Developmental regulation of dermal adipose tissue by BCL11b.

The distinct anatomic environment in which adipose tissues arise during organogenesis is a principle determinant of their adult expansion capacity. Metabolic disease results from a deficiency in hyperplastic adipose expansion within the dermal/subcutaneous depot; thus, understanding the embryonic origins of dermal adipose is imperative. Using single-cell transcriptomics throughout murine embryogenesis, we characterized cell populations, including Bcl11b + cells, that regulate the development of dermal white adipose tissue (dWAT). We discovered that BCL11b expression modulates the Wnt signaling microenvironment to enable adipogenic differentiation in the dermal compartment. Subcutaneous and visceral adipose arises from a distinct population of Nefl + cells during embryonic organogenesis, whereas Pi16 + /Dpp4 + fibroadipogenic progenitors support obesity-stimulated hypertrophic expansion in the adult. Together, these results highlight the unique regulatory pathways used by anatomically distinct adipose depots, with important implications for human metabolic disease.

Midnolin, a Genetic Risk Factor for Parkinson's Disease, Promotes Neurite Outgrowth Accompanied by Early Growth Response 1 Activation in PC12 Cells.

Parkinson's disease (PD) is an age-related progressive neurodegenerative disease. Previously, we identified midnolin (MIDN) as a genetic risk factor for PD. Although MIDN copy number loss increases the risk of PD, the molecular function of MIDN remains unclear. To investigate the role of MIDN in PD, we established monoclonal Midn knockout (KO) PC12 cell models. Midn KO inhibited neurite outgrowth and neurofilament light chain (Nefl) gene expression. Although MIDN is mainly localized in the nucleus, it does not encode DNA-binding domains. We therefore hypothesized that MIDN might bind to certain transcription factors and regulate gene expression. Of the candidate transcription factors, we focused on early growth response 1 (EGR1) because it is required for neurite outgrowth and its target genes are downregulated by Midn KO. An interaction between MIDN and EGR1 was confirmed by immunoprecipitation. Surprisingly, although EGR1 protein levels were significantly increased in Midn KO cells, the binding of EGR1 to the Nefl promoter and resulting transcriptional activity were downregulated as measured by luciferase assay and chromatin immunoprecipitation quantitative real-time polymerase chain reaction. Overall, we identified the MIDN-dependent regulation of EGR1 function. This mechanism may be an underlying reason for the neurite outgrowth defects of Midn KO PC12 cells.

Glial fibrillary acidic protein, neurofilament light, matrix metalloprotease 3 and fatty acid binding protein 4 as non-invasive brain tumor biomarkers.

BACKGROUND: Gliomas are aggressive malignant tumors, with poor prognosis. There is an unmet need for the discovery of new, non-invasive biomarkers for differential diagnosis, prognosis, and management of brain tumors. Our objective is to validate four plasma biomarkers - glial fibrillary acidic protein (GFAP), neurofilament light (NEFL), matrix metalloprotease 3 (MMP3) and fatty acid binding protein 4 (FABP4) - and compare them with established brain tumor molecular markers and survival. METHODS: Our cohort consisted of patients with benign and malignant brain tumors (GBM = 77, Astrocytomas = 26, Oligodendrogliomas = 23, Secondary tumors = 35, Meningiomas = 70, Schwannomas = 15, Pituitary adenomas = 15, Normal individuals = 30). For measurements, we used ultrasensitive electrochemiluminescence multiplexed immunoassays. RESULTS: High plasma GFAP concentration was associated with GBM, low GFAP and high FABP4 were associated with meningiomas, and low GFAP and low FABP4 were associated with astrocytomas and oligodendrogliomas. NEFL was associated with progression of disease. Several prognostic genetic alterations were significantly associated with all plasma biomarker levels. We found no independent associations between plasma GFAP, NEFL, FABP4 and MMP3, and overall survival. The candidate biomarkers could not reliably discriminate GBM from primary or secondary CNS lymphomas. CONCLUSIONS: GFAP, NEFL, FABP4 and MMP3 are useful for differential diagnosis and prognosis, and are associated with molecular changes in gliomas.

Cerebrospinal Fluid Protein Biomarker Discovery in CLN3.

