The ERK5 and ERK1/2 signaling pathways play opposing regulatory roles during chondrogenesis of adult human bone marrow-derived multipotent progenitor cells

J Cell Physiol. 2010 Jul;224(1):178-86. doi: 10.1002/jcp.22120.


Adult human bone marrow-derived multipotent progenitor cells (MPCs) are able to differentiate into a variety of specialized cell types, including chondrocytes, and are considered a promising candidate cell source for use in cartilage tissue engineering. In this study, we examined the regulation of MPC chondrogenesis by mitogen-activated protein kinases in an attempt to better understand how to generate hyaline cartilage in the laboratory that more closely resembles native tissue. Specifically, we employed the high-density pellet culture model system to assess the roles of ERK5 and ERK1/2 pathway signaling in MPC chondrogenesis. Western blotting revealed that high levels of ERK5 phosphorylation correlate with low levels of MPC chondrogenesis and that as TGF-beta 3-enhanced MPC chondrogenesis proceeds, phospho-ERK5 levels steadily decline. Conversely, levels of phospho-ERK1/2 paralleled the progression of MPC chondrogenesis. siRNA-mediated knockdown of ERK5 pathway components MEK5 and ERK5 resulted in increased MPC pellet mRNA transcript levels of the cartilage-characteristic marker genes SOX9, COL2A1, AGC, L-SOX5, and SOX6, as well as enhanced accumulation of SOX9 protein, collagen type II protein, and Alcian blue-stainable proteoglycan. In contrast, knockdown of ERK1/2 pathway members MEK1 and ERK1 decreased expression of all chondrogenic markers tested. Finally, overexpression of MEK5 and ERK5 also depressed MPC chondrogenesis, as indicated by diminished activity of a co-transfected collagen II promoter-luciferase reporter construct. In conclusion, our results suggest a novel role for the ERK5 pathway as an important negative regulator of adult human MPC chondrogenesis and illustrate that the ERK5 and ERK1/2 kinase cascades play opposing roles regulating MPC cartilage formation.

Publication types

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

MeSH terms

  • Adult Stem Cells / enzymology*
  • Aged
  • Aged, 80 and over
  • Bone Marrow Cells / enzymology*
  • Cartilage / metabolism
  • Cell Differentiation
  • Cells, Cultured
  • Chondrogenesis* / genetics
  • Female
  • Fibroblast Growth Factor 2 / metabolism
  • Gene Expression Regulation
  • Humans
  • MAP Kinase Kinase 1 / metabolism
  • MAP Kinase Kinase 5 / metabolism
  • MAP Kinase Signaling System
  • Male
  • Middle Aged
  • Mitogen-Activated Protein Kinase 1 / genetics
  • Mitogen-Activated Protein Kinase 1 / metabolism*
  • Mitogen-Activated Protein Kinase 3 / genetics
  • Mitogen-Activated Protein Kinase 3 / metabolism*
  • Mitogen-Activated Protein Kinase 7 / genetics
  • Mitogen-Activated Protein Kinase 7 / metabolism*
  • Multipotent Stem Cells / enzymology*
  • Phosphorylation
  • RNA Interference
  • RNA, Messenger / metabolism
  • Stem Cells / enzymology*
  • Time Factors
  • Transfection
  • Transforming Growth Factor beta3 / metabolism


  • RNA, Messenger
  • Transforming Growth Factor beta3
  • Fibroblast Growth Factor 2
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinase 7
  • MAP Kinase Kinase 1
  • MAP Kinase Kinase 5
  • MAP2K5 protein, human