Essential role of paternal chromatin in the regulation of transcriptional activity during mouse preimplantation development.
Several lines of evidence indicate that the formation of a transcriptionally repressive state during the two-cell stage in the preimplantation mouse embryo is superimposed on the activation of the embryonic genome. However, it is difficult to determine the profile of newly synthesized (nascent) RNA during this phase because large amounts of maternal RNA accumulate in maturing oocytes to support early development. Using 5-bromouridine-5'-triphosphate labeling of RNA, we have verified that nascent RNA synthesis was repressed between the two-cell and four-cell transition in normally fertilized but not in parthenogenetic embryos. Moreover, this repression was contributed by sperm (male) chromatin, which we confirmed by studying androgenetic embryos. The source of factors responsible for repressing nascent RNA production was investigated using different stages of sperm development. Fertilization with immature round spermatids resulted in a lower level of transcriptional activity than with ICSI at the two-cell stage, and this was consistent with further repression at the four-cell stage in the ICSI group. Finally, study on DNA replication and chromatin remodeling was performed using labeled histones H3 and H4 to differentiate between male and female pronuclei. The combination of male and female chromatin appeared to decrease nascent RNA production in the fertilized embryo. This study indicates that paternal chromatin is important in the regulation of transcriptional activity during mouse preimplantation development and that this capacity is acquired during spermiogenesis.
Bui
Hong-Thuy
HT
Department of Animal Biotechnology, College of Animal Bioscience and Biotechnology/Animal Resources Research Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul, Republic of Korea. bthuy@konkuk.ac.kr
Wakayama
Sayaka
S
Mizutani
Eiji
E
Park
Keun-Kyu
KK
Kim
Jin-Hoi
JH
Van Thuan
Nguyen
N
Wakayama
Teruhiko
T
D000728:Androgens / Q000378:metabolism; D000818:Animals; D001755:Blastocyst / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly; D004261:DNA Replication; D046149:Embryo Culture Techniques; D005260:Female; D005307:Fertilization in Vitro; D018507:Gene Expression Regulation, Developmental; D006657:Histones / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D010312:Parthenogenesis; D012313:RNA / Q000096:biosynthesis*; D020554:Sperm Injections, Intracytoplasmic; D013094:Spermatozoa / Q000378:metabolism*; D013997:Time Factors; D014158:Transcription, Genetic
D000728:Androgens; D002843:Chromatin; D006657:Histones; D012313:RNA