Lee B, Bradford P G, Laychock S G
Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, 14214-3000, USA.
J Mol Endocrinol. 1998 Aug;21(1):31-9. doi: 10.1677/jme.0.0210031.
The inositol 1,4,5-trisphosphate receptor (InsP3R) is an intracellular Ca2+ channel that plays a role in the regulation of insulin secretion. In rat isolated pancreatic islets the expression of types I, II and III InsP3R mRNA was identified by reverse transcriptase-polymerase chain reaction and confirmed by cDNA cloning and sequencing. The islet ratios of types I, II and III InsP3R mRNA to beta-actin mRNA were 0.08 +/- 0.02, 0.08 +/- 0.03 and 0.25 +/- 0.04 respectively. Types I, II and III InsP3R mRNA were also expressed in rat (RINm5F) and mouse (betaHC9) pancreatic beta-cell lines, and rat cerebellum. Type III InsP3R mRNA was quantitatively the most abundant form in rat islets and RINm5F cells. In betaHC9 cells, types II and III InsP3R mRNA were expressed at similar levels, and in much greater abundance than type I mRNA. Type III was the least abundant InsP3R mRNA in cerebellum. Culture of betaHC9 cells for 5 days at 2.8 and 25 mM glucose, or RINm5F cells for 7 days at 5.5 and 20 mM glucose, resulted in significantly enhanced expression of type III, but not types I and II, InsP3R mRNA in the cells at the higher glucose concentrations. During short-term (0.5-2 h) incubations, betaHC9 cell type III InsP3R mRNA levels increased in response to glucose in a time- and concentration-dependent manner. Actinomycin D inhibited the glucose response. Alpha-ketoisocaproic acid also stimulated betaHC9 cell type III InsP3R mRNA expression in a concentration-dependent manner, whereas 2-deoxyglucose and 3-O-methylglucose were without effect. The different levels of expression of mRNA for three InsP3R isoforms in islets and insulinoma cells, and the influence of glucose and alpha-ketoisocaproic acid on the expression of type III mRNA, suggests that nutrient metabolism plays a role in the regulation of this gene and that the function of InsP3R subtypes may be unique with each playing a distinct role in beta-cell signal transduction and insulin secretion.
肌醇1,4,5 -三磷酸受体（InsP3R）是一种细胞内钙离子通道，在胰岛素分泌调节中发挥作用。通过逆转录 - 聚合酶链反应在大鼠分离的胰岛中鉴定出I型、II型和III型InsP3R mRNA的表达，并通过cDNA克隆和测序得到证实。I型、II型和III型InsP3R mRNA与β -肌动蛋白mRNA的胰岛比率分别为0.08±0.02、0.08±0.03和0.25±0.04。I型、II型和III型InsP3R mRNA也在大鼠（RINm5F）和小鼠（βHC9）胰腺β细胞系以及大鼠小脑中表达。III型InsP3R mRNA在大鼠胰岛和RINm5F细胞中在数量上是最丰富的形式。在βHC9细胞中，II型和III型InsP3R mRNA以相似水平表达，且比I型mRNA丰富得多。III型是小脑中最不丰富的InsP3R mRNA。将βHC9细胞在2.8和25 mM葡萄糖浓度下培养5天，或将RINm5F细胞在5.5和20 mM葡萄糖浓度下培养7天，导致在较高葡萄糖浓度下细胞中III型InsP3R mRNA的表达显著增强，但I型和II型没有增强。在短期（0.5 - 2小时）孵育期间，βHC9细胞III型InsP3R mRNA水平以时间和浓度依赖性方式响应葡萄糖而增加。放线菌素D抑制葡萄糖反应。α -酮异己酸也以浓度依赖性方式刺激βHC9细胞III型InsP3R mRNA表达，而2 -脱氧葡萄糖和3 - O -甲基葡萄糖则无作用。三种InsP3R亚型mRNA在胰岛和胰岛素瘤细胞中的不同表达水平，以及葡萄糖和α -酮异己酸对III型mRNA表达的影响，表明营养物质代谢在该基因的调节中起作用，并且InsP3R亚型的功能可能是独特的，每种亚型在β细胞信号转导和胰岛素分泌中发挥不同作用。
