Molecular Biological Studies of Calcium Signaling in Insulin Secretion ; their implication for the development of diabetes mellitus

细胞内钙[Ca^2+]i是胰岛素分泌的主要信号。由于引起胰腺β细胞中[Ca^<2+>]i增加的主要途径是跨β细胞膜的内流和细胞内钙库的动员，因此参与这些途径的蛋白质在调节胰岛素分泌中起关键作用。我们克隆并鉴定了大鼠β细胞/神经内分泌型电压依赖性钙（VDCC）的aopha 1亚基，在CHO细胞和非洲爪蟾卵母细胞中的功能表达表明aopha 1和β亚基的共表达产生了典型的L型VDCC活性，提示β细胞/神经内分泌型VDCC在胰岛素分泌中起作用。我们已经确定了人类β细胞/神经内分泌型VDCC α 1亚单位的基因结构，该基因定位于3号染色体p14.3带。该基因跨度超过120 kb，有50个外显子。非胰岛素依赖型糖尿病患者该基因的序列变异分析 ...更多信息 糖尿病（NIDDM）目前正在进行中。我们还克隆了编码在胰岛和克隆β细胞系中表达的肌醇1，4，5三磷酸（IP 3）受体（IP 3R-3）的第三亚型的cDNA。由于一些胰岛素促分泌素如CCK和乙酰胆碱通过PI水解来刺激胰岛素分泌，因此建议IP 3R-3参与胰岛素的调节。我们克隆了胰岛中生长抑素受体（SSTR-3）和垂体腺苷酸环化酶激活多肽（PACAP）受体（PACAPR-3）的cDNA。PACAPR-3的功能性表达表明，它可以偶联到磷脂酶C以及腺苷酸环化酶，表明PACAPR-3参与胰岛素分泌中的钙信号传导。总之，我们的研究阐明了胰岛素分泌中钙信号传导的一些重要因素的分子基础，并为这些基因对NIDDM发展的贡献以及对胰岛素分泌分子机制的理解提供了有价值的见解。少

Intracellular calcium[Ca^<2+>]i is the principal signal for insulin secretion. Since major pathways causing an increase in [Ca^<2+>]i in pancreatic beta-cells are the influx across beta-cell membrane and the mobilization from intracellular calcium stores, the proteins involved in these pathways play crucial roles in the regulation insulin secretion. We have cloned and characterized a aopha1-subunit of rat beta-cell/neuroendocrine type voltage-dependent calcium (VDCC).Functional expression using CHO CELLS AND Xenopus oocytes shows that coexpression of the aopha1 and beta subunit generates a typical L-type VDCC activity, suggesting that the beta-cell/neuroendocrine type VDCC plays a role in insulin secretion. We have determined the structure of the human gene for the alpha1 subunit of beta-cell/neuroendocrine type VDCC.The gene has been localized to chromosome 3, band p14.3. The gene spans more than 120kb and has 50 exons. Analysis of sequence variations of this gene in non-insulin depen … More dent diabetes mellitus (NIDDM) is currently underway. We have also cloned a cDNA encoding a third subtype of inositol 1,4,5 triphosphate (IP3) receptor (IP3R-3) expressed in pancreatic islets and a clonal beta-cell line. Since some insulin secretagogues such as CCK and acetylcholine stimulate insulin secretion via PI hydrolysis, the IP3R-3 is suggested to be involved in the regulation of insulin. Many hormones and neurotransmtters are known to modulate insulin secretion through their specific receptors.We have cloned cDNAs encoding a somatostatin receptor (SSTR-3) and a pituitary adenylyl cyclase-activating, polypeptide (PACAP) receptor (PACAPR-3) expressed in pancreatic islets. Functional expression of PACAPR-3 shows that it can be coupled to phospholipase C as well as to adenylyl cyclase, suggesting that PACAPR-3 is involved in calcium signaling in insulin secretion. In conclusion, our studies have clarified molecular basis for some of the important factors involved in calcium signaling in insulin secretion and have provided valuable insight into the contribution of these genes to the development of NIDDM as well as the understanding of the molecular mechanisms of insulin secretion. Less