A specific inhibitor of janus kinase-3 increases survival in a transgenic mouse model of amyotrophic lateral sclerosis

Dioxinodehydroeckol: A Potential Neuroprotective Marine Compound Identified by In Silico Screening for the Treatment and Management of Multiple Brain Disorders

Neurodegenerative disorders such as Alzheimer's disease (AD), Glioblastoma multiforme (GBM), Amyotrophic lateral sclerosis (ALS), and Parkinson's disease (PD) are some of the most prevalent neurodegenerative disorders in humans. Even after a variety of advanced therapies, prognosis of all these disorders is not favorable, with survival rates of 14-20 months only. To further improve the prognosis of these disorders, it is imperative to discover new compounds which will target effector proteins involved in these disorders. In this study, we have focused on in silico screening of marine compounds against multiple target proteins involved in AD, GBM, ALS, and PD. Fifty marine-origin compounds were selected from literature, out of which, thirty compounds passed ADMET parameters. Ligand docking was performed after ADMET analysis for AD, GBM, ALS, and PD-associated proteins in which four protein targets Keap1, Ephrin A2, JAK3 Kinase domain, and METTL3-METTL14 N6-methyladenosine methyltransferase (MTA70) were found to be binding strongly with the screened compound Dioxinodehydroeckol (DHE). Molecular dynamics simulations were performed at 100 ns with triplicate runs to validate the docking score and assess the dynamics of DHE interactions with each target protein. The results indicated Dioxinodehydroeckol, a novel marine compound, to be a putative inhibitor among all the screened molecules, which might be effective against multiple target proteins involved in neurological disorders, requiring further in vitro and in vivo validations.

The multifaceted functions of β-arrestins and their therapeutic potential in neurodegenerative diseases

Arrestins are multifunctional proteins that regulate G-protein-coupled receptor (GPCR) desensitization, signaling, and internalization. The arrestin family consists of four subtypes: visual arrestin1, β-arrestin1, β-arrestin2, and visual arrestin-4. Recent studies have revealed the multifunctional roles of β-arrestins beyond GPCR signaling, including scaffolding and adapter functions, and physically interacting with non-GPCR receptors. Increasing evidence suggests that β-arrestins are involved in the pathogenesis of a variety of neurodegenerative diseases, including Alzheimer's disease (AD), frontotemporal dementia (FTD), and Parkinson's disease (PD). β-arrestins physically interact with γ-secretase, leading to increased production and accumulation of amyloid-beta in AD. Furthermore, β-arrestin oligomers inhibit the autophagy cargo receptor p62/SQSTM1, resulting in tau accumulation and aggregation in FTD. In PD, β-arrestins are upregulated in postmortem brain tissue and an MPTP model, and the β2AR regulates SNCA gene expression. In this review, we aim to provide an overview of β-arrestin1 and β-arrestin2, and describe their physiological functions and roles in neurodegenerative diseases. The multifaceted roles of β-arrestins and their involvement in neurodegenerative diseases suggest that they may serve as promising therapeutic targets.

Comparing therapeutic modulators of the SOD1 G93A Amyotrophic Lateral Sclerosis mouse pathophysiology

Introduction

Amyotrophic Lateral Sclerosis (ALS) is a paralyzing, multifactorial neurodegenerative disease with limited therapeutics and no known cure. The study goal was to determine which pathophysiological treatment targets appear most beneficial.

Methods

A big data approach was used to analyze high copy SOD1 G93A experimental data. The secondary data set comprised 227 published studies and 4,296 data points. Treatments were classified by pathophysiological target: apoptosis, axonal transport, cellular chemistry, energetics, neuron excitability, inflammation, oxidative stress, proteomics, or systemic function. Outcome assessment modalities included onset delay, health status (rotarod performance, body weight, grip strength), and survival duration. Pairwise statistical analysis (two-tailed t-test with Bonferroni correction) of normalized fold change (treatment/control) assessed significant differences in treatment efficacy. Cohen's d quantified pathophysiological treatment category effect size compared to "all" (e.g., all pathophysiological treatment categories combined).

Results

Inflammation treatments were best at delaying onset (d = 0.42, p > 0.05). Oxidative stress treatments were significantly better for prolonging survival duration (d = 0.18, p < 0.05). Excitability treatments were significantly better for prolonging overall health status (d = 0.22, p < 0.05). However, the absolute best pathophysiological treatment category for prolonging health status varied with disease progression: oxidative stress was best for pre-onset health (d = 0.18, p > 0.05); excitability was best for prolonging function near onset (d = 0.34, p < 0.05); inflammation was best for prolonging post-onset function (d = 0.24, p > 0.05); and apoptosis was best for prolonging end-stage function (d = 0.49, p > 0.05). Finally, combination treatments simultaneously targeting multiple pathophysiological categories (e.g., polytherapy) performed significantly (p < 0.05) better than monotherapies at end-stage.

