Protein fraction isolated from epididymal fluid re-associates sperm in vitro: possible role of serpins in rat rosettes assembly.
In many mammalian species, sperm associate as a consequence of the epididymal transit. From the classic Rouleaux in guinea pig to the most recent work in mouse and echidna, authors have focused mainly on a detailed morphological description of this phenomenon. Some of these articles have also begun to describe the nature of the material present between sperm heads. Here, we try to better understand the factor/s involved in rat sperm association (Rosette). Based on previous work describing 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 with each other. By an in vitro sperm re-associating assay, we try to determine the in vivo phenomenon observed in 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 alpha-1 antitrypsin and a new protein with an alpha-1 antitrypsin like domain which includes a sequence compatible with the serpins' reactive center loop. These serpins may play a role in the assembly/disassembly process of Rosettes by modulating lumenal protease activity. Finally, a biochemical-morphological model which explains the sperm-proteases interaction was proposed.
Instituto de Histología y Embriología de Mendoza (IHEM), Histology and Embryology Area, Department of Morphology and Physiology, School of Medicine, National University of Cuyo - CONICET, Mendoza, Argentina. mmonclus@fcm.uncu.edu.ar
María A
MA
Monclus
Cesari
C
Andreina
María E
ME
Cabrillana
Tania E Saez
TE
Lancellotti
Daniel E
DE
Rensetti
Marisa A
MA
Clementi
Paola V
PV
Boarelli
Amanda E
AE
Vincenti
Miguel W
MW
Fornés
D000704:Analysis of Variance; D000818:Animals; D002846:Chromatography, Affinity; D003208:Concanavalin A; D004591:Electrophoresis, Polyacrylamide Gel; D004822:Epididymis / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D015843:Serpins / Q000032:analysis / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013094:Spermatozoa / Q000737:chemistry / Q000378:metabolism*
D015843:Serpins; D003208:Concanavalin A