Protein kinase and protein phosphatase expression in amyotrophic lateral sclerosis spinal cord

Current clinical trials in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is caused by selective degeneration of motor neurons in the brain and spinal cord. There are still no other effective therapies 10 years after the approval of riluzole for the treatment of amyotrophic lateral sclerosis, but advances in drug development and screening are substantially increasing the number of potential therapeutic agents. This review provides an overview of clinical trial methodology in amyotrophic lateral sclerosis followed by a systematic evaluation of drugs that are presently in Phase I, II and III clinical trials. There is an emphasis on the scientific evidence supporting the selection of each drug being tested, as well as on trial design.

Inhibition of glycogen synthase kinase-3 suppresses the onset of symptoms and disease progression of G93A-SOD1 mouse model of ALS

Glycogen synthase kinase (GSK)-3 has recently been implicated in the pathogenesis of neurodegenerative diseases. Although the neuroprotective effects of GSK-3 inhibitors in Alzheimer's disease have been established, their effects on amyotrophic lateral sclerosis (ALS) have not been well defined. This study was undertaken to evaluate the effects of GSK-3 inhibition in the G93A-SOD1 mouse model of ALS. Groups of G93A-SOD1 mice were treated with varying concentrations of GSK-3 inhibitor VIII, a specific GSK-3 inhibitor that crosses the BBB, intraperitoneally 5 days a week after 60 days of age. The GSK-3 inhibitor VIII treatment significantly delayed the onset of symptoms and prolonged the life span of the animals, and inhibited the activity of GSK-3 in a concentration-dependent manner. Furthermore, this treatment preserved survival signals and attenuated death and inflammatory signals. These data suggest that GSK-3 plays an important role in the pathogenic mechanisms of ALS and that inhibition of GSK-3 could be a potential therapeutic candidate for ALS.

Overexpression of GRK2 in Alzheimer disease and in a chronic hypoperfusion rat model is an early marker of brain mitochondrial lesions

Heterotrimeric guanine nucleotide-binding (G) protein-coupled receptor kinases (GRKs) are cytosolic proteins that are known to contribute to the adaptation of the heptahelical G protein-coupled receptors (GPCRs) and to regulate downstream signals through these receptors. GPCRs mediate the action of messengers that are key modulators of cardiac and vascular cell function, such as growth and differentiation. GRKs are members of a multigene family, which are classified into three subfamilies and are found in cardiac, vascular and cerebral tissues. Increasing evidence strongly supports the hypothesis that vascular damage is an early contributor to the development of Alzheimer disease (AD) and/or other pathology that can mimic human AD. Based on this hypothesis, and since kinases of this family are known to regulate numerous receptor functions both in the brain, myocardium and elsewhere, we explored cellular and subcellular localization by immunoreactivity of G protein-coupled receptor kinase 2 (GRK2), also known as beta-adrenergic receptor kinase-1(betaARK1), in the early pathogenesis of AD and in ischemia reperfusion injury models of brain hypoperfusion. In the present study, we used the two-vessel carotid artery occlusion model, namely the 2-VO system that results in chronic brain hypoperfusion (CBH) and mimics mild cognitive impairment (MCI) and vascular changes in AD pathology. Our findings demonstrate the early overexpression of GRK2 member kinase in the cerebrovasculature, especially endothelial cells (EC) following CBH, as well as in select cells from human AD tissue. We found a significant increase in GRK2 immunoreactivity in the EC of AD patients and after CBH, which preceded any amyloid deposition. Since GRK2 activity is associated with certain compensatory changes in brain cellular compartments and in ischemic cardiac tissue, our findings suggest that chronic hypoperfusion initiates oxidative stress in these conditions and appears to be the main initiating injury stimulus for disruption of brain and cerebrovascular homeostasis and metabolism.