Discussion

In summary, the most effective pathophysiological treatments change as function of assessment modality and disease progression. Shifting pathophysiological treatment category efficacy with disease progression supports the homeostatic instability theory of ALS disease progression.

Integrative Analysis of Motor Neuron and Microglial Transcriptomes from SOD1G93A Mice Models Uncover Potential Drug Treatments for ALS

Amyotrophic lateral sclerosis (ALS) is a fatal disease of motor neurons that mainly affects the motor cortex, brainstem, and spinal cord. Under disease conditions, microglia could possess two distinct profiles, M1 (toxic) and M2 (protective), with the M2 profile observed at disease onset. SOD1 (superoxide dismutase 1) gene mutations account for up to 20% of familial ALS cases. Comparative gene expression differences in M2-protective (early) stage SOD1^G93A microglia and age-matched SOD1^G93A motor neurons are poorly understood. We evaluated the differential gene expression profiles in SOD1^G93A microglia and SOD1^G93A motor neurons utilizing publicly available transcriptomics data and bioinformatics analyses, constructed biomolecular networks around them, and identified gene clusters as potential drug targets. Following a drug repositioning strategy, 5 small compounds (belinostat, auranofin, BRD-K78930611, AZD-8055, and COT-10b) were repositioned as potential ALS therapeutic candidates that mimic the protective state of microglia and reverse the toxic state of motor neurons. We anticipate that this study will provide new insights into the ALS pathophysiology linking the M2 state of microglia and drug repositioning.

The multifaceted role of kinases in amyotrophic lateral sclerosis: genetic, pathological and therapeutic implications

Amyotrophic lateral sclerosis is the most common degenerative disorder of motor neurons in adults. As there is no cure, thousands of individuals who are alive at present will succumb to the disease. In recent years, numerous causative genes and risk factors for amyotrophic lateral sclerosis have been identified. Several of the recently identified genes encode kinases. In addition, the hypothesis that (de)phosphorylation processes drive the disease process resulting in selective motor neuron degeneration in different disease variants has been postulated. We re-evaluate the evidence for this hypothesis based on recent findings and discuss the multiple roles of kinases in amyotrophic lateral sclerosis pathogenesis. We propose that kinases could represent promising therapeutic targets. Mainly due to the comprehensive regulation of kinases, however, a better understanding of the disturbances in the kinome network in amyotrophic lateral sclerosis is needed to properly target specific kinases in the clinic.

Targeting STATs in neuroinflammation: The road less traveled!

JAK/STAT transduction pathway is a highly conserved pathway implicated in regulating cellular proliferation, differentiation, survival and apoptosis. Dysregulation of this pathway is involved in the onset of autoimmune, haematological, oncological, metabolic and neurological diseases. Over the last few years, the research of anti-neuroinflammatory agents has gained considerable attention. The ability to diminish the STAT-induced transcription of inflammatory genes is documented for both natural compounds (such as polyphenols) and chemical drugs. Among polyphenols, quercetin and curcumin directly inhibit STAT, while Berberis vulgaris L. and Sophora alopecuroides L extracts act indirectly. Also, the Food and Drug Administration has approved several JAK/STAT inhibitors (direct or indirect) for treating inflammatory diseases, indicating STAT can be considered as a therapeutic target for neuroinflammatory pathologies. Considering the encouraging data obtained so far, clinical trials are warranted to demonstrate the effectiveness and potential use in the clinical practice of STAT inhibitors to treat inflammation-associated neurodegenerative pathologies.

Selection and Prioritization of Candidate Drug Targets for Amyotrophic Lateral Sclerosis Through a Meta-Analysis Approach

Amyotrophic lateral sclerosis (ALS) is a progressive and incurable neurodegenerative disease. Although several compounds have shown promising results in preclinical studies, their translation into clinical trials has failed. This clinical failure is likely due to the inadequacy of the animal models that do not sufficiently reflect the human disease. Therefore, it is important to optimize drug target selection by identifying those that overlap in human and mouse pathology. We have recently characterized the transcriptional profiles of motor cortex samples from sporadic ALS (SALS) patients and differentiated these into two subgroups based on differentially expressed genes, which encode 70 potential therapeutic targets. To prioritize drug target selection, we investigated their degree of conservation in superoxide dismutase 1 (SOD1) G93A transgenic mice, the most widely used ALS animal model. Interspecies comparison of our human expression data with those of eight different SOD1^G93A datasets present in public repositories revealed the presence of commonly deregulated targets and related biological processes. Moreover, deregulated expression of the majority of our candidate targets occurred at the onset of the disease, offering the possibility to use them for an early and more effective diagnosis and therapy. In addition to highlighting the existence of common key drivers in human and mouse pathology, our study represents the basis for a rational preclinical drug development.