Syndromic CLN3-Batten is a fatal, pediatric, neurodegenerative disease caused by variants in CLN3, which encodes the endolysosomal transmembrane CLN3 protein. No approved treatment for CLN3 is currently available. The protracted and asynchronous disease presentation complicates the evaluation of potential therapies using clinical disease progression parameters. Biomarkers as surrogates to measure the progression and effect of potential therapeutics are needed. We performed proteomic discovery studies using cerebrospinal fluid (CSF) samples from 28 CLN3-affected and 32 age-similar non-CLN3 individuals. Proximal extension assay (PEA) of 1467 proteins and untargeted data-dependent mass spectrometry [MS; MassIVE FTP server (ftp://MSV000090147@massive.ucsd.edu)] were used to generate orthogonal lists of protein marker candidates. At an adjusted p-value of <0.1 and threshold CLN3/non-CLN3 fold-change ratio of 1.5, PEA identified 54 and MS identified 233 candidate biomarkers. Some of these (NEFL, CHIT1) have been previously linked with other neurologic conditions. Others (CLPS, FAM217B, QRICH2, KRT16, ZNF333) appear to be novel. Both methods identified 25 candidate biomarkers, including CHIT1, NELL1, and ISLR2 which had absolute fold-change ratios >2. NELL1 and ISLR2 regulate axonal development in neurons and are intriguing new candidates for further investigation in CLN3. In addition to identifying candidate proteins for CLN3 research, this study provides a comparison of two large-scale proteomic discovery methods in CSF.

Axonal Transport Defect in Gigaxonin Deficiency Rescued by Tubastatin A.

Giant axonal neuropathy (GAN) is a disease caused by a deficiency of gigaxonin, a mediator of the degradation of intermediate filament (IF) proteins. A lack of gigaxonin alters the turnover of IF proteins, provoking accumulation and disorganization of neurofilaments (NFs) in neurons, a hallmark of the disease. However, the effects of IF disorganization on neuronal function remain unknown. Here, we report that cultured embryonic dorsal root ganglia (DRG) neurons derived from Gan-/- mice exhibit accumulations of IF proteins and defects in fast axonal transport of organelles. Kymographs generated by time-lapse microscopy revealed substantial reduction of anterograde movements of mitochondria and lysosomes in axons of Gan-/- DRG neurons. Treatment of Gan-/- DRG neurons with Tubastatin A (TubA) increased the levels of acetylated tubulin and it restored the normal axonal transport of these organelles. Furthermore, we tested the effects of TubA in a new mouse model of GAN consisting of Gan-/- mice with overexpression of peripherin (Prph) transgene. Treatment of 12-month-old Gan-/-;TgPer mice with TubA led to a slight amelioration of motor function, especially a significant improvement of gait performance as measured by footprint analyses. Moreover, TubA treatment reduced the abnormal accumulations of Prph and NF proteins in spinal neurons and it boosted the levels of Prph transported into peripheral nerve axons. These results suggest that drug inhibitors of histone deacetylase aiming to enhance axonal transport should be considered as a potential treatment for GAN disease.

Changes in neurofilament light chain protein (NEFL) in children and adolescents with Schizophrenia and Bipolar Disorder: Early period neurodegeneration.

AIM: Neurofilament light chain protein (NEFL), is defined as a structural protein which exists particularly in axones of neurons and is released to the cerum in consequence of neuroaxonal damage. The aim of this study is to investigate the peripheral cerumNEFLlevels of children and adolescents with early onset schizophrenia and bipolar disorder. METHOD: In this study, we evaluated serum levels of NEFL in children and adolescents (13-17 years) with schizophrenia, bipolar disorder and healthy control group. The study is conducted with 35 schizophrenia, 38 bipolar disorder manic episode patients and 40 healthy controls. RESULTS: The median age of the patient and control groups was 16 (IQR- Interquartile Range: 2). There was no statistical difference in median age (p = 0.52) and gender distribution(p = 0.53) between groups. NEFL levels of the patients with schizophrenia were significantly higher than the controls. NEFL levels of the patients with bipolar disorder were significantly higher than the controls. Serum levels of NEFL of the schizophrenia were higher than the bipolar disorder; however, the difference was not statistically significant. CONCLUSION: In conclusion, serum NEFL level, as a confidential marker of neural damage, is increased in the children and adolescents with bipolar disorder and schizophrenia. This result may indicatea degenerative period in neurons of children and adolescents with schizophrenia or bipolar disorder and may play a role in the pathophisiology of these disorders. This result shows that there is neuronal damage in both diseases, but neuronal damage may be more in schizophrenia.

