一种蛋白激酶Cε-抗凋亡激酶信号复合物通过诱导Bcl-2表达保护人血管内皮细胞免受凋亡。

A protein kinase Cepsilon-anti-apoptotic kinase signaling complex protects human vascular endothelial cells against apoptosis through induction of Bcl-2.

作者信息

Steinberg Rivka, Harari Olivier A, Lidington Elaine A, Boyle Joseph J, Nohadani Mahrokh, Samarel Allen M, Ohba Motoi, Haskard Dorian O, Mason Justin C

机构信息

Bywaters Center for Vascular Inflammation and Histopathology Section, Imperial College London, Hammersmith Hospital, London, W12 ONN United Kingdom.

出版信息

J Biol Chem. 2007 Nov 2;282(44):32288-97. doi: 10.1074/jbc.M704001200. Epub 2007 Sep 4.

Abstract

Endothelial cell apoptosis is associated with vascular injury and predisposes to atherogenesis. Endothelial cells express anti-apoptotic genes including Bcl-2, Bcl-XL and survivin, which also contribute to angiogenesis and vascular remodeling. We report a central role for protein kinase Cepsilon (PKCepsilon) in the regulation of Bcl-2 expression and cytoprotection of human vascular endothelium against apoptosis. Using myristoylated inhibitory peptides, a predominant role for PKCepsilon in vascular endothelial growth factor-mediated endothelial resistance to apoptosis was revealed. Immunoblotting of endothelial cells infected with an adenovirus expressing a constitutively active form of PKCepsilon (Adv-PKCepsilon-CA) or control Adv-beta-galactosidase demonstrated a 3-fold, PKCepsilon-dependent increase in Bcl-2 expression, with no significant change in Bcl-XL, Bad, Bak, or Bax. The induction of Bcl-2 inhibited apoptosis induced by serum starvation or etoposide, and PKCepsilon activation attenuated etoposide-induced caspase-3 cleavage. The functional role of Bcl-2 was confirmed with Bcl-2 antagonist HA-14-1. Inhibition of phosphoinositide 3-kinase attenuated vascular endothelial growth factor-induced protection against apoptosis, and this was rescued by overexpression of constitutively active PKCepsilon, suggesting PKCepsilon acts downstream of phosphoinositide 3-kinase. Co-immunoprecipitation studies demonstrated a physical interaction between PKCepsilon and Akt, which resulted in formation of a signaling complex, leading to optimal induction of Bcl-2. This study reveals a pivotal role for PKCepsilon in endothelial cell cytoprotection against apoptosis. We demonstrate that PKCepsilon forms a signaling complex and acts co-operatively with Akt to protect human vascular endothelial cells against apoptosis through induction of the anti-apoptotic protein Bcl-2 and inhibition of caspase-3 cleavage.

摘要

内皮细胞凋亡与血管损伤相关,并易引发动脉粥样硬化。内皮细胞表达抗凋亡基因,包括Bcl-2、Bcl-XL和生存素,这些基因也有助于血管生成和血管重塑。我们报道蛋白激酶Cε(PKCε)在调节Bcl-2表达以及保护人血管内皮细胞免受凋亡方面发挥核心作用。使用肉豆蔻酰化抑制肽,揭示了PKCε在血管内皮生长因子介导的内皮细胞抗凋亡中的主要作用。对感染表达组成型活性形式PKCε的腺病毒(Adv-PKCε-CA)或对照Adv-β-半乳糖苷酶的内皮细胞进行免疫印迹分析表明,Bcl-2表达增加了3倍,且依赖于PKCε,而Bcl-XL、Bad、Bak或Bax无显著变化。Bcl-2的诱导抑制了血清饥饿或依托泊苷诱导的凋亡,PKCε激活减弱了依托泊苷诱导的半胱天冬酶-3切割。用Bcl-2拮抗剂HA-14-1证实了Bcl-2的功能作用。抑制磷酸肌醇3-激酶减弱了血管内皮生长因子诱导的抗凋亡保护作用,而组成型活性PKCε的过表达挽救了这种作用,表明PKCε在磷酸肌醇3-激酶下游起作用。免疫共沉淀研究表明PKCε与Akt之间存在物理相互作用,这导致形成信号复合物,从而导致Bcl-2的最佳诱导。本研究揭示了PKCε在内皮细胞抗凋亡保护中的关键作用。我们证明PKCε形成信号复合物并与Akt协同作用,通过诱导抗凋亡蛋白Bcl-2和抑制半胱天冬酶-3切割来保护人血管内皮细胞免受凋亡。

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