The chaperone Hsp70 is a BH3 receptor activated by the pro-apoptotic Bim to stabilize anti-apoptotic clients
The chaperone Hsp70 is a BH3 receptor activated by the pro-apoptotic Bim to stabilize anti-apoptotic clients
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分子伴侣 Hsp70 是一种 BH3 受体，由促凋亡 Bim 激活，可稳定抗凋亡客户
DOI：
10.1074/jbc.ra120.013364
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发表时间：
2020-09-11
影响因子：
4.8
通讯作者：
Zhang, Zhichao
中科院分区：
文献类型：
--
作者：
Guo, Zongwei;Song, Ting;Zhang, Zhichao
分子伴侣热休克蛋白70（Hsp 70）对于避免应激下的蛋白质错误折叠至关重要，但在许多类型的癌症中也被上调，其中其缓冲细胞应激的能力防止细胞凋亡。先前的研究表明，Hsp 70与促凋亡Bcl-2家族蛋白（包括Bim和Bax）相互作用。然而，这种相互作用的明确证明尚待进行，对结构基础和分子机制的深入了解仍不清楚。早期的研究已经鉴定了存在于Bcl-2家族成员中的Bcl-2同源3（BH 3）结构域，其接合受体以刺激细胞凋亡。我们现在表明，热休克蛋白70的物理相互作用与促凋亡的多域和BH 3-只有蛋白质通过BH 3结构域，从而作为一种新的BH 3受体，使用在体外荧光偏振（FP），等温滴定量热法（ITC），和基于细胞的共免疫沉淀（co-IP）实验，1H-15 N-横向弛豫优化光谱（TROSY-HSQC）、胰蛋白酶蛋白水解、ATP酶活性和变性罗丹氏聚集测量进一步证明BimBH 3结合至Hsp 70的核苷酸结合结构域（NBD）中的新变构位点，Bim作为一种正性共分子伴侣，促进ATP酶活性和分子伴侣功能。揭示了Hsp 70的抗凋亡功能的双重作用，即当它保持Bim抑制凋亡时，它同时在Bim的帮助下稳定致癌客户包括AKT和Raf-1。Bim在细胞命运调控中的两面性被揭示，与其公认的促凋亡激活剂作用相反，Bim可以帮助致癌蛋白的折叠。
The chaperone heat shock protein 70 (Hsp70) is crucial for avoiding protein misfolding under stress, but is also up-regulated in many kinds of cancers, where its ability to buffer cellular stress prevents apoptosis. Previous research has suggested Hsp70 interacts with pro-apoptotic Bcl-2 family proteins, including Bim and Bax. However, a definitive demonstration of this interaction awaits, and insights into the structural basis and molecular mechanism remain unclear. Earlier studies have identified a Bcl-2 homology 3 (BH3) domain present in Bcl-2 family members that engages receptors to stimulate apoptosis. We now show that Hsp70 physically interacts with pro-apoptotic multidomain and BH3-only proteins via a BH3 domain, thereby serving as a novel BH3 receptor, using in vitro fluorescent polarization (FP), isothermal titration calorimetry (ITC), and cell-based co-immunoprecipitation (co-IP) experiments, 1H-15N-transverse relaxation optimized spectroscopy (TROSY-HSQC), trypsin proteolysis, ATPase activity, and denatured rhodanese aggregation measurements further demonstrated that BimBH3 binds to a novel allosteric site in the nucleotide-binding domain (NBD) of Hsp70, by which Bim acts as a positive co-chaperone to promote the ATPase activity and chaperone functions. A dual role of Hsp70's anti-apoptotic function was revealed that when it keeps Bim in check to inhibit apoptosis, it simultaneously stabilizes oncogenic clients including AKT and Raf-1 with the aid of Bim. Two faces of Bim in cell fate regulation were revealed that in opposite to its well-established pro-apoptotic activator role, Bim could help the folding of oncogenic proteins.