Submitted September 5, 2007
Returned for revision September 28, 2007
Accepted January 23, 2008
Mechanisms of Hormone Action
Prostaglandin E2-Mediated Migration of Human Trophoblast Requires RAC1 and CDC42
Catalin Nicola ,
Peeyush K. Lala ,
and
Chandan Chakraborty *
* To whom correspondence should be addressed. E-mail: cchakrab{at}uwo.ca.
Abstract
The invasion of maternal decidua and uterine spiral arteries by a trophoblast subpopulation called extravillous trophoblast (EVT) is essential for the establishment of a normal placenta and an adequate blood flow towards the fetus. Derangements in these processes underlie pregnancy-related diseases like preeclampsia and intrauterine growth restriction. Many growth factors, growth factor binding proteins and extracellular matrix components can positively or negatively regulate the proliferation, migration and/or invasiveness of these EVT cells. RHO GTPases, including RHOA, RAC1 and CDC42 are ubiquitous proteins that control cytoskeletal changes by forming stress fibers and projecting lamellipodia and filopodia during cellular migration. We had previously shown that prostaglandin (PG) E2 produced in abundance by the decidua promotes the migration of first trimester human extravillous trophoblast by increasing the intracellular concentration of calcium and activating calpain. Using our well-characterized immortalized EVT cell line, HTR-8/SVneo as well as villus explants from first trimester placentae, this study examined the role of RHO GTPases RAC1 and CDC42 in PGE2-mediated migratory responses of these cells. Though a RAC1 inhibitor, NSC23766 as well as RAC1 knockdown by siRNA decreased the migration of HTR-8/SVneo cells in a Transwell migration assay, this inhibition could not be restored by PGE2 or 17-phenyl trinor PGE2 (PGE receptor PTGER1 agonist) or PGE1 Alcohol (PGE receptor PTGER4 agonist). Similar results were noted for EVT cell spreading in villus explants. Furthermore, CDC42 silencing using siRNA inhibited PGE2-induced migration of HTR-8/SVneo cells. Finally, the treatment of EVT cells with PGE2 or PTGER1 agonist or PTGER4 agonist activated RAC1 and CDC42 at 10 minutes, suggesting that RAC1 and CDC42 play an essential role in PGE2-mediated migration of human extravillous trophoblast.
Key words:
Mechanisms of Hormone Action •
Pregnancy •
Placenta •
Signal transduction