Clinical and genetic characterization of NEFL-related neuropathy in Taiwan.

BACKGROUND: Mutations in the neurofilament light polypeptide gene (NEFL) are an uncommon cause of Charcot-Marie-Tooth disease (CMT). The aim of this study is to elucidate the clinical characteristics and genetic spectrum of NEFL-related neuropathy in a Taiwanese CMT cohort. METHODS: Mutational analysis of the coding regions of NEFL was performed by Sanger sequencing or targeted resequencing. Twenty-one patients from nine CMT pedigrees, identified from a cohort of 508 unrelated CMT patients, were found to have a NEFL mutation. Genetic, clinical and electrophysiological features were analyzed. RESULTS: Six NEFL mutations were identified, including two novel ones (p.P8S, p.N98Y). NEFL p.E396K was the most common mutation, accounting for 33.3% of the patients in our cohort. All patients manifested sensorimotor polyneuropathy with a mean age of disease onset of 13.5 ± 9.6 (1-40) years. Their motor nerve conduction velocities (MNCVs) of the ulnar nerve ranged from 22.1 to 48.7 m/s. Seventy percent of the patients could be classified as intermediate CMT with ulnar MNCVs between 25 and 45 m/s. Six of the 21 patients (28.6%) had additional features of central nervous system (CNS) involvement, including motor developmental delay, spasticity, cerebellar signs, neuropathic pain and scoliosis. CONCLUSION: NEFL mutations account for 1.8% (9/508) of the CMT patients in Taiwan. The present study delineates the clinical and genetic characteristics of NEFL-related neuropathy in Taiwan, and highlights that ulnar MNCV above 25 m/s and CNS involvement may serve as diagnostic clues for NEFL-related neuropathy.

MiR-30b-5p attenuates the inflammatory response and facilitates the functional recovery of spinal cord injury by targeting the NEFL/mTOR pathway.

BACKGROUND: Neurofilament light chain (NEFL) has been identified as a biomarker for spinal cord injury (SCI), but its effect and underlying mechanism in SCI remain unclear. METHODS: SCI rat models were established for in vivo studies. Lipopolysaccharide (LPS)-induced cell models were used for in vitro studies. The protein and mRNA expression levels of genes were evaluated by western blotting and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The pathological changes in rats after SCI were subjected to histological examinations. The interaction of NEFL and upstream miRNAs was explored using dual-luciferase reporter gene assays. RESULTS: NEFL was highly expressed in SCI rat spinal cord tissues and LPS-stimulated PC12 cells. NEFL silencing showed an inhibitory effect on the morphological changes of SCI rats and the secretion of inflammatory factors and facilitated functional recovery of SCI rats. MiR-30b-5p was demonstrated to target NEFL and negatively regulate NEFL mRNA and protein levels. Downregulation of miR-30b-5p in SCI cell and rat models was demonstrated. MiR-30b-5p alleviated the inflammatory response in SCI rat models and LPS-stimulated PC12 cells and promoted functional recovery in rats by targeting NEFL. NEFL activated mTOR signaling. MiR-30b-5p inactivated mTOR signaling by negatively regulating NEFL. CONCLUSION: MiR-30b-5p alleviated the inflammatory response and facilitated the functional recovery of SCI rats by targeting NEFL to inactivate the mTOR pathway.

Molecular characterization of Turkish patients with demyelinating Charcot-Marie-Tooth disease.

