title: Identification and validation of mouse sperm proteins correlated with epididymal maturation.
abstract: Sperm need to mature in the epididymis to become capable of fertilization. To understand the molecular mechanisms of mouse sperm maturation, we conducted a proteomic analysis using saturation dye labeling to identify proteins of caput and cauda epididymal sperm that exhibited differences in amounts or positions on two-dimensional gels. Of eight caput epididymal sperm-differential proteins, three were molecular chaperones and three were structural proteins. Of nine cauda epididymal sperm-differential proteins, six were enzymes of energy metabolism. To validate these proteins as markers of epididymal maturation, immunoblotting and immunofluorescence analyses were performed. During epididymal transit, heat shock protein 2 was eliminated with the cytoplasmic droplet and smooth muscle γ-actin exhibited reduced fluorescence from the anterior acrosome while the signal intensity of aldolase A increased, especially in the principal piece. Besides these changes, we observed protein spots, such as glutathione S-transferase mu 5 and the E2 component of pyruvate dehydrogenase complex, shifting to more basic isoelectric points, suggesting post-translational changes such dephosphorylation occur during epididymal maturation. We conclude that most caput epididymal sperm-differential proteins contribute to the functional modification of sperm structures and that many cauda epididymal sperm-differential proteins are involved in ATP production that promotes sperm functions such as motility.
authors.affiliation: Center for Research on Reproduction and Women's Health, Department of Obstetrics and Gynecology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6080, USA.
authors.forename: Takashi W
authors.initials: TW
authors.lastname: Ijiri
authors.forename: Tanya
authors.initials: T
authors.lastname: Merdiushev
authors.forename: Wenlei
authors.initials: W
authors.lastname: Cao
authors.forename: George L
authors.initials: GL
authors.lastname: Gerton
mesh_terms: D000818:Animals; D015180:Electrophoresis, Gel, Two-Dimensional; D004822:Epididymis / Q000737:chemistry* / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D015151:Immunoblotting; D008297:Male; D051379:Mice; D040901:Proteomics; D015203:Reproducibility of Results; D013079:Sperm Maturation; D013094:Spermatozoa / Q000737:chemistry* / Q000378:metabolism