Epididymosome-mediated acquisition of MMSDH, an androgen-dependent and developmentally regulated epididymal sperm protein.
A differential proteomics approach led to the identification of several  novel epididymal sperm proteins. One of the novel proteins was  methylmalonate-semialdehyde dehydrogenase (MMSDH). In the present study, we  carried out an in-depth characterization to study its regulation by androgen,  its appearance during ontogeny, and the mechanism of its interaction with and  acquisition by the sperm. Western blotting and immunohistochemical studies  suggest that the protein is present in both tissue and sperm from all regions  of the epididymis, indicating synthesis as well as acquisition of the protein  in these regions. Androgen depletion resulted in reduction of the MMSDH  protein level in the epididymis, which completely disappeared 1 week after  castration. The protein reappeared after testosterone propionate injection,  indicating that the protein is regulated by androgens. Ontogeny studies  indicated that the protein appeared from day 10 postnatal with a gradual  increase at day 30, which maximized at day 50, indicating that the protein is  developmentally regulated and is probably involved in epididymal development.  Sequential extraction of sperm proteins indicated that MMSDH exists both as a  peripheral and integral form on the plasma membrane. We also found that the  protein can be transferred from the epididymosomes to testicular sperm in  vitro. The study provides evidence regarding the acquisition of this  multidomain androgen and developmentally regulated protein in the epididymis  via the epididymosomes. The molecule has generated enough interest and  deserves to be investigated further for its physiological relevance.
Department of Gamete Immunobiology, National Institute for Research in Reproductive Health (ICMR), J. M. St, Parel, Mumbai-400012, India.
Amol R
AR
Suryawanshi
Shagufta A
SA
Khan
Chetanchandra S
CS
Joshi
Vrinda V
VV
Khole
D000367:Age Factors; D000818:Animals; D015153:Blotting, Western; D002462:Cell Membrane / Q000201:enzymology; D004822:Epididymis / Q000187:drug effects / Q000196:embryology / Q000201:enzymology* / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D007150:Immunohistochemistry; D007267:Injections; D008297:Male; D050646:Methylmalonate-Semialdehyde Dehydrogenase (Acylating) / Q000235:genetics / Q000378:metabolism*; D009024:Morphogenesis; D009919:Orchiectomy; D021381:Protein Transport; D051381:Rats; D017207:Rats, Sprague-Dawley; D013094:Spermatozoa / Q000187:drug effects / Q000201:enzymology*; D013739:Testosterone / Q000378:metabolism*; D043343:Testosterone Propionate / Q000008:administration & dosage; D013997:Time Factors
D013739:Testosterone; D050646:Methylmalonate-Semialdehyde Dehydrogenase (Acylating); D043343:Testosterone Propionate