Charcot-Marie-Tooth (CMT) disease represents a distinct subgroup of inherited peripheral neuropathies with a significant prevalence throughout the world and manifests both phenotypic and genetic heterogeneity. Electrophysiological studies subclassify CMT mainly as demyelinating or axonal types. In this study, we investigated the molecular characteristics of a Turkish cohort of 23 probands out of 34 symptomatic demyelinating CMT individuals from January 2019 to December 2021. In order to identify the underlying genetic cause, we applied a rational algorithm: PMP22 gene was initially analyzed for duplication, if PMP22-duplication testing was negative, other most causative genes (GJB1, MPZ) and PMP22 were then sequenced and if no variant was detected at aforementioned tests, whole exome sequencing (WES) test was finally performed. A total of 17 patients (≅ 74%; n = 23) were found to harbor a disease-causing variant in demyelinating CMT-related genes and among the variants, PMP22-duplication was the most frequent (≅ 41%). CMT1, CMTX, and CMT4 subtypes were manifested in ten, five, and two individuals respectively. GJB1 and SBF2 genes were the only detected genes associated with the CMTs other than CMT1. We also reported totally five novel variants: c.379A > C (p.Ile127Leu) and c.548G > T (p.Arg183Leu) variants in GJB1, c.988G > T (p.Glu330Ter) variant in NEFL, c.765_770delCCCTAT (p.Pro256_Ile257del) and c.2552A > C (p.His851Pro) variants in SBF2. As the understanding of pathophysiology and molecular mechanisms of CMT continues to evolve rapidly, many therapeutic strategy options including promising small-molecular compounds, gene replacement therapy, or disease-modifying therapies will soon be implemented in the clinical setting.

NEFL promotes invasion and migration of esophageal squamous carcinoma cells via the EGFR/AKT/S6 pathway.

To explore the expression, the roles and the underlying mechanism of neurofilament light chain (NEFL) in esophageal squamous cell carcinoma (ESCC), we firstly analyzed the NEFL mRNA and protein expression in ESCC and paired normal tissues by using Gene Expression Omnibus (GEO) database, and real-time quantitative reverse transcription PCR (qRT-PCR). The results showed that NEFL mRNA level was significantly upregulated in ESCC tissues compared with that of normal tissues. Western blot analysis revealed that NEFL protein level was also significantly upregulated in ESCC tissues. CCK8 and transwell assays were performed to analyze the effect of NEFL overexpression on the malignant phenotypes of ESCC cells, and the results showed that NEFL knockdown significantly impaired the ESCC cell invasion and migration in vitro. Xenograft assay in nude mice indicated that NEFL silencing suppressed tumor growth in vivo. At the molecular level, NEFL knockdown significantly upregulated E-cadherin and downregulated N-cadherin expression, suggesting that NEFL overexpression might influence the epithelial-mesenchymal transition (EMT) process. Furthermore, we found that NEFL knockdown significantly reduced the mRNA and protein expression of epidermal growth factor receptor (EGFR) and the phosphorylation levels of protein kinase B (PKB; also known as AKT) and ribosomal protein S6 (S6). Ectopic expression of EGFR after NEFL knockdown significantly restored the phosphorylation levels of AKT and S6 as well as the invasion and migration of ESCC cells. These data indicate that NEFL overexpression might promote the EMT process of ESCC cells via the EGFR/AKT/S6 pathway, ultimately enhancing the invasion and migration of ESCC cells.

Serum Creatine, Not Neurofilament Light, Is Elevated in CHCHD10-Linked Spinal Muscular Atrophy.

OBJECTIVE: To characterize serum biomarkers in mitochondrial CHCHD10-linked spinal muscular atrophy Jokela (SMAJ) type for disease monitoring and for the understanding of pathogenic mechanisms. METHODS: We collected serum samples from a cohort of 49 patients with SMAJ, all carriers of the heterozygous c.197G>T p.G66V variant in CHCHD10. As controls, we used age- and sex-matched serum samples obtained from Helsinki Biobank. Creatine kinase and creatinine were measured by standard methods. Neurofilament light (NfL) and glial fibrillary acidic protein (GFAP) were measured with single molecule array (Simoa), fibroblast growth factor 21 (FGF-21), and growth differentiation factor 15 (GDF-15) with an enzyme-linked immunosorbent assay. For non-targeted plasma metabolite profiling, samples were analyzed with liquid chromatography high-resolution mass spectrometry. Disease severity was evaluated retrospectively by calculating a symptom-based score. RESULTS: Axon degeneration marker, NfL, was unexpectedly not altered in the serum of patients with SMAJ, whereas astrocytic activation marker, GFAP, was slightly decreased. Creatine kinase was elevated in most patients, particularly men. We identified six metabolites that were significantly altered in serum of patients with SMAJ in comparison to controls: increased creatine and pyruvate, and decreased creatinine, taurine, N-acetyl-carnosine, and succinate. Creatine correlated with disease severity. Altered pyruvate and succinate indicated a metabolic response to mitochondrial dysfunction; however, lactate or mitochondrial myopathy markers FGF-21 or GDF-15 was not changed. CONCLUSIONS: Biomarkers of muscle mass and damage are altered in SMAJ serum, indicating a role for skeletal muscle in disease pathogenesis in addition to neurogenic damage. Despite the minimal mitochondrial pathology in skeletal muscle, signs of a metabolic shift can be detected.