TDP-43 is a component of ubiquitin-positive tau-negative inclusions in frontotemporal lobar degeneration and amyotrophic lateral sclerosis

Ubiquitin-positive tau-negative neuronal cytoplasmic inclusions and dystrophic neurites are common pathological features in frontotemporal lobar degeneration (FTLD) with or without symptoms of motor neuron disease and in amyotrophic lateral sclerosis (ALS). Using biochemical and immunohistochemical analyses, we have identified a TAR DNA-binding protein of 43 kDa (TDP-43), a nuclear factor that functions in regulating transcription and alternative splicing, as a component of these structures in FTLD. Furthermore, skein-like inclusions, neuronal intranuclear inclusions, and glial inclusions in the spinal cord of ALS patients are also positive for TDP-43. Dephosphorylation treatment of the sarkosyl insoluble fraction has shown that abnormal phosphorylation takes place in accumulated TDP-43. The common occurrence of intracellular accumulations of TDP-43 supports the hypothesis that these disorders represent a clinicopathological entity of a single disease, and suggests that they can be newly classified as a proteinopathy of TDP-43.

Inhibitor of double stranded RNA-dependent protein kinase protects against cell damage induced by ER stress

Endoplasmic reticulum (ER)-stress is known to induce neuronal cell death and to play roles in neurodegenerative diseases. Phosphorylation of double stranded RNA-dependent protein kinase (PKR) has been demonstrated in brain tissues in patients with Alzheimer's, Parkinson's, and Huntington's diseases. Here, we examined the effect of a PKR inhibitor (an imidazolo-oxindole derivative that acts as an ATP-binding site-directed inhibitor of PKR) on the neuronal cell death induced by ER-stress in cultured human neuroblastoma cells (SH-SY5Y). Cell damage was induced by tunicamycin (an ER-stress inducer), and cell viability was measured by Hoechst 33342 and YO-PRO-1 double staining and by the resazurin-reduction test (to evaluate metabolic activity). Treatment with tunicamycin at 2 microg/ml for 24 h induced apoptotic cell death accompanied by nuclear condensation and/or fragmentation, and these cells were positive for YO-PRO-1 (early-phase apoptosis and necrosis indicator). Treatment with the PKR inhibitor at 0.1 or 0.3 microM led to a decrease in the number of apoptotic cells induced by tunicamycin. In the resazurin-reduction test, the PKR inhibitor (at 0.1 and 0.3 microM) concentration-dependently inhibited the tunicamycin-induced decrease in metabolic activity. On the other hand, treatment with the PKR inhibitor alone (at 0.3 microM) had no effect on cell morphology or viability (versus in normal control cells). These results indicate that inhibition of PKR activation may be neuroprotective against ER stress-induced cell damage.

Informatics-assisted Protein Profiling in a Transgenic Mouse Model of Amyotrophic Lateral Sclerosis

One of the causes of amyotrophic lateral sclerosis (ALS) is due to mutations in Cu,Zn-superoxide dismutase (SOD1). The mutant protein exhibits a toxic gain of function that adversely affects the function of neurons in the spinal cord, brain stem, and motor cortex. A proteomic analysis of protein expression in a widely used mouse model of ALS was undertaken to identify differences in protein expression in the spinal cords of mice expressing a mutant protein with the G93A mutation found in human ALS. Protein profiling was done on soluble and particulate fractions of spinal cord extracts using high throughput two-dimensional liquid chromatography coupled to tandem mass spectrometry. An integrated proteomics-informatics platform was used to identify relevant differences in protein expression based upon the abundance of peptides identified by database searching of mass spectrometry data. Changes in the expression of proteins associated with mitochondria were particularly prevalent in spinal cord proteins from both mutant G93A-SOD1 and wild-type SOD1 transgenic mice. G93A-SOD1 mouse spinal cord also exhibited differences in proteins associated with metabolism, protein kinase regulation, antioxidant activity, and lysosomes. Using gene ontology analysis, we found an overlap of changes in mRNA expression in presymptomatic mice (from microarray analysis) in three different gene categories. These included selected protein kinase signaling systems, ATP-driven ion transport, and neurotransmission. Therefore, alterations in selected cellular processes are detectable before symptomatic onset in ALS mouse models. However, in late stage disease, mRNA expression analysis did not reveal significant changes in mitochondrial gene expression but did reveal concordant changes in lipid metabolism, lysosomes, and the regulation of neurotransmission. Thus, concordance of proteomic and mRNA expression data within multiple categories validates the use of gene ontology analysis to compare different types of "omic" data.

