title: L2dtl is essential for cell survival and nuclear division in early mouse embryonic development.
abstract: l(2)dtl (lethal (2) denticleless), is an embryonic lethal homozygous mutation initially identified in Drosophila melanogaster that produces embryos that lack ventral denticle belts. In addition to nucleotide sequence, bioinformatic analysis has revealed a conservation of critical functional motifs among the human L2DTL, mouse L2dtl, and Drosophila l(2)dtl proteins. The function of the L2DTL protein in the development of mammalian embryos was studied using targeted disruption of the L2dtl gene in mice. The knock-out resulted in early embryonic lethality. L2dtl-/- embryos were deformed and terminated development at the 4-8-cell stage. Microinjection of a small interfering RNA (siRNA) vector (siRNA-L2dtl) into the two-cell stage nuclei of wild-type mouse embryos led to cell cycle progression failure, termination of cell division, and, eventually, embryonic death during the preimplantation stage. Morphological studies of the embryos 54 h after injection showed fragmentation of mitotic chromosomes and chromosomal lagging, hallmarks of mitotic catastrophe. The siRNA-L2dtl-treated embryos eventually lysed and failed to develop into blastocysts after 72 h of in vitro culturing. However, the embryos developed normally after they were microinjected into one nucleus of the two-celled embryos. The siRNA studies in HeLa cells showed that L2dtl protein depletion results in multinucleation and down-regulation of phosphatidylinositol 3-kinase, proliferating cell nuclear antigen, and PTTG1/securin, which might partially explain the mitotic catastrophe observed in L2dtl-depleted mouse embryos. Based on these findings, we conclude that L2dtl gene expression is essential for very early mouse embryonic development.
authors.affiliation: Graduate Institute of Pathology and Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Chao-Lien
authors.initials: CL
authors.lastname: Liu
authors.forename: I-Shing
authors.initials: IS
authors.lastname: Yu
authors.forename: Hung-Wei
authors.initials: HW
authors.lastname: Pan
authors.forename: Shu-Wha
authors.initials: SW
authors.lastname: Lin
authors.forename: Hey-Chi
authors.initials: HC
authors.lastname: Hsu
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001757:Blastomeres / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D053595:Embryonic Stem Cells / Q000166:cytology; D005260:Female; D018507:Gene Expression Regulation, Developmental; D005804:Genes, Lethal; D006367:HeLa Cells; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D010641:Phenotype; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering; D044767:Ubiquitin-Protein Ligases; D008025:Ligases
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D009687:Nuclear Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D044767:Ubiquitin-Protein Ligases; C429530:DTL protein, human; C517536:Dtl protein, mouse; D008025:Ligases