Phenotypic heterogeneity in patients with NEFL-related Charcot-Marie-Tooth disease.

Charcot-Marie-Tooth disease (CMT) is the most common hereditary peripheral neuropathy. Mutations in the neurofilament light polypeptide (NEFL) gene produce diverse clinical phenotypes, including demyelinating (CMT1F), axonal (CMT2E), and intermediate (CMTDIG) neuropathies. From 2005 to 2020, 1,143 Korean CMT families underwent gene sequencing, and we investigated the clinical, genetic, and neuroimaging spectra of NEFL-related CMT patients. Ten NEFL mutations in 17 families (1.49%) were identified, of which three (p.L312P, p.Y443N, and p.K467N) were novel. Eight de novo cases were identified at a rate of 0.47 based on a cosegregation analysis. The age of onset was ≤3 years in five cases (13.5%). The patients revealed additional features including delayed walking, ataxia, dysphagia, dysarthria, dementia, ptosis, waddling gait, tremor, hearing loss, and abnormal visual evoked potential. Signs of ataxia were found in 26 patients (70.3%). In leg MRI analyses, various degrees of intramuscular fat infiltration were found. All compartments were evenly affected in CMT1F patients. The anterior and anterolateral compartments were affected in CMT2E, and the posterior compartment was affected in CMTDIG. Thus, NEFL-related CMT patients showed phenotypic heterogeneities. This study's clinical, genetic, and neuroimaging results could be helpful in the evaluation of novel NEFL variants and differential diagnosis against other CMT subtypes.

Transcriptomic Profile Reveals Deregulation of Hearing-Loss Related Genes in Vestibular Schwannoma Cells Following Electromagnetic Field Exposure.

Hearing loss (HL) is the most common sensory disorder in the world population. One common cause of HL is the presence of vestibular schwannoma (VS), a benign tumor of the VIII cranial nerve, arising from Schwann cell (SC) transformation. In the last decade, the increasing incidence of VS has been correlated to electromagnetic field (EMF) exposure, which might be considered a pathogenic cause of VS development and HL. Here, we explore the molecular mechanisms underlying the biologic changes of human SCs and/or their oncogenic transformation following EMF exposure. Through NGS technology and RNA-Seq transcriptomic analysis, we investigated the genomic profile and the differential display of HL-related genes after chronic EMF. We found that chronic EMF exposure modified the cell proliferation, in parallel with intracellular signaling and metabolic pathways changes, mostly related to translation and mitochondrial activities. Importantly, the expression of HL-related genes such as NEFL, TPRN, OTOGL, GJB2, and REST appeared to be deregulated in chronic EMF exposure. In conclusion, we suggest that, at a preclinical stage, EMF exposure might promote the transformation of VS cells and contribute to HL.

A review and analysis of the clinical literature on Charcot-Marie-Tooth disease caused by mutations in neurofilament protein L.

Charcot-Marie-Tooth disease (CMT) is one of the most common inherited neurological disorders and can be caused by mutations in over 100 different genes. One of the causative genes is NEFL on chromosome 8 which encodes neurofilament light protein (NEFL), one of five proteins that co-assemble to form neurofilaments. At least 34 different CMT-causing mutations in NEFL have been reported which span the head, rod, and tail domains of the protein. The majority of these mutations are inherited dominantly, but some are inherited recessively. The resulting disease is classified variably in clinical reports based on electrodiagnostic studies as either axonal (type 2; CMT2E), demyelinating (type 1; CMT1F), or a form intermediate between the two (dominant intermediate; DI-CMTG). In this article, we first present a brief introduction to CMT and neurofilaments. We then collate and analyze the data from the clinical literature on the disease classification, age of onset and electrodiagnostic test results for the various mutations. We find that mutations in the head, rod, and tail domains can all cause disease with early onset and profound neurological impairment, with a trend toward greater severity for head domain mutations. We also find that the disease classification does not correlate with specific mutation or domain. In fact, different individuals with the same mutation can be classified as having axonal, demyelinating, or dominant intermediate forms of the disease. This suggests that the classification of the disease as CMT2E, CMT1F or DI-CMTG has more to do with variable disease presentation than to differences in the underlying disease mechanism, which is most likely primarily axonal in all cases.

