Biochemical Parameters of Initiation and Regulation of Sperm Motility

Abstract

Studies of in vitro models demonstrate that a forward motility protein (FMP) is required for the initiation of forward motility in the immature epididymal spermatozoa. FMP is a heat-stable glycoprotein derived from epididymal plasma. During the epididymal maturation of spermatozoa in vivo, there is a marked increase of intrasperm pH and level of cyclic adenosine monophosphate (CAMP). Several studies suggest that exogenous FMP in concert with elevated intrasperm pH and level of cAMP initiates flagellar motility during the epididymal transit of sperm. cAMP activates sperm cytosolic CAMPdependent protein kinases, which in turn phosphorylate multiple intrasperm phosphoproteins that may regulate flagellar motility. Exogenous calcium ion activates intact sperm motility, although it inhibits motility of demembranated cells on reactivation. Occurrence of CAMP-dependent type I and II protein kinases, a novel CAMP-independent protein kinase, and a phosphoprotein phosphatase has been demonstrated on the external surface of spermatozoa. The sperm surface has a coupled-enzyme system: ecto-CAMP-independent protein kinase and phosphoprotein phosphatase that regulate the phosphorylation and dephosphorylation of endogenous sperm ectophosphoproteins. The specific activities of these ectoenzymes increase markedly during forward progression, suggesting that they may have a role in regulating flagellar motility.

Effect of Tyrosine Kinase Inhibitors on Tyrosine Phosphorylation and Motility Parameters in Human Sperm

“…Initiation of sperm motility has been associated with protein phosphorylation as well as changes in intracellular calcium and pH [7,8,25,30]. Several proteins become phosphorylated at the time sperm start moving actively [32].…”

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.…”

“…1B). Earlier studies on the intact spermatozoa of rat [19], dog [20,21], goat [22], bull [5,23] and man [16] had provided conclusive evidence for the presence of cAMP independent protein kinases in these spermatozoa, and they were also shown to be associated with the sperm plasma membrane [29,21]. Protein kinase activity in the acrosomal membranes of hamster spermatozoa was also not seen to be stimulated by cAMP or inhibited by H8 (Table 1), an inhibitor of protein kinase A, thus suggesting that in the hamster sperm acrosomal membranes the protein kinase activity was of the cAMP independent type.…”

Lithium carbonate inducing disorders in three parameters of rat sperm

“…[7] According to the previous studies, motility is known as one of the important parameters of qualitative evaluation of sperm cell as an impaired motility extremely affects male fertility negatively and reduces fertilization of ovules. [8] Apart from sperm motility, morphology of sperm is influenced by cytotoxic agents that target testicular tissue.…”