Effects of GSTA1 and GPX3 Polymorphisms on the Risk of Schizophrenia in Chinese Han Population

Current Understanding of Human Polymorphism in Selenoprotein Genes: A Review of Its Significance as a Risk Biomarker

Selenium has been proven to influence several biological functions, showing to be an essential micronutrient. The functional studies demonstrated the benefits of a balanced selenium diet and how its deficiency is associated with diverse diseases, especially cancer and viral diseases. Selenium is an antioxidant, protecting the cells from damage, enhancing the immune system response, preventing cardiovascular diseases, and decreasing inflammation. Selenium can be found in its inorganic and organic forms, and its main form in the cells is the selenocysteine incorporated into selenoproteins. Twenty-five selenoproteins are currently known in the human genome: glutathione peroxidases, iodothyronine deiodinases, thioredoxin reductases, selenophosphate synthetase, and other selenoproteins. These proteins lead to the transport of selenium in the tissues, protect against oxidative damage, contribute to the stress of the endoplasmic reticulum, and control inflammation. Due to these functions, there has been growing interest in the influence of polymorphisms in selenoproteins in the last two decades. Selenoproteins' gene polymorphisms may influence protein structure and selenium concentration in plasma and its absorption and even impact the development and progression of certain diseases. This review aims to elucidate the role of selenoproteins and understand how their gene polymorphisms can influence the balance of physiological conditions. In this polymorphism review, we focused on the PubMed database, with only articles published in English between 2003 and 2023. The keywords used were "selenoprotein" and "polymorphism". Articles that did not approach the theme subject were excluded. Selenium and selenoproteins still have a long way to go in molecular studies, and several works demonstrated the importance of their polymorphisms as a risk biomarker for some diseases, especially cardiovascular and thyroid diseases, diabetes, and cancer.

Oxidative Stress-Related Mechanisms in Schizophrenia Pathogenesis and New Treatment Perspectives

Schizophrenia is recognized to be a highly heterogeneous disease at various levels, from genetics to clinical manifestations and treatment sensitivity. This heterogeneity is also reflected in the variety of oxidative stress-related mechanisms contributing to the phenotypic realization and manifestation of schizophrenia. At the molecular level, these mechanisms are supposed to include genetic causes that increase the susceptibility of individuals to oxidative stress and lead to gene expression dysregulation caused by abnormal regulation of redox-sensitive transcriptional factors, noncoding RNAs, and epigenetic mechanisms favored by environmental insults. These changes form the basis of the prooxidant state and lead to altered redox signaling related to glutathione deficiency and impaired expression and function of redox-sensitive transcriptional factors (Nrf2, NF-κB, FoxO, etc.). At the cellular level, these changes lead to mitochondrial dysfunction and metabolic abnormalities that contribute to aberrant neuronal development, abnormal myelination, neurotransmitter anomalies, and dysfunction of parvalbumin-positive interneurons. Immune dysfunction also contributes to redox imbalance. At the whole-organism level, all these mechanisms ultimately contribute to the manifestation and development of schizophrenia. In this review, we consider oxidative stress-related mechanisms and new treatment perspectives associated with the correction of redox imbalance in schizophrenia. We suggest that not only antioxidants but also redox-regulated transcription factor-targeting drugs (including Nrf2 and FoxO activators or NF-κB inhibitors) have great promise in schizophrenia. But it is necessary to develop the stratification criteria of schizophrenia patients based on oxidative stress-related markers for the administration of redox-correcting treatment.

Association Between Glutathione Peroxidase-1 (GPx-1) Polymorphisms and Schizophrenia in the Chinese Han Population

OBJECTIVE

The dopamine and oxidative stress hypotheses are leading theories of the pathoetiology of schizophrenia (SCZ). Glutathione Peroxidase 1 (GPx-1), a major antioxidant enzyme, and the most abundantly expressed member of the GPx family, plays an important role in metabolic dopamine changes, which are closely related to neurological and psychiatric disorders. The impact of GPx-1 polymorphisms has rarely been explored in the field of SCZ. Here, we explored the possible relationship between GPx-1 gene polymorphisms and SCZ in Chinese Han subjects by using the polymerase chain reaction-restriction fragment length polymorphism method.

METHODS

DNA from 786 patients (360 patients with schizophrenia and 426 healthy controls) was genotyped for the single-nucleotide polymorphisms rs1800668 C/T and rs1050450 C/T in GPx-1 using polymerase chain reaction-restriction fragment length polymorphism analysis. Analysis of the association between GPx-1 and SCZ was performed using SPSS 22.0, while Haploview 4.2 software and SHEsis software were used to perform linkage disequilibrium analysis and haplotype analysis.

RESULTS

The results indicated that the GPx-1 polymorphisms rs1050450 and rs1800668 were associated with SCZ. We found that the C-allele of rs1800668 C/T may be a protection factor against SCZ in general, but in particular, for males. Furthermore, the CT and TC (GPx-1 rs1800668 C/T and rs1050450 C/T) haplotypes may be susceptible to SCZ in the population. Finally, no significant differences in allelic or genotypic frequencies of rs1050450 were detected between cases and controls from whole or stratification analyses by gender.

CONCLUSION

GPx-1 polymorphisms are related to SCZ in Chinese Han subjects. Our results suggested that GPx-1 may be a potential gene that influences SCZ.