Combined minocycline plus pyruvate treatment enhances effects of each agent to inhibit inflammation, oxidative damage, and neuronal loss in an excitotoxic animal model of Huntington's disease

The combination effects of minocycline (MC), a second-generation tetracycline compound and pyruvate (PY), a glycolysis end metabolite with antioxidant activity were investigated in the rat striatum following an excitotoxic insult. Striatal injection of quinolinic acid (QUIN) resulted in marked inflammation characterized by microgliosis, astrogliosis and enhanced expressions of pro-inflammatory enzymes inducible nitric oxide synthase and cyclooxygenase-2. Inflammatory responses were attenuated with administration of either MC or PY, however, the combination of both compounds was significantly more effective in reducing inflammation relative to MC or PY applied alone. Immunohistochemical analysis at 7 days post-intrastriatal QUIN injection showed extensive oxidative stress evident as lipid peroxidation, oxidative DNA damage and reactive oxygen species formation which was partially decreased by each agent applied separately but markedly inhibited with the combination of the two compounds. In addition, combination treatments significantly reduced neuronal loss in QUIN-injected striatum compared with the agents applied separately. Furthermore, long-term combination treatment decreased striatal lesions and inflammation after QUIN injection. These results demonstrate that MC and PY confer a considerably enhanced anti-inflammatory and neuroprotective efficacy when applied together and suggest this combinatorial procedure as a novel therapeutic strategy in neurodegenerative disorders such as Huntington's disease which exhibit excitotoxic insults.

Activated double-stranded RNA-dependent protein kinase and neuronal death in models of Alzheimer's disease

Neuronal death is a pathological hallmark of Alzheimer's disease. We have shown previously that phosphorylated double-stranded RNA-dependent protein kinase is present in degenerating hippocampal neurons and in senile plaques of Alzheimer's disease brains and that genetically down-regulating double-stranded RNA-dependent protein kinase activity protects against in vitro beta-amyloid peptide neurotoxicity. In this report, we showed that two double-stranded RNA-dependent protein kinase blockers attenuate, in human neuroblastoma cells, beta-amyloid peptide toxicity evaluated by caspase 3 assessment. In addition, we have used the newly engineered APP(SL)/presenilin 1 knock-in transgenic mice, which display a severe neuronal loss in hippocampal regions, to analyze the activation of double-stranded RNA-dependent protein kinase. Western blots revealed the increased levels of activated double-stranded RNA-dependent protein kinase and the inhibition of eukaryotic initiation factor 2 alpha activity in the brains of these double transgenic mice. Phosphorylated RNA-dependent protein kinase-like endoplasmic reticulum-resident kinase was also increased in the brains of these mice. The levels of activated double-stranded RNA-dependent protein kinase were also increased in the brains of patients with Alzheimer's disease. At 3, 6 and 12 months, hippocampal neurons display double stranded RNA-dependent protein kinase labelings in both the nucleus and the cytoplasm. Confocal microscopy showed that almost constantly activated double-stranded RNA-dependent protein kinase co-localized with DNA strand breaks in apoptotic nuclei of CA1 hippocampal neurons. Taken together these results demonstrate that double-stranded RNA-dependent protein kinase is associated with neurodegeneration in APP(SL)/presenilin 1 knock-in mice and could represent a new therapeutic target for neuroprotection.

