Moghadasi Mona, Taherimoghaddam Mozhgan, Babaeenezhad Esmaeel, Birjandi Mehdi, Kaviani Mozhgan, Moradi Sarabi Mostafa
Nutritional Health Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran; Department Clinical Biochemistry and Genetics, School of Medicine, Lorestan University of Medical Sciences, Khorramabad, Iran.
Hepatitis Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran; Department of Biostatistics and Epidemiology, School of Health and Nutrition, Lorestan University of Medical Sciences, Khorramabad, Iran.
Diabetes Metab Syndr. 2024 Oct;18(10):103156. doi: 10.1016/j.dsx.2024.103156. Epub 2024 Nov 7.
This study aimed to investigate the roles of DNA methylation and miR-34a in the regulation of peroxisome proliferator-activated receptor gamma (PPARγ) in patients with type 2 diabetes (T2D).
We investigated the methylation status of four regions of the PPARγ promoter and PPARγ expression in a panel of 84 T2D patients using methylation-specific PCR (MSP) and RT-qPCR, respectively. Moreover, we quantified DNA methyltransferases (DNMTs) expression and global DNA methylation levels by RT-qPCR and ELISA, respectively. We measured the expression levels of miR-34a and protein expression of PPARγ by stem-loop RT-qPCR and ELISA, respectively.
We found significant DNA hypermethylation in the R2 and R3 regions of the PPARγ promoter in people with diabetes. Functionally, this was associated with a significant reduction in PPARγ expression. In addition, we observed a significant increase in 5-methylcytosine levels in people with diabetes. A marked increase in circulating miR-34a in the early stages of T2D (up to 10 years) and a significant decrease in circulating miR-34a with increasing diabetes duration from 10 years after the onset of diabetes. Interestingly, upregulation of DNA methyltransferases 1 (DNMT1), DNMT3A, and DNMT3B was observed in people with diabetes, and the average expression of DNMTs was negatively correlated with circulating miR-34a levels. In contrast, the serum protein level of PPARγ, a direct target of miR-34a, increased considerably with diabetes duration and showed a negative correlation with circulating miR-34a, cholesterol, triglyceride, and low-density lipoprotein.
PPARγ promoter hypermethylation and miR-34a upregulation are associated with T2D pathogenesis through PPARγ dysregulation.
本研究旨在探讨DNA甲基化和miR-34a在2型糖尿病（T2D）患者中对过氧化物酶体增殖物激活受体γ（PPARγ）调控的作用。
我们分别使用甲基化特异性PCR（MSP）和RT-qPCR，对84例T2D患者的PPARγ启动子四个区域的甲基化状态和PPARγ表达进行了研究。此外，我们分别通过RT-qPCR和ELISA对DNA甲基转移酶（DNMTs）表达和整体DNA甲基化水平进行了定量。我们分别通过茎环RT-qPCR和ELISA测量了miR-34a的表达水平和PPARγ的蛋白表达。
我们发现糖尿病患者PPARγ启动子的R2和R3区域存在显著的DNA高甲基化。在功能上，这与PPARγ表达的显著降低相关。此外，我们观察到糖尿病患者5-甲基胞嘧啶水平显著升高。在T2D早期（长达10年）循环miR-34a显著增加，而从糖尿病发病10年后随着糖尿病病程延长循环miR-34a显著降低。有趣的是，在糖尿病患者中观察到DNA甲基转移酶1（DNMT1）、DNMT3A和DNMT3B上调，并且DNMTs的平均表达与循环miR-34a水平呈负相关。相反，miR-34a的直接靶点PPARγ的血清蛋白水平随着糖尿病病程显著升高，并且与循环miR-34a、胆固醇、甘油三酯和低密度脂蛋白呈负相关。
PPARγ启动子高甲基化和miR-34a上调通过PPARγ失调与T2D发病机制相关。
