Down-Regulation of CRMP-1 in Patients with Epilepsy and a Rat Model

Mitochondrial protein prohibitin promotes learning memory recovery in mice following intracerebral hemorrhage via CAMKII/CRMP signaling pathway

Prohibitin (PHB) is a mitochondrial inner membrane protein with neuroprotective, antioxidant, and apoptosis-reducing effects. This study aimed to explore the role of PHB in pathological symptoms, behavioral deficits, and cognitive impairment in a collagenase-IV-induced intracerebral hemorrhage (ICH) murine model. In this study, mice that received collagenase IV injection were pretreated with PHB or saline 21 days prior to modeling. The role of PHB in memory and learning ability was monitored using the Morris water maze, Y-maze, and rotarod, social, startle, and nest-building tests. The effect of PHB on depression-like symptoms was examined using the forced swimming, tail suspension, and sucrose preference tests. Subsequently, mouse samples were analyzed using immunohistochemistry, western blotting, Perls staining, Nissl staining, and gene sequencing. Results showed that collagenase IV significantly induced behavioral deficits, brain edema, cognitive impairment, and depressive symptoms. PHB overexpression effectively alleviated memory, learning, and motor deficits in mice with ICH. PHB markedly inhibited the number of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling-positive cells and protein levels of ionized calcium-binding adapter molecule 1, glial fibrillary acidic protein, and interleukin-1β in the perihematomal region of ICH mice. PHB overexpression also remarkably promoted production of neurologin1 (NLGL1), and upregulated levels of Ca2+-calmodulin-dependent kinase II (CaMKII) and collapsin response mediator protein-1 (CRMP1) proteins. In conclusion, PHB overexpression can effectively alleviate the neurological deficits and neurodegeneration around the hematoma region. This may play a protective role by upregulating the expression of NLGL1 and promoting expression of CaMKII and CRMP1.

Inhibition of Crmp1 Phosphorylation at Ser522 Ameliorates Motor Function and Neuronal Pathology in Amyotrophic Lateral Sclerosis Model Mice

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive and fatal neurodegenerative disorder that affects upper and lower motor neurons; however, its pathomechanism has not been fully elucidated. Using a comprehensive phosphoproteomic approach, we have identified elevated phosphorylation of Collapsin response mediator protein 1 (Crmp1) at serine 522 in the lumbar spinal cord of ALS model mice overexpressing a human superoxide dismutase mutant (SOD1G93A). We investigated the effects of Crmp1 phosphorylation and depletion in SOD1G93A mice using Crmp1S522A (Ser522→Ala) knock-in (Crmp1ki/ki ) mice in which the S522 phosphorylation site was abolished and Crmp1 knock-out (Crmp1-/-) mice, respectively. Crmp1ki/ki /SOD1G93A mice showed longer latency to fall in a rotarod test while Crmp1-/-/SOD1G93A mice showed shorter latency compared with SOD1G93A mice. Survival was prolonged in Crmp1ki/ki /SOD1G93A mice but not in Crmp1-/-/SOD1G93A mice. In agreement with these phenotypic findings, residual motor neurons and innervated neuromuscular junctions (NMJs) were comparatively well-preserved in Crmp1ki/ki /SOD1G93A mice without affecting microglial and astroglial pathology. Pathway analysis of proteome alterations showed that the sirtuin signaling pathway had opposite effects in Crmp1ki/ki /SOD1G93A and Crmp1-/-/SOD1G93A mice. Our study indicates that modifying CRMP1 phosphorylation is a potential therapeutic strategy for ALS.

Proteogenomics Reveals Orthologous Alternatively Spliced Proteoforms in the Same Human and Mouse Brain Regions with Differential Abundance in an Alzheimer's Disease Mouse Model

Alternative splicing (AS) may increase the number of proteoforms produced by a gene. Alzheimer's disease (AD) is a neurodegenerative disease with well-characterized AS proteoforms. In this study, we used a proteogenomics strategy to build a customized protein sequence database and identify orthologous AS proteoforms between humans and mice on publicly available shotgun proteomics (MS/MS) data of the corpus callosum (CC) and olfactory bulb (OB). Identical proteotypic peptides of six orthologous AS proteoforms were found in both species: PKM1 (gene PKM/Pkm), STXBP1a (gene STXBP1/Stxbp1), Isoform 3 (gene HNRNPK/Hnrnpk), LCRMP-1 (gene CRMP1/Crmp1), SP3 (gene CADM1/Cadm1), and PKCβII (gene PRKCB/Prkcb). These AS variants were also detected at the transcript level by publicly available RNA-Seq data and experimentally validated by RT-qPCR. Additionally, PKM1 and STXBP1a were detected at higher abundances in a publicly available MS/MS dataset of the AD mouse model APP/PS1 than its wild type. These data corroborate other reports, which suggest that PKM1 and STXBP1a AS proteoforms might play a role in amyloid-like aggregate formation. To the best of our knowledge, this report is the first to describe PKM1 and STXBP1a overexpression in the OB of an AD mouse model. We hope that our strategy may be of use in future human neurodegenerative studies using mouse models.

