Connexin36 contributes to INS-1E cells survival through modulation of cytokine-induced oxidative stress, ER stress and AMPK activity
Connexin36 contributes to INS-1E cells survival through modulation of cytokine-induced oxidative stress, ER stress and AMPK activity
复制标题
DOI：
10.1038/cdd.2013.134
复制
发表时间：
2013-12-01
影响因子：
12.4
通讯作者：
Haefliger, J-A
中科院分区：
文献类型：
--
作者：
Allagnat, F.;Klee, P.;Haefliger, J-A
由连接蛋白36（Cx 36）构成的间隙连接介导的细胞间通讯有助于胰腺β细胞功能。我们最近已经证明，Cx 36也支持B细胞存活的机制尚不清楚。使用特定的Cx 36 siRNA或腺病毒载体，我们现在表明，Cx 36下调促进INS-1 E细胞暴露于1型糖尿病发病时涉及的促炎细胞因子（IL-1 β，TNF-α和IFN-γ）的凋亡，而Cx 36过表达则保护免受这种影响。Cx 36过表达还保护INS-1 E细胞免受内质网（ER）应激介导的凋亡，并抑制了奎宁诱导的活性氧的产生、ER Ca 2+储存的耗尽、CHOP过表达以及抗凋亡蛋白Bcl-2和Mcl-1的降解。我们进一步表明，细胞因子激活AMP依赖性蛋白激酶（AMPK）在NO依赖性和ER应激依赖性的方式和AMPK抑制Cx 36的表达。总之，这些数据表明，Cx 36参与ER内的Ca 2+稳态，并且在ER应激和随后的AMPK激活后Cx 36表达下调。因此，苦参碱诱导的Cx 36下调激活了一个放大ER应激和AMPK激活的正反馈回路，导致Cx 36进一步下调。这些数据表明，Cx 36在细胞因子诱导的氧化应激和ER应激以及随后的AMPK活性调节中起核心作用，AMPK活性反过来控制Cx 36表达和胰岛素产生细胞的胰岛素依赖性凋亡。
Cell-to-cell communication mediated by gap junctions made of Connexin36 (Cx36) contributes to pancreatic beta-cell function. We have recently demonstrated that Cx36 also supports b-cell survival by a still unclear mechanism. Using specific Cx36 siRNAs or adenoviral vectors, we now show that Cx36 downregulation promotes apoptosis in INS-1E cells exposed to the pro-inflammatory cytokines (IL-1 beta, TNF-alpha and IFN-gamma) involved at the onset of type 1 diabetes, whereas Cx36 overexpression protects against this effect. Cx36 overexpression also protects INS-1E cells against endoplasmic reticulum (ER) stress-mediated apoptosis, and alleviates the cytokine-induced production of reactive oxygen species, the depletion of the ER Ca2+ stores, the CHOP overexpression and the degradation of the anti-apoptotic protein Bcl-2 and Mcl-1. We further show that cytokines activate the AMP-dependent protein kinase (AMPK) in a NO-dependent and ER-stress-dependent manner and that AMPK inhibits Cx36 expression. Altogether, the data suggest that Cx36 is involved in Ca2+ homeostasis within the ER and that Cx36 expression is downregulated following ER stress and subsequent AMPK activation. As a result, cytokine-induced Cx36 downregulation elicits a positive feedback loop that amplifies ER stress and AMPK activation, leading to further Cx36 downregulation. The data reveal that Cx36 plays a central role in the oxidative stress and ER stress induced by cytokines and the subsequent regulation of AMPK activity, which in turn controls Cx36 expression and mitochondria-dependent apoptosis of insulin-producing cells.