title: MicroRNA-1 and MicroRNA-133 in spontaneous myocardial differentiation of mouse embryonic stem cells.
abstract: BACKGROUND
  MicroRNAs (miRNAs) regulate various biological processes through inhibiting the translation of RNA transcripts. Although miRNA-1 (miR-1) and miRNA-133 (miR-133) are abundantly expressed in the adult heart and involved in cardiac hypertrophy, the roles of these miRNAs in spontaneous myocardial differentiation are unknown.
  
  
  RESULTS
  The levels of miR-1 and miR-133 in mouse embryonic stem (ES) cells were increased during spontaneous differentiation by 2-dimensional culture, but reduced during forced myocardial differentiation by a histone deacetylase inhibitor, trichostatin A. The overexpression of miR-1 or miR-133 by lentiviral infection reduced the expression of a cardiac-specific gene, Nkx2.5, during differentiation of ES cells. In addition, miR-1 also inhibited alpha-myosin heavy chain expression. The results of luciferase assays revealed that miR-1 recognizes and targets the 3' untranslated region of cyclin-dependent kinase-9 (Cdk9) in ES cells. Overexpression of miR-1 decreased the protein amounts of Cdk9 without affecting the mRNA levels, indicating that miR-1 post-transcriptionally inhibits Cdk9 translation.
  
  
  CONCLUSIONS
  miR-1 and miR-133 may play significant roles in the myocardial differentiation of mouse ES cells, and Cdk9 may be involved in this process as a target of miR-1.
authors.affiliation: Division of Translational Research, Kyoto Medical Center, National Hospital Organization, Kyoto, Japan.
authors.forename: Tomohide
authors.initials: T
authors.lastname: Takaya
authors.forename: Koh
authors.initials: K
authors.lastname: Ono
authors.forename: Teruhisa
authors.initials: T
authors.lastname: Kawamura
authors.forename: Rieko
authors.initials: R
authors.lastname: Takanabe
authors.forename: Shinji
authors.initials: S
authors.lastname: Kaichi
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Morimoto
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Wada
authors.forename: Toru
authors.initials: T
authors.lastname: Kita
authors.forename: Akira
authors.initials: A
authors.lastname: Shimatsu
authors.forename: Koji
authors.initials: K
authors.lastname: Hasegawa
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D042863:Cyclin-Dependent Kinase 9 / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D053595:Embryonic Stem Cells / Q000166:cytology*; D020869:Gene Expression Profiling; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins / Q000037:antagonists & inhibitors; D006877:Hydroxamic Acids / Q000494:pharmacology; D051379:Mice; D035683:MicroRNAs / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000166:cytology*; D018995:Myosin Heavy Chains / Q000037:antagonists & inhibitors; D014157:Transcription Factors / Q000037:antagonists & inhibitors
chemical_list: D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins; D006877:Hydroxamic Acids; D035683:MicroRNAs; C517731:Mirn1 microRNA, mouse; C517732:Mirn133 microRNA, mouse; C484469:Nkx2-5 protein, mouse; D014157:Transcription Factors; C519276:myosin heavy chain-1, mouse; C012589:trichostatin A; C467972:Cdk9 protein, mouse; D042863:Cyclin-Dependent Kinase 9; D018995:Myosin Heavy Chains