
Do people with autism tend to have full heads of thicker hair, as well as bigger heads?
Do the minority of people with autism and small heads have thinning hair?
Some readers of this blog are already using statins to treat autism. As has been pointed out in earlier posts, other than lowing cholesterol, statins have potent anti-inflammatory effects and they also affect expression of RAS, PTEN and BCL2, all of which are implicated in autism and all affect dendritic spines. It seems plausible that these readers are already modifying dendritic spine morphology.




Saturday 24 June 2017

Modulating Wnt Signaling in Autism and Cancer








In earlier posts I have covered various signaling pathways such as Wnt, mTOR and the unusually sounding Hedgehog.
You can go into huge detail if you want to understand these pathways, or just take a more superficial view. In most cases, things only start to go wrong if you are hypo/hyper (too little/too much) in these pathways.
We saw with mTOR that most people with autism are likely to have too much activity and so might benefit from mTOR inhibition, but a minority will have the opposite status and stand to benefit from more mTOR activity.
When it comes to Wnt signaling the research suggests the same situation. Wnt signaling is likely to be aberrant, but both extremes exist.

Given the large volume of genetic data, analyzing each gene on its own is not a feasible approach and will take years to complete, let alone attempt to use the information to develop novel therapeutics. To make sense of independent genomic data, one approach is to determine whether multiple risk genes function in common signaling pathways that identify signaling “hubs” where risk genes converge. This approach has led to multiple pathways being implicated, such as synaptic signaling, chromatin remodeling, alternative splicing, and protein translation, among many others. In this review, we analyze recent and historical evidence indicating that multiple risk genes, including genes denoted as high-confidence and likely causal, are part of the Wingless (Wnt signaling) pathway. In the brain, Wnt signaling is an evolutionarily conserved pathway that plays an instrumental role in developing neural circuits and adult brain function.
While the human genetic data is an important supporting factor, it is not the only one. There are a number of mouse genetic knockout (KO) models targeting Wnt signaling molecules, describing molecular, cellular, electrophysiological, and behavioral deficits that are consistent with ASD and ID. Furthermore, the genes involved in Wnt signaling are of significant clinical interest because there are a variety of approved drugs that either inhibit or stimulate this pathway.
There are many drugs developed and tested as modulators of Wnt signaling in the cancer field that could potentially be repurposed for developmental cognitive disorders. In cases where a reduction in Wnt signaling is thought to underlie the pathology of the disorder, usage of compounds that elevated canonical Wnt signaling could be applied. An example of this is GSK-3β inhibitors that have failed in cancer trials but may be effective for ASDs and ID (e.g., Tideglusig, ClinicalTrials.gov identifier: NCT02586935). In cases where elevated Wnt signaling is thought to contribute to disease pathology, there are many potential options to inhibit canonical Wnt signaling using chemicals (Fig. 1) that inhibit the interaction between β-catenin and its targets (e.g., inhibiting β-catenin interaction with the TCF factors), disheveled inhibitors (through targeting of the PDZ domain which generally inhibit the Frizzled–PDZ interaction), and tankyrase inhibitors (e.g., XAV939, which induces the stabilization of axin by inhibiting the poly (ADP)-ribosylating enzymes tankyrase 1 and tankyrase 2)

In recent years, strong autism ties have cropped up for one group of genes in particular: those that make up a well-known signaling pathway called WNT, which also has strong links to cancer. This pathway is especially compelling because some people with autism carry mutations in various members of it, including one of its central players: beta-catenin1. What’s more, studies from the past year indicate that several of the strongest autism candidate genes, including CHD8 and PTEN, interact with this pathway.
“There might be a particular subgroup of genes associated with autism that could all be feeding into or be regulating this pathway,” says Albert Basson, reader in developmental and stem cell biology at King’s College London, who studies CHD8 and WNT. “That clearly has emerged as a relatively major theme over the last few years.”

