Identification of L84F mutation with a novel nucleotide change c.255G > T in the superoxide dismutase gene in a North Indian family with amyotrophic lateral sclerosis

Functional consequences of familial ALS-associated SOD1L84F in neuronal and muscle cells

Amyotrophic lateral sclerosis is a fatal neurodegenerative disorder characterized by progressive skeletal muscle denervation and loss of motor neurons that results in muscle atrophy and eventual death due to respiratory failure. Previously, we identified a novel SOD1L84F variation in a familial ALS case. In this study, we examined the functional consequences of SOD1L84F overexpression in the mouse motor neuron cell line (NSC-34). The cells expressing SOD1L84F showed increased oxidative stress and increased cell death. Interestingly, SOD1L84F destabilized the native dimer and formed high molecular weight SDS-resistant protein aggregates. Furthermore, SOD1L84F also decreased the percentage of differentiated cells and significantly reduced neurite length. A plethora of evidence suggested active involvement of skeletal muscle in disease initiation and progression. We observed differential processing of the mutant SOD1 and perturbations of cellular machinery in NSC-34 and muscle cell line C2C12. Unlike neuronal cells, mutant protein failed to accumulate in muscle cells probably due to the activated autophagy, as evidenced by increased LC3-II and reduced p62. Further, SOD1L84F altered mitochondrial dynamics only in NSC-34. In addition, microarray analysis also revealed huge variations in differentially expressed genes between NSC-34 and C2C12. Interestingly, SOD1L84F hampered the endogenous FUS autoregulatory mechanism in NSC-34 by downregulating retention of introns 6 and 7 resulting in a two-fold upregulation of FUS. No such changes were observed in C2C12. Our findings strongly suggest the differential processing and response towards the mutant SOD1 in neuronal and muscle cell lines.

Analysis of ERBB4 Variants in Amyotrophic Lateral Sclerosis Within a Chinese Cohort

ERBB4 is related to amyotrophic lateral sclerosis (ALS) in patients with a family history and is thought to cause ALS-19. We screened 448 ALS patients, including 364 sporadic ALS (sALS) and 84 familial ALS (fALS) patients with ERBB4 variants, in a Chinese cohort. In total, 12 missense variants were identified in this study. Of these, 3 (p.Arg106His, p.Gln164Pro, and p.Val212Leu) were absent from the in-house healthy control cohort and population databases and predicted to be likely pathogenic. Genetic burden analysis did not reveal an increase in damaging variants of the ERBB4 gene. We considered that most of the missense variants in ERBB4 were not pathogenic, but certain variants, such as p.Arg106His, p.Gln164Pro, and p.Val212Leu, were likely pathogenic. The phenotype of these three patients carrying ERBB4 variants revealed the typical clinical manifestations of ALS without cognitive dysfunction. We concluded that ERBB4 likely pathogenic variants account for ~0.67% of ALS patients in China. It is necessary to interpret the relationship between the disease and variants carefully for ALS patients with ERBB4 gene variants.

Efficacy of Antioxidant Supplementation to Non-Surgical Periodontal Therapy on Metabolic Control in Type 2 Diabetes Patients: A Network Meta-Analysis

This network meta-analysis (NMA) investigated the effectiveness of antioxidants as adjuncts to non-surgical periodontal therapy (NSPT) in the glycated hemoglobin (HbA1c) control of type 2 diabetes (T2D) patients with periodontitis. PubMed, Cochrane, LILACS, Web of Science, Scopus, Embase, LIVIVO, and grey literature were searched. Risk of bias was assessed with the RoB v2.0 tool. A frequentist NMA assessed HbA1c improvement, through standardized mean difference under a random-effects model. Certainty of evidence was addressed through the GRADE (Grading of Recommendations, Assessment, Development and Evaluations) partially contextualized framework. Ten randomized controlled clinical trials were included, with 234 patients receiving alpha lipoic acid (ALA), cranberry juice, cranberry juice enriched with omega-3, fenugreek, ginger, grape seed, lycopene, melatonin, omega-3, propolis or vitamin C supplementation to NSPT, and 220 patients receiving NSPT alone or with placebo. Nine studies were meta-analyzed. HbA1c improved when NSPT was combined with propolis, ALA and melatonin supplementation (moderate-to-low certainty), compared to NSPT alone or with placebo. Risk of bias issues were found in eight studies. In conclusion, the use of propolis supplementation to NSPT probably results in HbA1c improvement in T2D patients with periodontitis (large effect with moderate certainty), while ALA and melatonin supplementation may contribute to reduce the HbA1c in T2D patients with periodontitis (large effects with low certainty).

