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Calmodulin binding to the Fas‐Mediated death‐inducing signaling complex in cholangiocarcinoma cells
Author(s) -
Chen Yabing,
Pawar Pritish,
Pan George,
Ma Liping,
Liu Hui,
McDonald Jay M.
Publication year - 2007
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.21447
Subject(s) - apoptosis , calmodulin , fas ligand , microbiology and biotechnology , jurkat cells , fas receptor , trifluoperazine , programmed cell death , signal transduction , chemistry , cancer research , biology , immunology , calcium , biochemistry , t cell , immune system , organic chemistry
We have previously demonstrated that the antagonists of calmodulin (CaM) induce apoptosis of cholangiocarcinoma cells partially through Fas‐mediated apoptosis pathways. Recently, CaM has been shown to bind to Fas, which is regulated during Fas or CaM antagonist‐mediated apoptosis in Jurkat cells and osteoclasts. Accordingly, the present studies were designed to determine whether Fas interacts with CaM in cholangiocarcinoma cells and to elucidate its role in regulating Fas‐mediated apoptosis. CaM bound to Fas in cholangiocarcinoma cells. CaM was identified in the Fas‐mediated death inducing signaling complex (DISC). The amount of CaM recruited into the DISC was increased after Fas‐stimulation, a finding confirmed by immunofluorescent analysis that demonstrated increased membrane co‐localization of CaM and Fas upon Fas‐stimulation. Consistently, increased Fas microaggregates in response to Fas‐stimulation were found to bind to CaM. Fas‐induced recruitment of CaM into the DISC was inhibited by the Ca 2+ chelator, EGTA, and the CaM antagonist, trifluoperazine (TFP). TFP decreased DISC‐induced cleavage of caspase‐8. Further, inhibition of actin polymerization, which has been demonstrated to abolish DISC formation, inhibited the recruitment of CaM into the DISC. These results suggest an important role of CaM in mediating DISC formation, thus regulating Fas‐mediated apoptosis in cholangiocarcinoma cells. Characterization of the role of CaM in Fas‐mediated DISC formation and apoptosis signaling may provide important insights in the development of novel therapeutic targets for cholangiocarcinoma. J. Cell. Biochem. 103: 788–799, 2008. © 2007 Wiley‐Liss, Inc.

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