Phosphorylation of SNAP-25 on serine-187 is induced by secretagogues in insulin-secreting cells, but is not correlated with insulin secretion
Phosphorylation of SNAP-25 on serine-187 is induced by secretagogues in insulin-secreting cells, but is not correlated with insulin secretion
复制标题
DOI：
10.1042/bj20020896
复制
发表时间：
2002-11-15
影响因子：
4.1
通讯作者：
Halban, P
中科院分区：
文献类型：
--
作者：
Gonelle-Gispert, C;Costa, M;Halban, P
25 kDa的tSNARE（靶膜可溶性NSF附着蛋白受体，其中NSF是N-乙基马来酰亚胺敏感性融合蛋白）突触体相关蛋白（SNAP-25）参与调节胰岛素分泌。在嗜铬细胞瘤PC 12细胞中，SNAP-25在Ser（187）处磷酸化，其位于对其功能重要的区域。本研究的目的是确定SNAP-25是否在胰岛素分泌细胞中的Ser（187）磷酸化，如果是这样，这是否对调节胰岛素分泌很重要。主要研究结果如下：（i）在大鼠胰岛素瘤INS-1细胞和大鼠胰岛中，SNAP-25在Ser（187）上响应佛波醇酯PMA而被快速和可逆地磷酸化;（ii）在INS-1细胞中，少于35%的SNAP-25响应PMA而被磷酸化，并且磷酸化限于质膜相关的SNAP-25;（iii）两种SNAP-25同种型（a和B）都被磷酸化，响应于PMA，SNAP-25 B的磷酸化高1.8倍;（iv）在大鼠胰岛中，葡萄糖或卡巴胆碱刺激Ser（187）磷酸化，尽管程度低于PMA，但cAMP不刺激;（v）用毒素抗性Ser（187）->Ala或Ser（187）->Asp突变体SNAP-25转染的肉毒杆菌神经毒素E处理的仓鼠胰岛素瘤（HIT）细胞的胰岛素分泌与野生型HIT细胞相似。此外，在大鼠胰岛中，在响应促分泌素的Ser（187）处的SNAP-25磷酸化程度与胰岛素释放的刺激之间没有发现相关性;（vi）蛋白激酶C（PKQ抑制剂）的使用表明葡萄糖通过常规和非常规PKC同种型刺激SNAP-25磷酸化。总之，尽管SNAP-25在Ser（187）处的磷酸化发生在胰岛素分泌细胞中并且由PKC介导，但它似乎在调节胰岛素分泌中不起主要作用。
The tSNARE (the target-membrane soluble NSF-attachment protein receptor, where NSF is N-ethylmaleimide-sensitive fusion protein) synaptosomal-associated protein of 25 kDa (SNAP-25) is implicated in regulated insulin secretion. In pheochromocytoma PC12 cells, SNAP-25 is phosphorylated at Ser(187), which lies in a region that is important for its function. The aims of the present study were to determine whether SNAP-25 is phosphorylated at Ser(187) in insulin-secreting cells and, if so, whether this is important for regulated insulin secretion. The major findings are: (i) SNAP-25 is rapidly and reversibly phosphorylated on Ser(187) in both rat insulinoma INS-1 cells and rat islets in response to the phorbol ester, PMA; (ii) less than 35 % of SNAP-25 in INS-I cells is phosphorylated in response to PMA, and phosphorylation is limited to plasma-membrane-associated SNAP-25; (iii) both SNAP-25 isoforms (a and b) are phosphorylated, with 1.8-fold greater phosphorylation for SNAP-25b in response to PMA; (iv) in rat islets, Ser(187) phosphorylation is stimulated by glucose or carbachol, albeit to a lesser extent than by PMA, but not by cAMP; (v) insulin secretion from botulinum neurotoxin E-treated hamster insulinoma tumour (HIT) cells, transfected with toxin-resistant Ser(187)-->Ala or Ser(187)-->Asp mutant SNAP-25, was similar to that of wild-type HIT cells. Furthermore, in rat islets no correlation was found between the extent of SNAP-25 phosphorylation at Ser(187) in response to secretagogues and stimulation of insulin release; (vi) use of protein kinase C (PKQ inhibitors suggests that glucose stimulates SNAP-25 phosphorylation via conventional and non-conventional PKC isoforms. In summary, although SNAP-25 phosphorylation at Ser(187) occurs in insulin-secreting cells and is mediated by PKC, it does not appear to play a major role in regulated insulin secretion.