Autoantibodies to Heat-Shock Protein, HSPA5, and Epitope Spreading: High-Dose Dexamethasone Therapy Rescues Ovarian Function in Experimental Autoimmune Ovarian Insufficiency Mouse Model.

PROBLEM: Role of autoantibodies to heat-shock protein 70 isoform, HSPA5, both alone or in combination with other antigenic peptides in epitope spreading and effect of high-dose dexamethasone to overcome this. METHOD OF STUDY: Experimental autoimmune premature ovarian insufficiency mouse model generated by immunization with immunodominant epitopes of HSPA5 alone or in combination with other antigenic peptides. Two doses of dexamethasone treatment are given to the latter group. Immunosorbent assay and Western blot analysis were undertaken to detect cross-reactivity. Hormonal estimations, histological evaluation, and fertility studies were performed to assess treatment efficacy. RESULTS: One of the immunodominant epitopes of HSPA5 led to epitope spreading. Of the two doses, 100 mg was more effective in rescuing fertility. CONCLUSIONS: We postulate that the shared immunodominant peptide could be included in a peptide array to detect both HSAP5 and HSP90ß autoantibodies for early diagnosis or prognosis of aPOI and customized glucocorticoid therapy for such subjects.

Prostate Secretory Protein of 94 amino acids (PSP94) binds to prostatic acid phosphatase (PAP) in human seminal plasma.

Prostate Secretory Protein of 94 amino acids (PSP94) is one of the major proteins present in the human seminal plasma. Though several functions have been predicted for this protein, its exact role either in sperm function or in prostate pathophysiology has not been clearly defined. Attempts to understand the mechanism of action of PSP94 has led to the search for its probable binding partners. This has resulted in the identification of PSP94 binding proteins in plasma and seminal plasma from human. During the chromatographic separation step of proteins from human seminal plasma by reversed phase HPLC, we had observed that in addition to the main fraction of PSP94, other fractions containing higher molecular weight proteins also showed the presence of detectable amounts of PSP94. This prompted us to hypothesize that PSP94 could be present in the seminal plasma complexed with other protein/s of higher molecular weight. One such fraction containing a major protein of ~47 kDa, on characterization by mass spectrometric analysis, was identified to be Prostatic Acid Phosphatase (PAP). The ability of PAP present in this fraction to bind to PSP94 was demonstrated by affinity chromatography. Co-immunoprecipitation experiments confirmed the presence of PSP94-PAP complex both in the fraction studied and in the fresh seminal plasma. In silico molecular modeling of the PSP94-PAP complex suggests that ß-strands 1 and 6 of PSP94 appear to interact with domain 2 of PAP, while ß-strands 7 and 10 with domain 1 of PAP. This is the first report which suggests that PSP94 can bind to PAP and the PAP-bound PSP94 is present in human seminal plasma.

Identification of cellular isoform of oviduct-specific glycoprotein: role in oviduct tissue remodeling?

The oviduct is known to secrete mucins (MUC1 and MUC9) under the influence of ovarian steroids. The secreted form of MUC1 binds gametes in the oviduct, whereas the cellular form seen in breast cancers has been implicated in cell adhesion and morphogenesis. The secreted MUC9 or oviduct-specific glycoprotein (OGP), in addition to being a mucin, belongs to family 18 glycosylhydrolases and is known to bind gametes and embryos in the oviduct. Studies in our laboratory have identified non-muscle myosin IIA (involved in cell shape, polarity, and morphogenesis) as the protein partner to OGP in gametes. In view of the crucial role of the cortical cytoskeleton in the selective internalization of tight junctions (TJs) /adherent junctions (AJs) or apical junctional complex (AJC) in simple epithelial cells during tissue remodeling, the present study has been undertaken to evaluate the existence of a cellular form of OGP in oviductal tissue, which itself undergoes cyclic tissue remodeling. In silico analysis of the deduced amino-acid sequence of OGP has revealed the presence of several conserved motifs; these imply that OGP is a component of multi-protein complexes such as TJs. Corroborative immunoelectron-microscopic analysis in peri-ovulatory oviduct epithelia in the bonnet monkey has revealed the presence of OGP at the TJ. Co-localization studies of OGP and cadherin demonstrate that, whereas OGP is localized at the tonofilaments of the TJs, cadherin is localized at the intercellular space of the AJ. The possible role of OGP in oviductal tissue remodeling is discussed in light of the present findings and those reported in the literature.