Scarim Anna L, Nishimoto Sheri Y, Weber Sarah M, Corbett John A
Edward A Doisy Department of Biochemistry and Molecular Biology, St Louis University School of Medicine, St Louis, Missouri 63104, USA.
Endocrinology. 2003 Aug;144(8):3415-22. doi: 10.1210/en.2002-0112.
Treatment of rat islets with the cytokine IL-1 results in the inhibition of mitochondrial function and insulin secretion, events that are mediated by beta-cell expression of iNOS [inducible nitric oxide (NO) synthase] and production of NO. beta-Cells recover from the inhibitory actions of NO, produced following 24 h incubation with IL-1, on islet oxidative metabolism and insulin secretion if iNOS enzymatic activity is inhibited and the islets are cultured (in the presence of IL-1 and iNOS inhibitors) for a brief period of 8 h. Islet recovery from cytokine- and NO-mediated damage is an active process that requires new gene expression, and NO itself is one activator of this recovery process. In this study, the mechanism by which NO stimulates islet recovery has been examined. Incubation of rat islets or RINm5F cells with the NO donor compound, sodium (Z)-1(N,N-diethylamino) diazen-1-ium-1,2-diolate (DEA-NO) for 1 h results in a 60% inhibition of mitochondrial aconitase activity. beta-Cells completely recover aconitase activity if the cells are washed to remove the NO donor compound and incubated for an additional 5 h in the absence of DEA-NO. The recovery of mitochondrial aconitase activity correlates with a 4-fold increase in cyclic GMP accumulation and is prevented by the inhibition of guanylate cyclase. The recovery of aconitase activity also correlates with the activation of members of the MAPKs, p38, c-Jun N-terminal kinase (JNK) and ERK, and the activation p38 and JNK is attenuated by inhibition of guanylate cyclase. ERK and p38 do not appear to participate in the recovery process as selective inhibition of these kinases fails to prevent recovery of aconitase activity; however, transduction of beta-cells with a dominant negative mutant JNK prevents beta-cell recovery from NO-mediated damage. These findings support a role for guanylate cyclase and JNK in the recovery of beta-cells from NO-mediated damage.
用细胞因子白细胞介素-1（IL-1）处理大鼠胰岛会导致线粒体功能和胰岛素分泌受到抑制，这些事件是由胰岛β细胞中诱导型一氧化氮合酶（iNOS）的表达和一氧化氮（NO）的产生介导的。如果iNOS酶活性受到抑制，并且胰岛在（存在IL-1和iNOS抑制剂的情况下）短暂培养8小时，那么β细胞就能从与IL-1孵育24小时后产生的NO对胰岛氧化代谢和胰岛素分泌的抑制作用中恢复。胰岛从细胞因子和NO介导的损伤中恢复是一个需要新基因表达的活跃过程，而NO本身就是这个恢复过程的一种激活剂。在本研究中，已经对NO刺激胰岛恢复的机制进行了研究。用NO供体化合物（Z）-1（N，N-二乙氨基）重氮-1，2-二醇酸钠（DEA-NO）孵育大鼠胰岛或RINm5F细胞1小时，会导致线粒体乌头酸酶活性受到60%的抑制。如果将细胞洗涤以去除NO供体化合物，并在不存在DEA-NO的情况下再孵育5小时，β细胞的乌头酸酶活性会完全恢复。线粒体乌头酸酶活性的恢复与环磷酸鸟苷（cGMP）积累增加4倍相关，并且会被鸟苷酸环化酶的抑制所阻止。乌头酸酶活性的恢复还与丝裂原活化蛋白激酶（MAPK）成员p38、c-Jun氨基末端激酶（JNK）和细胞外信号调节激酶（ERK）的激活相关，并且p38和JNK的激活会被鸟苷酸环化酶的抑制所减弱。ERK和p38似乎不参与恢复过程，因为对这些激酶的选择性抑制并不能阻止乌头酸酶活性的恢复；然而，用显性负性突变体JNK转导β细胞会阻止β细胞从NO介导的损伤中恢复。这些发现支持鸟苷酸环化酶和JNK在β细胞从NO介导的损伤中恢复过程中发挥作用。
