Ortega-Cuellar Daniel, González-Sánchez Ignacio, Piñón-Zárate Gabriela, Cerbón Marco A, De la Rosa Víctor, Franco-Juárez Yuliana, Castell-Rodríguez Andrés, Islas León D, Coronel-Cruz Cristina
Laboratorio de Nutrición Experimental, Instituto Nacional de Pediatría, Secretaría de Salud, Mexico City 04530, Mexico.
Departamento de Biología, Facultad de Química, UNAM, Mexico City 04510, Mexico.
Biology (Basel). 2024 Jun 25;13(7):468. doi: 10.3390/biology13070468.
Glucotoxicity may exert its deleterious effects on pancreatic β-cell function via a myriad of mechanisms, leading to impaired insulin secretion and, eventually, type 2 diabetes. β-cell communication requires gap junction channels to be present among these cells. Gap junctions are constituted by transmembrane proteins of the connexins (Cxs) family. Two Cx genes have been identified in β cells, Cx36 and Cx30.2. We have found evidence that the glucose concentration on its own is sufficient to regulate Cx30.2 gene expression in mouse islets. In this work, we examine the involvement of the Cx30.2 protein in the survival of β cells (RIN-m5F).
RIN-m5F cells were cultured in 5 mM D-glucose (normal) or 30 mM D-glucose (high glucose) for 24 h. Cx30.2 siRNAs was used to downregulate Cx30.2 expression. Apoptosis was measured by means of TUNEL, an annexin V staining method, and the cleaved form of the caspase-3 protein was determined using Western blot.
High glucose did not induce apoptosis in RIN-m5F β cells after 24 h; interestingly, high glucose increased the Cx30.2 total protein levels. Moreover, this work found that the downregulation of Cx30.2 expression in high glucose promoted apoptosis in RIN-m5F cells.
The data suggest that the upregulation of Cx30.2 protects β cells from hyperglycemia-induced apoptosis. Furthermore, Cx30.2 may be a promising avenue of therapeutic investigation for the treatment of glucose metabolic disorders.
糖毒性可能通过多种机制对胰腺β细胞功能产生有害影响，导致胰岛素分泌受损，最终引发2型糖尿病。β细胞之间的通讯需要间隙连接通道的存在。间隙连接由连接蛋白（Cxs）家族的跨膜蛋白构成。在β细胞中已鉴定出两个Cx基因，即Cx36和Cx30.2。我们已发现证据表明，葡萄糖浓度本身足以调节小鼠胰岛中Cx30.2基因的表达。在本研究中，我们检测了Cx30.2蛋白在β细胞（RIN-m5F）存活中的作用。
将RIN-m5F细胞在5 mM D-葡萄糖（正常）或30 mM D-葡萄糖（高糖）中培养24小时。使用Cx30.2小干扰RNA（siRNAs）下调Cx30.2的表达。通过TUNEL法、膜联蛋白V染色法检测细胞凋亡，并使用蛋白质免疫印迹法测定半胱天冬酶-3蛋白的裂解形式。
24小时后，高糖并未诱导RIN-m5F β细胞凋亡；有趣的是，高糖增加了Cx30.2的总蛋白水平。此外，本研究发现，在高糖环境下下调Cx30.2的表达会促进RIN-m5F细胞凋亡。
数据表明，Cx30.2的上调可保护β细胞免受高血糖诱导的凋亡。此外，Cx30.2可能是治疗葡萄糖代谢紊乱的一个有前景的治疗研究途径。
