Differential expression of TGF-β superfamily members and role of Smad1/5/9-signalling in chondral versus endochondral chondrocyte differentiation

Sci Rep. 2016 Nov 16:6:36655. doi: 10.1038/srep36655.

Abstract

Proteins of the transforming-growth-factor-β (TGF-β)-superfamily have a remarkable ability to induce cartilage and bone and the crosstalk of TGF-β - and BMP-signalling pathways appears crucial during chondrocyte development. Aim was to assess the regulation of TGF-β-superfamily members and of Smad2/3- and Smad1/5/9-signalling during endochondral in vitro chondrogenesis of mesenchymal stromal cells (MSC) relative to chondral redifferentiation of articular chondrocytes (AC) to adjust chondrocyte development of MSC towards a less hypertrophic phenotype. While MSC increased BMP4 and BMP7 and reduced TGFBR2 and TGFBR3-expression during chondrogenesis, an opposite regulation was observed during AC-redifferentiation. Antagonists CHRD and CHL2 rose significantly only in AC-cultures. AC showed higher initial BMP4, pSmad1/5/9 and SOX9 protein levels, a faster (re-)differentiation but a similar decline of pSmad2/3- and pSmad1/5/9-signalling versus MSC-cultures. BMP-4/7-stimulation of MSC-pellets enhanced SOX9 and accelerated ALP-induction but did not shift differentiation towards osteogenesis. Inhibition of BMP-signalling by dorsomorphin significantly reduced SOX9, raised RUNX2, maintained collagen-type-II and collagen-type-X lower and kept ALP-activity at levels reached at initiation of treatment. Conclusively, ALK1,2,3,6-signalling was essential for MSC-chondrogenesis and its prochondrogenic rather than prohypertrophic role may explain why inhibition of canonical BMP-signalling could not uncouple cartilage matrix production from hypertrophy as this was achieved with pulsed PTHrP-application.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bone Morphogenetic Protein 4 / genetics
  • Bone Morphogenetic Protein 4 / metabolism
  • Bone Morphogenetic Protein 7 / genetics
  • Bone Morphogenetic Protein 7 / metabolism
  • Cell Differentiation / physiology*
  • Chondrocytes / cytology
  • Chondrocytes / metabolism*
  • Gene Expression Regulation / physiology*
  • Humans
  • Mesenchymal Stem Cells / cytology
  • Mesenchymal Stem Cells / metabolism
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism
  • Proteoglycans / genetics
  • Proteoglycans / metabolism
  • Receptor, Transforming Growth Factor-beta Type II
  • Receptors, Transforming Growth Factor beta / genetics
  • Receptors, Transforming Growth Factor beta / metabolism
  • Signal Transduction / physiology*
  • Smad1 Protein / genetics
  • Smad1 Protein / metabolism*
  • Smad5 Protein / genetics
  • Smad5 Protein / metabolism*
  • Smad8 Protein / genetics
  • Smad8 Protein / metabolism*
  • Transforming Growth Factor beta / biosynthesis*
  • Transforming Growth Factor beta / genetics

Substances

  • BMP4 protein, human
  • BMP7 protein, human
  • Bone Morphogenetic Protein 4
  • Bone Morphogenetic Protein 7
  • Proteoglycans
  • Receptors, Transforming Growth Factor beta
  • SMAD1 protein, human
  • SMAD5 protein, human
  • SMAD9 protein, human
  • Smad1 Protein
  • Smad5 Protein
  • Smad8 Protein
  • Transforming Growth Factor beta
  • betaglycan
  • Protein Serine-Threonine Kinases
  • Receptor, Transforming Growth Factor-beta Type II