Transcriptional analysis reveals distinct subtypes in amyotrophic lateral sclerosis: implications for personalized therapy

Amyotrophic lateral sclerosis (ALS) is an incurable disease, caused by the loss of the upper and lower motor neurons. The lack of therapeutic progress is mainly due to the insufficient understanding of complexity and heterogeneity underlying the pathogenic mechanisms of ALS. Recently, we analyzed whole-genome expression profiles of motor cortex of sporadic ALS patients, classifying them into two subgroups characterized by differentially expressed genes and pathways. Some of the deregulated genes encode proteins, which are primary targets of drugs currently in preclinical or clinical studies for several clinical conditions, including neurodegenerative diseases. In this review, we discuss in-depth the potential role of these candidate targets in ALS pathogenesis, highlighting their possible relevance for personalized ALS treatments.

Pharmacophore and Virtual Screening of JAK3 inhibitors

Janus kinase 3 (JAK3) is a non-receptor tyrosine kinases family of protein which is comprised of JAK1, JAK2, JAK3 and TYK2. It plays an important role in immune function and lymphoid development and it only resides in the hematopoietic system. Therefore, selective targeting JAK3 is a rational approach in developing new therapeutic molecule. In this study, about 116 JAK3 inhibitors were collected from the literature and were used to build four-point pharmacophore model using Phase (Schrodinger module). The statistically significant pharmacophore hypothesis of AAHR.92 with r2 value of 0.942 was used as 3D query to search against 3D database namely Zincpharmer. A total of 2, 27,483 compounds obtained as hit were subjected to high throughput virtual screening (HTVS module of Schrodinger). Among the hits, ten compounds with good G-score ranging from -12.96 to -11.18 with good binding energy to JAK3 were identified.

Microarray analysis of the global gene expression profile following hypothermia and transient focal cerebral ischemia

BACKGROUND

Hypothermia is one of the most robust experimental neuroprotective interventions against cerebral ischemia. Identification of molecular pathways and gene networks together with single genes or gene families that are significantly associated with neuroprotection might help unravel the mechanisms of therapeutic hypothermia.

MATERIAL AND METHODS

We performed a microarray analysis of ischemic rat brains that underwent 90 min of middle cerebral artery occlusion (MCAO) and 48 h of reperfusion. Hypothermia was induced for 4 h, starting 1 h after MCAO in male Wistar rats. At 48 h, magnetic resonance imaging (MRI) was performed for infarct volumetry, and functional outcome was determined by a neuroscore. The brain gene expression profile of sham (S), ischemia (I), and ischemia plus hypothermia (HI) treatment were compared by analyzing changes of individual genes, pathways, and networks. Real-time reverse-transcribed polymerase chain reaction (RT-PCR) was performed on selected genes to validate the data.

RESULTS

Rats treated with HI had significantly reduced infarct volumes and improved neuroscores at 48 h compared with I. Of 4067 genes present on the array chip, HI compared with I upregulated 50 (1.23%) genes and downregulated 103 (3.20%) genes equal or greater than twofold. New genes potentially mediating neuroprotection by hypothermia were HNRNPAB, HIG-1, and JAK3. On the pathway level, HI globally suppressed the ischemia-driven gene response. Twelve gene networks were identified to be significantly altered by HI compared with I. The most significantly altered network contained genes participating in apoptosis suppression.

CONCLUSIONS

Our data suggest that although hypothermia at the pathway level restored gene expression to sham levels, it selectively regulated the expression of several genes implicated in protein synthesis and folding, calcium homeostasis, cellular and synaptic integrity, inflammation, cell death, and apoptosis.

Differential regulation of proliferation and differentiation in neural precursor cells by the Jak pathway

Neuronal precursor cells (NPCs) are temporally regulated and have the ability to proliferate and differentiate into mature neurons, oligodendrocytes, and astrocytes in the presence of growth factors (GFs). In the present study, the role of the Jak pathway in brain development was investigated in NPCs derived from neurosphere cultures using Jak2 and Jak3 small interfering RNAs and specific inhibitors. Jak2 inhibition profoundly decreased NPC proliferation, preventing further differentiation into neurons and glial cells. However, Jak3 inhibition induced neuronal differentiation accompanied by neurite growth. This phenomenon was due to the Jak3 inhibition-mediated induction of neurogenin (Ngn)2 and NeuroD in NPCs. Jak3 inhibition induced NPCs to differentiate into scattered neurons and increased the expression of Tuj1, microtubule associated protein 2 (MAP2), Olig2, and neuroglial protein (NG)2, but decreased glial fibrillary acidic protein (GFAP) expression, with predominant neurogenesis/polydendrogenesis compared with astrogliogenesis. Therefore, Jak2 may be important for NPC proliferation and maintenance, whereas knocking-down of Jak3 signaling is essential for NPC differentiation into neurons and oligodendrocytes but does not lead to astrocyte differentiation. These results suggest that NPC proliferation and differentiation are differentially regulated by the Jak pathway.

