Endoplasmic reticulum (ER) stress inducible factor cysteine-rich with EGF-like domains 2 (Creld2) is an important mediator of BMP9-regulated osteogenic differentiation of mesenchymal stem cells

PLoS One. 2013 Sep 3;8(9):e73086. doi: 10.1371/journal.pone.0073086. eCollection 2013.

Abstract

Mesenchymal stem cells (MSCs) are multipotent progenitors that can undergo osteogenic differentiation under proper stimuli. We demonstrated that BMP9 is one of the most osteogenic BMPs. However, the molecular mechanism underlying BMP9-initiated osteogenic signaling in MSCs remains unclear. Through gene expression profiling analysis we identified several candidate mediators of BMP9 osteogenic signaling. Here, we focus on one such signaling mediator and investigate the functional role of cysteine-rich with EGF-like domains 2 (Creld2) in BMP9-initiated osteogenic signaling. Creld2 was originally identified as an ER stress-inducible factor localized in the ER-Golgi apparatus. Our genomewide expression profiling analysis indicates that Creld2 is among the top up-regulated genes in BMP9-stimulated MSCs. We confirm that Creld2 is up-regulated by BMP9 in MSCs. ChIP analysis indicates that Smad1/5/8 directly binds to the Creld2 promoter in a BMP9-dependent fashion. Exogenous expression of Creld2 in MSCs potentiates BMP9-induced early and late osteogenic markers, and matrix mineralization. Conversely, silencing Creld2 expression inhibits BMP9-induced osteogenic differentiation. In vivo stem cell implantation assay reveals that exogenous Creld2 promotes BMP9-induced ectopic bone formation and matrix mineralization, whereas silencing Creld2 expression diminishes BMP9-induced bone formation and matrix mineralization. We further show that Creld2 is localized in ER and the ER stress inducers potentiate BMP9-induced osteogenic differentiation. Our results strongly suggest that Creld2 may be directly regulated by BMP9 and ER stress response may play an important role in regulating osteogenic differentiation.

Publication types

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

MeSH terms

  • Animals
  • Cell Adhesion Molecules / genetics
  • Cell Adhesion Molecules / physiology*
  • Cell Differentiation / physiology*
  • Cell Line
  • Endoplasmic Reticulum / metabolism*
  • Extracellular Matrix Proteins / genetics
  • Extracellular Matrix Proteins / physiology*
  • Gene Silencing
  • Growth Differentiation Factor 2 / physiology*
  • Humans
  • Mesenchymal Stem Cells / cytology*
  • Mice
  • Reverse Transcriptase Polymerase Chain Reaction

Substances

  • CRELD2 protein, human
  • CRELD2 protein, mouse
  • Cell Adhesion Molecules
  • Extracellular Matrix Proteins
  • Growth Differentiation Factor 2

Grants and funding

The reported work was supported in part by research grants from the National Institutes of Health (RCH, TCH and HHL), the 973 Program of the Ministry of Science and Technology of China (#2011CB707906 to TCH), the Natural Science Foundation of China (NSFC30872770 to QS), Chongqing Science and Technology Commission (CSTC2011BB5131 to QS), and Ministry of Education of China (KJ120327 to QS). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.