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环磷酸腺苷介导的肠细胞系细胞外信号调节激酶激活的新机制

Novel mechanism of cyclic AMP mediated extracellular signal regulated kinase activation in an intestinal cell line.

作者信息

Rudolph Jeffrey A, Pratt Julia, Mourya Reena, Steinbrecher Kris A, Cohen Mitchell B

机构信息

Division of Pediatric Gastroenterology, Hepatology, and Nutrition, Cincinnati Children's Hospital Medical Center and the University of Cincinnati, Cincinnati, Ohio, 45229, United States.

出版信息

Cell Signal. 2007 Jun;19(6):1221-8. doi: 10.1016/j.cellsig.2007.01.002. Epub 2007 Jan 21.

Abstract

The extracellular signal regulated kinase (ERK1/2) signaling cascade has been implicated as both a pro-apoptotic and anti-apoptotic pathway depending on cell type and context. In the T84 intestinal epithelial cell line, cAMP activates ERK1/2 resulting in the inhibition of apoptosis. Cyclic-AMP signaling relies on the binding and activation of a cAMP binding protein. In most cell types, the majority of this signaling occurs through an isoform of protein kinase A (PKAI or PKAII). Despite evidence to the contrary, we hypothesized that ERK1/2 activation is through a PKA isoform. Pharmacological activators and inhibitors of PKA as well as siRNA were used to further interrogate this potential signaling pathway. Our results demonstrate that at doses sufficient to increase PKA activity, PKAII specific cAMP analogs activate ERK1/2 while PKAI analogs do not. Pharmacological inhibition of the PKAII regulatory subunit and catalytic subunit as well as siRNA knockdown of the catalytic subunit blocks ERK1/2 activation. We conclude that in the T84 cell line, cAMP binding to the PKAII regulatory subunit leads to the subsequent phosphorylation of ERK1/2 and provides insight into the mechanism of cAMP mediated survival signaling in the intestinal epithelium. These results directly implicate PKAII as a mediator of cell survival in T84 cells and provide evidence for an additional means by which cAMP can influence intestinal cell turnover.

摘要

细胞外信号调节激酶(ERK1/2)信号级联反应根据细胞类型和环境,既被认为是促凋亡途径,也被认为是抗凋亡途径。在T84肠上皮细胞系中,环磷酸腺苷(cAMP)激活ERK1/2,从而抑制细胞凋亡。环磷酸腺苷信号传导依赖于环磷酸腺苷结合蛋白的结合和激活。在大多数细胞类型中,这种信号传导的大部分是通过蛋白激酶A的一种同工型(PKAI或PKAII)发生的。尽管有相反的证据,但我们假设ERK1/2的激活是通过蛋白激酶A的一种同工型。使用蛋白激酶A的药理学激活剂和抑制剂以及小干扰RNA(siRNA)来进一步探究这条潜在的信号通路。我们的结果表明,在足以增加蛋白激酶A活性的剂量下,PKAII特异性环磷酸腺苷类似物激活ERK1/2,而PKAI类似物则不能。对PKAII调节亚基和催化亚基的药理学抑制以及催化亚基的小干扰RNA敲低可阻断ERK1/2的激活。我们得出结论,在T84细胞系中,环磷酸腺苷与PKAII调节亚基的结合导致ERK1/2随后的磷酸化,并为环磷酸腺苷介导的肠上皮细胞存活信号传导机制提供了见解。这些结果直接表明PKAII是T84细胞中细胞存活的介质,并为环磷酸腺苷影响肠细胞更新的另一种方式提供了证据。

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