Concerted upregulation of CLP36 and smooth muscle actin protein expression in human endometrium during decidualization

The human endometrium prepares for implantation of the blastocyst
by reorganization of its whole cellular network. Endometrial stroma
cells change their phenotype starting around the 23rd day of the
menstrual cycle. These predecidual stroma cells first appear next
to spiral arteries, and after implantation these cells further
differentiate into decidual stroma cells. The phenotypical changes
in these cells during decidualization are characterized by distinct
changes in the actin filaments and filament-related proteins such
as α-actinin. The carboxyterminal LIM domain protein with a
molecular weight of 36 kDa (CLP36) is a cytoskeletal component that
has been shown to associate with contractile actin filaments and to
bind to α-actinin supporting a role for CLP36 in cytoskeletal
reorganization and signal transduction by binding to signaling
proteins. The expression patterns of CLP36, α-actinin and actin
were studied in endometrial stroma cells from different stages of
the menstrual cycle and in decidual stroma cells from the 6th week
of gestation until the end of pregnancy. During the menstrual
cycle, CLP36 is only expressed in the luminal and glandular
epithelium but not in endometrial stroma cells. During
decidualization and throughout pregnancy, a parallel upregulation
of CLP36 and smooth muscle actin, an early marker of
decidualization in the baboon, was observed in endometrial decidual
cells. Since both proteins maintain a high expression level
throughout pregnancy, a role of both proteins is suggested in the
stabilization of the cytoskeleton of these cells that come into
close contact with invading trophoblast cells. Copyright (C) 2005
S. Karger AG, Basel.