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Fertilization promoting peptide and adenosine, acting as first messengers, regulate cAMP production and consequent protein tyrosine phosphorylation in a capacitation‐dependent manner
Author(s) -
AdeoyaOsiguwa Susan A.,
Fraser Lynn R.
Publication year - 2000
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/1098-2795(200012)57:4<384::aid-mrd11>3.0.co;2-u
Subject(s) - capacitation , biology , phosphorylation , adenosine , second messenger system , tyrosine , tyrosine phosphorylation , human fertilization , microbiology and biotechnology , protein phosphorylation , peptide , signal transduction , medicine , endocrinology , biochemistry , protein kinase a , genetics
Fertilization promoting peptide (FPP) and adenosine have been shown to act as first messengers, regulating availability of the second messenger cAMP by initially stimulating cAMP production in uncapacitated spermatozoa and then inhibiting it in capacitated cells. This study investigated possible capacitation‐related changes in protein tyrosine phosphorylation in response to FPP and adenosine. Time‐dependent changes in phosphorylation of proteins of ∼30–140 kDa were observed in both uncapacitated and capacitated suspensions, the general level of phosphorylation being markedly greater in capacitated cells. In the presence of FPP, phosphorylation was stimulated in uncapacitated but inhibited in capacitated spermatozoa, compared with untreated control samples. Adenosine, cholera toxin, and CGS‐21680, a stimulatory A 2a adenosine receptor agonist, also stimulated phosphorylation in uncapacitated spermatozoa, while Gln‐FPP, a competitive inhibitor of FPP, blocked responses to FPP. In capacitated cells, FPP's inhibition of phosphorylation was abolished when cells were treated with FPP in the presence of pertussis toxin. Consistent with the capacitation‐dependent effects of FPP and adenosine on cAMP production, these results support the hypothesis that FPP and adenosine modulate sperm function by regulating the AC/cAMP signaling pathway and, consequently, protein tyrosine phosphorylation. Of particular significance is the identification of several phosphoproteins showing FPP‐induced alterations in phosphorylation. In uncapacitated spermatozoa, proteins of ∼116, 95, 82, 75, 66, 56, and 42 kDa showed increased phosphorylation, while in capacitated cells, phosphoproteins of ∼116, 95, 82, 75, 70, 66, 56, and 50 kDa showed decreased phosphorylation. This suggests that these particular proteins may be involved in stimulation and arrest of capacitation, respectively. Mol. Reprod. Dev. 57:384–392, 2000. © 2000 Wiley‐Liss, Inc.