Connective tissue growth factor (CTGF) is a cysteine-rich protein the synthesis and secretion of which are hypothesized to be selectively regulated by activins and other members of the TGF-β superfamily. To investigate the in vivo roles of CTGF in female reproduction, we generated Ctgf ovarian and uterine conditional knockout (cKO) mice. Ctgf cKO mice exhibit severe subfertility and multiple reproductive defects including disrupted follicle development, decreased ovulation rates, increased numbers of corpus luteum, and smaller but functionally normal uterine horns. Steroidogenesis is disrupted in the Ctgf cKO mice, leading to increased levels of serum progesterone. We show that disrupted follicle development is accompanied by a significant increase in granulosa cell apoptosis. Moreover, despite normal cumulus expansion, Ctgf cKO mice exhibit a significant decrease in oocytes ovulated, likely due to impaired ovulatory process. During analyses of mRNA expression, we discovered that Ctgf cKO granulosa cells show gene expression changes similar to our previously reported granulosa cell-specific knockouts of activin and Smad4, the common TGF-β family intracellular signaling protein. We also discovered a significant down-regulation of Adamts1, a progesterone-regulated gene that is critical for the remodeling of extracellular matrix surrounding granulosa cells of preovulatory follicles. These findings demonstrate that CTGF is a downstream mediator in TGF-β and progesterone signaling cascades and is necessary for normal follicle development and ovulation.
"The different stages in follicle development are characterized by specific molecular markers and hormonal profiles which differentiate early antral from pre-ovulatory and luteinized follicles. The gene expression profile of the early antral follicle typically shows low levels of follicle stimulating hormone receptor (FSHR) (Abdennebi et al., 1999; Camp et al., 1991; O'Shaughnessy et al., 1996; Weil et al., 1999), luteinizing hormone/choriogonadotrophin receptor (LHCGR) (Abdennebi et al., 1999; Camp et al., 1991), cholesterol side-chain cleavage enzyme (CYP11A1) (Oonk et al., 1990), aromatase (CYP19A1), amphiregulin (AREG) and epiregulin (EREG), (Ashkenazi et al., 2005; Zamah et al., 2010), whereas progression to the pre-ovulatory follicle consequent upon an increase in FSH secretion, results in an increase in FSHR and LHCGR (Ashkenazi et al., 2005; Zamah et al., 2010) along with concomitant increases in CYP11A1 (Oonk et al., 1990) and CYP19A1 (Clement and Monniaux, 2012; Fitzpatrick et al., 1997; Kawai et al., 2012; Nagashima et al., 2011) expression in preparation for the LH surge (Camp et al., 1991; Hillier, 2001; Hsueh et al., 2000). Following luteinization, the genetic profile shifts to AREG and EREG translation promoting progesterone synthesis and secretion, resulting in ovulation (Zamah et al., 2010; Clement and Monniaux, 2012; Conti et al., 2006; Su et al., 2010). "
[Show abstract][Hide abstract] ABSTRACT: Cell culture techniques of human mural granulosa cells (MGCs) serve as a major in vitro tool. However, the use of luteinized MGCs has major limitations due to their luteinized state. Our aim was to establish a standardized protocol for the culture of MGCs as a model for different stages of folliculogenesis. We showed that early-non-luteinized, preovulatory-non-luteinized and luteal-MGCs have distinct gene expression pattern. After 4 days of incubation of luteinized-MGCs, ovulatory genes mRNA's achieve expression levels similar to the early non-luteinized follicles. FSH stimulation for 48 hours of these 4 days cultured MGCs showed ovulatory genes mRNA's expression similar to the pre-ovulatory- non-luteinized follicles. These FSH-stimulated cells responded to hCG stimulation in a pattern similar to the response of pre-ovulatory follicles. This novel model may provide a standardized research tool for delineation of the molecular processes occurring during the latter stages of follicular development in the human ovary.
[Show abstract][Hide abstract] ABSTRACT: Members of the CCN family of matricellular proteins are crucial for embryonic development and have important roles in inflammation, wound healing and injury repair in adulthood. Deregulation of CCN protein expression or activities contributes to the pathobiology of various diseases - many of which may arise when inflammation or tissue injury becomes chronic - including fibrosis, atherosclerosis, arthritis and cancer, as well as diabetic nephropathy and retinopathy. Emerging studies indicate that targeting CCN protein expression or signalling pathways holds promise in the development of diagnostics and therapeutics for such diseases. This Review summarizes the biology of CCN proteins, their roles in various pathologies and their potential as therapeutic targets.
[Show abstract][Hide abstract] ABSTRACT: Connective tissue growth factor (CTGF) is a cysteine-rich, matrix-associated heparin-binding protein that is important in many cell types as a regulator of cell proliferation, angiogenesis, cell remodelling and other cellular processes. CTGF is necessary for normal follicle growth and luteinisation in mammals. The avian follicular hierarchy provides an excellent experimental model to study developmental events, particularly the role of cellular remodelling factors in the process of folliculogenesis. In this study, we examined CTGF expression and regulation in the hen ovary. CTGF expression was increased considerably as follicular development proceeds in pre-ovulatory follicles, peaking in expression at the time of ovulation. Immunohistochemistry revealed that CTGF protein was concentrated in the cytoplasm of follicular granulosa cells throughout the ovulation cycle. We isolated granulosa cells from the follicles at two key stages of the ovulation cycle (in terms of cellular alteration): during pre-ovulatory growth and during post-ovulatory regression. Follicle-stimulating hormone (FSH) and luteinising hormone (LH) inhibited CTGF expression in pre-ovulatory granulosa cells but stimulated CTGF expression in post-ovulatory granulosa cells. Moreover, TGFβ1 stimulated CTGF expression in both pre- and post-ovulatory granulosa cells. Nevertheless, TGFβ1 could rescue the inhibition of gonadotrophins on pre-ovulatory granulosa CTGF expression but could not further stimulate CTGF expression in gonadotrophin-treated post-ovulatory granulosa cells. The results of this study indicate that CTGF expression in avian granulosa cells is modulated by a combination of gonadotrophins and TGFβ1 according to the different stages of follicle maturation and degradation. The results also suggest that the gonadotrophic action on post-ovulatory follicles in the avian ovary differs from the gonadotrophin-induced luteinisation in mammals.
General and Comparative Endocrinology 06/2012; 178(2):314-22. DOI:10.1016/j.ygcen.2012.06.018 · 2.47 Impact Factor
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