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A calmodulin‐like protein as an extracellular mitogen for the keratinocyte
Author(s) -
GOBERDHAN N.J.,
DAWSON R.A.,
FRKEDLANDER E.,
NEIL S.MAC
Publication year - 1993
Publication title -
british journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.304
H-Index - 179
eISSN - 1365-2133
pISSN - 0007-0963
DOI - 10.1111/j.1365-2133.1993.tb03331.x
Subject(s) - calmodulin , extracellular , keratinocyte , microbiology and biotechnology , chemistry , biochemistry , biology , enzyme , in vitro
Summary This study investigated the importance of extracellular calmodulin to the proliferation of the keratinocyte. Normal keratinocytes in culture produced a calmodulin‐like protein in their culture media, the level of which increased abruptly and transiently during their growth. This protein was calmodulin‐like, in that it specifically bound to a calmodulin affinity column, exhibited calmodulin‐like immunoreactivity in both an ELISA and on immunoblots when immunostained with a monoclonal antibody against calmodulin, had an apparent Mr between 18,000 and 20,000, and stimulated activity in a calmodulin‐dependent phosphodiesterase enzyme assay. Addition of exogenous pure caimodulin was of no further mitogenic benefit to the keratinocytes. and slightly reduced proliferation under the culture conditions used. However, addition of either a neutralizing antibody to calmodulin, or W7‐agarose, to the culture media of proliferating cells markedly inhibited their proliferation. Accordingly, a calmodulin‐like protein was found to satisfy all but one of the criteria for its action as an autocrine growth factor for the keratinocyte. We propose that the lack of mitogenic response to calmodulin in vitro is due to the cell meeting its own requirement for extracellular calmodulin.