Heat-shock proteins attenuate SERCA inactivation by the anti-apoptotic protein Bcl-2: possible implications for the ER Ca2+-mediated apoptosis.
Heat-shock proteins attenuate SERCA inactivation by the anti-apoptotic protein Bcl-2: possible implications for the ER Ca2+-mediated apoptosis.
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DOI：
10.1042/bj20111114
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发表时间：
2012-05-15
期刊：
影响因子：
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通讯作者：
Schöneich C
中科院分区：
文献类型：
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作者：
Dremina ES;Sharov VS;Schöneich C
我们已经证明，Bcl-2和Bcl-2Δ21，一个C-末端截短的Bcl-2序列，在分离的肌浆网（SR）中取代SERCA 1，伴随着从SR的小窝相关结构域的易位。在这里，我们提出了Bcl-2与SERCA 2b在C2 C12成肌细胞和HEK 293细胞中相互作用的证据。Bcl-2和SERCA 2b从Bcl-2过表达细胞的裂解物和微粒体组分中共免疫沉淀。然而，Bcl-2过表达只导致轻微的易位从CRD和没有显着的SERCA失活。在分离的HEK 293细胞微粒体中，与Bcl-2Δ21孵育提供SERCA 2b失活和一些易位。HSP 70、HSP 90、HSP 27和α-晶状体蛋白减弱Bcl-2Δ21依赖的SERCA 2b失活。SERCA 1同种型的体外机制研究表明，HSP 70（i）保护SERCA 1免受Bcl-2Δ21的失活，（ii）抑制SERCA 1从CRD组分的易位，（iii）防止Bcl-2Δ21依赖性FITC标记的丢失。我们的数据表明，在体外建立的SERCA 1亚型的Bcl-2的SERCA失活的机制，可以扩展到主要的管家SERCA 2b亚型，和SERCA 2b和Bcl-2在细胞中的功能相互作用可能是由HSP 70和其他伴侣和应激调节蛋白质调制。
We had demonstrated that Bcl-2 and Bcl-2Δ21, a C-terminal truncated Bcl-2 sequence, inactivate SERCA1 in isolated sarcoplasmic reticulum (SR), accompanied by a translocation from caveolae-related domains of the SR. Here, we present evidence for the interaction of Bcl-2 with SERCA2b in C2C12 myoblast and HEK293 cells. Bcl-2 and SERCA2b co-immunoprecipitated from lysate and microsomal fractions of Bcl-2-overexpressing cells. However, Bcl-2 overexpression resulted only in a slight translocation from the CRD and no significant SERCA inactivation. In isolated HEK293 cell microsomes, incubation with Bcl-2Δ21 afforded SERCA2b inactivation and some translocation. HSP70, HSP90, HSP27, and alpha-crystallin attenuated Bcl-2Δ21-dependent SERCA2b inactivation. An in vitro mechanistic study with the SERCA1 isoform shows that HSP70 (i) protects SERCA1 from the inactivation by Bcl-2Δ21, (ii) inhibits SERCA1 translocation from CRD fractions, and (iii) prevents the Bcl-2Δ21-dependent loss of FITC labeling. Our data demonstrate that the mechanism of SERCA inactivation by Bcl-2 established in vitro for the SERCA1 isoform can be extended to the main housekeeping SERCA2b isoform, and that functional interactions of SERCA2b and Bcl-2 in the cell may be modulated by HSP70 and other chaperone and stress-regulated proteins.