title: Jumonji regulates cardiomyocyte proliferation via interaction with retinoblastoma protein.
abstract: Jumonji (JMJ) can function as a transcriptional repressor and plays critical roles in embryonic development including heart development in mice. Although JMJ has been suggested to play a role in cell growth, the molecular mechanisms have not been resolved. The present data demonstrate that JMJ interacts with the retinoblastoma protein (Rb), one of the master regulatory genes of cell cycle. JMJ potentiates the repression function of Rb on E2F activities, leading to reduced cell cycle progression. The transcriptional repression domain of JMJ is critical for the interaction with Rb as well as repression of cell cycle. The physiological relevance of the association between Rb and JMJ was assessed in cardiomyocytes. Primary cardiomyocytes cultured from homozygous jmj knock-out mouse embryos (jmj mutants) show increased cell mitosis in a cardiomyocyte-specific manner. Reporter gene analyses demonstrate that promoter activities of cyclin D1, cyclin D2, and Cdc2 are up-regulated in jmj mutant cardiomyocytes. These data suggest that JMJ down-regulates the cell growth via interaction with Rb, which would provide important insights into the cardiac defects observed in jmj mutant mice.
authors.affiliation: Department of Anatomy, University of Wisconsin Medical School, Madison, Wisconsin 53706, USA.
authors.forename: Jooyoung
authors.initials: J
authors.lastname: Jung
authors.forename: Tae-Gyun
authors.initials: TG
authors.lastname: Kim
authors.forename: Gary E
authors.initials: GE
authors.lastname: Lyons
authors.forename: Hyeong-Reh C
authors.initials: HR
authors.lastname: Kim
authors.forename: Youngsook
authors.initials: Y
authors.lastname: Lee
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D049109:Cell Proliferation; D002478:Cells, Cultured; D019938:Cyclin D1 / Q000378:metabolism; D056742:Cyclin D2; D016213:Cyclins / Q000378:metabolism; D004622:Embryo, Mammalian / Q000033:anatomy & histology / Q000502:physiology; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D051379:Mice; D032383:Myocytes, Cardiac / Q000166:cytology / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D063151:Polycomb Repressive Complex 2; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: C486196:Ccnd2 protein, mouse; D056742:Cyclin D2; D016213:Cyclins; C093650:Jarid2 protein, mouse; D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; D016160:Retinoblastoma Protein; D019938:Cyclin D1; D063151:Polycomb Repressive Complex 2