Reduction in Gsalpha induces osteogenic differentiation in human mesenchymal stem cells.
We hypothesized that a decrease in Gsalpha expression occurs with osteogenic differentiation and that when Gsalpha expression was decreased by antisense oligonucleotides or direct inhibition of protein kinase A there was a concomitant increase in Runx2/Cbfa1. We also investigated the mechanism involved in the change in Runx2/Cbfa1 levels and whether the expression of other genes known to be involved in bone formation was altered. There was a decrease in Gsalpha expression with osteogenic differentiation and antisense oligonucleotides, and protein kinase A inhibition led to increased expression and DNA binding of the osteoblast-specific Runx2/Cbfa1. Additionally, with decreased Gsalpha expression or protein kinase A inhibition, Runx2/Cbfa1 protein was serine phosphorylated and ubiquitinated less. Microarray analysis, after the addition of antisense Gsalpha, showed a more than 10-fold increase in collagen Type I Alpha 2 mRNA (a target of Runx2/Cbfa1). These data show that reduced expression of Gsalpha can induce an osteoblast-like phenotype. The results also indicate a potential pathophysiologic role in patients with heterozygous inactivating mutations in GNAS1, the gene for the alpha chain (Gsalpha) of the heterotrimeric G protein, present in three disorders with ectopic intramembranous bone: Albright's hereditary osteodystrophy, progressive osseous heteroplasia, and osteoma cutis.
Lietman
Steven A
SA
Department of Orthopaedic Surgery, The Cleveland Clinic Foundation, Cleveland, OH, USA. lietmas@ccf.org
Ding
Changlin
C
Cooke
David W
DW
Levine
Michael A
MA
D001483:Base Sequence; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured; D050659:Core Binding Factor Alpha 1 Subunit; D017077:Culture Media, Conditioned; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000502:physiology; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D010012:Osteogenesis / Q000235:genetics / Q000502:physiology*; D011336:Probability; D012333:RNA, Messenger / Q000032:analysis; D012016:Reference Values; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D050659:Core Binding Factor Alpha 1 Subunit; D017077:Culture Media, Conditioned; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D014157:Transcription Factors