Significance of Molecular Signaling for Protein Translation Control in Neurodegenerative Diseases

It has long been known that protein synthesis is inhibited in neurological disorders. Protein synthesis includes protein transcription and translation. While many studies about protein transcription have been done in the last decade, we are just starting to understand more about the impact of protein translation. Protein translation control can be accomplished at the initiation or elongation steps. In this review, we will focus on translation control at initiation. Neurons have long neurites in which proteins have to be transported from the cell body to the end of the neurite. Since supply of proteins cannot meet the need of neuronal activity at the spine, protein locally translated at the spine will be a good solution to replace the turnover of proteins. Therefore, local protein translation is an important mechanism to maintain normal neuronal functions. In this notion, we have to separate the concept of global and local protein translation control. Both global and local protein translation control modulate normal neuronal functions from development to cognitive functions. Increasing lines of evidence show that they also play significant roles in neurodegenerative diseases, e.g. neuronal apoptosis, synaptic degeneration and autophagy. We summarize all the evidence in this review and focus on the control at initiation. The new live-cell imaging technology together with photoconvertible fluorescent probes allows us to investigate newly translated proteins in situ. Protein translation control is another line to modulate neuronal function in neuron-neuron communication as well as in response to stress in neurodegenerative diseases.

Regulation of signaling phosphoproteins by epidermal growth factor and Iressa (ZD1839) in human endometrial cancer cells that model type I and II tumors

To understand how type I and II endometrial tumors uniquely respond to tyrosine kinase inhibitor treatments, we evaluated the signaling pathways of epidermal growth factor (EGF) receptor (EGFR) under the effects of EGF and Iressa (ZD1839, gefitinib) using Ishikawa H and Hec50co cells that model type I and II endometrial carcinomas, respectively. The cells were assayed for the expression of EGFR and both cell lines express an average of 100,000 EGFR per cell; however, Ishikawa H cells express higher levels of HER-2/neu compared with Hec50co cells (1.38 x 10(5) compared with 2.04 x 10(4), respectively). Using the Kinetworks multi-immunoblotting approach, which profiles 31 signaling phosphoproteins, the most striking result was that Hec50co cells show a higher number of basal phosphorylated sites compared with Ishikawa H cells. Furthermore, we identified targets of Iressa treatment in both cell lines. Iressa, at a dose of 1 micromol/L, blocked the autophosphorylation of EGFR in Ishikawa H and Hec50co cells with some distinctive effects on downstream effectors. Nevertheless, in both cell lines, EGF stimulated and Iressa blocked the major EGFR target mitogen-activated protein kinases extracellular signal-regulated kinase 1 and 2 equally. The high basal phosphorylation of numerous signaling molecules in Hec50co cells that were not inhibited by Iressa indicates that other growth factor pathways are active in addition to EGFR. We conclude that endometrial cancer cells that model type I and II carcinomas have the capacity to respond to EGFR inhibition as a therapeutic strategy; however, the response of the more aggressive type II tumors may be limited by the constitutive activation of other signaling pathways.

Reduced expression of kinase-associated phosphatase in cortical dendrites of MAP2-deficient mice

We previously demonstrated that cAMP-dependent protein kinase was reduced in the dendrites of MAP2-deficient mice. In this study, we compared the expression of various protein phosphatases (PPs) between wild-type and map2(-/-) dendrites. Kinase-associated phosphatase (KAP) was the only PP which showed difference between the two phenotypes: (1) the expression of KAP was reduced in map2(-/-) cortical dendrites, and (2) the amount of KAP bound to microtubules was reduced in map2(-/-) brains. We also demonstrated in cultured neuroblastoma cells that KAP is not only expressed in dividing cells, but also in the neurites of differentiated cells. Our findings propose that KAP, which has been reported to function in cell-cycle control, has an as yet uncovered role in regulating dendritic functions. We also propose MAP2-deficient mice as an ideal system for identifying protein phosphatases essential for dendritic functions.

