R. Straussman et al., Myosin II heavy chain isoforms are phosphorylated in an EGF-dependent manner: involvement of protein kinase C, J CELL SCI, 114(16), 2001, pp. 3047-3057
To explore the involvement and regulation of the nonmuscle myosin II heavy
chains isoforms, MHC-A and MHC-B in the chemotaxis of metastatic tumor cell
s, we analyzed the changes in phosphorylation and cellular localization of
these isoforms upon stimulation of prostate tumor cells with epidermal grow
th factor (EGF). EGF stimulation of prostate tumor cells resulted in transi
ent increases in MHC-A and MHC-B phosphorylation and subcellular localizati
on with quite different kinetics. Furthermore, the kinetics of subcellular
localization correlated with the in vivo kinetics of MHC-B phosphorylation
but not of MHC-A phosphorylation, suggesting different modes of regulation
for these myosin II isoforms. We further showed that protein kinase C (PKC)
is involved in the EGF-dependent phosphorylation of MHC-A and MHC-B. To ou
r knowledge, this is the first report demonstrating that MHC phosphorylatio
n might regulate its subcellular localization and that the EGF signal is tr
ansmitted to MHC-A and MHC-B via PKC. The correlation between MHC-B phospho
rylation and localization in response to EGF stimulation might suggest that
MHC-B is the myosin II isoform that is involved in chemotaxis.