title: Dyskerin ablation in mouse liver inhibits rRNA processing and cell division.
abstract: Dyskerin is a component of small nucleolar ribonucleoprotein complexes and acts as a pseudouridine synthase to modify newly synthesized ribosomal, spliceosomal, and possibly other RNAs. It is encoded by the DKC1 gene, the gene mutated in X-linked dyskeratosis congenita, and is also part of the telomerase complex. The yeast ortholog, Cbf5, is an essential protein, but in mammals the effect of dyskerin ablation at the cellular level is not known. Here we show that mouse hepatocytes can survive after induction of a Dkc1 deletion. In the absence of dyskerin, rRNA processing is inhibited with the accumulation of large precursors, and fibrillarin does not accumulate in nucleoli. A low rate of apoptosis is induced in the hepatocytes, which show an induction of the p53-dependent cell cycle checkpoint pathway. Signs of liver damage including an increase in serum alanine aminotransferase activity and a disordered structure at the histological and macroscopic levels are observed. In response to carbon tetrachloride administration, when wild-type hepatocytes mount a rapid proliferative response, those without dyskerin do not divide. We conclude that hepatocytes can survive without dyskerin but that the role of dyskerin in RNA modification is essential for cellular proliferation.
authors.affiliation: Division Hematology, Department Internal Medicine, Washington University School of Medicine, 660 S. Euclid Ave., Box 8125, St. Louis, MO 63110, USA.
authors.forename: Jingping
authors.initials: J
authors.lastname: Ge
authors.forename: David A
authors.initials: DA
authors.lastname: Rudnick
authors.forename: Jun
authors.initials: J
authors.lastname: He
authors.forename: Dan L
authors.initials: DL
authors.lastname: Crimmins
authors.forename: Jack H
authors.initials: JH
authors.lastname: Ladenson
authors.forename: Monica
authors.initials: M
authors.lastname: Bessler
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Mason
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division / Q000502:physiology*; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism; D017353:Gene Deletion; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D064547:Myxovirus Resistance Proteins; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; C510431:Dkc1 protein, mouse; D064547:Myxovirus Resistance Proteins; D009687:Nuclear Proteins; D012335:RNA, Ribosomal; C047458:fibrillarin; D019204:GTP-Binding Proteins