The connection between cancer and some autism is over-activated pro-growth signaling pathways. Many signaling pathways have growth at one extreme and cell death at the other. In cancer you actually want cell death to suppress tumor growth; in much autism there is also too much growth.  
Many cancers are associated with elevated signaling of mTOR, Wnt and indeed Hedgehog.  These are targets for cancer drug therapy and so there is already a great deal known.
A complication is that in a developmental neurological condition, like autism, it also matters when these signaling pathways were/are disturbed. For example Wnt signaling is known to play a role in dendritic spines and synaptic pruning, some of this is an ongoing process but other parts are competed at an early age, so it would matter when you intervene to modulate these pathways.
Historically cancer therapies involve potent drugs, often with potent side effects, however in recent years there has been growing awareness that some safe existing drugs can have equally potent anti-cancer effects. Many of these drugs are anti-parasite drugs, but even the very widely used diabetes drug Metformin has been shown to have significant anti-cancer effects, not to forget Simvastatin.
Many autism pathways/genes play a role in cancer (RAS, PTEN) and the upstream targets considered in cancer research are also autism targets.  For example many human cancers are RAS dependent and in theory could be treated by a RAS inhibitor, but after decades of looking nobody has found one. So instead scientists go upstream to find another target that will indirectly reduce RAS. This led to the development of PAK1 inhibitors that will reduce RAS.
RAS plays a role in some types of intellectual disability and indeed autism. The collective term is RASopathy.  Logically, drugs that modulate RAS to treat cancer might be helpful in modulating RAS for some autism.
Most types of cancers are complex and so there are multiple potential targets to attack them, but also the same target can have multiple possible approaches. RAS dependent cancers can be targeted via Wnt and even Hedgehog signaling.
This may sound all very complicated but does it have any relevance to autism?
It apparently does because almost all these pathways are known to be disturbed hypo/hyper in autism.  This means that clever insights developed for cancer can be repurposed for autism.


Anti-parasite drugs and Cancer
It is indeed remarkable how many anti-parasite drugs have an anticancer effect and indeed there is a much maligned theory to justify this.



Quite possibly it is just a coincidence.
There are many ways to kill parasites, one of which involves starving them of ATP. ATP is the fuel that is produced in your mitochondria.
Cancer cells and many parasites use a very inefficient way to produce ATP that does not require oxygen. In normal human cells the process followed is known as OXPHOS, by which glucose and oxygen from the blood is converted into ATP (energy) is very efficient. Only when you run low on oxygen, like a marathon runner at the end of the race, can you run into trouble because there is not enough oxygen for OXPHOS.  What happens next is anaerobic respiration, when a different process takes over to make ATP. It is much less efficient and causes lactic acidosis which makes marathon runners' muscles hurt.
A cheap anti-parasite drug Pyrvinium targets anaerobic respiration and starves the parasite of ATP and thus kills it. Another common children’s anti-parasite drug albendazole also works by starving the parasite of ATP.
Other anti-parasite drugs work in different ways.
We already know from the autism trials of Suramin, another anti-parasite drug,  that it works via P2X and P2Y purinergic channels.
Ivermectin  binds to glutamate-gated chloride channels (GluCls) in the membranes of invertebrate nerve and muscle cells, causing increased permeability to chloride ions, resulting in cellular hyper-polarization, followed by paralysis and death.  Fortunately in mammals ivermectin does not cross the BBB.
Ivermectin is also a PAK1 inhibitor and a positive allosteric modulator of P2X7.
Both PAK1 and P2X7 are relevant to many cancers and so not surprisingly research shows that Ivermectin has an anti-cancer effect.
Ivermectin appears to have a positive effect in some autism, but strangely it does not cross the BBB.
Mebendazole is another extremely cheap children’s anti-parasite drug which has remarkable potential anti-cancer properties. It inhibits hedgehog signaling and, via the inhibition of TNIK, it is a Wnt inhibitor.
Unfortunately in the US the private sector has also noticed the anticancer effects of Mebendazole and albendazole and they have recently become astronomically expensive. Mebendazole (MBZ), which costs almost nothing in many countries, now costs hundreds of dollar per dose in the US under the name Emverm. Outside of the US, Mebendazole is OTC in many developed countries. In poor countries it is donated free by big pharma.
In the cancer research they consider taking advantage of the fact that cimetidine (a cheap H2 antihistamine) interacts with Mebendazole to increase its bioavailability. Cimetidine is by chance another generic drug also being considered to be repurposed for cancer.
While some anti-parasite drugs like Suramin have side effects or cannot be taken regularly like Ivermectin, others are seen as safe for continued use even at high doses (e.g. Mebendazole and albendazole).  

