Lane M, Baltz J M, Bavister B D
Department of Animal Health and Biomedical Sciences, University of Wisconsin, 1655 Linden Drive, Madison, Wisconsin 53706, USA.
Dev Biol. 1999 Apr 1;208(1):244-52. doi: 10.1006/dbio.1999.9198.
This study characterized the activation of the regulatory activity of the Na+/H+ antiporter during fertilization of hamster embryos. Hamster oocytes appeared to lack any mechanism for the regulation of intracellular pH in the acid range. Similarly, no Na+/H+ antiporter activity could be detected in embryos that were collected from the reproductive tract between 1 and 5 h post-egg activation (PEA). Activity of the Na+/H+ antiporter was first detected in embryos collected at 5.5 h PEA and gradually increased to reach maximal activity in embryos collected at 7 h PEA. Parthenogenetically activated one-cell and two-cell embryos demonstrate Na+/H+ antiporter activity, indicating that antiporter activity is maternally derived and initiated by activation of the egg. The inability of cycloheximide, colchicine, or cytochalasin D to affect initiation of antiporter activity indicates that antiporter appearance is not dependent on the synthesis of new protein or recruitment of existing protein to the cell membrane. In contrast, incubation of one-cell embryos with sphingosine did inhibit the appearance of Na+/H+ antiporter activity, showing that inhibition of normal protein kinase C activity is detrimental to antiporter function. Furthermore, incubation of oocytes with a phorbol ester which stimulates protein kinase C activity induced Na+/H+ antiporter activity in oocytes in which the activity was previously absent. Incubation with an intracellular calcium chelator also reduced the appearance of antiporter activity. Taken together, these data indicate that the appearance of Na+/H+ antiporter activity following egg activation may be due, at least in part, to regulation by protein kinase C and intracellular calcium levels.
本研究对仓鼠胚胎受精过程中Na⁺/H⁺逆向转运体调节活性的激活进行了表征。仓鼠卵母细胞似乎缺乏在酸性范围内调节细胞内pH的任何机制。同样，在卵激活后1至5小时从生殖道收集的胚胎中未检测到Na⁺/H⁺逆向转运体活性。Na⁺/H⁺逆向转运体活性首先在卵激活后5.5小时收集的胚胎中检测到，并逐渐增加，在卵激活后7小时收集的胚胎中达到最大活性。孤雌激活的单细胞和双细胞胚胎表现出Na⁺/H⁺逆向转运体活性，表明逆向转运体活性是母源的，并由卵子激活引发。放线菌酮、秋水仙碱或细胞松弛素D无法影响逆向转运体活性的起始，这表明逆向转运体的出现不依赖于新蛋白质的合成或现有蛋白质向细胞膜的募集。相反，用鞘氨醇孵育单细胞胚胎确实抑制了Na⁺/H⁺逆向转运体活性的出现，表明抑制正常的蛋白激酶C活性对逆向转运体功能有害。此外，用刺激蛋白激酶C活性的佛波酯孵育卵母细胞，可在先前无活性的卵母细胞中诱导Na⁺/H⁺逆向转运体活性。用细胞内钙螯合剂孵育也减少了逆向转运体活性的出现。综上所述，这些数据表明，卵子激活后Na⁺/H⁺逆向转运体活性的出现可能至少部分归因于蛋白激酶C和细胞内钙水平的调节。
