Characterization of the DNA-binding properties of the Mohawk homeobox transcription factor

J Biol Chem. 2012 Oct 12;287(42):35351-35359. doi: 10.1074/jbc.M112.399386. Epub 2012 Aug 24.

Abstract

The homeobox transcription factor Mohawk (Mkx) is a potent transcriptional repressor expressed in the embryonic precursors of skeletal muscle, cartilage, and bone. MKX has recently been shown to be a critical regulator of musculoskeletal tissue differentiation and gene expression; however, the genetic pathways through which MKX functions and its DNA-binding properties are currently unknown. Using a modified bacterial one-hybrid site selection assay, we determined the core DNA-recognition motif of the mouse monomeric Mkx homeodomain to be A-C-A. Using cell-based assays, we have identified a minimal Mkx-responsive element (MRE) located within the Mkx promoter, which is composed of a highly conserved inverted repeat of the core Mkx recognition motif. Using the minimal MRE sequence, we have further identified conserved MREs within the locus of Sox6, a transcription factor that represses slow fiber gene expression during skeletal muscle differentiation. Real-time PCR and immunostaining of in vitro differentiated muscle satellite cells isolated from Mkx-null mice revealed an increase in the expression of Sox6 and down-regulation of slow fiber structural genes. Together, these data identify the unique DNA-recognition properties of MKX and reveal a novel role for Mkx in promoting slow fiber type specification during skeletal muscle differentiation.

Publication types

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

MeSH terms

  • Amino Acid Motifs
  • Animals
  • Cell Differentiation / physiology
  • DNA / genetics
  • DNA / metabolism*
  • Gene Expression Regulation / physiology*
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • Mice
  • Mice, Knockout
  • Muscle Proteins / genetics
  • Muscle Proteins / metabolism*
  • Muscle, Skeletal / cytology
  • Muscle, Skeletal / metabolism*
  • NIH 3T3 Cells
  • Protein Binding
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Response Elements / physiology*
  • SOXD Transcription Factors / biosynthesis
  • SOXD Transcription Factors / genetics

Substances

  • Homeodomain Proteins
  • Muscle Proteins
  • Repressor Proteins
  • SOXD Transcription Factors
  • Sox6 protein, mouse
  • mohawk protein, mouse
  • DNA