OVEREXPRESSION OF PDX-1 GENE INCREASES INS1 GENE mRNA EXPRESSION, NOT INS2 GENE mRNA EXPRESSION, IN INSULINOMA CELL LINE RIN-5F

γ-Glutamylcysteine restores glucolipotoxicity-induced islet β-cell apoptosis and dysfunction via inhibiting endoplasmic reticulum stress

PURPOSE

The impaired function of islet β-cell is associated with the pathogenesis of type 2 diabetes mellitus (T2DM). γ-glutamylcysteine (γ-GC), an immediate precursor of glutathione (GSH), has antioxidant and neuroprotective functions. Its level has been reported to be down-regulated in hyperglycemia. However, whether γ-GC has a protective effect on islet β-cell dysfunction remains elusive. Recently, we explore the molecular mechanism by which γ-GC protects islet β-cell from glucolipotoxicity-induced dysfunction.

METHODS

In vivo mice models and in vitro cell models were established to examine the therapeutic effects and molecular mechanisms of γ-GC.

RESULTS

db mice develop impaired glucose-stimulated insulin secretion (GSIS) due to reduced islet number and damaged islet microstructure. Serious oxidative damage, apoptosis and lipid accumulation are also observed in β-cell stimulated by glucolipotoxicity. Mechanistic studies suggest that glucolipotoxicity inhibits PDX-1 nuclear translocation by inducing endoplasmic reticulum (ER) stress, which leads to impaired insulin (INS) secretion in β-cell. Nevertheless, γ-GC as an inhibitor of ER stress can alleviate the damage of islet microstructure in db mice. Importantly, γ-GC promotes INS gene expression and GSIS through driving nuclear translocation of PDX-1, thereby enhancing intracellular INS content. Moreover, treatment with γ-GC can also mitigate oxidative damage, apoptosis and lipid accumulation of β-cell, resulting in ameliorating islet β-cell dysfunction induced by glucolipotoxicity.

CONCLUSION

Our results support the use of γ-GC as an inhibitor of ER stress for prevention and treatment of T2DM in the future.

Discovery of Glucose Metabolism-Associated Genes in Neuropathic Pain: Insights from Bioinformatics

Metabolic dysfunction has been demonstrated to contribute to diabetic pain, pointing towards a potential correlation between glucose metabolism and pain. To investigate the relationship between altered glucose metabolism and neuropathic pain, we compared samples from healthy subjects with those from intervertebral disc degeneration (IVDD) patients, utilizing data from two public datasets. This led to the identification of 412 differentially expressed genes (DEG), of which 234 were upregulated and 178 were downregulated. Among these, three key genes (Ins, Igfbp3, Plod2) were found. Kyoto Encyclopedia of Genes and Genomes pathway analysis demonstrated the enrichment of hub genes in pathways such as the positive regulation of the ErbB signaling pathway, monocyte activation, and response to reactive oxygen species; thereby suggesting a potential correlation between these biological pathways and pain sensation. Further analysis identified three key genes (Ins, Igfbp3, and Plod2), which showed significant correlations with immune cell infiltration, suggesting their roles in modulating pain through immune response. To validate our findings, quantitative real-time polymerase chain reaction (qPCR) analysis confirmed the expression levels of these genes in a partial sciatic nerve ligation (PSNL) model, and immunofluorescence studies demonstrated increased immune cell infiltration at the injury site. Behavioral assessments further corroborated pain hypersensitivity in neuropathic pain (NP) models. Our study sheds light on the molecular mechanisms underlying NP and aids the identification of potential therapeutic targets for future drug development.

OVEREXPRESSION OF PTEN GENE INCREASES INS2 GENE MRNA EXPRESSION, NOT INS1 GENE MRNA EXPRESSION, IN INSULINOMA CELL LINE RIN-5F

Objective

One functional neuroendocrine tumor that causes hypoglycemia due to inappropriately high insulin production is an insulinoma. In rats, two genes coding for insulin, insulin 1 (Ins1) and insulin 2 (Ins2) are found on chromosome 1. Ins1 was produced from an Ins2 transcript, and it was inserted into the genome via an RNA-mediated duplication-transposition event, according to some structural feature analyses.

Methods

In this study, the author has looked at how overexpression of the PTEN gene in the insulinoma cell line Rin-5F affects the expression of the insulin genes, Ins 1 and Ins 2.

Results

In the insulinoma cell line, overexpression of the PTEN gene boosts Ins2 gene mRNA expression but not Ins1 gene mRNA expression. It has been reported that PTEN upregulates insulin signaling by increasing insulin receptor substrate (IRS)-2 mRNA levels. Also, PTEN has been reported to be secreted in exosomes and thereafter, into extracellular space.

Conclusions

The present study suggested that overexpression of PTEN might induce the increasing Ins 2 gene expression, one of the phosphorylated genes against the IRS-2 through the insulin/IGF-1 receptor. Our knowledge of the molecular pathways of PTEN relating the synthesis of insulin has been increased by the present study.