CHP2 activates the calcineurin/nuclear factor of activated T cells signaling pathway and enhances the oncogenic potential of HEK293 cells.
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.
Li
Guo-Dong
GD
Department of Immunology, Peking University Health Science Center, Beijing 100191, China.
Zhang
Xi
X
Li
Rong
R
Wang
Yue-Dan
YD
Wang
Yan-Li
YL
Han
Ke-Jun
KJ
Qian
Xiao-Ping
XP
Yang
Cheng-Gang
CG
Liu
Ping
P
Wei
Qun
Q
Chen
Wei-Feng
WF
Zhang
Jun
J
Zhang
Yu
Y
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
C469743:CHP1 protein, human; D002135:Calcium-Binding Proteins; D050778:NFATC Transcription Factors; D019703:Calcineurin; D010744:Phosphoric Monoester Hydrolases