McGraw Serge, Vigneault Christian, Tremblay Karine, Sirard Marc-André
Department of Animal Sciences, Centre de Recherche en Biologie de la Reproduction, Université Laval, Québec, Canada.
Mol Reprod Dev. 2006 Jun;73(6):692-9. doi: 10.1002/mrd.20448.
Linker histones H1 are involved in various mechanisms, such as chromatin organization and gene transcription. In different organisms, a unique subtype can be found in the oocyte, however its function remains unclear. To assess the potential involvement of this oocyte linker histone (H1FOO) in chromatin modulation, we have cloned and sequenced the bovine H1FOO cDNA and followed its mRNA profile by quantitative RT-PCR in the oocyte and throughout bovine early embryo development. The highest level of mRNA was found in the germinal vesicle (GV) oocyte and diminished constantly throughout embryo development. In the 16-cell embryo and blastocyst, respectively, the mRNA levels were 200 and 2,000 times lower than in the GV oocyte. A specific antibody raised against bovine H1FOO was used to establish protein distribution in the oocyte and preimplantation embryo by immunocytochemistry. In the GV and metaphase II (MII) oocyte, as well as in the 1-, 2- and 4-cell embryo, H1FOO was localized in the cytoplasm and nucleus. The protein was uniformly spread within the cytoplasm, while it was concentrated onto the chromatin in the nucleus. In the 8- to 16-cell embryo, H1FOO's presence diminished in the cytoplasm, although it was still strongly expressed in nucleus. In the morula and blastocyst stages, the protein was totally lacking. By its position on chromatin, H1FOO could not only be involved in chromatin conformation but could also participate in activation or repression of genes during oogenesis and embryo development before embryonic genome activation.
连接组蛋白H1参与多种机制，如染色质组织和基因转录。在不同生物中，卵母细胞中可发现一种独特的亚型，但其功能仍不清楚。为了评估这种卵母细胞连接组蛋白（H1FOO）在染色质调控中的潜在作用，我们克隆并测序了牛H1FOO cDNA，并通过定量RT-PCR追踪其在卵母细胞和整个牛早期胚胎发育过程中的mRNA表达谱。在生发泡（GV）卵母细胞中发现了最高水平的mRNA，并且在胚胎发育过程中持续下降。在16细胞胚胎和囊胚中，mRNA水平分别比GV卵母细胞低200倍和2000倍。用针对牛H1FOO产生的特异性抗体通过免疫细胞化学确定其在卵母细胞和植入前胚胎中的蛋白质分布。在GV和中期II（MII）卵母细胞以及1、2和4细胞胚胎中，H1FOO定位于细胞质和细胞核。该蛋白质在细胞质中均匀分布，而在细胞核中则集中在染色质上。在8至16细胞胚胎中，H1FOO在细胞质中的存在减少，尽管它在细胞核中仍强烈表达。在桑葚胚和囊胚阶段，该蛋白质完全缺失。通过其在染色质上的位置，H1FOO不仅可能参与染色质构象，还可能在卵母细胞发生和胚胎基因组激活之前的胚胎发育过程中参与基因的激活或抑制。
