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

白细胞介素-1（IL-1）被认为是一种效应分子， 自身免疫性糖尿病中β-细胞破坏。 IL-1抑制胰岛素 通过刺激胰腺β细胞的表达， 诱导型一氧化氮合酶（iNOS），产生一氧化氮。 IL-1还诱导IL-1的诱导型同种型的共表达。 环氧合酶（考克斯-2）和促炎性因子的过度产生 拟南芥素和它们的前体花生四烯酸， 同位素稀释质谱法 目前的研究 表征蛋白酶参与信号通路 IL-1诱导的iNOS和考克斯-2表达。 生化和分子 使用大鼠胰岛素瘤β细胞系RINm 5 F进行研究。 一种丝氨酸蛋白酶抑制剂，N（-对甲苯磺酰基-L-赖氨酸氯甲基酮 （TLCK）和蛋白酶体复合物抑制剂MG 132， IL-1诱导的一氧化氮氧化产物亚硝酸盐的形成 由iNOS以浓度依赖性方式产生。TLCK和 MG 132还在mRNA水平抑制iNOS基因表达， 蛋白 TLCK和MG 132对IL-1诱导的考克斯-2酶也有抑制作用 活性（PGE 2形成）和考克斯-2基因表达水平 mRNA和蛋白质。 在人类胰岛中，蛋白酶体抑制剂MG 132， 抑制iNOS和考克斯-2酶产物的生成 活性、亚硝酸盐和PGE 2。 这些发现提示 TLCK和MG 132对iNOS和考克斯-2的抑制作用 表达先于转录。 转录因子NF（B）是 对于激活许多精氨酸诱导酶是必需的， 被评价为IL-1所必需的蛋白酶作用的可能位点 诱导iNOS和考克斯-2的共表达。 TLCK和MG 132抑制 IL-1诱导NF β B活化和1 β B降解（胰岛 RINm 5 F细胞 这些结果暗示蛋白酶激活是一种 IL-1诱导的β-细胞功能抑制中的早期信号事件。

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.