title: MicroRNAs miR-26a, miR-26b, and miR-29b accelerate osteogenic differentiation of unrestricted somatic stem cells from human cord blood.
abstract: BACKGROUND
  MicroRNAs are a population of short non-coding RNAs with widespread negative regulatory impact on mRNA translation. Unrestricted somatic stem cells (USSC) are a rare population in human cord blood that can be induced into cells representative of all three germinal layers. Here we analyzed the functional impact of miRNAs on the osteogenic differentiation in USSC.
  
  
  RESULTS
  Gene expression profiling identified 20 microRNAs that were consistently upregulated during osteogenic differentiation of two different USSC cell lines (SA5/73 and SA8/25). Bioinformatic target gene prediction indicated that among these microRNAs, miR-10a, -22, -26a, -26b, and -29b recognize transcripts that encode a set of proteins inhibiting osteogenesis. We subsequently verified osteo-inhibitory CDK6, CTNNBIP1, HDAC4, and TOB1 and osteo-promoting SMAD1 as targets of these microRNAs. In Western blot analyses demonstrated that endogenous levels of CDK6 and HDAC4 were downregulated during osteogenic differentiation of USSC and reduced following ectopic expression of miR-26a/b and miR-29b. In contrast, endogenous expression of SMAD1, targeted by miR-26a/b, was unaltered during osteogenic differentiation of USSC or following ectopic expression of miR-26a/b. Functional overexpression analyses using microRNA mimics revealed that miR-26a/b, as well as miR-29b strongly accelerated osteogenic differentiation of USSC as assessed by Alizarin-Red staining and calcium-release assays.
  
  
  CONCLUSIONS
  miR-26a/b and miR-29b are upregulated during osteogenic differentiation of USSC and share target genes inhibiting osteogenesis. Furthermore, these microRNAs accelerate osteogenic differentiation, likely mediated by osteo-inhibitory proteins such as CDK6 and HDAC4.
authors: University Düsseldorf, Medical Faculty, Institute for Transplantation Diagnostics and Cell Therapeutics (ITZ), Düsseldorf, Germany. trompeter@itz.uni-duesseldorf.de
authors: Hans-Ingo
authors: HI
authors: Trompeter
authors: Janine
authors: J
authors: Dreesen
authors: Eugenie
authors: E
authors: Hermann
authors: Katharina M
authors: KM
authors: Iwaniuk
authors: Markus
authors: M
authors: Hafner
authors: Neil
authors: N
authors: Renwick
authors: Thomas
authors: T
authors: Tuschl
authors: Peter
authors: P
authors: Wernet
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D053687:Adult Stem Cells / Q000166:cytology* / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics*; D019295:Computational Biology; D051361:Cyclin-Dependent Kinase 6 / Q000235:genetics / Q000378:metabolism; D005312:Fetal Blood / Q000166:cytology* / Q000378:metabolism; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics*; D010012:Osteogenesis / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome / Q000235:genetics; D053782:Transforming Growth Factor beta3 / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051361:Cyclin-Dependent Kinase 6; D006655:Histone Deacetylases; D047908:Intracellular Signaling Peptides and Proteins; D035683:MicroRNAs; D012097:Repressor Proteins; D053782:Transforming Growth Factor beta3; D025521:Tumor Suppressor Proteins; C411982:CTNNBIP1 protein, human; C528163:MIRN26 microRNA, human; C532045:MIRN29a microRNA, human; C098669:TOB1 protein, human; C400300:HDAC4 protein, human