Induction of tissue factor pathway inhibitor 2 by hCG regulates periovulatory gene expression and plasmin activity

Abstract

Increased proteolytic activity is a key event that AIDS in breakdown of the follicular wall to permit oocyte release. How the protease activity is regulated is still unknown. We hypothesize that tissue factor pathway inhibitor 2(TFPI2), aKunitz-type serine protease inhibitor,plays a role inregulatingperiovulatory proteolytic activity as in other tissues. TFPI2 is secreted into the extracellular matrix (ECM) where it is postulated to regulate physiological ECMremodeling. The expression profile of TFPI2 during the periovulatory period was assessedutilizinga well-characterizedhumanmenstrual cyclemodel and agonadotropin-primed ratmodel. Administration of an ovulatory dose of human chorionic gonadotropin (hCG) increased TFPI2 expression dramatically in human and rat granulosa and theca cells. This increase in Tfpi2 expression in rat granulosa cells required hCG-mediated epidermal growth factor, protein kinase A, mitogen-activated protein kinase (MAPK) 1/2, p38MAPK and protease activated receptor 1-dependent cell signaling.Asmall interferingRNAmediated knockdown of TFPI2 in rat granulosa cells resulted in increased plasmin activity in the granulosa cell conditionedmedia.Knockdownof TFPI2 alsoreducedexpressionofmultiplegenes includinginterleukin 6 (Il6) and amphiregulin (Areg). Overexpression of TFPI2 using an adenoviral vector partially restored the expression of Il6 and Areg in TFPI2 siRNA treated rat granulosa cells. These data support the hypothesis that TFPI2 is important formoderating plasmin activity and regulating granulosa cell gene expression during the periovulatory period. We, therefore, propose that through these actions, TFPI2 AIDS in the tissue remodeling taking place during follicular rupture and corpus luteum formation.