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.

Alteration of sperm protein profile induced by cigarette smoking

“…Thus, the energy pathway can affect sperm mobility in flagellum. Previous studies showed that spermatocytes and spermatids prefer oxidative phosphorylation for ATP production [22]. However, the oxygen partial pressure was found to be very low in this study.…”

“…Aldoa is a glycolysis enzyme that promotes reversible FBP cleavage to triose phosphate, G-3-P and DHAP. Aloda is in the mouse sperm flagellum accessory structures [22,23]. The flagellum is an important organ for sperm mobility.…”

Head and flagella subcompartmental proteomic analysis of human spermatozoa

“…To date, there have been several attempts to conduct subcellular proteomic analyses of spermatozoa from the mouse (see [57][58][59][60][61]) and human sperm proteomes [9][10][11]15,26,27,[62][63][64][65][66][67][68] most of which reported less than 100 protein identifications. One of the more comprehensive lists published to date surveyed the entire sperm proteome and documented 1057 unique identifications [64].…”

New insights into epididymal function in relation to sperm maturation

“…Most of them have combined 2D gel electrophoresis and MS on the total extracts of immature and mature epididymal sperm from the mouse (Ijiri et al 2011), rat (Guo et al 2007), or hamster (Kameshwari et al 2010), or on subcellular compartments such as the head and flagella (Suryawanshi et al 2011), acrosomal and membranous proteins (Park et al 2012), and phosphopeptides (Baker et al 2012), or on purified sperm surface proteins (Belleannee et al 2011a). About 20 proteins involved in sperm maturation have been identified by these studies, of which only two or three have been found to be common between two studies or species.…”