Key Laboratory of Protein Chemistry & Developmental Biology of Education Ministry of China, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China.
Curr Mol Med. 2012 Feb;12(2):177-87. doi: 10.2174/156652412798889036.
The small heat shock protein, α-crystallin, exists in two isoforms, αA and αB, and displays strong ability against stress-induced apoptosis. Regarding their functional mechanisms, we and others have demonstrated that they are able to regulate members in both caspase and Bcl-2 families. In addition, we have also shown that αA and αB may display differential anti-apoptotic mechanisms under certain stress conditions. While αA-crystallin regulates activation of the AKT signaling pathway, αB negatively regulates the MAPK pathway to suppress apoptosis induced by UV and oxidative stress. Although previous studies revealed that αA and αB could regulate members in both caspase and Bcl-2 families, the molecular mechanism, especially the in vivo regulation still waits to be elucidated. In the present communication, we present both in vitro and in vivo evidence to further demonstrate the regulation of caspase-3 and Bax by αA and αB. First, Surface Plasmon Resonance (SPR) and yeast two-hybrid selection analysis demonstrate that αA and αB directly bind to caspase-3 and Bax with differential affinities. Second, immunohistochemistry reveals that αA and αB regulate caspase-3 and Bax at different developmental stages of mouse embryo. Third, coimmunoprecipitation shows that αA and αB form in vivo interacting complexes with caspase-3 and Bax. Together, our results further confirm that αA and αB regulate caspase-3 and Bax in vitro and in vivo to regulate lens differentiation.
小分子热休克蛋白 α-晶状体蛋白存在两种同工型，即 αA 和 αB，具有很强的抗应激诱导细胞凋亡的能力。关于它们的功能机制，我们和其他人已经证明它们能够调节半胱天冬酶和 Bcl-2 家族的成员。此外，我们还表明，αA 和 αB 可能在某些应激条件下表现出不同的抗凋亡机制。虽然αA-晶状体蛋白调节 AKT 信号通路的激活，但αB 负调节 MAPK 通路，以抑制 UV 和氧化应激诱导的细胞凋亡。尽管先前的研究表明αA 和 αB 可以调节半胱天冬酶和 Bcl-2 家族的成员，但分子机制，特别是体内调节仍有待阐明。在本通讯中，我们提供了体外和体内证据，进一步证明了αA 和 αB 对 caspase-3 和 Bax 的调节作用。首先，表面等离子体共振（SPR）和酵母双杂交选择分析表明，αA 和 αB 以不同的亲和力直接与 caspase-3 和 Bax 结合。其次，免疫组织化学显示，αA 和 αB 在小鼠胚胎的不同发育阶段调节 caspase-3 和 Bax。第三，共免疫沉淀显示αA 和 αB 在体内与 caspase-3 和 Bax 形成相互作用复合物。总之，我们的结果进一步证实，αA 和 αB 调节体外和体内的 caspase-3 和 Bax，以调节晶状体分化。