Semaphorins in Adult Nervous System Plasticity and Disease

Semaphorins, originally discovered as guidance cues for developing axons, are involved in many processes that shape the nervous system during development, from neuronal proliferation and migration to neuritogenesis and synapse formation. Interestingly, the expression of many Semaphorins persists after development. For instance, Semaphorin 3A is a component of perineuronal nets, the extracellular matrix structures enwrapping certain types of neurons in the adult CNS, which contribute to the closure of the critical period for plasticity. Semaphorin 3G and 4C play a crucial role in the control of adult hippocampal connectivity and memory processes, and Semaphorin 5A and 7A regulate adult neurogenesis. This evidence points to a role of Semaphorins in the regulation of adult neuronal plasticity. In this review, we address the distribution of Semaphorins in the adult nervous system and we discuss their function in physiological and pathological processes.

Appropriateness of array-CGH in the ADHD clinics: A comparative study

Attention deficit hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorder with a worldwide prevalence of about 5%. The disorder is characterized by inattentive, hyperactive and impulsive behavior and is often comorbid with other neuropsychiatric conditions. Array comparative genomic hybridization (array-CGH) testing has been proved to be useful to detect chromosomal aberrations in several neuropsychiatric conditions including autism spectrum disorders (ASD) and intellectual disability (ID). The usefulness of array-CGH in the ADHD clinics is still debated and no conclusive evidence has been reached to date. We performed array-CGH in 98 children and adolescents divided in two similarly sized groups according to the clinical diagnosis: (a) one group diagnosed with ADHD as primary diagnosis; (b) the other group in which ADHD was co-morbid with ASD and/or ID. We detected pathogenetic and likely pathogenetic copy number variants (CNVs) in 12% subjects in which ADHD was co-morbid with autism and/or intellectual disability and in 8.5% subjects diagnosed with ADHD as primary diagnosis. Detection of CNVs of unknown clinical significance was similar in the two groups being 27% and 32%, respectively. Benign and likely benign CNVs accounted for 61% and 59.5% in the first and second group, respectively. Differences in the diagnostic yield were not statistically significant between the two groups (P > .05). Our data strongly suggest that array-CGH (a) is a valuable diagnostic tool to detect clinically significant CNVs in individuals with ADHD even in the absence of comorbidity with ASD and/or ID and (b) should be implemented routinely in the ADHD clinics.

Copy number variation in 19 Italian multiplex families with autism spectrum disorder: Importance of synaptic and neurite elongation genes

Autism Spectrum Disorder (ASD) is endowed with impressive heritability estimates and high recurrence rates. Its genetic underpinnings are nonetheless very heterogeneous, with common, and rare contributing variants located in hundreds of different loci, each characterized by variable levels of penetrance. Multiplex families from single ethnic groups represent a useful means to reduce heterogeneity and enhance genetic load. We screened 19 Italian ASD multiplex families (3 triplets and 16 duplets, total N = 41 ASD subjects), using array-CGH (Agilent 180 K). Causal or ASD-relevant CNVs were detected in 36.6% (15/41) of ASD probands, corresponding to 36.8% (7/19) multiplex families with at least one affected sibling genetically positive. However, only in less than half (3/7) of positive families, affected siblings share the same causal or ASD-relevant CNV. Even in these three families, additional potentially relevant CNVs not shared by affected sib pairs were also detected. These results provide further evidence of genetic heterogeneity in ASD even within multiplex families belonging to a single ethnic group. Differences in CNV burden may likely contribute to the substantial clinical heterogeneity observed between affected siblings. In addition, Gene Ontology enrichment analysis indicates that most potentially causal or relevant ASD genes detected in our cohort belong to nervous system-specific categories, especially involved in neurite elongation and synaptic structure/function. These findings point toward the existence of genomic instability in these families, whose underlying genetic and epigenetic mechanisms deserve further scrutiny.

