Peculiar subcellular localization of Fas antigen in human and mouse spermatozoa.
The highly polarized structure and function of mammalian spermatozoa dictate that these cells compartmentalize specific metabolic and signaling pathways to regions where they are needed. Fas was initially identified as membrane receptor for pro-apoptotic signals, has been recently recognized as a molecule with pleiotropic functions. In this article, we provide evidence of a peculiar Fas localization: it is closely associated to the perinucleus, mainly at the level of the inner acrosomal membrane, as well as in the inner compartment of mitochondria. Immunoelectron microscopy and Western blot analysis indicated that intracellular Fas was associated with mitochondria in mouse epididymal spermatozoa. Accordingly, also in human ejaculated sperm, immunofluorescence analysis showed Fas localized in the middle piece of sperm flagellum where mitochondria are grouped. The potential functional implications of these findings are discussed.
Starace
Donatella
D
Department of Histology and Medical Embryology, Istituto Pasteur-Fondazione Cenci Bolognetti, "Sapienza" University of Rome, 00161 Rome, Italy.
Muciaccia
Barbara
B
Morgante
Emanuela
E
Russo
Matteo A
MA
Pensini
Simona
S
D'agostino
Angela
A
De Cesaris
Paola
P
Filippini
Antonio
A
Ziparo
Elio
E
Riccioli
Anna
A
D000818:Animals; D015153:Blotting, Western; D006801:Humans; D008297:Male; D051379:Mice; D016253:Microscopy, Immunoelectron; D008928:Mitochondria / Q000737:chemistry*; D013094:Spermatozoa / Q000737:chemistry*; D019014:fas Receptor / Q000032:analysis*
C491901:FAS protein, human; C491899:Fas protein, mouse; D019014:fas Receptor