HIT Center for Life Sciences, School of Life Science and Technology, Harbin Institute of Technology, Harbin, China.
Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China.
Diabetologia. 2023 Jun;66(6):1084-1096. doi: 10.1007/s00125-023-05900-z. Epub 2023 Mar 15.
AIMS/HYPOTHESIS: N-methyladenosine (mA) mRNA methylation and mA-related proteins (methyltransferase-like 3 [METTL3], methyltransferase-like 14 [METTL14] and YTH domain containing 1 [YTHDC1]) have been shown to regulate islet beta cell function and the pathogenesis of diabetes. However, whether Wilms' tumour 1-associating protein (WTAP), a key regulator of the mA RNA methyltransferase complex, regulates islet beta cell failure during pathogenesis of diabetes is largely unknown. The present study aimed to investigate the role of WTAP in the regulation of islet beta cell failure and diabetes.
Islet beta cell-specific Wtap-knockout and beta cell-specific Mettl3-overexpressing mice were generated for this study. Blood glucose, glucose tolerance, serum insulin, glucose-stimulated insulin secretion (both in vivo and in vitro), insulin levels, glucagon levels and beta cell apoptosis were examined. RNA-seq and MeRIP-seq were performed, and the data were well analysed.
WTAP was downregulated in islet beta cells in type 2 diabetes, due to lipotoxicity and chronic inflammation, and islet beta cell-specific deletion of Wtap (Wtap-betaKO) induced beta cell failure and diabetes. Wtap-betaKO mice showed severe hyperglycaemia (above 20 mmol/l [360 mg/dl]) from 8 weeks of age onwards. Mechanistically, WTAP deficiency decreased mA mRNA modification and reduced the expression of islet beta cell-specific transcription factors and insulin secretion-related genes by reducing METTL3 protein levels. Islet beta cell-specific overexpression of Mettl3 partially reversed the abnormalities observed in Wtap-betaKO mice.
CONCLUSIONS/INTERPRETATION: WTAP plays a key role in maintaining beta cell function by regulating mA mRNA modification depending on METTL3, and the downregulation of WTAP leads to beta cell failure and diabetes.
The RNA-seq and MeRIP-seq datasets generated during the current study are available in the Gene Expression Omnibus database repository ( https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE215156 ; https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE215360 ).
目的/假设：N6-甲基腺苷（mA）mRNA 甲基化和 mA 相关蛋白（甲基转移酶样 3 [METTL3]、甲基转移酶样 14 [METTL14]和 YTH 结构域包含蛋白 1 [YTHDC1]）已被证明可调节胰岛β细胞功能和糖尿病的发病机制。然而，Wilms 瘤 1 相关蛋白（WTAP）作为 mA RNA 甲基转移酶复合物的关键调节因子，是否在糖尿病发病过程中调节胰岛β细胞衰竭，在很大程度上尚不清楚。本研究旨在探讨 WTAP 在调节胰岛β细胞衰竭和糖尿病中的作用。
本研究生成了胰岛β细胞特异性 Wtap 敲除和胰岛β细胞特异性 Mettl3 过表达小鼠。检测血糖、葡萄糖耐量、血清胰岛素、体内和体外葡萄糖刺激胰岛素分泌、胰岛素水平、胰高血糖素水平和胰岛β细胞凋亡。进行了 RNA-seq 和 MeRIP-seq 实验，并对数据进行了深入分析。
在 2 型糖尿病中，由于脂毒性和慢性炎症，胰岛β细胞中的 WTAP 下调，胰岛β细胞特异性敲除 Wtap（Wtap-βKO）诱导胰岛β细胞衰竭和糖尿病。Wtap-βKO 小鼠从 8 周龄开始出现严重的高血糖症（超过 20 mmol/l [360 mg/dl]）。机制上，WTAP 缺失通过降低 METTL3 蛋白水平，减少 mA mRNA 修饰，并降低胰岛β细胞特异性转录因子和胰岛素分泌相关基因的表达，导致胰岛β细胞功能障碍。胰岛β细胞特异性过表达 Mettl3 部分逆转了 Wtap-βKO 小鼠观察到的异常。
结论/解释：WTAP 通过调节 METTL3 依赖的 mA mRNA 修饰在维持胰岛β细胞功能方面发挥关键作用，WTAP 的下调导致胰岛β细胞衰竭和糖尿病。
本研究中生成的 RNA-seq 和 MeRIP-seq 数据集可在基因表达综合数据库存储库中获得（ https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE215156 ； https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE215360 ）。
