Albumin Is Synthesized in Epididymis and Aggregates in a High Molecular Mass Glycoprotein Complex Involved in Sperm-Egg Fertilization

Author(s)

Arroteia, Kelen Fabiola ^[1] ; Barbieri, Mainara Ferreira ^[1] ; Martins Ferreira Souza, Gustavo Henrique ^{[2, 3]} ; Tanaka, Hiromitsu ^[4] ; Eberlin, Marcos Nogueira ^[3] ; Hyslop, Stephen ^[2] ; Alvares, Lucia Elvira ^[1] ; Violin Dias Pereira, Luis Antonio ^[1]

Affiliation

^[1] State Univ Campinas UNICAMP, Inst Biol, Dept Histol & Embryol, Campinas, SP - Brazil

^[2] State Univ Campinas UNICAMP, Fac Med Sci, Dept Pharmacol, Campinas, SP - Brazil

^[3] State Univ Campinas UNICAMP, Inst Chem, Dept Organ Chem, ThoMSon Mass Spectrometry Lab, Campinas, SP - Brazil

^[4] Nagasaki Int Univ, Fac Pharmaceut Sci, Nagasaki - Japan

• Document type: Journal article
• Source: PLoS One; v. 9, n. 8 AUG 1 2014.
• Web of Science Citations: 3

Abstract

The epididymis has an important role in the maturation of sperm for fertilization, but little is known about the epididymal molecules involved in sperm modifications during this process. We have previously described the expression pattern for an antigen in epididymal epithelial cells that reacts with the monoclonal antibody (mAb) TRA 54. Immunohistochemical and immunoblotting analyses suggest that the epitope of the epididymal antigen probably involves a sugar moiety that is released into the epididymal lumen in an androgen-dependent manner and subsequently binds to luminal sperm. Using column chromatography, SDS-PAGE with in situ digestion and mass spectrometry, we have identified the protein recognized by mAb TRA 54 in mouse epididymal epithelial cells. The similar to 65 kDa protein is part of a high molecular mass complex (similar to 260 kDa) that is also present in the sperm acrosomal vesicle and is completely released after the acrosomal reaction. The amino acid sequence of the protein corresponded to that of albumin. Immunoprecipitates with anti-albumin antibody contained the antigen recognized by mAb TRA 54, indicating that the epididymal molecule recognized by mAb TRA 54 is albumin. RT-PCR detected albumin mRNA in the epididymis and fertilization assays in vitro showed that the glycoprotein complex containing albumin was involved in the ability of sperm to recognize and penetrate the egg zona pellucida. Together, these results indicate that epididymal-derived albumin participates in the formation of a high molecular mass glycoprotein complex that has an important role in egg fertilization. (AU)

• FAPESP's process: 05/04007-3 - Biochemical and functional characterization of the antigen recognized by the monoclonal antibody TRA 54 in male reproductive tract
• Grantee: Luís Antônio Violin Dias Pereira
• Support Opportunities: Regular Research Grants