title: Heterochromatin reprogramming in rabbit embryos after fertilization, intra-, and inter-species SCNT correlates with preimplantation development.
abstract: To investigate the embryonic genome organization upon fertilization and somatic cell nuclear transfer (SCNT), we tracked HP1β and CENP, two well-characterized protein markers of pericentric and centromeric compartments respectively, in four types of embryos produced by rabbit in vivo fertilization, rabbit parthenogenesis, rabbit-to-rabbit, and bovine-to-rabbit SCNT. In the interphase nuclei of rabbit cultured fibroblasts, centromeres and associated pericentric heterochromatin are usually isolated. Clustering into higher-order chromatin structures, such as the chromocenters seen in mouse and bovine somatic cells, could not be observed in rabbit fibroblasts. After fertilization, centromeres and associated pericentric heterochromatin are quite dispersed in rabbit embryos. The somatic-like organization is progressively established and completed only by the 8/16-cell stage, a stage that corresponds to major embryonic genome activation in this species. In SCNT embryos, pericentric heterochromatin distribution typical for rabbit and bovine somatic cells was incompletely reverted into the 1-cell embryonic form with remnants of heterochromatin clusters in 100% of bovine-to-rabbit embryos. Subsequently, the donor cell nuclear organization was rapidly re-established by the 4-cell stage. Remarkably, the incomplete remodeling of bovine-to-rabbit 1-cell embryos was associated with delayed transcriptional activation compared with rabbit-to-rabbit embryos. Together, the results confirm that pericentric heterochromatin spatio-temporal reorganization is an important step of embryonic genome reprogramming. It also appears that genome reorganization in SCNT embryos is mainly dependent on the nuclear characteristics of the donor cells, not on the recipient cytoplasm.
authors.affiliation: INRA, UMR 1198 Biologie du Developpement et Reproduction, F-78350 Jouy en Josas, France.
authors.forename: Cai-Xia
authors.initials: CX
authors.lastname: Yang
authors.forename: Zichuan
authors.initials: Z
authors.lastname: Liu
authors.forename: Renaud
authors.initials: R
authors.lastname: Fleurot
authors.forename: Pierre
authors.initials: P
authors.lastname: Adenot
authors.forename: Véronique
authors.initials: V
authors.lastname: Duranthon
authors.forename: Xavier
authors.initials: X
authors.lastname: Vignon
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhou
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Renard
authors.forename: Nathalie
authors.initials: N
authors.lastname: Beaujean
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002417:Cattle; D042002:Chromatin Assembly and Disassembly / Q000235:genetics / Q000502:physiology*; D004622:Embryo, Mammalian; D047108:Embryonic Development / Q000235:genetics* / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D006570:Heterochromatin / Q000235:genetics / Q000378:metabolism*; D006822:Hybrid Cells / Q000166:cytology / Q000378:metabolism; D008297:Male; D051379:Mice; D053652:Nuclear Transfer Techniques / Q000662:veterinary; D011247:Pregnancy; D011817:Rabbits / Q000196:embryology; D013045:Species Specificity
chemical_list: D006570:Heterochromatin