Targeting protein kinases in central nervous system disorders

Protein kinases are a growing drug target class in disorders in peripheral tissues, but the development of kinase-targeted therapies for central nervous system (CNS) diseases remains a challenge, largely owing to issues associated specifically with CNS drug discovery. However, several candidate therapeutics that target CNS protein kinases are now in various stages of preclinical and clinical development. We review candidate compounds and discuss selected CNS protein kinases that are emerging as important therapeutic targets. In addition, we analyse trends in small-molecule properties that correlate with key challenges in CNS drug discovery, such as blood-brain barrier penetrance and cytochrome P450-mediated metabolism, and discuss the potential of future approaches that will integrate molecular-fragment expansion with pharmacoinformatics to address these challenges.

Design, power, and interpretation of studies in the standard murine model of ALS

Identification of SOD1 as the mutated protein in a significant subset of familial amyotrophic lateral sclerosis (FALS) cases has led to the generation of transgenic rodent models of autosomal dominant SOD1 FALS. Mice carrying 23 copies of the human SOD1(G93A) transgene are considered the standard model for FALS and ALS therapeutic studies. To date, there have been at least 50 publications describing therapeutic agents that extend the lifespan of this mouse. However, no therapeutic agent besides riluzole has shown corresponding clinical efficacy. We used computer modeling and statistical analysis of 5429 SOD1(G93A) mice from our efficacy studies to quantify the impact of several critical confounding biological variables that must be appreciated and should be controlled for when designing and interpreting efficacy studies. Having identified the most critical of these biological variables, we subsequently instituted parameters for optimal study design in the SOD1(G93A) mouse model. We retested several compounds reported in major animal studies (minocycline, creatine, celecoxib, sodium phenylbutyrate, ceftriaxone, WHI-P131, thalidomide, and riluzole) using this optimal study design and found no survival benefit in the SOD1(G93A) mouse for any compounds (including riluzole) administered by their previously reported routes and doses. The presence of these uncontrolled confounding variables in the screening system, and the failure of these several drugs to demonstrate efficacy in adequately designed and powered repeat studies, leads us to conclude that the majority of published effects are most likely measurements of noise in the distribution of survival means as opposed to actual drug effect. We recommend a minimum study design for this mouse model to best address and manage this inherent noise and to facilitate more significant and reproducible results among all laboratories employing the SOD1(G93A) mouse.

Neurodegeneration and peroxidases

Alzheimer's disease (AD), Parkinson's disease (PD) and amyotrophic lateral sclerosis (ALS) are neurodegenerative diseases that affect different parts of the central nervous system. However, a review of the literature indicates that certain biochemical reactions involved in neurodegeneration in these three diseases are quite similar and could be partly identical. This article critically examines the similarities and, based on data from our own and other laboratories, proposes a novel explanation for neurodegeneration in these three diseases. We identified about 20 commonalities that exist in the neurodegenerative process of each disease. We hypothesize that there are two enzyme-catalyzed pathways that operate in affected neurons: an oxidative pathway leading to destruction of various neuronal proteins and lipids, and an apoptotic pathway which the body normally uses to remove unwanted and dysfunctional cells. Data from many laboratories indicate that oxidative reactions are primarily responsible for neurodegeneration, whereas apoptosis may well be a secondary response to the presence of neurons that have already been severely damaged by oxidative reactions. Attempts to inhibit apoptosis for the purpose of attenuating progression of these diseases may therefore be only of marginal benefit. Specific oxidative reactions within affected neurons led us to propose that one or more heme peroxidases may be the catalyst(s) involved in oxidation of proteins and lipids. Support for this proposal is provided by the recent finding that amyloi-beta peptide may act as a peroxidase in AD. Possible participation of the peroxidase activity of cytochrome c, herein designated as cytochrome c(px) to distinguish it from yeast cytochrome c peroxidase, is discussed. Of special interest is our recent finding that many compounds that cause attenuation of neurodegeneration are inhibitors of the peroxidase activity of cytochrome c. Several inhibitors were subsequently identified as suicide substrates. Such inhibitors could be ideally suited for targeted clinical approaches aimed at arresting progression of neurodegeneration. Finally, it is possible that immobilized yet still active peroxidase(s) may be present in protein aggregates in AD, PD, and ALS. This activity could be the catalyst for the slow, self-perpetuating and irreversible degeneration of affected neurons that occurs over long periods of time in these neurodegenerative diseases.