Expression of GSK3ß, PICK1, NEFL, C4, NKCC1 and Synaptophysin in peripheral blood mononuclear cells of the first-episode schizophrenia patients.

Schizophrenia (SZ) is a severe neurodevelopmental disease with unknown pathogenic mechanisms characterized with impaired cognitive function. The disturbed synaptic plasticity and synaptic loss have been widely reported in SZ. In this study, 41 first-episode schizophrenia (FES) patients and 44 healthy controls (HC) were recruited and the expression of six genes commonly relevant to synaptic functions was examined in the peripheral blood mononuclear cells (PBMCs). These genes were glycogen synthase kinase 3ß (GSK3ß), protein interacting with C-kinase 1 (PICK1), synaptophysin (SYP), neurofilament light (NEFL), complement component 4 (C4) and Na+-K--2Cl- cotransporter 1 (NKCC1). Real-time quantitative polymerase chain reaction (qPCR) was performed to determine the quantity of individual mRNA template. Compared to HC, the expression of PICK1 and NKCC1 genes in FES patients was relatively lower whereas the expression of NEFL was higher. No difference for the mRNA expression of GSK3ß, SYP and C4 genes was detected between FES patients and HC, nor was the gender difference; Interestingly, the mRNA expression of PICK1 in female FES patients was significantly decreased compared to female HC, but not in males; and the NEFL gene was up-regulated in male FES patients but not in females. Our findings support an abnormal expression profile of synapse-related genes in the PBMCs of FES patients.

New evidence for secondary axonal degeneration in demyelinating neuropathies.

Development of peripheral nervous system (PNS) myelin involves a coordinated series of events between growing axons and the Schwann cell (SC) progenitors that will eventually ensheath them. Myelin sheaths have evolved out of necessity to maintain rapid impulse propagation while accounting for body space constraints. However, myelinating SCs perform additional critical functions that are required to preserve axonal integrity including mitigating energy consumption by establishing the nodal architecture, regulating axon caliber by organizing axonal cytoskeleton networks, providing trophic and potentially metabolic support, possibly supplying genetic translation materials and protecting axons from toxic insults. The intermediate steps between the loss of these functions and the initiation of axon degeneration are unknown but the importance of these processes provides insightful clues. Prevalent demyelinating diseases of the PNS include the inherited neuropathies Charcot-Marie-Tooth Disease, Type 1 (CMT1) and Hereditary Neuropathy with Liability to Pressure Palsies (HNPP) and the inflammatory diseases Acute Inflammatory Demyelinating Polyneuropathy (AIDP) and Chronic Inflammatory Demyelinating Polyneuropathy (CIDP). Secondary axon degeneration is a common feature of demyelinating neuropathies and this process is often correlated with clinical deficits and long-lasting disability in patients. There is abundant electrophysiological and histological evidence for secondary axon degeneration in patients and rodent models of PNS demyelinating diseases. Fully understanding the involvement of secondary axon degeneration in these diseases is essential for expanding our knowledge of disease pathogenesis and prognosis, which will be essential for developing novel therapeutic strategies.

A hereditary spastic paraplegia predominant phenotype caused by variants in the NEFL gene.

INTRODUCTION: This study reports a large series of patients with a clinical picture dominated by spastic paraplegia in whom variants in the NEFL gene, a known cause for Charcot-Marie-Tooth disease, were identified. METHODS: Index patients referred for a suspicion of hereditary spastic paraplegia (HSP) were clinically assessed and genetic analysis by next-generation sequencing was undertaken. Additional family members were clinically examined and subjected to targeted testing. RESULTS: We identified two different heterozygous dominant variants in the NEFL gene in 25 patients from 14 families. Most of them (21/25) had a clinical diagnosis of HSP, often with a concomitant clinical diagnosis of polyneuropathy (16/21). Two patients were identified with a polyneuropathy with a pyramidal reflex pattern, but without spasticity. Two patients had isolated polyneuropathy. Out of the 21 patients with a diagnosis of HSP, two had co-occurring cerebellar signs. The c.262A > C p.(Thr88Pro) variant was detected in 13 families. Genealogical analysis showed shared ancestors or a similar geographical origin in 12, suggesting a founder effect. The other variant, c.296A > C p.(Asp99Ala), was found in only one family, in which limited segregation analysis could be performed. DISCUSSION: Variants in the NEFL gene can cause HSP, with or without co-existing polyneuropathy, and should be included in diagnostic testing strategies for HSP patients.