ALS2/Alsin regulates Rac-PAK signaling and neurite outgrowth

Rac and its downstream effectors p21-activated kinase (PAK) family kinases regulate actin dynamics within growth cones to control neurite outgrowth during development. The activity of Rac is stimulated by guanine nucleotide exchange factors (GEFs) that promote GDP release and GTP binding. ALS2/Alsin is a recently described GEF that contains a central domain that is predicted to regulate the activities of Rac and/or Rho and Cdc42 activities. Mutations in ALS2 cause some recessive familial forms of amyotrophic lateral sclerosis (ALS) but the function of ALS2 is poorly understood. Here we demonstrate that ALS2 is present within growth cones of neurons, in which it co-localizes with Rac. Furthermore, ALS2 stimulates Rac but not Rho or Cdc42 activities, and this induces a corresponding increase in PAK1 activity. Finally, we demonstrate that ALS2 promotes neurite outgrowth. Defects in these functions may therefore contribute to motor neuron demise in ALS.

Role of GSK-3β activity in motor neuronal cell death induced by G93A or A4V mutant hSOD1 gene

Point mutations such as G93A and A4V in the human Cu/Zn-superoxide dismutase gene (hSOD1) cause familial amyotrophic lateral sclerosis (fALS). In spite of several theories to explain the pathogenic mechanisms, the mechanism remains largely unclear. Increased activity of glycogen synthase kinase-3 (GSK-3) has recently been emphasized as an important pathogenic mechanism of neurodegenerative diseases, including Alzheimer's disease and ALS. To investigate the effects of G93A or A4V mutations on the phosphatidylinositol-3-kinase (PI3-K)/Akt and GSK-3 pathway as well as the caspase-3 pathway, VSC4.1 motoneuron cells were transfected with G93A- or A4V-mutant types of hSOD1 (G93A and A4V cells, respectively) and, 24 h after neuronal differentiation, their viability and intracellular signals, including PI3-K/Akt, GSK-3, heat shock transcription factor-1 (HSTF-1), cytochrome c, caspase-3 and poly(ADP-ribose) polymerase (PARP), were compared with those of wild type (wild cells). Furthermore, to elucidate the role of the GSK-3beta-mediated cell death mechanism, alterations of viability and intracellular signals in those mutant motoneurons were investigated after treating the cells with GSK-3beta inhibitor. Compared with wild cells, viability was greatly reduced in the G93A and A4V cells. However, the treatment of G93A and A4V cells with GSK-3beta inhibitor increased their viability by activating HSTF-1 and by reducing cytochrome c release, caspase-3 activation and PARP cleavage. However, the treatment did not affect the expression of PI3-K/Akt and GSK-3beta. These results suggest that the G93A or A4V mutations inhibit PI3-K/Akt and activate GSK-3beta and caspase-3, thus becoming vulnerable to oxidative stress, and that the GSK-3beta-mediated cell death mechanism is important in G93A and A4V cell death.

Functional Genomics meets neurodegenerative disorders

The transcriptomic and proteomic techniques presented in part I (Functional Genomics meets neurodegenerative disorders. Part I: transcriptomic and proteomic technology) of this back-to-back review have been applied to a range of neurodegenerative disorders, including Huntington's disease (HD), Prion diseases (PrD), Creutzfeldt-Jakob disease, amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), frontotemporal dementia (FTD) and Parkinson's disease (PD). Samples have been derived either from human brain and cerebrospinal fluid, tissue culture cells or brains and spinal cord of experimental animal models. With the availability of huge data sets it will firstly be a major challenge to extract meaningful information and secondly, not to obtain contradicting results when data are collected in parallel from the same source of biological specimen using different techniques. Reliability of the data highly depends on proper normalization and validation both of which are discussed together with an outlook on developments that can be anticipated in the future and are expected to fuel the field. The new insight undoubtedly will lead to a redefinition and subdivision of disease entities based on biochemical criteria rather than the clinical presentation. This will have important implications for treatment strategies.