Differentially expressed proteins underlying childhood cortical dysplasia with epilepsy identified by iTRAQ proteomic profiling

Cortical dysplasia accounts for at least 14% of epilepsy cases, and is mostly seen in children. However, the understanding of molecular mechanisms and pathogenesis underlying cortical dysplasia is limited. The aim of this cross-sectional study is to identify potential key molecules in the mechanisms of cortical dysplasia by screening the proteins expressed in brain tissues of childhood cortical dysplasia patients with epilepsy using isobaric tags for relative and absolute quantitation-based tandem mass spectrometry compared to controls, and several differentially expressed proteins that are not reported to be associated with cortical dysplasia previously were selected for validation using real-time polymerase chain reaction, immunoblotting and immunohistochemistry. 153 out of 3340 proteins were identified differentially expressed between childhood cortical dysplasia patients and controls. And FSCN1, CRMP1, NDRG1, DPYSL5, MAP4, and FABP3 were selected for validation and identified to be increased in childhood cortical dysplasia patients, while PRDX6 and PSAP were identified decreased. This is the first report on differentially expressed proteins in childhood cortical dysplasia. We identified differential expression of FSCN1, CRMP1, NDRG1, DPYSL5, MAP4, FABP3, PRDX6 and PSAP in childhood cortical dysplasia patients, these proteins are involved in various processes and have various function. These results may provide new directions or targets for the research of childhood cortical dysplasia, and may be helpful in revealing molecular mechanisms and pathogenesis and/or pathophysiology of childhood cortical dysplasia if further investigated.

Neurofibromin Regulates Seizure Attacks in the Rat Pilocarpine-Induced Model of Epilepsy

Studies have shown that neurofibromin (NF1) restricts GABA release at inhibitory synapses and regulates dendritic spine formation, which may play an important role in temporal lobe epilepsy (TLE). NF1 expression was detected by double-label immunofluorescence, immunohistochemistry, and western blot analysis in the brains of pilocarpine-induced epilepsy model rats at 6 h, 24 h, 72 h, 7 days, 14 days, 30 days, and 60 days after kindling. NF1 was localized primarily in the nucleus and cytoplasm of neurons. NF1 protein levels significantly increased in the chronic phase (from 7 days until 60 days) in this epileptic rat model. After NF1 expression was knocked down by specific siRNA, the effects of kindling with pilocarpine were evaluated on the 7th day after kindling. The onset latencies of pilocarpine-induced seizures were elevated, and the seizure frequency and duration were reduced in these rats. Our study demonstrates that NF1 promoted seizure attacks in rats with pilocarpine-induced epilepsy.

CRMPs: critical molecules for neurite morphogenesis and neuropsychiatric diseases

Neuronal polarity and spatial rearrangement of neuronal processes are central to the development of all mature nervous systems. Recent studies have highlighted the dynamic expression of Collapsin-Response-Mediator Proteins (CRMPs) in neuronal dendritic/axonal compartments, described their interaction with cytoskeleton proteins, identified their ability to activate L- and N-type voltage-gated calcium channels (VGCCs) and delineated their crucial role as signaling molecules essential for neuron differentiation and neural network development and maintenance. In addition, evidence obtained from genome-wide/genetic linkage/proteomic/translational approaches revealed that CRMP expression is altered in human pathologies including mental (schizophrenia and mood disorders) and neurological (Alzheimer's, prion encephalopathy, epilepsy and others) disorders. Changes in CRMPs levels have been observed after psychotropic treatments, and disrupting CRMP2 binding to calcium channels blocked neuropathic pain. These observations, altogether with those obtained from genetically modified mice targeting individual CRMPs and RNA interference approaches, pave the way for considering CRMPs as potential early disease markers and modulation of their activity as therapeutic strategy for disorders associated with neurite abnormalities.

CRMP1 Inhibits Proliferation of Medulloblastoma and Is Regulated by HMGA1

Many facets of the tumor biology of medulloblastoma (MB) have not been fully elucidated. Collapsin response mediator protein 1 (CRMP1) is a member of cytoplasmic family of proteins that regulate the development of central nervous system. Recent studies demonstrated that CRMP1 could function as an invasion suppressor. We reported previously that high mobility group AT-hook 1 (HMGA1) contributed to development of MB and regulated its growth and migration/invasion. Transcriptional profiling and quantitative RT-PCR revealed increased expression of CRMP1 in HMGA1-depleted cells, suggesting that CRMP1 may be a downstream target of HMGA1 in MB. In this study, we showed HMGA1 can bind CRMP1 promoter by chromatin immunoprecipitation (ChIP) assay. Luciferase assay demonstrated a marked enhancement of CRMP1 transcription activity in HMGA1-depleted cells. Furthermore, quantitative RT-PCR revealed a negative correlation between HMGA1 and CRMP1 in 32 MB samples. To investigate the biological roles of CRMP1 in MB pathogenesis, we established MB clones stably expressing CRMP1. Functional analysis revealed that expression of CRMP1 significantly inhibited proliferation, migration, invasion and formation of filopodia and intense stress fiber of MB cells. Our data suggest that HMGA1 regulates CRMP1 expression and CRMP1 is implicated in MB pathogenesis.