Singh Durgesh Kumar, Deshmukh Rohit Kumar, Narayanan Praveen Kumar, Shivaji Sisinthy, Siva Archana Bharadwaj
CSIR-Centre for Cellular and Molecular BiologyHyderabad 500007, India
Reproduction. 2017 May;153(5):655-669. doi: 10.1530/REP-16-0591. Epub 2017 Mar 1.
Sperm capacitation is a prerequisite for successful fertilization. Increase in tyrosine phosphorylation is considered the hallmark of capacitation and attempts to understand its regulation are ongoing. In this regard, we attempted to study the role of SRC family kinases (SFKs) in the hamster sperm functions. Interestingly, we found the presence of the lymphocyte-specific protein tyrosine kinase, LCK, in mammalian spermatozoa and further characterized it in terms of its localization and function. LCK was found in spermatozoa of several species, and its transcript was identified in the hamster testis. Autophosphorylation of LCK at the Y394 residue increased as capacitation progressed, indicating an upregulation of LCK activity during capacitation. Inhibition of LCK (and perhaps the other SFKs) with the use of a specific inhibitor showed a significant decrease in protein tyrosine phosphorylation of several proteins, implying LCK/SFKs as key tyrosine kinase(s) regulating tyrosine phosphorylation during hamster sperm capacitation. Dihydrolipoamide dehydrogenase was identified as a substrate for LCK/SFK. LCK/SFKs inhibition significantly reduced the percentage fertilization () but had no effect on sperm motility, hyperactivation and acrosome reaction. In summary, this is the first report on the presence of LCK, an SFK of hematopoietic lineage in spermatozoa besides being the first study on the role of SFKs in the spermatozoa of Syrian hamsters.
精子获能是成功受精的前提条件。酪氨酸磷酸化增加被认为是获能的标志，目前人们仍在努力了解其调控机制。在这方面，我们试图研究SRC家族激酶（SFKs）在仓鼠精子功能中的作用。有趣的是，我们发现哺乳动物精子中存在淋巴细胞特异性蛋白酪氨酸激酶LCK，并进一步对其定位和功能进行了表征。在多个物种的精子中都发现了LCK，并且在仓鼠睾丸中鉴定出了它的转录本。随着获能进程的推进，LCK在Y394残基处的自磷酸化增加，这表明在获能过程中LCK活性上调。使用特异性抑制剂抑制LCK（可能还有其他SFKs）后，几种蛋白质的酪氨酸磷酸化显著降低，这意味着LCK/SFKs是仓鼠精子获能过程中调节酪氨酸磷酸化的关键酪氨酸激酶。二氢硫辛酰胺脱氢酶被鉴定为LCK/SFK的底物。抑制LCK/SFKs显著降低了受精率（），但对精子活力、超活化和顶体反应没有影响。总之，这是关于精子中造血谱系SFK——LCK存在的首次报道，也是关于SFKs在叙利亚仓鼠精子中作用的首次研究。
