Title: Identification and validation of mouse sperm proteins correlated with epididymal maturation.

Authors: Ijiri, Takashi W; Merdiushev, Tanya; Cao, Wenlei; Gerton, George L

Published In Proteomics, (2011 Oct)

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 ýý-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.

PubMed ID: 21805633

MeSH Terms: Animals; Electrophoresis, Gel, Two-Dimensional; Epididymis/chemistry*; Epididymis/metabolism*; Fluorescent Antibody Technique; Immunoblotting; Male; Mice; Proteomics*; Reproducibility of Results; Sperm Maturation; Spermatozoa/chemistry*; Spermatozoa/metabolism