BAG3 sensitizes cancer cells exposed to DNA damaging agents via direct interaction with GRP78.
Bcl-2 associated athanogene 3 (BAG3) has a modular structure that contains a BAG domain, a WW domain, a proline-rich (PxxP) domain to mediate potential interactions with chaperons and other proteins that participate in more than one signal transduction. In search for novel interacting partners, the current study identified that 78kDa glucose-regulated protein (GRP78) was a novel partner interacting with BAG3. Interaction between GRP78 and BAG3 was confirmed by coimmunoprecipitation and glutathione S-transferase (GST) pulldown. We also identified that the ATPase domain of GRP78 and BAG domain of BAG3 mediated their interaction. Counterintuitive for a prosurvival protein, BAG3 was found to promote the cytotoxicity of breast cancer MCF7, thyroid cancer FRO and glioma U87 cells subjected to genotoxic stress. In addition, the current study demonstrated that BAG3 interfered with the formation of the antiapoptotic GRP78-procaspase-7 complex, which resulted in an increased genotoxic stress-induced cytotoxicity in cancer cells. Furthermore, overexpression of GRP78 significantly blocked the enhancing effects of BAG3 on activation of caspase-7 and induction of apoptosis by genotoxic stress. Overall, these results suggested that through direct interaction BAG3 could prevent the antiapoptotic effect of GRP78 upon genotoxic stress.
Department of Biochemistry & Molecular Biology, China Medical University, Shenyang 110001, China; Key Laboratory of Cell Biology, Ministry of Public Health, China Medical University, Shenyang 110001, China; Key Laboratory of Medical Cell Biology, Ministry of Education, China Medical University, Shenyang 110001, China.
De-Hui
DH
Kong
Department of Biochemistry & Molecular Biology, China Medical University, Shenyang 110001, China; Key Laboratory of Cell Biology, Ministry of Public Health, China Medical University, Shenyang 110001, China; Key Laboratory of Medical Cell Biology, Ministry of Education, China Medical University, Shenyang 110001, China.
Qiang
Q
Zhang
Department of Biochemistry & Molecular Biology, China Medical University, Shenyang 110001, China.
Xin
X
Meng
Department of Biochemistry & Molecular Biology, China Medical University, Shenyang 110001, China.
Zhi-Hong
ZH
Zong
Department of Biochemistry & Molecular Biology, China Medical University, Shenyang 110001, China.
Chao
C
Li
Department of Biochemistry & Molecular Biology, China Medical University, Shenyang 110001, China.
Bao-Qin
BQ
Liu
Department of Biochemistry & Molecular Biology, China Medical University, Shenyang 110001, China.
Yifu
Y
Guan
Department of Biochemistry & Molecular Biology, China Medical University, Shenyang 110001, China; Key Laboratory of Cell Biology, Ministry of Public Health, China Medical University, Shenyang 110001, China; Key Laboratory of Medical Cell Biology, Ministry of Education, China Medical University, Shenyang 110001, China. Electronic address: wanghq_doctor@hotmail.com.
Hua-Qin
HQ
Wang
D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000378:metabolism*; D051017:Apoptosis Regulatory Proteins; D001667:Binding, Competitive / Q000187:drug effects; D053179:Caspase 7 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D004249:DNA Damage; D004317:Doxorubicin / Q000494:pharmacology; D000091342:Endoplasmic Reticulum Chaperone BiP; D005047:Etoposide / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D009153:Mutagens / Q000633:toxicity*; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary
D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; C414431:BAG3 protein, human; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D009153:Mutagens; D005047:Etoposide; D004317:Doxorubicin; D053179:Caspase 7
BAG3; Caspase-7; DNA damage; GRP78