MS-KIF18A, a kinesin, is associated with estrogen receptor

The study of MS‐KIF18A kinesin protein is focused on its cellular distribution and association with a cargo protein. Indirect immunofluorescence (IF) analyzed the intracellular distribution of endogenous MS‐KIF18A and the transfected enhanced green fluorescence protein (eGFP)‐MS‐KIF18A in osteogenic cells. In both cases, the proteins were localized at the plasma membrane, cytosol, and nucleus. Bioinformatics analysis suggested interactions between MS‐KIF18A and estrogen receptor (ERα) which were further elucidated by immunoprecipitation (IP). We identified interaction between endogenous MS‐KIF18A with 66 and 46 kDa isoforms of ERα in MBA‐15 cells. Moreover, MS‐KIF18A and 66 kDa ERα complex has been demonstrated between ectopically expressed proteins in COS‐7 cells. We have shown that anti‐MS‐KIF18A antibody immunoprecipitated the ERα and pERK in cells challenged with 17β‐estrogen (17β‐E2). The hormone activation induced mitogen‐activated protein kinases (MAPK) pathway and increased p‐ERK. The activation was interfered when cells were pre‐treated with either ICI‐182,780 or MAPK inhibitor PD98059 prior the challenge with 17β‐E2 that resulted in a decrease in association between MS‐KIF18A and p‐ERK1/2. The obtained results suggest a role for the proteins in a non‐genomic response of MBA‐15 cells challenged with 17β‐E2. This study presents a novel interaction between MS‐KIF18A and ER that may have important physiological and pharmacological implications for estrogen action in various cells. J. Cell. Biochem. 100: 693–702, 2007. © 2006 Wiley‐Liss, Inc.