Neuromuscular Junction Dysfunction in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurological disorder characterized by progressive degeneration of motor neurons leading to skeletal muscle denervation. Earlier studies have shown that motor neuron degeneration begins in motor cortex and descends to the neuromuscular junction (NMJ) in a dying forward fashion. However, accumulating evidences support that ALS is a distal axonopathy where early pathological changes occur at the NMJ, prior to onset of clinical symptoms and propagates towards the motor neuron cell body supporting "dying back" hypothesis. Despite several evidences, series of events triggering NMJ disassembly in ALS are still obscure. Neuromuscular junction is a specialized tripartite chemical synapse which involves a well-coordinated communication among the presynaptic motor neuron, postsynaptic skeletal muscle, and terminal Schwann cells. This review provides comprehensive insight into the role of NMJ in ALS pathogenesis. We have emphasized the molecular alterations in cellular components of NMJ leading to loss of effective neuromuscular transmission in ALS. Further, we provide a preview into research involved in exploring NMJ as potential target for designing effective therapies for ALS.

Periodontitis is an inflammatory disease of oxidative stress: We should treat it that way

Periodontitis is a highly prevalent disease. As it progresses, it causes serious morbidity in the form of periodontal abscesses and tooth loss and, in the latter stages, pain. It is also now known that periodontitis is strongly associated with several nonoral diseases. Thus, patients with periodontitis are at greater risk for the development and/or exacerbation of diabetes, chronic obstructive pulmonary disease, and cardiovascular diseases, among other conditions. Although it is without question that specific groups of oral bacteria which populate dental plaque play a causative role in the development of periodontitis, it is now thought that once this disease has been triggered, other factors play an equal, and possibly more important, role in its progression, particularly in severe cases or in cases that prove difficult to treat. In this regard, we allude to the host response, specifically the notion that the host, once infected with oral periodontal pathogenic bacteria, will mount a defense response mediated largely through the innate immune system. The most abundant cell type of the innate immune system - polymorphonuclear neutrophils - can, when protecting the host from microbial invasion, mount a response that includes upregulation of proinflammatory cytokines, matrix metalloproteinases, and reactive oxygen species, all of which then contribute to the tissue damage and loss of teeth commonly associated with periodontitis. Of the mechanisms referred to here, we suggest that upregulation of reactive oxygen species might play one of the most important roles in the establishment and progression of periodontitis (as well as in other diseases of inflammation) through the development of oxidative stress. In this overview, we discuss both innate and epigenetic factors (eg, diabetes, smoking) that lead to the development of oxidative stress. This oxidative stress then provides an environment conducive to the destructive processes observed in periodontitis. Therefore, we shall describe some of the fundamental characteristics of oxidative stress and its effects on the periodontium, discuss the diseases and other factors that cause oxidative stress, and, finally, review potentially novel therapeutic approaches for the management (and possibly even the reversal) of periodontitis, which rely on the use of therapies, such as resveratrol and other antioxidants, that provide increased antioxidant activity in the host.

Improved regression model to predict an impact of SOD1 mutations on ALS patients survival time based on analysis of hydrogen bond stability

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease characterised by the inevitable degeneration of central and peripheral motor neurons. Aggregation of mutant SOD1 is one of the molecular mechanisms underlying the onset of the disease. There are a number of regression models designed to predict the survival of patients based on an analysis of experimental data on thermostability, heterodimerisation energy, and changes in the hydrophobicity of SOD1 mutants. Previously, we proposed regression models linking the change in the stability of hydrogen bonds in mutant SOD1 calculated using molecular dynamics and elastic networks with patients survival time. In this study, these models were improved in terms of accuracy of survival time prediction by taking into account the variance of survival time values relative to the mean, the number of patients carrying each specific mutation, and the use of random forest regression as a regression method. The accuracy of the previous models was roughly 5.2 years while the accuracy of the new ones are up to 4 years. The model is also superior to those published by other authors. It was found that the hydrogen bonds important for prediction of survival time are formed by residues at positions located in the regions of the protein responsible for aggregation as well as in structural and functionally important sites.

Targeted next-generation sequencing reveals novel and rare variants in Indian patients with amyotrophic lateral sclerosis

Studies on genetic aberrations among Indian amyotrophic lateral sclerosis (ALS) patients are limited to C9orf72 and ATXN2 repeat expansions and mutations in the SOD1 gene. In this study, we used targeted next-generation sequencing to analyze 25 ALS-associated genes in a cohort of 154 Indian ALS patients. We identified known pathogenic mutations in SOD1 (G148D; H44R), TARDBP (M337V; N267S), DAO (R199Q), and ANG (K41I). In addition, we also identified 7 potentially pathogenic missense variants that have not been previously reported in ALS patients; this includes 3 novel variants (OPTN: K489E, DAO: E121K, and SETX: L2163V) that are not reported in large population databases and 4 rare variants (CHMP2B: E45K, SQSTM1: G262R and P438L, ERBB4: R103H) with a minor allele frequency of <0.01 in large population databases. All known pathogenic, novel, and rare variants were detected in only 1 ALS patient each with the exception of the OPTN (K489E) variant that was detected in 2 patients in our cohort. In sum, we identified known and potentially pathogenic novel and rare mutations in 14 (9.1%) ALS patients in our cohort. This study represents the first comprehensive genetic analysis in the ethnically diverse population and thus provides a new insight into the genetics of Indian ALS patients.