Functional Characterization of Neurofilament Light Splicing and Misbalance in Zebrafish.

Neurofilaments (NFs), a major cytoskeletal component of motor neurons, play a key role in the differentiation, establishment and maintenance of their morphology and mechanical strength. The de novo assembly of these neuronal intermediate filaments requires the presence of the neurofilament light subunit (NEFL), whose expression is reduced in motor neurons in amyotrophic lateral sclerosis (ALS). This study used zebrafish as a model to characterize the NEFL homologue neflb, which encodes two different isoforms via a splicing of the primary transcript (neflbE4 and neflbE3). In vivo imaging showed that neflb is crucial for proper neuronal development, and that disrupting the balance between its two isoforms specifically affects the NF assembly and motor axon growth, with resultant motor deficits. This equilibrium is also disrupted upon the partial depletion of TDP-43 (TAR DNA-binding protein 43), an RNA-binding protein encoded by the gene TARDBP that is mislocalized into cytoplasmic inclusions in ALS. The study supports the interaction of the NEFL expression and splicing with TDP-43 in a common pathway, both biologically and pathogenetically.

Association between (GT)n Promoter Polymorphism and Recovery from Concussion: A Pilot Study.

Variability in recovery among concussed athletes can be attributed to several risk factors. One risk factor not definitively explored is genetic variation. Genetic variations such as variable number tandem repeats (VNTR) in the promotor region are normal in the population, and can lead to disparities in the amount of protein produced, which could be associated with neuronal recovery. Little research has been conducted to investigate promoter VNTRs within genes responsible for recovery following a concussion. The authors implemented a prospective cohort design using a standardized concussion protocol to diagnose and follow 93 athletes to full recovery at three different sites to determine the association between promotor GT(n) VNTR polymorphisms and recovery time within concussed athletes. The GT(n) VNTR within the promoter region of glutamate ionotropic receptor N-methyl-d-aspartate (NMDA) type subunit 2A (GRIN2A), potassium voltage-gated channel subfamily H member 2 (KCNH2), glutamate ionotropic receptor kainate type subunit 1 (GRIK1), and neurofilament light (NEFL) were genotyped using capillary electrophoresis. GT(n) VNTR promotor polymorphisms were dichotomized into long (L) and short (s) alleles. Using adjusted negative binomial regression models we found that athletes carrying the LL GRIN2A GT(n) VNTR within the promoter region were more likely to experience a prolonged concussion recovery, which resulted in their not being able to return to play for ∼60 days. Additionally, there was a trend toward significance, in which the ss NEFL GT(n) Caucasian athletes had prolonged concussion recovery. This could presumably be attributed to altered proteins or protein levels that disrupt neuronal recovery. This pilot study suggests that these VNTRs are associated with prolonged concussion recovery. In future studies, we plan to measure the extent to which the L or s alleles alter the level and the activity of the GluNR2a and NEFL proteins that GRIN2A and NEFL produce, respectively.

The first Portuguese family with NEFL-related Charcot-Marie-Tooth type 2 disease.

CMT disease caused by NEFL gene mutations is rare. The mode of inheritance can be dominant or recessive and nerve conduction velocities can be normal, reduced (demyelinating) or presenting intermediate values. Two Portuguese adult related members in two successive generations were affected by peripheral neuropathy, one with a chronic ataxic peripheral neuropathy and the other with a classical Charcot-Marie-Tooth phenotype. An axonal sensorimotor peripheral neuropathy was described at neurophysiology. A missense heterozygous mutation, c.794A > G (p.Tyr265Cys), in the NEFL gene was found in both patients. This is the first Portuguese family reported with NEFL-related CMT type 2.