Regulation of glycogen metabolism by the CRE-1, RCO-1 and RCM-1 proteins in Neurospora crassa. The role of CRE-1 as the central transcriptional regulator

Fungal Genet Biol. 2015 Apr;77:82-94. doi: 10.1016/j.fgb.2015.03.011. Epub 2015 Apr 16.

Abstract

The transcription factor CreA/Mig1/CRE-1 is a repressor protein that regulates the use of alternative carbon sources via a mechanism known as Carbon Catabolite Repression (CCR). In Saccharomyces cerevisiae, Mig1 recruits the complex Ssn6-Tup1, the Neurospora crassa RCM-1 and RCO-1 orthologous proteins, respectively, to bind to promoters of glucose-repressible genes. We have been studying the regulation of glycogen metabolism in N. crassa and the identification of the RCO-1 corepressor as a regulator led us to investigate the regulatory role of CRE-1 in this process. Glycogen content is misregulated in the rco-1(KO), rcm-1(RIP) and cre-1(KO) strains, and the glycogen synthase phosphorylation is decreased in all strains, showing that CRE-1, RCO-1 and RCM-1 proteins are involved in glycogen accumulation and in the regulation of GSN activity by phosphorylation. We also confirmed the regulatory role of CRE-1 in CCR and its nuclear localization under repressing condition in N. crassa. The expression of all glycogenic genes is misregulated in the cre-1(KO) strain, suggesting that CRE-1 also controls glycogen metabolism by regulating gene expression. The existence of a high number of the Aspergillus nidulans CreA motif (5'-SYGGRG-3') in the glycogenic gene promoters led us to analyze the binding of CRE-1 to some DNA motifs both in vitro by DNA gel shift and in vivo by ChIP-qPCR analysis. CRE-1 bound in vivo to all motifs analyzed demonstrating that it down-regulates glycogen metabolism by controlling gene expression and GSN phosphorylation.

Keywords: CRE-1; ChIP-qPCR; Gene expression; Glycogen; Neurospora crassa.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Activating Transcription Factor 2 / metabolism*
  • Carbon / metabolism
  • Fungal Proteins / metabolism*
  • Glycogen / biosynthesis
  • Glycogen / genetics
  • Glycogen / metabolism*
  • Glycogen Synthase / metabolism
  • Mutation
  • Neurospora crassa / genetics
  • Neurospora crassa / metabolism*
  • Phosphorylation
  • Promoter Regions, Genetic
  • Repressor Proteins / metabolism*
  • Transcription Factors / metabolism*

Substances

  • Activating Transcription Factor 2
  • Fungal Proteins
  • RCO-1 protein, Neurospora crassa
  • Repressor Proteins
  • Transcription Factors
  • Carbon
  • Glycogen
  • Glycogen Synthase