title: CHP2 activates the calcineurin/nuclear factor of activated T cells signaling pathway and enhances the oncogenic potential of HEK293 cells.
abstract: CHP2 (calcineurin B homologous protein 2) was initially identified as a tumor-associated antigen highly expressed in hepatocellular carcinoma. Its biological function remains largely unknown except for a potential role in transmembrane Na(+)/H(+) exchange. In the present study, we observed that ectopic expression of CHP2 promoted the proliferation of HEK293 cells, whereas knockdown of endogenous CHP2 expression in HepG2 inhibited cell proliferation. When inoculated into nude mice, CHP2 transfected HEK293 cells displayed markedly increased oncogenic potential. In analysis of the underlying molecular mechanisms, we found that like calcineurin B, CHP2 was able to bind to and stimulate the phosphatase activity of calcineurin A. In accord with this, CHP2-transfected cells showed increased nuclear presence of NFATc3 (nuclear factor of activated T cells) and enhanced NFAT activity. Finally, both accelerated cell proliferation and NFAT activation following CHP2 transfection could be suppressed by the calcineurin inhibitor cyclosporine A, suggesting an intrinsic connection between these events. Taken together, our results highlighted a potential role of CHP2 in tumorigenesis and revealed a novel function of CHP2 as an activator of the calcineurin/NFAT signaling pathway.
authors.affiliation: Department of Immunology, Peking University Health Science Center, Beijing 100191, China.
authors.forename: Guo-Dong
authors.initials: GD
authors.lastname: Li
authors.forename: Xi
authors.initials: X
authors.lastname: Zhang
authors.forename: Rong
authors.initials: R
authors.lastname: Li
authors.forename: Yue-Dan
authors.initials: YD
authors.lastname: Wang
authors.forename: Yan-Li
authors.initials: YL
authors.lastname: Wang
authors.forename: Ke-Jun
authors.initials: KJ
authors.lastname: Han
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Qian
authors.forename: Cheng-Gang
authors.initials: CG
authors.lastname: Yang
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
authors.forename: Qun
authors.initials: Q
authors.lastname: Wei
authors.forename: Wei-Feng
authors.initials: WF
authors.lastname: Chen
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000818:Animals; D019703:Calcineurin / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D049109:Cell Proliferation; D006801:Humans; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D050778:NFATC Transcription Factors / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000378:metabolism*; D014162:Transfection
chemical_list: C469743:CHP1 protein, human; D002135:Calcium-Binding Proteins; D050778:NFATC Transcription Factors; D019703:Calcineurin; D010744:Phosphoric Monoester Hydrolases