Recently, the applicant has conducted studies to explore the function of the plasma glycoproteins of the inter-alpha-inhibitor family (inter-alpha-inhibitor; (IalphaI) and pre-alpha-inhibitor (PalphaI) in the processes of cumulus expansion and ovulation. Briefly, the LH-nitric oxide-mediated grating of a blood-follicle barrier allows influx of IalphaI and PalphaI from the plasma into the follicle and their subsequent binding to newly synthesized hyaluronic acid (HA) and stabilization of the cumulus extracellular matrix (cECM). Then, catalyzed by a factor produced by membrana glanulosa cells, the light chain (bikunin)-chondroitin sulfate moieties of IalphaI and PalphaI are released and hyaluronic acid becomes covalently bound to the heavy chain(s). This apparent transesterification reaction results in an increase in COC viscosity and elasticity and thus, the """"""""superstabilization"""""""" of the cECM. Meanwhile some of the bikunin becomes incorporated into an, as yet unknown compartment of the COC. They have been keenly interested in the reproductive significance of these reactions and have reasoned that an understanding of these dramatic biochemical and physical transformation within the cECM may hold a key to the function of these molecules in reproductive functions of the COC including: (1) extrusion of the COC from the follicle; (2) integrity of the COC and its viability within the reproductive tract, and (3) fertilizability of the oocyte. Experiments in the present proposal are therefore designed to perturb biochemical and physical properties of COCs related to the synthesis of HA and the incorporation and reactions of IalphaI and PalphaI within the cECM. Experiments described in the following three specific aims are thus designed to analyze the following general hypothesis: Incorporation and covalent binding of IalphaI heavy chains into the cECM is required for function of the cumulus mass in ovulation, oocyte viability and fertilization. Effects of these perturbations will be carefully monitored and controlled by measurements of HA, IalphaI/PalphaI, heavy chain and bikunin levels within the CoC. In addition the elasticity and viscosity of the COC as well as qualities of the zona will be measured. These parameters will then be related to reproductive variables such as follicle rupture, extrusion of the COC from the follicle, integrity of the cumulus and viability and fertizability of the oocyte. The studies will establish fundamental conditions of cumulus expansion that may (1) reveal ovarian targets of diseases that affect female fertility, (2) enhance reproductive efficency in human or domestic animal IVF protocols or (3) provide a basis for targeted and reversible contraceptive strategies. (4) The studies may also elucidate aspects of IalphaI/PalphaI function relevant to functions of extracellular matrix in other tissues.
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