PROTEASOME COMPLEX IN IL 1: NITRIC OXIDE & PROSTAGLANDIN BY RAT ISLETS & B CELLS

白介素1(IL-1)被认为是一种效应分子 自身免疫性糖尿病的(-)细胞破坏。IL-1对胰岛素的抑制作用 胰腺(-)细胞通过刺激其表达分泌 诱导型一氧化氮合酶(INOS)，可产生一氧化氮。 IL-1还可诱导可诱导的同种异构体 环氧合酶(COX-2)与促炎因子的过度产生 前列腺素及其前体花生四烯酸 用同位素稀释质谱仪测定。当前的研究 蛋白水解酶(S)参与信号通路的特征 抑制IL-1诱导的iNOS和COX-2的表达。生化与分子 使用大鼠胰岛素瘤(-)细胞系RINm5F进行研究。 丝氨酸蛋白酶抑制剂N(-对甲苯磺基-L-赖氨酸氯甲基酮) (TLCK)和蛋白酶体复合体抑制剂MG 132被抑制 IL-1诱导一氧化氮氧化产物亚硝酸盐的形成 由iNOS在浓度依赖的甘露糖中产生。TLCK和 MG132还可从基因表达水平抑制iNOS基因的表达 蛋白。TLCK和MG 132也抑制IL-1诱导的COX-2酶 活性(PGE2形成)和COX-2基因表达水平 信使核糖核酸和蛋白质在人类胰岛中，蛋白酶体抑制剂MG 132， 也抑制iNOS和COX-2酶产物的形成 活性、亚硝酸盐和前列腺素E_2。这些发现表明 TLCK和MG 132对iNOS和COX-2的抑制作用 表达先于转录。转录因子NF(B)是 对于激活一些细胞因子诱导的酶是必不可少的 被评估为IL-1所必需的可能的蛋白酶作用部位 诱导型一氧化氮合酶和环氧合酶-2共表达。TLCK和MG 132被抑制 IL-1诱导核因子(B)的活化和1(B)的降解(由胰岛 和RINm5F细胞。这些结果暗示了蛋白酶的激活是一种 IL-1抑制(-细胞)功能的早期信号事件。

Interleukin-1( (IL-1) has been implicated as an effector molecule of (-cell destruction in autoimmune diabetes. IL-1 inhibits insulin secretion from pancreatic (-cells by stimulating the expression of inducible nitric oxide synthase (iNOS) that generates nitric oxide. IL-1 also induces co-expression of the inducible isoform of cyclooxygenase (COX-2) and overproduction of pro-inflammatory prostaglandins and their precursor arachidonic acid, as demonstrated by isotope dilution mass spectrometry. The current studies characterize the involvement of protease(s) in the signaling pathway of IL-1-induced iNOS and COX-2 expression. Biochemical and molecular studies were performed using the rat insulinoma (-cell line, RINm5F. A serine protease inhibitor, N(-p-tosyl-L-lysine chloromethyl ketone (TLCK) and a proteasome complex inhibitor, MG 132, inhibited Il-1-induced nitrite formation, an oxidation product of nitric oxide produced by iNOS, in a concentration-dependent manne r. Both TLCK and MG 132 also inhibited iNOS gene expression at the level of mRNA and protein. TLCK and MG 132 also inhibited IL-1 induced COX-2 enzyme activity (PGE2 formation) and COX-2 gene expression at the level of mRNA and protein. In human islets, the proteasome inhibitor, MG 132, also inhibited the formation of the products of iNOS and COX-2 enzyme activity, nitrite and PGE2 respectively. These findings suggested that the inhibitory action of TLCK and MG 132 on iNOS and COX-2 expression precedes transcription. The transcription factor, NF(B, is essential for activation of a number of cytokine-inducible enzymes and was evaluated as a possible site of protease action necessary for IL-1 induced co-expression of iNOS and COX-2. TLCK and MG 132 inhibited both IL-1 induced activation of NF(B and degradation of 1(B( by islets and RINm5F cells. These results implicate protease activation as an early signaling event in IL-1-induced inhibition of (-cell function.