Hey1 basic helix-loop-helix protein plays an important role in mediating BMP9-induced osteogenic differentiation of mesenchymal progenitor cells

J Biol Chem. 2009 Jan 2;284(1):649-659. doi: 10.1074/jbc.M806389200. Epub 2008 Nov 5.


Pluripotent mesenchymal stem cells (MSCs) are bone marrow stromal progenitor cells that can differentiate into osteogenic, chondrogenic, adipogenic, and myogenic lineages. We previously demonstrated that bone morphogenetic protein (BMP) 9 is one of the most potent and yet least characterized BMPs that are able to induce osteogenic differentiation of MSCs both in vitro and in vivo. Here, we conducted gene expression-profiling analysis and identified that Hey1 of the hairy/Enhancer of split-related repressor protein basic helix-loop-helix family was among the most significantly up-regulated early targets in BMP9-stimulated MSCs. We demonstrated that Hey1 expression was up-regulated at the immediate early stage of BMP9-induced osteogenic differentiation. Chromatin immunoprecipitation analysis indicated that Hey1 may be a direct target of the BMP9-induced Smad signaling pathway. Silencing Hey1 expression diminished BMP9-induced osteogenic differentiation both in vitro and in vivo and led to chondrogenic differentiation. Likewise, constitutive Hey1 expression augmented BMP9-mediated bone matrix mineralization. Hey1 and Runx2 were shown to act synergistically in BMP9-induced osteogenic differentiation, and Runx2 expression significantly decreased in the absence of Hey1, suggesting that Runx2 may function downstream of Hey1. Accordingly, the defective osteogenic differentiation caused by Hey1 knockdown was rescued by exogenous Runx2 expression. Thus, our findings suggest that Hey1, through its interplay with Runx2, may play an important role in regulating BMP9-induced osteoblast lineage differentiation of MSCs.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Basic Helix-Loop-Helix Transcription Factors / genetics
  • Basic Helix-Loop-Helix Transcription Factors / metabolism*
  • Calcification, Physiologic / physiology
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Cell Differentiation / physiology*
  • Core Binding Factor Alpha 1 Subunit / genetics
  • Core Binding Factor Alpha 1 Subunit / metabolism
  • Gene Expression Profiling / methods
  • Growth Differentiation Factor 2 / genetics
  • Growth Differentiation Factor 2 / metabolism*
  • Growth Differentiation Factors / genetics
  • Growth Differentiation Factors / metabolism*
  • Humans
  • Mesenchymal Stem Cells / cytology
  • Mesenchymal Stem Cells / metabolism*
  • Mice
  • Oligonucleotide Array Sequence Analysis / methods
  • Osteoblasts / cytology
  • Osteoblasts / metabolism*
  • Osteogenesis / physiology
  • Smad Proteins / genetics
  • Smad Proteins / metabolism
  • Up-Regulation / physiology


  • Basic Helix-Loop-Helix Transcription Factors
  • Cell Cycle Proteins
  • Core Binding Factor Alpha 1 Subunit
  • GDF2 protein, human
  • Gdf2 protein, mouse
  • Growth Differentiation Factor 2
  • Growth Differentiation Factors
  • HEY1 protein, human
  • Hey1 protein, mouse
  • RUNX2 protein, human
  • Runx2 protein, mouse
  • Smad Proteins