A signal transduction pathway model prototype I: From agonist to cellular endpoint

The postgenomic era is providing a wealth of information about the genes involved in many cellular processes. However, the ability to apply this information to understanding cellular signal transduction is limited by the lack of tools that quantitatively describe cellular signaling processes. The objective of the current studies is to provide a framework for modeling cellular signaling processes beginning at a plasma membrane receptor and ending with a measurable endpoint in the signaling process. Agonist-induced Ca(2+) mobilization coupled to down stream phosphorylation events was modeled using knowledge of in vitro and in vivo process parameters. The simulation process includes several modules that describe cellular processes involving receptor activation phosphoinositide metabolism, Ca(2+)-release, and activation of a calmodulin-dependent protein kinase. A Virtual Cell-based simulation was formulated using available literature data and compared to new and existing experimental results. The model provides a new approach to facilitate hypothesis-driven investigation and experimental design based upon simulation results. These investigations may be directed at the timing of multiple phosphorylation/dephosphorylation events affecting key enzymatic activities in the signaling pathway.

Neuroprotective effect of activity-dependent neurotrophic factor against toxicity from familial amyotrophic lateral sclerosis-linked mutant SOD1 in vitro and in vivo

Amyotrophic lateral sclerosis (ALS) is the most common fatal motor neuron disease, affecting mostly middle-aged people. There are no curative therapies for ALS. Several lines of evidence have supported the notion that the proapoptotic property of familial ALS (FALS)-linked mutant Cu/Zn-superoxide dismutase-1 (SOD1) genes may play an important role in the pathogenesis of some FALS cases. Here we found that activity-dependent neurotrophic factor (ADNF), a neurotrophic factor originally identified to have the anti-Alzheimer's disease (AD) activity, protected against neuronal cell death caused by FALS-linked A4T-, G85R- and G93R-SOD1 in a dose-responsive fashion. Notably, ADNF-mediated complete suppression of SOD1 mutant-induced neuronal cell death occurs at concentrations as low as 100 fM. ADNF maintains the neuroprotective activity even at concentrations of more than 1 nM. This is in clear contrast to the previous finding that ADNF loses its protective activity against neurotoxicity induced by AD-relevant insults, including some familial AD genes and amyloid beta peptide at concentrations of more than 1 nM. Characterization of the neuroprotective activity of ADNF against cell death caused by SOD1 mutants revealed that CaMKIV and certain tyrosine kinases are involved in ADNF-mediated neuroprotection. Moreover, in vivo studies showed that intracerebroventricularly administered ADNF significantly improved motor performance of G93A-SOD1 transgenic mice, a widely used model of FALS, although survival was extended only marginally. Thus, the neuroprotective activity of ADNF provides a novel insight into the development of curative drugs for ALS.

Increased phospho-adducin immunoreactivity in a murine model of amyotrophic lateral sclerosis

Adducins alpha, beta and gamma are proteins that link spectrin and actin in the regulation of cytoskeletal architecture and are substrates for protein kinase C and other signaling molecules. Previous studies have shown that expressions of phosphorylated adducin (phospho-adducin) and protein kinase C are increased in spinal cord tissue from patients who died with amyotrophic lateral sclerosis, a neurodegenerative disorder of motoneurons and other cells. However, the distribution of phospho-adducin immunoreactivity has not been described in the mammalian spinal cord. We have evaluated the distribution of immunoreactivity to serine/threonine-dependent phospho-adducin at a region corresponding to the myristoylated alanine-rich C kinase substrate-related domain of adducin in spinal cords of mice over-expressing mutant human superoxide dismutase, an animal model of amyotrophic lateral sclerosis, and in control littermates. We find phospho-adducin immunoreactivity in control spinal cord in ependymal cells surrounding the central canal, neurons and astrocytes. Phospho-adducin immunoreactivity is localized to the cell bodies, dendrites and axons of some motoneurons, as well as to astrocytes in the gray and white matter. Spinal cords of mutant human superoxide dismutase mice having motoneuron loss exhibit significantly increased phospho-adducin immunoreactivity in ventral and dorsal horn spinal cord regions, but not in ependyma surrounding the central canal, compared with control animals. Increased phospho-adducin immunoreactivity localizes predominantly to astrocytes and likely increases as a consequence of the astrogliosis that occurs in the mutant human superoxide dismutase mouse with disease progression. These findings demonstrate increased immunoreactivity against phosphorylated adducin at the myristoylated alanine-rich C kinase substrate domain in a murine model of amyotrophic lateral sclerosis. As adducin is a substrate for protein kinase C at the myristoylated alanine-rich C kinase substrate domain, the increased phospho-adducin immunoreactivity is likely a consequence of protein kinase C activation in neurons and astrocytes of the spinal cord and evidence for aberrant phosphorylation events in mutant human superoxide dismutase mice that may affect neuron survival.