Lost in translation: treatment trials in the SOD1 mouse and in human ALS

Therapeutic success in the superoxide dismutase (SOD1) mouse model of amyotrophic lateral sclerosis (ALS) has not translated into effective therapy for human ALS, calling into question the utility of such preclinical data for identifying therapeutic agents that are worthy of further study in humans. This random effects meta-analysis of treatment trials in the superoxide dismutase (SOD1) mouse was undertaken in order to explore possible reasons for this failure of translational research and to identify potential pharmacological interventions that might be used in either a preventative or therapeutic trial in familial ALS. Among studies in which treatment was initiated presymptomatically, the weighted mean differences (WMDs) comparing the active treatment to control treated animals were 12 days (onset), 13 days (survival) and 5 days (survival interval). Among studies in which treatment was initiated at the time of symptom onset, the WMDs were 15 days (survival) and 8 days (survival interval). Subgroup analysis suggests that drugs such as minocycline and Cox-2 inhibitors with an anti-inflammatory mechanism of action, and anti-oxidative agents such as creatine or the manganese porphyrin AEOL-10150, appear to be the most promising for preventative and therapeutic trials respectively in patients with familial ALS. These conclusions should be tempered by the methodological limitations of the relevant literature.

Soy isoflavones and cognitive function

There is growing interest in the physiological functions of soy isoflavones, especially in whether they affect cognitive function and have beneficial effects on neurodegenerative diseases. Here we review the recent evidence from clinical and experimental studies supporting a role for soy isoflavones in cognitive function. Soy isoflavones may mimic the actions and functions of estrogens on brain, and they have been shown to have positive effects on the cognitive function in females; however, studies on their effects on spatial memory have not provided consistent results in males. Although data from humans, cultures, and animal models are currently insufficient for elucidating the metabolism of soy isoflavone actions on cognitive function and the nervous system, we suggest two putative pathways; (1) an estrogen receptor-mediated pathway and (2) via the inhibition of tyrosine kinase, in particular by genistein, which is one of the soy isoflavones. Although soy isoflavones appear to have a positive effect on brain function, further research is needed to determine not only the efficacy but also the safety of soy isoflavones on the nervous system and cognitive function.

Janus kinase 3: a novel target for selective transplant immunosupression

Existing immunosuppressants inhibit lymphocyte activation and T cell cytokine signal transduction pathways, reducing the rate of acute rejection episodes to < 10%. However, the widespread tissue distribution of their molecular targets engenders pleiotropic toxicities. One strategy to address this problem seeks to identify compounds that selectively inhibit a target restricted in distribution to the lymphoid system. Janus kinase (Jak) 3 is such a molecule; it mediates signal transduction via the gamma common chain of lymphokine surface receptors. Disruption of this lymphoid-restricted enzyme would not be predicted to produce collateral damage in other organ systems. Development of selective Jak3 inhibitors has been difficult due to crossreactivity with its homologue, Jak2. In contrast to all other putative antagonists, which are discussed in detail herein, one Jak3 inhibitor, NC1153, shows at least 40-fold greater selective inhibition for Jak3 than for Jak2, is robustly synergistic with calcineurin antagonists, and, either alone or in combination with cyclosporin, produces no adverse effects in rodents preconditioned to be at heightened risk for nephrotoxicity, bone marrow suppression, or altered lipid metabolism.

Protein phosphorylation networks in motor neuron death

The disorder amyotrophic lateral sclerosis (ALS) is characterized by the death of specific groups of neurons, especially motor neurons, which innervate skeletal muscle, and neurons connecting the cerebral cortex with motor neurons, such as corticospinal tract neurons. There have been numerous attempts to elucidate why there is selective involvement of motor neurons in ALS. Recent observations have demonstrated altered activities and protein levels of diverse kinases in the brain and spinal cord of transgenic mice that overexpress a mutant superoxide dismutase (mSOD) gene that is found in patients with the familial form of ALS, as well as in patients who have died with ALS. These results suggest that the alteration of protein phosphorylation may be involved in the pathogenesis of ALS. The changes in protein kinase and phosphatase expression and activity can affect the activation of important neuronal neurotransmitter receptors such as NMDA receptors or other signaling proteins and can trigger, or modify, the process producing neuronal loss in ALS. These various kinases, phosphatases and signaling proteins are involved in many signaling pathways; however, they have close interactions with each other. Therefore, an understanding of the role of protein kinases and protein phosphatases and the molecular organization of protein phosphorylation networks are useful to determine the mechanisms of selective motor neuron death.

Amyotrophic lateral sclerosis: progress and prospects for treatment

Fifteen years ago, a role for excitotoxic damage in the pathology of amyotrophic lateral sclerosis (ALS) was postulated. This stimulated the development of riluzole, the only available treatment for the disease. Since then, the identification of abnormal forms of superoxide dismutase as the genetic basis of certain familial forms of ALS has provided a huge impetus to the search for new effective treatments for this devastating disease. Transgenic mouse models have been developed expressing these aberrant mutants that develop a form of motor neurone disease the progress of which can be slowed by riluzole. Studies in these mice have provided evidence for a role for excitotoxic, apoptotic and oxidative processes in the development of pathology. The mice can be used for testing molecules targeting these processes as potential therapies, to allow the most promising to be evaluated in humans. Several such agents are currently in clinical trials. Many previous clinical trials in ALS were insufficiently powered to demonstrate any relevant effect on disease progression. This situation has been to some extent remedied in the more recent trials, which have recruited many hundreds of patients. However, with the exception of studies with riluzole, the results of these have been disappointing. In particular, a number of large trials with neurotrophic agents have revealed no evidence for efficacy. Nonetheless, the need for large multinational trials of long duration limits the number that can be carried out and makes important demands on investment. For this reason, surrogate markers that can be used for rapid screening in patients of potential treatments identified in the transgenic mice are urgently needed.

