SOD1 Gene +35A/C (exon3/intron3) Polymorphism in Type 2 Diabetes Mellitus among South Indian Population

Glutathione S-Transferase (GSTT1 rs17856199) and Nitric Oxide Synthase (NOS2 rs2297518) Genotype Combination as Potential Oxidative Stress-Related Molecular Markers for Type 2 Diabetes Mellitus

BACKGROUND

Deregulation of the antioxidant enzymes was implicated in pathogenesis and complications of type 2 diabetes mellitus (T2DM). The data relate the genetic variants of these enzymes to T2DM are inconsistent among various populations.

PURPOSE

We aimed to explore the association of 13 genetic variants of "superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and nitric oxide synthase (NOS)" with T2DM susceptibility and the available clinical laboratory data.

SUBJECTS AND METHODS

A total of 384 individuals were enrolled in this work. Different genotypes of the genes mentioned above were characterized using TaqMan OpenArray Genotyping assays on a Real-Time polymerase chain reaction system.

RESULTS

After age- and sex-adjustment, among the studied 13 variants, GSTT1 rs17856199 was associated with T2DM under homozygote (OR=3.42; 95% CI:1.04-11.2, p=0.031), and recessive (OR=3.57; 95% CI: 1.11-11.4, p=0.029) comparison models. The NOS2 rs2297518*A allele was more frequent among the T2DM cohort (58.1% vs 35.4%, p<0.001) and showed a dose-response effect; being heterozygote was associated with higher odds for developing DM (OR=4.06, 95% CI=2.13-7.73, p<0.001), whereas being AA homozygote had double the risk (OR=9.06, 95% CI=3.41-24.1, p<0.001). Combined NOS2 rs2297518*A and either GSTT1 rs17856199*A or *C genotype carriers were more likely to develop T2DM. Different associations with sex, BMI, hyperglycemia, and/or hyperlipidemia were evident. The principal component analysis revealed NOS2 rs2297518*G, old age, dyslipidemia, high systolic blood pressure, and elevated HbA1c were the main classifiers of T2DM patients.

CONCLUSION

The oxidative stress-related molecular markers, GSTT1 rs17856199 and NOS2 rs2297518 variants were significantly associated with T2DM risk and phenotype in the study population.

Protein Quality Control and the Amyotrophic Lateral Sclerosis/Frontotemporal Dementia Continuum

Protein homeostasis, or proteostasis, has an important regulatory role in cellular function. Protein quality control mechanisms, including protein folding and protein degradation processes, have a crucial function in post-mitotic neurons. Cellular protein quality control relies on multiple strategies, including molecular chaperones, autophagy, the ubiquitin proteasome system, endoplasmic reticulum (ER)-associated degradation (ERAD) and the formation of stress granules (SGs), to regulate proteostasis. Neurodegenerative diseases are characterized by the presence of misfolded protein aggregates, implying that protein quality control mechanisms are dysfunctional in these conditions. Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are neurodegenerative diseases that are now recognized to overlap clinically and pathologically, forming a continuous disease spectrum. In this review article, we detail the evidence for dysregulation of protein quality control mechanisms across the whole ALS-FTD continuum, by discussing the major proteins implicated in ALS and/or FTD. We also discuss possible ways in which protein quality mechanisms could be targeted therapeutically in these disorders and highlight promising protein quality control-based therapeutics for clinical trials.