Katoh Yuki, Tamba Michiko, Matsuda Manabu, Kikuchi Kazuhiro, Okamura Naomichi
Division of Cellular Signaling, Institute for Advanced Medical Research, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan; Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
Biochem Biophys Res Commun. 2018 Feb 26;497(1):374-380. doi: 10.1016/j.bbrc.2018.02.087. Epub 2018 Feb 13.
In order to understand the molecular mechanisms involved in the sperm capacitation, we have identified the proteins tyrosine-phosphorylated during the capacitation especially in conjunction with the regulation of the levels of reactive oxygen species (ROS) in sperm. In the present study, the effects of the tyrosine phosphorylation of cytosolic NADP-dependent isocitrate dehydrogenase (IDPc) on its catalytic activity and on the levels of ROS in sperm have been studied. The tyrosine phosphorylated IDPc showed a significantly lowered enzymatic activity. The immunocytochemical analyses using the highly specific antisera against IDPc revealed that IDPc was mainly localized to the principal piece of the porcine sperm flagellum. As IDPc is one of the major NADPH regenerating enzymes in porcine sperm, it is strongly suggested that the decrease in IDPc activity is involved in the increased levels of ROS, which results in the induction of hyperactivated flagellar movement and capacitation.
为了了解精子获能所涉及的分子机制，我们鉴定了在获能过程中发生酪氨酸磷酸化的蛋白质，特别是与精子中活性氧（ROS）水平调节相关的蛋白质。在本研究中，我们研究了胞质NADP依赖性异柠檬酸脱氢酶（IDPc）的酪氨酸磷酸化对其催化活性以及精子中ROS水平的影响。酪氨酸磷酸化的IDPc显示出显著降低的酶活性。使用针对IDPc的高度特异性抗血清进行的免疫细胞化学分析表明，IDPc主要定位于猪精子鞭毛的主段。由于IDPc是猪精子中主要的NADPH再生酶之一，强烈提示IDPc活性的降低与ROS水平的升高有关，而ROS水平的升高导致超活化鞭毛运动和获能的诱导。