Expression analysis of protein homeostasis pathways in the peripheral blood mononuclear cells of sporadic amyotrophic lateral sclerosis patients

Misfolded protein aggregates are the hallmark of Amyotrophic Lateral Sclerosis (ALS) which suggests involvement of protein homeostasis pathways in etiology of ALS. However, status of protein homeostasis in peripheral blood of ALS is not well established. We analyzed expression levels of key genes of proteostasis pathways in peripheral blood mononuclear cells (PBMCs) of sporadic ALS (sALS) patients and healthy controls. Increased protein carbonylation was observed in patients reflecting oxidative damage in PBMCs. We observed increased transcript and protein levels of GRP78 suggesting Endoplasmic reticulum (ER) insult to cells. Further, significant upregulation of spliced XBP1 and two stress sensors: IRE1α/ERN1 and ATF6 indicated induction of unfolded protein response (UPR). Genes involved in autophagosome initiation (ULK1, ULK2, ATG13); nucleation and elongation (BECLIN1, ATG7, ATG16L1, ATG5, ATG10) and vesicular trafficking genes were significantly increased in patients. Increased lipidation of LC3 validated induction of autophagy. Accumulation of low molecular weight ubiquitinated proteins in patients suggested deregulation of proteasome (UPS) pathway. In addition, cytosolic chaperones (HSP70 and HSP27) and HSF1 were elevated in patients. Increased TDP43 indicated role of TDP43 in disease pathology. Our findings suggest that there is oxidative insult and upregulation of UPR, vesicular trafficking and autophagy in PBMCs of sALS patients.

Molecular epidemiological study of familial amyotrophic lateral sclerosis in Japanese population by whole-exome sequencing and identification of novel HNRNPA1 mutation

To elucidate the genetic epidemiology of familial amyotrophic lateral sclerosis (FALS) in the Japanese population, we conducted whole-exome sequencing analysis of 30 FALS families in whom causative mutations have not been identified in previous studies. Consequently, whole-exome sequencing analysis revealed novel mutations in HNRNPA1, TBK1, and VCP. Taken together with our previous results of mutational analyses by direct nucleotide sequencing analysis, a microarray-based resequencing method, or repeat-primed PCR analysis, causative mutations were identified in 41 of the 68 families (60.3%) with SOD1 being the most frequent cause of FALS (39.7%). Of the mutations identified in this study, a novel c.862/1018C>G (p.P288A/340A) mutation in HNRNPA1 located in the nuclear localization signal domain of hnRNPA1, enhances the recruitment of mutant hnRNPA1 into stress granules, indicating that an altered nuclear localization signal activity plays an essential role in amyotrophic lateral sclerosis pathogenesis.

Probing the inhibitory activity of epigallocatechin-gallate on toxic aggregates of mutant (L84F) SOD1 protein through geometry based sampling and steered molecular dynamics

Amyloid formation and protein aggregation are considered to be at the core of the disease pathology for the various neurodegenerative disorders such as Amyotrophic lateral sclerosis (ALS). Considerable experimental reports have suggested that epigallocatechin-gallate (EGCG), a natural polyphenol from the green tea inhibits the amyloid formation in multiple neurodegenerative disease. Mutations in SOD1 protein are considered to a key factor that contributes towards the rapid disease progression and the pathogenesis in both, the sporadic and familial form. In our study, we computationally examined the inhibitory action of EGCG against the native and the mutant SOD1 through molecular docking, steered molecular dynamics and conformational sampling methods From the outcome, we could conjecture that the protein destabilization and increased β-sheet propensity that occurred due to mutation were regained upon the binding of EGCG. Moreover, the concepts of the free energy landscape analysis are introduced to establish the visual appearance of protein aggregation upon mutation. Altogether, we come to know that the binding of EGCG on mutant SOD1 has reduced the formation of the toxic aggregates upon mutation. Hence, our study could be an initiative in deciphering the inhibitory action of EGCG against the aggregated mutant SOD1, which could be a therapeutic potential against the treatment for the incurable neurodegenerative disorder (ALS) affecting the mankind.