title: Phosphorylation of heat shock protein 27 antagonizes TNF-α induced HeLa cell apoptosis via regulating TAK1 ubiquitination and activation of p38 and ERK signaling.
abstract: Tumor necrosis factor (TNF)-α is a potent cytokine that regulates critical cellular processes including apoptosis. TNF-α usually triggers both survival and apoptotic signals in various cell types. Heat shock protein 27 (HSP27), an important cellular chaperone, is believed to protect cells from apoptosis. HSP27 can be phosphorylated and changed its cellular function according to different stimuli. However, available reports on the role of HSP27 phosphorylation in apoptosis remain elusive. In this study, we investigated the role of HSP27 phosphorylation in TNF-α induced apoptosis in human cervical carcinoma (HeLa) cells. We found that TNF-α induced apoptosis was enhanced if we suppressed the TNF-α induced HSP27 phosphorylation by specific inhibitor CMPD1 or MAPKAPK2 (MK2) knockdown or by overexpression of non-phosphorylatable mutant HSP27-3A. Through co-immunoprecipitation and confocal microscopy, we observed that HSP27 associated with transforming growth factor-β (TGF-β)-activated kinase 1 (TAK1) in response to TNF-α stimulation. By blocking MK2 activity or overexpressing phospho-mimetic mutant Hsp27-3D, we further showed that HSP27 phosphorylation facilitated the TNF-α induced ubiquitination and phosphorylation of TAK1 and the activations of p38 MAPK and ERK, the TAK1 downstream pro-survival signaling. In addition, we also found that increased HSP27 phosphorylation inhibited TRADD ubiquitination but did not influence the binding between TRADD and FADD in a pro-apoptotic complex. Taken together, our data indicated that HSP27 phosphorylation was involved in modulating the TNF-α induced apoptosis via interacting with TAK1 and regulating TAK1 post-translational modifications in HeLa cells. This study demonstrates that HSP27 phosphorylation serves as a novel regulator in TNF-α-induced apoptosis, and provides a new insight into the cytoprotective role of HSP27 phosphorylation.
authors.affiliation: Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, Jiangsu, PR China; Department of Biochemistry, Wannan Medical College, Wuhu, Anhui, PR China.
authors.forename: Zhilin
authors.initials: Z
authors.lastname: Qi
authors.affiliation: Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, Jiangsu, PR China.
authors.forename: Lei
authors.initials: L
authors.lastname: Shen
authors.affiliation: Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, Jiangsu, PR China.
authors.forename: Huiting
authors.initials: H
authors.lastname: Zhou
authors.affiliation: Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, Jiangsu, PR China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, Jiangsu, PR China. Electronic address: lanlei1978@gmail.com.
authors.forename: Lei
authors.initials: L
authors.lastname: Lan
authors.affiliation: State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, PR China. Electronic address: lanluo@nju.edu.cn.
authors.forename: Lan
authors.initials: L
authors.lastname: Luo
authors.affiliation: Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, Jiangsu, PR China. Electronic address: yinzhimin@njnu.edu.cn.
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Yin
mesh_terms: D017209:Apoptosis; D001713:Biphenyl Compounds / Q000494:pharmacology; D045744:Cell Line, Tumor; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D053200:Fas-Associated Death Domain Protein / Q000378:metabolism; D005260:Female; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006360:Heat-Shock Proteins; D056945:Hep G2 Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D020930:MAP Kinase Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D061986:MCF-7 Cells; D018832:Molecular Chaperones; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D034622:RNA Interference; D034741:RNA, Small Interfering; D053199:TNF Receptor-Associated Death Domain Protein / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors; D054875:Ubiquitination; D002583:Uterine Cervical Neoplasms / Q000473:pathology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*; D000099190:MAP-Kinase-Activated Kinase 2; D000099151:MAP Kinase Kinase Kinase 7
chemical_list: D001713:Biphenyl Compounds; D048049:Extracellular Signal-Regulated MAP Kinases; D053200:Fas-Associated Death Domain Protein; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D020930:MAP Kinase Kinase Kinases; D018832:Molecular Chaperones; D017346:Protein Serine-Threonine Kinases; D034741:RNA, Small Interfering; D053199:TNF Receptor-Associated Death Domain Protein; D014409:Tumor Necrosis Factor-alpha; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2; D000099151:MAP Kinase Kinase Kinase 7; C505533:FADD protein, human; C057725:HSPB1 protein, human; C492719:p38alpha inhibitor CMPD1
keywords: Apoptosis; ERK; HSP27 phosphorylation; TAK1; TNF-α; p38 MAPK