Anti-parasite drugs and Autism
Just as many anti-parasite drugs seem to have a positive effect on some cancers it looks likely that the same may be true for autism.  This does not mean that parasites cause either cancer or autism.
We know from Professor Naviaux that some people respond to Suramin.
Two people who comment on this blog have found their child responds to PAK1 inhibitors, one of which is the drug Ivermectin.
There are groups of people on the internet who think parasites cause autism and you will find some of them if you google “autism mebendazole”, but there are some very valid reasons why some people’s autism may respond to mebendazole, but nothing to do with little worms.

Potency of Anticancer drugs
Failed anticancer drugs are already considered as possible drugs to treat neurological conditions.
The same pathways do seem to be involved in some cancer and some neurological conditions, but the severity by which that pathway is affected may be very different, so a new drug may lack potency to treat a type of cancer but be potent enough to benefit others.
In the case of the anti-parasite drugs Ivermectin and indeed mebendazole the dosage being used in current cancer studies are very much higher than normally used.
Very little mebendazole makes its way out of your intestines and so researchers counter this by using a dose 15 times higher and even taking advantage of the interaction with the H2 antagonist cimetidine to boost bioavailability.
The standard human dose of Ivermectin is 3mg, but in the cancer trials (IVINCA trial - IVermectin IN CAncer) in Switzerland and Spain the trial dose is 12, 30 and 60 mg.
So when it comes to autism and the possible repurposing of these drugs, the cancer studies will give valuable safety information, but the likely dose required to fine-tune these signaling pathways will likely be a tiny fraction of the cancer dose.
The newly developed cancer drugs that fail in clinical trials, may have potential in autism but it is unlikely that anyone will develop them, test them and bring them to the market.
The clever thing for autism seems to be to keep an eye on the existing generic drugs considered to benefit the overlapping cancer pathways.

Conclusion
Aberrant Wnt signaling has been identified by researchers as playing a key role in autism; the Simons Foundation is among those now funding further research.

In practical terms you can be either hypo or hyper, but hyper seems more likely. It may be a case of shutting the stable door after the horse has bolted, because the ideal time to modulate Wnt signaling is probably as a baby, or before. Nonetheless some older people may indeed benefit from modulating Wnt; the Simons Foundation must also believe so.
In the case of people with hyperactive Wnt signaling, there is a case to make for the potential use of the cheap anti-parasite drug Mebendazole.
The drug Mebendazole (MBZ) can found in three states/polymorphs called Polymorph A, B or C. This is relevant because they do not cross the blood brain barrier to the same extent.


To treat brain tumors, or indeed potentially some autism, you need MBZ-B or MBZ-C, it looks like MBZ-A does not cross the blood brain barrier.
Fortunately, MBZ-C is  the polymorph found most commonly in generic mebendazole tablets.  
Ivermectin is known not to cross the blood brain barrier but yet has been shown to show anti-tumor activity in brain cancer. The anti-cancer effect is thought to be as a PAK1 inhibitor, but this effect must be occurring outside the brain. Some people do use Ivermectin for autism.
The people using Ivermectin for autism are told they cannot use it continuously. Perhaps as the high dose cancer trials evolve the safety advice may change.





Friday 19 August 2016

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. 



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 GABAA 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.