Protein fraction isolated from epididymal fluid re associates sperm in vitro. Possible role of serpins in rat Rosettes assembling

MONCLUS MARIA DE LOS ANGELES; CESARI ANDREíNA; CABRILLANA MARíA EUGENIA; SAEZ LANZELLOTTI TANIA ESTEFANIA; RENSETTI DANIEL EDGARDO; CLEMENTI MARISA ALEJANDRA; BOARELLI PAOLA VANINA; VINCENTI AMANDA EDITH; FORNES MIGUEL WALTER

MOLECULAR REPRODUCTION AND DEVELOPMENT

Wiley

Año: 2009

1040-452X

In many mammalian  species, sperm associate as a consequence of the epididymal transit. From the classic Rouleaux in Guinea pig to the most recent works in mouse and echidna,   authors have focused mainly   on a detailed morphological description of this phenomenon. Some of these papers have also made approaches to the nature of the material present between sperm   heads. However we try to better understand the factor/s    involved in   rat sperm association (Rosette). Based on previous works which described the appearance of Rosettes in the distal segments of the rat epididymis,   we consider that sperm during their transit must be in contact with factor/s present in the caudal lumen in order to   associate each other. By an in vitro sperm re- associating assay we try to determine the in vivo phenomenon verified inside the   lumen. The assay      consists of   co-incubating   non associated   sperm with several protein fractions obtained from epididymal caudal fluid. After establishing   the most active   fraction, the proteins were characterized by MALDI-TOF   mass spectrometry.  Among the proteins   we found two members of the serine protease inhibitors family; an   á-1 antitrypsin and a new protein with an á-1 antitrypsin like domain which includes   a sequence compatible with the serpins reactive centre loop. These serpins may play a role in the assembling/des-assembling process of Rosettes modulating in this way   the luminal proteases activity.  Finally, a   biochemical-morphological model   which   explains the sperm – proteases interaction   was proposed.