Efficient three-drug cocktail for disease induced by mutant superoxide dismutase

There is currently no effective pharmacological treatment for amyotrophic lateral sclerosis (ALS). Because evidence suggests that multiple pathways may contribute to ALS pathogenesis, we tested in a mouse model of ALS (SOD1(G37R) mice) a combination approach consisting of three drugs for distinct targets in the complex pathway to neuronal death: minocycline, an antimicrobial agent that inhibits microglial activation, riluzole, a glutamate antagonist, and nimodipine, a voltage-gated calcium channel blocker. The efficacy of this three-drug cocktail was remarkable when administered in the diet from late presymptomatic stage (8-9 months). It delayed the onset of disease, slowed the loss of muscle strength, and increased the average longevity of SOD1(G37R) mice by 6 weeks. The protective effect of the treatment was corroborated by the reduced immunodetection signals for markers of gliosis and neurodegeneration in the spinal cord of SOD1(G37R) mice. These results indicate that such three-drug combination may represent an effective strategy for ALS treatment.

Protein kinase and protein phosphatase expression in the central nervous system of G93A mSOD over-expressing mice

The expressions of 78 protein kinases, 24 protein phosphatases and 31 phosphoproteins were investigated by Kinetworks trade mark analysis in brain and spinal cord tissue of transgenic mice over-expressing G93A mutant superoxide dismutase (mSOD), a murine model of amyotrophic lateral sclerosis (ALS). In the brains of affected mSOD mice, we observed increased expression of cAMP-dependent protein kinase (PKA, 111% increase compared with control), and protein phosphatase 2B Aalpha-catalytic subunit (calcineurin, 109% increase), and reductions in the levels of PAK3 (76% decrease) and protein phosphatase 2C Cbeta-subunit (32% decrease). Increased Ser259 phosphorylation of Raf1 (126% increase) in mSOD mice correlated with higher expression of p73 Raf1 (147% increase). There was also increased p73 Raf1 (69% increase) and Ser259 phosphorylation (45% increase) in the spinal cords of mSOD mice. While adducin underwent enhanced phosphorylation (alphaS724, 90% increase; gammaS662, 290% increase) in mSOD brain, its phosphorylation was lower in the mSOD spinal cord (alphaS724, 53% decrease; gammaS662, 46% decrease). In spinal cords of affected mSOD mice, we also observed elevated expression of casein kinase 1delta (CK1delta, 157% increase), JAK2 (84% increase), PKA (183% increase), protein kinase C (PKC) delta (123% increase), p124 PKC micro (142% increase), and RhoA kinase (221% increase), and enhanced phosphorylation of extracellular regulated kinases 1 (ERK1, T202/Y204, 90% increase), and 2 (ERK2, T185/Y187, 73% increase), p38 MAP kinase (T180/Y182, 1570% increase), and PKBalpha (T308, 154% increase; S473, 61% increase). There was also reduced phosphorylation of RB (S780, 45% decrease; S807/S811, 65% decrease), Src (Y418, 63% decrease) and p40 SAPK/JNKbeta (T183/Y185, 43% decrease). Variability in the expression of kinases, phosphatases and phosphorylation of their substrates was observed even in mutant animals having a similar phenotype. The expression and phosphorylation differences between mSOD and control mice were dissimilar to those between ALS patients and controls. This finding indicates that the activation of protein kinases and phosphoproteins is different with neuron loss in the mSOD mouse compared with that seen in patients with the sporadic form of ALS.

Altered levels and distribution of microtubule-associated proteins before disease onset in a mouse model of amyotrophic lateral sclerosis

Alterations of the axonal transport and microtubule network are potential causes of motor neurodegeneration in mice expressing a mutant form of the superoxide dismutase 1 (SOD1G37R) linked to amyotrophic lateral sclerosis (ALS). In the present study, we investigated the biology of microtubule-associated proteins (MAPs), responsible for the formation and stabilization of microtubules, in SOD1G37R mice. Our results show that the protein levels of MAP2, MAP1A, tau 100 kDa and tau 68 kDa species decrease significantly as early as 5 months before onset of symptoms in the spinal cord of SOD1G37R mice, whereas decrease in levels of tau 52-55 kDa species is most often noted with the manifestation of the clinical symptoms. Interestingly, there was no change in the protein levels of MAPs in the brain of SOD1G37R mice, a CNS organ spared by the mutant SOD1 toxicity. Remarkably, as early as 5 months before disease onset, the binding affinities of MAP1A, MAP2 and tau isoforms to the cytoskeleton decreased in spinal cord of SOD1G37R mice. This change correlated with a hyperphosphorylation of the soluble tau 52-55 kDa species at epitopes recognized by the antibodies AT8 and PHF-1. Finally, a shift in the distribution of MAP2 from the cytosol to the membrane is detected in SOD1G37R mice at the same stage. Thus, alterations in the integrity of microtubules are early events of the neurodegenerative processes in SOD1G37R mice.

