Role of the N-methyl-d-aspartate receptors complex in amyotrophic lateral sclerosis

AbstractAmyotrophic lateral sclerosis (ALS) is an adult onset neurodegenerative disease pathologically characterized by the massive loss of motor neurons in the spinal cord, brain stem and cerebral cortex. There is a consensus in the field that ALS is a multifactorial pathology and a number of possible mechanisms have been suggested. Among the proposed hypothesis, glutamate toxicity has been one of the most investigated. Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor mediated cell death and impairment of the glutamate-transport system have been suggested to play a central role in the glutamate-mediated motor neuron degeneration. In this context, the role played by the N-methyl-d-aspartate (NMDA) receptor has received considerable less attention notwithstanding its high Ca2+ permeability, expression in motor neurons and its importance in excitotoxicity. This review overviews the critical role of NMDA-mediated toxicity in ALS, with a particular emphasis on the endogenous modulators of the NMDAR

Neurosteroids as Neuromodulators in the Treatment of Anxiety Disorders

Anxiety disorders are the most common psychiatric disorders. They are frequently treated with benzodiazepines, which are fast acting highly effective anxiolytic agents. However, their long-term use is impaired by tolerance development and abuse liability. In contrast, antidepressants such as selective serotonin reuptake inhibitors (SSRIs) are considered as first-line treatment but have a slow onset of action. Neurosteroids are powerful allosteric modulators of GABAA and glutamate receptors. However, they also modulate sigma receptors and they are modulated themselves by SSRIs. Both pre-clinical and clinical studies have shown that neurosteroid homeostasis is altered in depression and anxiety disorders and antidepressants may act in part through restoring neurosteroid disbalance. Moreover, novel drugs interfering with neurosteroidogenesis such as ligands of the translocator protein (18 kDa) may represent an attractive pharmacological option for novel anxiolytics which lack the unwarranted side effects of benzodiazepines. Thus, neurosteroids are important endogenous neuromodulators for the physiology and pathophysiology of anxiety and they may constitute a novel therapeutic approach in the treatment of these disorders

Benign dermatoses of the male genital areas: A review of the literature

The male genitalia are a common site of dermatoses. Patients with penile diseases often delay or avoid medical care due to anxiety and embarrassment. In this narrative review, we describe some of the main benign dermatoses localized to male genital, focusing on their epidemiology, clinical and dermoscopic features, as well as available therapies

Impact of Pharmacological Inhibition of Hydrogen Sulphide Production in the SOD1G93A-ALS Mouse Model

A number of factors can trigger amyotrophic lateral sclerosis (ALS), although its precise pathogenesis is still uncertain. In a previous study done by us, poisonous liquoral levels of hydrogen sulphide (H2S) in sporadic ALS patients were reported. In the same study very high concentrations of H2S in the cerebral tissues of the familial ALS (fALS) model of the SOD1G93A mouse, were measured. The objective of this study was to test whether decreasing the levels of H2S in the fALS mouse could be beneficial. Amino-oxyacetic acid (AOA)\u2014a systemic dual inhibitor of cystathionine--synthase and cystathionine- lyase (two key enzymes in the production of H2S)\u2014was administered to fALS mice. AOA treatment decreased the content of H2S in the cerebral tissues, and the lifespan of female mice increased by approximately ten days, while disease progression in male mice was not aected. The histological evaluation of the spinal cord of the females revealed a significant increase in GFAP positivity and a significant decrease in IBA1 positivity. In conclusion, the results of the study indicate that, in the animal model, the inhibition of H2S production is more eective in females. The findings reinforce the need to adequately consider sex as a relevant factor in AL

NOS1AP is a novel molecular target and critical factor in TDP-43 pathology

Cappelli et al. reported that Nitric Oxide Synthase 1 Adaptor Protein is a co-regulated transcript of the TAR DNA-binding protein 43 kDa, reduced in amyotrophic lateral sclerosis and frontotemporal lobar degeneration patients with TAR DNA-binding protein 43 kDa pathology. Overall, their results highlight Nitric Oxide Synthase 1 Adaptor Protein as a novel druggable disease-relevant gene in TAR DNA-binding protein 43 kDa-related proteinopathies.Many lines of evidence have highlighted the role played by heterogeneous nuclear ribonucleoproteins in amyotrophic lateral sclerosis. In this study, we have aimed to identify transcripts co-regulated by TAR DNA-binding protein 43 kDa and highly conserved heterogeneous nuclear ribonucleoproteins which have been previously shown to regulate TAR DNA-binding protein 43 kDa toxicity (deleted in azoospermia-associated protein 1, heterogeneous nuclear ribonucleoprotein -Q, -D, -K and -U). Using the transcriptome analyses, we have uncovered that Nitric Oxide Synthase 1 Adaptor Protein mRNA is a direct TAR DNA-binding protein 43 kDa target, and in flies, its modulation alone can rescue TAR DNA-binding protein 43 kDa pathology. In primary mouse cortical neurons, we show that TAR DNA-binding protein 43 kDa mediated downregulation of Nitric Oxide Synthase 1 Adaptor Protein expression strongly affects the NMDA-receptor signalling pathway. In human patients, the downregulation of Nitric Oxide Synthase 1 Adaptor Protein mRNA strongly correlates with TAR DNA-binding protein 43 kDa proteinopathy as measured by cryptic Stathmin-2 and Unc-13 homolog A cryptic exon inclusion. Overall, our results demonstrate that Nitric Oxide Synthase 1 Adaptor Protein may represent a novel disease-relevant gene, potentially suitable for the development of new therapeutic strategies