PKR activation in neurodegenerative disease

Interferon-inducible, double-stranded RNA-dependent protein kinase PKR is well known as an early cellular responder to viral infection. Activation of PKR has been associated with a number of downstream cell stress and cell death events, including a generalized shutdown of protein translation, activation of caspase-8, participation in JNK and p38 MAPK pathways, activation of NF-kappaB, etc. Recently, the activation of PKR has also been described in several neurodegenerative diseases, including Huntington disease, Alzheimer disease, and amyotrophic lateral sclerosis. Although the relationship between PKR and these diseases is still unclear, the overlap between known functions of PKR and biochemical events that occur in these neuropathologies are discussed here.

Protein kinase and protein phosphatase expression in amyotrophic lateral sclerosis spinal cord

The Kinetworks trade mark multi-immunoblotting technique was used to evaluate the expressions of 78 protein kinases, 24 protein phosphatases and phosphorylation states of 31 phosphoproteins in thoracic spinal cord tissue from control subjects and patients having the sporadic form of amyotrophic lateral sclerosis (ALS). In both the cytosolic (C) and particulate (P) fractions of spinal cord from ALS patients as compared with controls, there were increased levels of calcium/calmodulin-dependent protein kinase kinase (CaMKK; C = 120% increase/P = 580% increase;% change, compared with control), extracellular regulated kinase 2 (ERK2; C = 120% increase/P = 170% increase), G protein-coupled receptor kinase 2 (GRK2; C = 140% increase/P = 140% increase), phospho-Y279/216 glycogen synthase kinase 3 alpha/beta (GSK3alpha/beta; C = 90% increase/P = 220% increase), protein kinase B alpha (PKBalpha; C = 360% increase/P = 200% increase), phospho-T638 PKCalpha/beta (C = 630% increase/P = 170% increase), cGMP-dependent protein kinase (PKG; C = 100% increase/P = 75% increase), phospho-T451 dsRNA-dependent protein kinase (PKR; C = 2600% increase/P = 3330% increase), ribosomal S6 kinase 1 (RSK1; C = 750% increase/P = 630% increase), phospho-T389 p70 S6 kinase (S6K; C = 1000% increase/P = 460% increase), and protein-tyrosine phosphatase 1 delta (PTP1delta; C = 43% increase/P = 70% increase). Cytosolic increases in phospho-alpha-S724/gamma-S662 adducin (C = 15650% increase), PKCalpha (C = 100% increase) and PKCzeta (C = 190% increase) were found in ALS patients as compared with controls, while particulate increases in cAMP-dependent protein kinase (PKA; 43% increase), protein kinase C beta (PKCbeta; 330% increase), and stress-activated protein kinase beta (SAPKbeta; 34% increase) were also observed. Cyclin-dependent kinase-associated phosphatase (KAP) was apparently translocated, as it was reduced (31% decrease) in cytosolic fractions but elevated (100% increase) in particulate fractions of ALS spinal cord tissue. Our observations indicate that ALS is associated with the elevated expression and/or activation of many protein kinases, including PKCalpha, PKCbeta, PKCzeta and GSK3alpha/beta, which may augment neural death in ALS, and CaMKK, PKBalpha, Rsk1, S6K, and SAPK, which may be a response to neuronal injury that potentially can mitigate cell death.

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.