State Key Laboratory for Agrobiotechnology, College of Biological Sciences, Agricultural University, Beijing, People's Republic of China.
PLoS One. 2009 Oct 7;4(10):e7372. doi: 10.1371/journal.pone.0007372.
Partitioning-defective proteins (PAR) are detected to express mainly in the cytoplast, and play an important role in cell polarity. However, we showed here that PAR6, one kind of PAR protein, was localized in the nuclei of mouse oocytes that formed primordial follicles during the perinatal period, suggesting a new role of PAR protein. It is the first time we found that, in mouse fetal ovaries, PAR6 appeared in somatic cell cytoplasm and fell weak when somatic cells invaded germ cell cysts at 17.5 days post coitus (dpc). Meanwhile, the expression of PAR6 was observed in cysts, and became strong in the nuclei of some germ cells at 19.5 dpc and all primordial follicular oocytes at 3 day post parturition (dpp), and then obviously declined when the primordial follicles entered the folliculogenic growth phase. During the primordial follicle pool foundation, the number of PAR6 positive germ cells remained steady and was consistent with that of formed follicles at 3 dpp. There were no TUNEL (apoptosis examination) positive germ cells stained with PAR6 at any time studied. The number of follicles significantly declined when 15.5 dpc ovaries were treated with the anti-PAR6 antibody and PAR6 RNA interference. Carbenoxolone (CBX, a known blocker of gap junctions) inhibited the expression of PAR6 in germ cells and the formation of follicles. Our results suggest that PAR6 could be used as a potential marker of germ cells for the primordial follicle formation, and the expression of PAR6 by a gap junction-dependent process may contribute to the formation of primordial follicles and the maintenance of oocytes at the diplotene stage.
分隔缺陷蛋白（PAR）主要在胞质体中表达，在细胞极性中发挥重要作用。然而，我们在这里表明，PAR 蛋白的一种 PAR6，在形成原始卵泡的围产期小鼠卵母细胞的核中定位，这表明 PAR 蛋白具有新的作用。这是我们第一次发现，在小鼠胎儿卵巢中，PAR6 出现在体细胞细胞质中，并在体细胞侵入 17.5 天合胞体（dpc）的生殖细胞小泡时减弱。同时，在小泡中观察到 PAR6 的表达，并在 19.5 dpc 的一些生殖细胞核中变得强烈，在产后 3 天（dpp）的所有原始卵泡卵母细胞中变得强烈，然后在原始卵泡进入卵泡生成生长阶段时明显下降。在原始卵泡库建立期间，PAR6 阳性生殖细胞的数量保持稳定，与 3 dpp 时形成的卵泡数量一致。在任何研究时间点，用 PAR6 染色的 TUNEL（凋亡检查）阳性生殖细胞均未染色。当用抗 PAR6 抗体和 PAR6 RNA 干扰处理 15.5 dpc 卵巢时，卵泡数量明显减少。卡波酮（CBX，已知的间隙连接阻断剂）抑制了生殖细胞中 PAR6 的表达和卵泡的形成。我们的结果表明，PAR6 可用作原始卵泡形成的生殖细胞的潜在标记物，并且 PAR6 的表达可能通过间隙连接依赖性过程有助于原始卵泡的形成和二倍体期卵母细胞的维持。
