Sukonset Chompoonut, Surinlert Piyaporn, Thongsum Orawan, Watthammawut Atthaboon, Somrit Monsicha, Nakeim Jirasuda, Weerachatyanukul Wattana, Asuvapongpatana Somluk
Department of Anatomy, Faculty of Science, Mahidol University, Ratchathewee, Bangkok, Thailand.
Chulabhon International College of Medicine, Thammasat University, Prathumtani, Pratumtani, Thailand.
PeerJ. 2020 Nov 11;8:e10218. doi: 10.7717/peerj.10218. eCollection 2020.
Cathepsin D (CAT-D) is a well-known aspartic protease that serves a function as house-keeping lysosomal enzyme in all somatic cells. Its existence in reproductive tissues is highly variable, even in the somatic derived epithelial cells of reproductive tract. In , existence of MrCAT-D and its translational product was detected in both somatic cells (Sertoli-like supporting cells) and developing spermatogenic cells as well as along accessory spermatic ducts. Specifically, MrCAT-D was localized onto the sperm surface rather than within the acrosomal matrix, as evident by similar staining pattern of anti-CAT-D on live and aldehyde fixed sperm. MrCAT-D in testicular extracts and sperm isolates showed active enzyme activities towards its specific fluorogenic substrate (MCA-Gly-Lys-Pro-Ile-Leu-Phe-Phe-Arg-Leu-Lys (Dnp)-D-Arg-NH). MrCAT-D also exerted its function towards hydrolyzing filamentous actin, the meshwork of which is shown to be localized at the junction between germ cells and supporting cells and spermatogonia in testicular epithelium. Together, we have localized MrCAT-D transcript and its translational product in both supporting and germ cells of testis and claimed its enzymatic function towards actin degradation, which may be related to sperm release from the epithelial cell interaction.
组织蛋白酶D（CAT-D）是一种著名的天冬氨酸蛋白酶，在所有体细胞中作为管家溶酶体酶发挥作用。其在生殖组织中的存在高度可变，即使在生殖道的体细胞衍生上皮细胞中也是如此。在[具体文献或研究中]，在体细胞（类支持细胞）和发育中的生精细胞以及附属输精管中均检测到MrCAT-D及其翻译产物的存在。具体而言，MrCAT-D定位于精子表面而非顶体基质内，这通过抗CAT-D对活精子和醛固定精子的类似染色模式得以证明。睾丸提取物和精子分离物中的MrCAT-D对其特定的荧光底物（MCA-甘氨酸-赖氨酸-脯氨酸-异亮氨酸-亮氨酸-苯丙氨酸-苯丙氨酸-精氨酸-亮氨酸-赖氨酸（Dnp）-D-精氨酸-NH）显示出活性酶活性。MrCAT-D还对丝状肌动蛋白发挥水解作用，其网络显示定位于睾丸上皮中生殖细胞与支持细胞以及精原细胞之间的连接处。总之，我们已在睾丸的支持细胞和生殖细胞中定位了MrCAT-D转录本及其翻译产物，并宣称其对肌动蛋白降解具有酶促功能，这可能与精子从上皮细胞相互作用中释放有关。
