Hu Wei, Wang Ya-Ping, Zhu Zuo-Yan
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
Yi Chuan Xue Bao. 2003 May;30(5):485-92.
Despite cloned animals becoming almost commonplace, there is no perfect cloning technique system yet and behind every success lies hundreds of failures. Moreover, cloned animals often age and die quickly. All of those problems hinder further research in nuclear transplantation. The key to make a break-through in the research of cloned animals relies on elucidating mechanism of nuclear reprogramming. Therefore, progress on nuclear reprogramming in nuclear transplantation has been reviewed in some aspects, for example remodeling of the nuclear structure, nucleocytoplasmic interactions and effects of the cell cycle, difference of gene expression and genomic imprinting between reconstructed embryos and fertilized embryos, etc. These results indicate that cytoplasmic environment is very important for the reprogramming of transplanted nuclei. When a donor nucleus in any stage of the cell cycle is transferred into the cytoplasm of an oocyte, there are the twin processes of structural remodeling and molecular reprogramming of the nucleus after transplantation. It is evident that the cell cycle coordination between donor cell and recipient cytoplast to avoid DNA damage and to maintain correct ploidy of the reconstructed embryo is of critical importance in determining the developmental capacity of reconstructed embryos. A dramatic reprogramming of gene expression occurs during zygotic gene activation. The time of zygotic gene activation may affect nuclear reprogramming and consequently the development of reconstructed embryo to off-spring. Imprinted genes are related to the reprogramming and aberrant development seen in manipulated embryos, and may be critical in the reprogramming of transplanted somatic cell.
尽管克隆动物已几乎屡见不鲜，但目前尚无完美的克隆技术体系，每一次成功的背后都有数百次失败。此外，克隆动物往往衰老和死亡得很快。所有这些问题都阻碍了核移植的进一步研究。在克隆动物研究方面取得突破的关键在于阐明核重编程的机制。因此，本文从核结构重塑、核质相互作用和细胞周期的影响、重构胚胎与受精胚胎之间基因表达差异和基因组印记等几个方面，对核移植中核重编程的研究进展进行了综述。这些结果表明，细胞质环境对移植细胞核的重编程非常重要。当处于细胞周期任何阶段的供体细胞核被转移到卵母细胞的细胞质中时，移植后细胞核会发生结构重塑和分子重编程这两个过程。显然，供体细胞与受体细胞质体之间的细胞周期协调，以避免DNA损伤并维持重构胚胎的正确倍性，对于决定重构胚胎的发育能力至关重要。在合子基因激活期间会发生基因表达的剧烈重编程。合子基因激活的时间可能会影响核重编程，进而影响重构胚胎发育为后代。印记基因与操作胚胎中出现的重编程和异常发育有关，可能在移植体细胞的重编程中起关键作用。
