Synergistic co-regulation and competition by a SOX9-GLI-FOXA phasic transcriptional network coordinate chondrocyte differentiation transitions

PLoS Genet. 2018 Apr 16;14(4):e1007346. doi: 10.1371/journal.pgen.1007346. eCollection 2018 Apr.

Abstract

The growth plate mediates bone growth where SOX9 and GLI factors control chondrocyte proliferation, differentiation and entry into hypertrophy. FOXA factors regulate hypertrophic chondrocyte maturation. How these factors integrate into a Gene Regulatory Network (GRN) controlling these differentiation transitions is incompletely understood. We adopted a genome-wide whole tissue approach to establish a Growth Plate Differential Gene Expression Library (GP-DGEL) for fractionated proliferating, pre-hypertrophic, early and late hypertrophic chondrocytes, as an overarching resource for discovery of pathways and disease candidates. De novo motif discovery revealed the enrichment of SOX9 and GLI binding sites in the genes preferentially expressed in proliferating and prehypertrophic chondrocytes, suggesting the potential cooperation between SOX9 and GLI proteins. We integrated the analyses of the transcriptome, SOX9, GLI1 and GLI3 ChIP-seq datasets, with functional validation by transactivation assays and mouse mutants. We identified new SOX9 targets and showed SOX9-GLI directly and cooperatively regulate many genes such as Trps1, Sox9, Sox5, Sox6, Col2a1, Ptch1, Gli1 and Gli2. Further, FOXA2 competes with SOX9 for the transactivation of target genes. The data support a model of SOX9-GLI-FOXA phasic GRN in chondrocyte development. Together, SOX9-GLI auto-regulate and cooperate to activate and repress genes in proliferating chondrocytes. Upon hypertrophy, FOXA competes with SOX9, and control toward terminal differentiation passes to FOXA, RUNX, AP1 and MEF2 factors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bone Development / genetics
  • Bone Development / physiology
  • Cell Differentiation / genetics
  • Cell Differentiation / physiology
  • Chondrocytes / cytology
  • Chondrocytes / metabolism*
  • Chondrogenesis / genetics
  • Chondrogenesis / physiology
  • Core Binding Factor alpha Subunits / genetics
  • Core Binding Factor alpha Subunits / metabolism
  • Female
  • Gene Regulatory Networks
  • Growth Plate / cytology
  • Growth Plate / growth & development
  • Growth Plate / metabolism
  • Hepatocyte Nuclear Factor 3-beta / genetics
  • Hepatocyte Nuclear Factor 3-beta / metabolism*
  • MEF2 Transcription Factors / genetics
  • MEF2 Transcription Factors / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mice, Inbred CBA
  • Models, Biological
  • SOX9 Transcription Factor / genetics
  • SOX9 Transcription Factor / metabolism*
  • Signal Transduction
  • Transcriptional Activation
  • Zinc Finger Protein GLI1 / genetics
  • Zinc Finger Protein GLI1 / metabolism*

Substances

  • Core Binding Factor alpha Subunits
  • Foxa2 protein, mouse
  • Gli1 protein, mouse
  • MEF2 Transcription Factors
  • SOX9 Transcription Factor
  • Sox9 protein, mouse
  • Zinc Finger Protein GLI1
  • Hepatocyte Nuclear Factor 3-beta