Adeoya-Osiguwa S A, Fraser L R
Endocrinology and Reproduction Research Group, School of Biomedical Sciences, King's College London, Guy's Campus, London Bridge, London, UK.
Mol Reprod Dev. 2000 Dec;57(4):384-92. doi: 10.1002/1098-2795(200012)57:4<384::AID-MRD11>3.0.CO;2-U.
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 approximately 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 approximately 116, 95, 82, 75, 66, 56, and 42 kDa showed increased phosphorylation, while in capacitated cells, phosphoproteins of approximately 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.
促受精肽（FPP）和腺苷已被证明可作为第一信使，通过最初刺激未获能精子中的环磷酸腺苷（cAMP）生成，然后在获能细胞中抑制其生成，来调节第二信使cAMP的可用性。本研究调查了响应FPP和腺苷时，与获能相关的蛋白质酪氨酸磷酸化可能发生的变化。在未获能和获能的悬浮液中均观察到约30 - 140 kDa蛋白质磷酸化的时间依赖性变化，获能细胞中的磷酸化总体水平明显更高。与未处理的对照样品相比，在FPP存在的情况下，未获能精子中的磷酸化受到刺激，但获能精子中的磷酸化受到抑制。腺苷、霍乱毒素和刺激性A(2a)腺苷受体激动剂CGS - 21680也刺激未获能精子中的磷酸化，而FPP的竞争性抑制剂Gln - FPP则阻断对FPP的反应。在获能细胞中，当在百日咳毒素存在的情况下用FPP处理细胞时，FPP对磷酸化的抑制作用被消除。与FPP和腺苷对cAMP生成的获能依赖性作用一致，这些结果支持以下假设：FPP和腺苷通过调节腺苷酸环化酶/ cAMP信号通路，进而调节蛋白质酪氨酸磷酸化，来调节精子功能。特别重要的是鉴定出了几种显示FPP诱导的磷酸化改变的磷蛋白。在未获能精子中，约116、95、82、75、66、56和42 kDa的蛋白质显示磷酸化增加，而在获能细胞中，约116、95、82、75、70、66、56和50 kDa的磷蛋白显示磷酸化减少。这表明这些特定蛋白质可能分别参与获能的刺激和终止。
