Hur Chang-Gi, Choe Changyong, Kim Gyu-Tae, Cho Seong-Keun, Park Jae-Yong, Hong Seong-Geun, Han Jaehee, Kang Dawon
CHO-A Biotechnology Research Institute, CHO-A Pharmaceutical Company Ltd, Seoul, South Korea.
Reproduction. 2009 Feb;137(2):237-44. doi: 10.1530/REP-08-0035. Epub 2008 Nov 5.
Two-pore domain K(+) (K(2P)) channels that help set the resting membrane potential of excitable and nonexcitable cells are expressed in many kinds of cells and tissues. However, the expression of K(2P) channels has not yet been reported in bovine germ cells. In this study, we demonstrate for the first time that K(2P) channels are expressed in the reproductive organs and germ cells of Korean cattle. RT-PCR data showed that members of the K(2P) channel family, specifically KCNK3, KCNK9, KCNK2, KCNK10, and KCNK4, were expressed in the ovary, testis, oocytes, embryo, and sperm. Out of these channels, KCNK2 and KCNK4 mRNAs were abundantly expressed in the mature oocytes, eight-cell stage embryos, and blastocysts compared with immature oocytes. KCNK4 and KCNK3 were significantly increased in eight-cell stage embryos. Immunocytochemical data showed that KCNK2, KCNK10, KCNK4, KCNK3, and KCNK9 channel proteins were expressed at the membrane of oocytes and blastocysts. KCNK10 and KCNK4 were strongly expressed and distributed in oocyte membranes. These channel proteins were also localized to the acrosome sperm cap. In particular, KCNK3 and KCNK4 were strongly localized to the post-acrosomal region of the sperm head and the equatorial band within the sperm head respectively. These results suggest that K(2P) channels might contribute to the background K(+) conductance of germ cells and regulate various physiological processes, such as maturation, fertilization, and development.
双孔结构域钾离子（K(2P)）通道有助于设定可兴奋细胞和非可兴奋细胞的静息膜电位，在多种细胞和组织中均有表达。然而，尚未有关于牛生殖细胞中K(2P)通道表达的报道。在本研究中，我们首次证明K(2P)通道在韩牛的生殖器官和生殖细胞中表达。逆转录聚合酶链反应（RT-PCR）数据显示，K(2P)通道家族成员，特别是钾离子通道亚家族3（KCNK3）、钾离子通道亚家族9（KCNK9）、钾离子通道亚家族2（KCNK2）、钾离子通道亚家族10（KCNK10）和钾离子通道亚家族4（KCNK4），在卵巢、睾丸、卵母细胞、胚胎和精子中均有表达。在这些通道中，与未成熟卵母细胞相比，KCNK2和KCNK4的信使核糖核酸（mRNA）在成熟卵母细胞、八细胞期胚胎和囊胚中大量表达。在八细胞期胚胎中，KCNK4和KCNK3显著增加。免疫细胞化学数据显示，KCNK2、KCNK10、KCNK4、KCNK3和KCNK9通道蛋白在卵母细胞和囊胚的膜上表达。KCNK10和KCNK4在卵母细胞膜上强烈表达并分布。这些通道蛋白也定位于精子顶体帽。特别是，KCNK3和KCNK4分别强烈定位于精子头部的顶体后区域和精子头部内的赤道带。这些结果表明，K(2P)通道可能有助于生殖细胞的背景钾离子电导，并调节各种生理过程，如成熟、受精和发育。