Therapeutic developments in the treatment of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a progressive neurodegenerative disease characterised by the selective death of motor neurones. The mechanisms and processes responsible for the selective loss of motor neurones are still unknown, however several hypotheses have been put forward, including oxidative damage and/or toxicity from intracellular aggregates due to mutant superoxide dismutase-1 activity, axonal strangulation from cytoskeletal abnormalities, loss of trophic factor support and glutamate-mediated excitotoxicity. These theories are based on a better understanding of the genetics of amyotrophic lateral sclerosis and on biochemical and pathological analysis of post-mortem tissue. They have led to the development of appropriate animal and cell culture models, allowing the sequence of events in motor neuronal degeneration to be unravelled and potential therapeutic agents to be screened. Unfortunately, the majority of therapeutics found to be efficacious in the animal and cell culture models have failed in human trials. Riluzole is still the only proven therapy in humans, shown to extend survival of amyotrophic lateral sclerosis patients by approximately 3 months, but it has no effect on muscle strength. Other potential therapeutic approaches are being identified, including inhibition of caspase-mediated cell death, maintenance of mitochondrial integrity and energy production, regulation of glutamate homeostasis, reduction of inflammation and control of neurofilament synthesis. Hopefully, in the near future some new agents will be found that can alter the course of this devastating and fatal disease.

Jak3-regulated genes: DNA array analysis of concanavalin a-interleukin-2-activated chicken T cells treated with a specific jak3 inhibitor

Janus kinase 3 (Jak3) is important in the activation and proliferation of lymphoid cells and binds to the common gamma subunit of several cytokine receptors, including the interleukin-2 (IL-2) receptor (IL-2R). DNA arrays were used to measure mRNA levels of a large number of genes regulated by signaling through the Jak3 tyrosine kinase pathway by blocking concanavalin A (ConA)-IL-2-activated chicken splenic T cells with a specific Jak3 inhibitor (WHI-P154). Of the 635 genes detected by arrays containing about 1200 cDNAs, 12 were upregulated in control cells compared with inhibitor-treated cells, and 6 were expressed at higher levels in the inhibitor-treated group. By identifying genes that are directly or indirectly regulated by Jak3, we can gain insight into the roles of this key intermediate in avian T cell activation and further our understanding of intracellular signaling networks in the immune response.

Minocycline delays disease onset and mortality in a transgenic model of ALS

Microglial activation is thought to contribute to the progression of selective motor neuron death during amyotrophic lateral sclerosis (ALS). As minocycline has been shown to inhibit microglial activation, the therapeutic efficacy of this tetracycline derivative in the G93A mice model for familial ALS was tested. This drug with proven safety delayed disease onset and dose-dependently extended the survival of the G93A mice. At 120 days of age, minocycline protected mice from loss of motor neurons and from vacuolization. These results demonstrate that interference with immuno-inflammatory responses has a beneficial effect in the ALS mice model, suggesting this to be a potential new strategy to treat ALS.

Photochemical preparation of a pyridone containing tetracycle: a Jak protein kinase inhibitor

Jak3 is a protein tyrosine kinase that is associated with the shared gamma chain of receptors for cytokines IL2, IL4, IL7, IL9, and IL13. We have discovered that a pyridone-containing tetracycle (6) may be prepared from trisubstituted imidazole (5) in high yield by irradiation with >350 nm light. Compound 6 inhibits Jak3 with K(I)=5 nM; it also inhibits Jak family members Tyk2 and Jak2 with IC(50)=1 nM and murine Jak1with IC(50)=15 nM. Compound 6 was tested as an inhibitor of 21 other protein kinases; it inhibited these kinases with IC(50)s ranging from 130 nM to >10 microM. Compound 6 also blocks IL2 and IL4 dependent proliferation of CTLL cells and inhibits the phosphorylation of STAT5 (an in vivo substrate of the Jak family) as measured by Western blotting.

