The CCAAT/enhancer binding protein beta (C/EBPbeta) cooperates with NFAT to control expression of the calcineurin regulatory protein RCAN1-4

J Biol Chem. 2010 May 28;285(22):16623-31. doi: 10.1074/jbc.M109.098236. Epub 2010 Apr 6.

Abstract

Regulator of calcineurin 1 (RCAN1) inhibits the protein phosphatase calcineurin and is required for appropriate immune responses, synaptic plasticity, vascular tone, angiogenesis, and cardiac remodeling. Expression of the RCAN1-4 isoform is under the control of the calcineurin-responsive transcription factor NFAT. Typically, NFATs act in cooperation with other transcription factors to achieve maximal activation of gene expression. In this study, we identify the CCAAT/enhancer binding protein beta (C/EBPbeta) as an NFAT binding partner that cooperates with NFAT to regulate RCAN1-4 expression. Numerous C/EBPbeta binding sites are conserved in the RCAN1-4 proximal promoter. Overexpression of C/EBPbeta increased activity of both the endogenous mouse Rcan1-4 gene and a human RCAN1-4 luciferase reporter. Binding of C/EBPbeta to multiple sites in the promoter was verified using electrophoretic mobility shift assays and chromatin immunoprecipitation. A direct interaction between C/EBPbeta and NFAT was demonstrated by co-immunoprecipitation of proteins and complex formation at NFAT-C/EBPbeta composite sites. Depletion of endogenous C/EBPbeta decreased maximal activation of RCAN1-4 expression by calcineurin, whereas inhibition of calcineurin did not alter the ability of C/EBPbeta to activate RCAN1-4 expression. Together, these findings suggest that calcineurin/NFAT activation of RCAN1-4 expression is in part dependent upon C/EBPbeta, whereas activation by C/EBPbeta is not dependent on calcineurin and may provide a calcineurin-independent pathway for regulating RCAN1-4 expression. Importantly, nuclear localization, C/EBPbeta DNA binding activity and occupancy of the Rcan1-4 promoter increased in mouse models of heart failure demonstrating in vivo activation of this pathway to regulate Rcan1-4 expression and ultimately shape the dynamics of calcineurin-dependent signaling.

Publication types

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

MeSH terms

  • Animals
  • Base Sequence
  • Binding Sites
  • CCAAT-Enhancer-Binding Protein-beta / metabolism*
  • Calcineurin / metabolism
  • Calcium-Binding Proteins
  • Cell Line
  • Cell Nucleus / metabolism
  • Gene Expression Regulation*
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Molecular Sequence Data
  • Muscle Proteins / metabolism*
  • NFATC Transcription Factors / metabolism*
  • Signal Transduction
  • Subcellular Fractions / metabolism

Substances

  • CCAAT-Enhancer-Binding Protein-beta
  • Calcium-Binding Proteins
  • DSCR1 protein, mouse
  • Intracellular Signaling Peptides and Proteins
  • Muscle Proteins
  • NFATC Transcription Factors
  • Calcineurin