Activation of Phosphotyrosine-Mediated Signaling Pathways in the Cortex and Spinal Cord of SOD1G93A, a Mouse Model of Familial Amyotrophic Lateral Sclerosis

Degeneration of cortical and spinal motor neurons is the typical feature of amyotrophic lateral sclerosis (ALS), a progressive neurodegenerative disease for which a pathogenetic role for the Cu/Zn superoxide dismutase (SOD1) has been demonstrated. Mice overexpressing a mutated form of the SOD1 gene (SOD1G93A) develop a syndrome that closely resembles the human disease. The SOD1 mutations confer to this enzyme a “gain-of-function,” leading to increased production of reactive oxygen species. Several oxidants induce tyrosine phosphorylation through direct stimulation of kinases and/or phosphatases. In this study, we analyzed the activities of src and fyn tyrosine kinases and of protein tyrosine phosphatases in synaptosomal fractions prepared from the motor cortex and spinal cord of transgenic mice expressing SOD1G93A. We found that (i) protein phosphotyrosine level is increased, (ii) src and fyn activities are upregulated, and (iii) the activity of tyrosine phosphatases, including the striatal-enriched tyrosine phosphatase (STEP), is significantly decreased. Moreover, the NMDA receptor (NMDAR) subunit GluN2B tyrosine phosphorylation was upregulated in SOD1G93A. Tyrosine phosphorylation of GluN2B subunits regulates the NMDAR function and the recruitment of downstream signaling molecules. Indeed, we found that proline-rich tyrosine kinase 2 (Pyk2) and ERK1/2 kinase are upregulated in SOD1G93A mice. These results point out an involvement of tyrosine kinases and phosphatases in the pathogenesis of ALS

\u2018PathensTDP\u2019. Defining the role of hnRNP proteins in enhancing TDP-43 pathology

Heterogeneous ribonucleoproteins (hnRNPs) are a family of RNA-binding proteins (RBPs) implicated in several steps of RNA metabolism, including transcription, pre-mRNA splicing, mRNA transport and turnover. In particular, TDP-43 is a member of this family that was discovered in 2006 as the major component of ubiquitin-positive inclusions in brain tissues from ALS and FTLD patients. Since then, many additional RBPs have been found to play a role in neurological disorders. Unfortunately, these proteins do not represent good therapeutic targets due to the multitude of functions they play in cells. However, the identification of key transcripts regulated by their overexpression/depletion may represent a valid alternative. In the PathensTDP project we have focused on five hnRNPs (DAZAP1, hnRNPD, hnRNPK, hnRNPQ and hnRNPU) that we previously identified as strong functional modulators of TDP-43 activity in Drosophila and human cells. Our preliminary data following whole transcriptome analysis of neuronal-like cells depleted for each hnRNP, including TDP-43, have shown the presence of several commonly regulated mRNAs that could play an important role in modulating TDP-43 pathology. To assess the therapeutic implications of these candidate genes, we will now examine their effects on the synaptic plasticity/death-signalling pathways both in cellular and animal models

Autophagy and amyotrophic lateral sclerosis: The multiple roles of lithium

In a pilot clinical study that we recently published we found that lithium administration slows the progression of Amyotrophic Lateral Sclerosis (ALS) in human patients. This clinical study was published in addition with basic (in vitro) and pre-clinical (in vivo) data demonstrating a defect of autophagy as a final common pathway in the genesis of ALS. In fact, lithium was used as an autophagy inducer. In detailing the protective effects of lithium we found for the first time that this drug stimulates the biogenesis of mitochondria in the central nervous system and, uniquely in the spinal cord, it induces neuronogenesis and neuronal differentiation. In particular, the effects induced by lithium can be summarized as follows: (i) the removal of altered mitochondria and protein aggregates; (ii) the biogenesis of well-structured mitochondria; (iii) the suppression of glial proliferation; (iv) the differentiation of newly formed neurons in the spinal cord towards a specific phenotype. In this addendum we focus on defective autophagy as a "leit motif" in ALS and the old and novel features of lithium which bridge autophagy activation to concomitant effects that may be useful for the treatment of a variety of neurodegenerative disorders. In particular, the biogenesis of mitochondria and the increase of calbindin D 28K-positive neurons, which are likely to support powerful neuroprotection towards autophagy failure, mitochondriopathy and neuronal loss in the spinal cord

TDP-43 Epigenetic Facets and Their Neurodegenerative Implications

Since its initial involvement in numerous neurodegenerative pathologies in 2006, either as a principal actor or as a cofactor, new pathologies implicating transactive response (TAR) DNA-binding protein 43 (TDP-43) are regularly emerging also beyond the neuronal system. This reflects the fact that TDP-43 functions are particularly complex and broad in a great variety of human cells. In neurodegenerative diseases, this protein is often pathologically delocalized to the cytoplasm, where it irreversibly aggregates and is subjected to various post-translational modifications such as phosphorylation, polyubiquitination, and cleavage. Until a few years ago, the research emphasis has been focused particularly on the impacts of this aggregation and/or on its widely described role in complex RNA splicing, whether related to loss- or gain-of-function mechanisms. Interestingly, recent studies have strengthened the knowledge of TDP-43 activity at the chromatin level and its implication in the regulation of DNA transcription and stability. These discoveries have highlighted new features regarding its own transcriptional regulation and suggested additional mechanistic and disease models for the effects of TPD-43. In this review, we aim to give a comprehensive view of the potential epigenetic (de)regulations driven by (and driving) this multitask DNA/RNA-binding protein