CYP1A-mediated metabolism of the Janus kinase-3 inhibitor 4-(4'-hydroxyphenyl)-amino-6,7-dimethoxyquinazoline: structural basis for inactivation by regioselective O-demethylation

Here we report the phase I metabolism of the rationally designed Janus kinase-3 (JAK) inhibitor 4-(4'-hydroxyphenyl)-amino-6,7-dimethoxyquinazoline (WHI-P131; JANEX-1). JANEX-1 was metabolized by the cytochrome P450 enzymes CYP1A1 and CYP1A2 in a regioselective fashion to form the biologically inactive 7-O-demethylation product 4-(4'-hydroxyphenyl)-amino-6-methoxy-7-hydroxyquinazoline (JANEX-1-M). Our molecular modeling studies indicated that the CYP1A family enzymes bind and demethylate JANEX-1 at the C-7 position of the quinazoline ring since the alternative binding conformation with demethylation at the C-6 position would result in a severe steric clash with the binding site residues. The metabolism of JANEX-1 to JANEX-1-M in pooled human liver microsomes followed Michaelis-Menten kinetics with V(max) and K(m) values (mean +/- S.D.) of 34.6 +/- 9.8 pmol/min/mg and 107.3 +/- 66.3 microM, respectively. alpha-Naphthoflavone and furafylline, which both inhibit CYP1A2, significantly inhibited the formation of JANEX-1-M in human liver microsomes. There was a direct correlation between CYP1A activities and the magnitude of JANEX-1-M formation in the liver microsomes from different animal species. A significantly increased metabolic rate for JANEX-1 was observed in Aroclor 1254-, beta-naphthoflavone-, and 3-methylcholanthrene-induced microsomes but not in clofibrate-, dexamethasone-, isoniazid-, and phenobarbital-induced microsomes. The formation of JANEX-1-M in the presence of baculovirus-expressed CYP1A1 and 1A2 was consistent with Michaelis-Menten kinetics. The systemic clearance of JANEX-1-M was much faster than that of JANEX-1 (5525.1 +/- 1926.2 ml/h/kg versus 1458.0 +/- 258.6 ml/h/kg). Consequently, the area under the curve value for JANEX-1-M was much smaller than that for JANEX-1 (27.5 +/- 8.0 versus 94.8 +/- 18.4 microM. h; P < 0.001).

Progress in the modeling of neurodegenerative diseases in transgenic mice

Transgenic mouse models exist for the major neurodegenerative diseases, including Alzheimer's disease, tauopathy and amyotrophic lateral sclerosis. Although many of the mice do not completely replicate the human disease they are intended to model, they have provided insight into the mechanisms that underlie disease etiology. In the case of the Alzheimer's disease and amyotrophic lateral sclerosis models, the mice have also provided a therapeutic testing ground for the testing of agents that have been shown to have considerable clinical promise.

Gene therapy for amyotrophic lateral sclerosis and other motor neuron diseases

There are several incurable diseases of motor neuron degeneration, including amyotrophic lateral sclerosis (ALS), primary lateral sclerosis, hereditary spastic hemiplegia, spinal muscular atrophy, and bulbospinal atrophy. Advances in gene transfer techniques coupled with new insights into molecular pathology have opened promising avenues for gene therapy aimed at halting disease progression. Nonviral preparations and recombinant adenoviruses, adeno-associated viruses, herpesviruses, and lentiviruses may ultimately transduce sufficient numbers of cerebral, brainstem, and spinal cord neurons for therapeutic applications. This could be accomplished by direct injection, transduction of lower motor neurons via retrograde transport after intramuscular injection, or cell-based therapies. Studies using transgenic mice expressing mutant superoxide dismutase 1 (SOD1), a model for one form of ALS, established that several proteins were neuroprotective, including calbindin, bcl-2, and growth factors. These same molecules promoted neuronal survival in other injury models, suggesting general applicability to all forms of ALS. Potentially correctable genetic lesions have also been identified for hereditary spastic hemiplegia, bulbospinal atrophy, and spinal muscular atrophy. Finally, it may be possible to repopulate lost corticospinal and lower motor neurons by transplanting stem cells or stimulating native progenitor populations. The challenge ahead is to translate these basic science breakthroughs into workable clinical practice.

Jaks and stats as therapeutic targets

Cytokines have critical functions in regulating immune responses. A large number of these factors bind related receptors termed the Type I and Type II families of cytokine receptors. These receptors activate Janus kinases (Jaks) and Stat family of transcription factors. The essential and specific function of Jaks and Stats is particularly well illustrated by human and mouse mutations. The possibility that these molecules could be targeted to produce novel immunosuppressive compounds is considered in this review.

Pharmaceutical intervention in the JAK/STAT signaling pathway

Many cytokines exert their effect via the JAK/STAT signal transduction pathway. Due to the medical relevance of many of these cytokines, they are being exploited, either directly, or through antagonists, as therapeutics for a variety of serious diseases. Currently, these therapeutics consist almost entirely of protein products, with all of their attendant drawbacks. Delineation of the signaling mechanisms for the cytokines, however, has allowed the design and implementation of a variety of cell-based and biochemical screens for small molecule mimics or antagonists of these cytokines. Several successful assays will be described along with the advantages of each type of assay. Use of assays of this type should make it possible to discover numerous small molecule cytokine modulators with significant utility in the clinic. Oncogene (2000).