Following an ovulatory surge of LH and FSH, cumulus cells surrounding the oocyte disaggregate as they endocytose their cell-cell junctions and then synthesize a hyaluronic acid-rich extracellular matrix (ECM). This ECM entraps the cells and in most mammalian species, the integrity of this mucoid mass of matrix and cells is maintained during ovulation. The expanded cumulus mass is ultimately dissolved within the oviduct. Recently we have purified a fraction from bovine serum which is required for stabilization of the cumulus ECM in vitro. Immunoblot and sequence analyses support the view that the single protein in this fraction is a major blood proteinase, inter-alpha-inhibitor (IalphaI), or a member of the IalphaI family of serine protease's. Further evidence of its identity is derived from experiments involving depletion of bovine serum with an anti-IalphaI IgG antibody-agarose complex thus suppressing matrix stabilizing activity. Immunoblot and immunocytochemical localization techniques reveal the presence of this protein only in preovulatory follicles responding to an ovulatory stimulus and in these follicles, IalphaI is specifically localized in the cumulus extra-cellular matrix and at the follicle basement membrane. Moreover Western blot analysis of follicular fluid shows that IalphaI is present within the antral compartment of responding follicles within minutes following an ovulatory stimulus. These findings support the hypothesis that cumulus ECM stabilization in vivo requires the breakdown of a blood-follicle barrier allowing the influx of IalphaI into the follicular antrum where it becomes incorporated into the cumulus ECM. While IalphaI may stabilize the cumulus mass by inhibiting active proteinases within the ECM, it is also possible that this molecule serves as a linker to bind hyaluronic acid within the ECM. Additional preliminary results support the hypothesis that in addition to follicular wall rupture, normal synthesis and stabilization of the cumulus ECM during the preovulatory period are required for normal ovulation. Therefore, the objectives of the present proposal are to further define temporal, physical, and molecular characteristics of the postulated blood-follicle barrier, the molecular mode of action of IalphaI in stabilization of the cumulus ECM, and the possible role of the blood- barrier and IalphaI in the process of ovulation. Finally, we hope to explore possible roles of blood IalphaI levels in idiopathic human anovulatory syndrome focusing initially on anovulation in diabetes mellitus.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
1R01HD029894-01A1
Application #
3331374
Study Section
Reproductive Biology Study Section (REB)
Project Start
1993-08-01
Project End
1996-07-31
Budget Start
1993-08-01
Budget End
1994-07-31
Support Year
1
Fiscal Year
1993
Total Cost
Indirect Cost
Name
University of Cincinnati
Department
Type
Schools of Medicine
DUNS #
City
Cincinnati
State
OH
Country
United States
Zip Code
45221
Nemade, Rashmi V; Carrette, Odile; Larsen, William J et al. (2002) Involvement of nitric oxide and the ovarian blood follicle barrier in murine follicular cyst development. Fertil Steril 78:1301-8
Jean, L; Mizon, C; Larsen, W J et al. (2001) Unmasking a hyaluronan-binding site of the BX(7)B type in the H3 heavy chain of the inter-alpha-inhibitor family. Eur J Biochem 268:544-53
Carrette, O; Nemade, R V; Day, A J et al. (2001) TSG-6 is concentrated in the extracellular matrix of mouse cumulus oocyte complexes through hyaluronan and inter-alpha-inhibitor binding. Biol Reprod 65:301-8
Mio, K; Carrette, O; Maibach, H I et al. (2000) Evidence that the serum inhibitor of hyaluronidase may be a member of the inter-alpha-inhibitor family. J Biol Chem 275:32413-21
Hess, K A; Chen, L; Larsen, W J (1999) Inter-alpha-inhibitor binding to hyaluronan in the cumulus extracellular matrix is required for optimal ovulation and development of mouse oocytes. Biol Reprod 61:436-43
Hess, K A; Chen, L; Larsen, W J (1998) The ovarian blood follicle barrier is both charge- and size-selective in mice. Biol Reprod 58:705-11
Larsen, W J; Chen, L; Powers, R et al. (1996) Cumulus expansion initiates physical and developmental autonomy of the oocyte. Zygote 4:335-41
Powers, R W; Chambers, C; Larsen, W J (1996) Diabetes-mediated decreases in ovarian superoxide dismutase activity are related to blood-follicle barrier and ovulation defects. Endocrinology 137:3101-10
Chen, L; Zhang, H; Powers, R W et al. (1996) Covalent linkage between proteins of the inter-alpha-inhibitor family and hyaluronic acid is mediated by a factor produced by granulosa cells. J Biol Chem 271:19409-14
Powers, R W; Chen, L; Russell, P T et al. (1995) Gonadotropin-stimulated regulation of blood-follicle barrier is mediated by nitric oxide. Am J Physiol 269:E290-8

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