No abstract

To explore the identity and possible function of endometriosis protein-I (ENDO-I), which is an acidic glycoprotein synthesized and secreted by endometriotic lesions, partial amino acid sequence and cDNA sequence were determined. Partially purified, de novo-synthesized rat endometriosis glycoproteins were separated by two-dimensional SDS-PAGE, transferred to polyvinyl difluoride membranes, and stained with Coomassie blue. Protein corresponding to the size and pI of ENDO-I was cut from the membranes and analyzed by automated Edman degradation. ENDO-I amino acid sequence analysis identified 15 residues that shared significant homology with the beta-chain of rat, mouse, and human haptoglobin (Hp) and human Hp-related protein. Western blot analyses using anti-Hp antibody demonstrated cross-reactivity with de novo-synthesized ENDO-I protein in endometriosis culture media. For nucleotide sequence analysis, poly A-enriched mRNA was isolated from rat endometriotic tissues. A gene-specific oligonucleotide primer was designed and used for 3' rapid amplification of cDNA ends (RACE). Automated sequencing of RACE cDNA fragments identified 859 base pairs, of which 858 were identical to rat Hp. Reverse transcription-polymerase chain reaction was used to demonstrate that ENDO-I transcripts are differentially expressed by endometriosis but not by uterine tissues. In the human, distinct subtypes of Hp as well as proteins sharing epitopes with Hp have been used to diagnose a variety of diseases; therefore, Hp-like ENDO-I may prove to be a nonsurgical diagnostic tool to assess endometriosis. Hepatic Hp, induced by acute-phase stimuli, modulates macrophage function and angiogenic activity. If ENDO-I possesses similar activities, it may be involved with anomalies of the immune system or the etiology and pathophysiology of endometriosis.

Major vault protein (MVP), also called lung resistance-related protein is a ribonucleoprotein comprising a major part (>70%) of the vault particle. The function of vault particle is not known, although it appears to be involved in multi-drug resistance and cellular signaling. Here we show that MVP is expressed in mammalian, porcine, and human ova and in the porcine preimplantation embryo. MVP was identified by matrix-assisted laser-desorption ionization-time-of-flight (MALDI-TOF) peptide sequencing and Western blotting as a protein accumulating in porcine zygotes cultured in the presence of specific proteasomal inhibitor MG132. MVP also accumulated in poor-quality human oocytes donated by infertile couples and porcine embryos that failed to develop normally after in vitro fertilization or somatic cell nuclear transfer. Normal porcine oocytes and embryos at various stages of preimplantation development showed mostly cytoplasmic labeling, with increased accumulation of vault particles around large cytoplasmic lipid inclusions and membrane vesicles. Occasionally, MVP was associated with the nuclear envelope and nucleolus precursor bodies. Nucleotide sequences with a high degree of homology to human MVP gene sequence were identified in porcine oocyte and endometrial cell cDNA libraries. We interpret these data as the evidence for the expression and ubiquitin-proteasome-dependent turnover of MVP in the mammalian ovum. Similar to carcinoma cells, MVP could fulfill a cell-protecting function during early embryonic development.

Endometrium from US-E differentially responds to specific inflammatory cytokines by production of eHp. We propose that up-regulation of endometrial eHp by inflammatory mediators disrupts normal endometrial function and may facilitate the pathogenesis of endometriosis.