Presence and Role of c-myc Proto-oncogene Product in Mammalian Sperm Cell Function1

Abstract

The presence and role of c-myc protein was investigated in mature sperm cells of the human, mouse, and rabbit. The monoclonal antibodies against c-myc protein (c-myc) reacted with the acrosomal region of the sperm of these mammalian species in the indirect immunofluorescence technique. The c-myc monoclonal antibody (MCA) recognized c-myc protein of 62 and 64 kDa on Western blots of lithium diiodosalicylate-solubilized sperm preparations of these species. The c-myc MCA showed a dose-dependent inhibition of human sperm penetration of zona-free hamster eggs, inhibition of murine in vitro fertilization, and reduced in vivo fertilization in rabbits. There was no effect of the antibody on percent sperm motility, though the antibody significantly affected various motility characteristics such as mean and maximum amplitude of lateral head displacement and curvilinear velocity involved in hyperactivation phenomenon of human sperm cells. These results suggest that c-myc or c-myc-like protein is present in mature sperm cells and may have a role in sperm cell function especially in capacitation and/or acrosome reaction.

Acrosome membrane associated protein kinase activity in hamster spermatozoa

“…In goat spermatozoa, the protein kinases phosphorylated only serine and threonine residues [18,22] but in addition to these residues phosphotyrosine was also detected in certain phosphoproteins of spermatozoa of mouse, rat, rabbit, boar and man [1,18,27]. In the present study, phosphoamino acid analysis of the phosphorylated acrosomal membrane proteins of hamster spermatozoa indicated that phospho-tyr was the predominant residue although phospho-ser and phospho-thr were also present in trace amounts ( Fig.…”

“…However, as yet, the molecular basis underlying the sperm acrosome reaction is not clearly understood. Recent studies have clearly indicated that phosphorylation of proteins in spermatozoa, especially at the tyrosine residue, is an important regulatory event that modulates events associated with capacitation such as the acrosome reaction and fertilizing ability of spermatozoa [1][2][3]. Further, inhibition of protein tyrosine kinase activity was observed to prevent acrosomal exocytosis [4] and the fertilizing ability of spermatozoa.…”

“…Thus, it is likely that phosphorylation of proteins in both the plasma membrane and acrosomal membrane, the two membranes involved in acrosomal exocytosis, may be a prerequisite for the acrosome reaction. Though studies have been directed specifically towards identification of the enzyme tyrosine protein kinase and its substrates in the plasma membrane of spermatozoa [1,2,5,6] nothing is known about either the enzyme or its substrates in the acrosomal membranes of spermatozoa.…”

RNA dynamics of fertile and infertile spermatozoa

“…However, our results suggest a weak but a potential function of some transcripts during capacitation and/or acrosome reaction. c-myc, which was one of the first transcripts described in spermatozoa [14] and the protein corresponding reported in human sperm cells [15], has been carefully studied, and we have observed an incomplete or total disappearance of cmyc transcripts after 4 h of capacitation without modification of the mRNA encoding Prm-2. Moreover, the levels of c-myc transcripts are roughly identical with those before capacitation when spermatozoa are incubated with cycloheximide.…”

NRF2 mRNA Expression in Ejaculate Spermatozoa from Men with Asthenozoospermia and Oligoasthenozoospermia

“…18 There are some studies researching the levels of different transcripts of mRNA encoding molecules containing nuclear condensation, capasity and sperm function of spermatozoa. 19,20 In these studies, it has been submitted that the quality of sperm can be related with its mRNA distribution. Also in same other studies, it has been concluded that human semen with low quality is related with abnormal sperm mRNA content for certain genes.…”