Differential activation of lung-specific genes by two forkhead proteins, FREAC-1 and FREAC-2

J Biol Chem. 1996 Feb 23;271(8):4482-90. doi: 10.1074/jbc.271.8.4482.

Abstract

We describe the cDNA sequences for two human transcription factors, Forkhead RElated ACtivator (FREAC)-1 and -2, that belong to the forkhead family of eukaryotic DNA binding proteins. FREAC-1 and -2 are encoded by distinct genes, are almost identical within their DNA binding domains and in the COOH termini, but are otherwise divergent. Cotransfections with a reporter carrying FREAC binding sites showed that both proteins are transcriptional activators, and deletions located the activation domains to the COOH-terminal side of the forkhead domains. Expression of FREAC-1 and FREAC-2 is restricted to lung and placenta. We show that the promoters of genes for lung-specific proteins such as pulmonary surfactant proteins A, B, and C (SPA, SPB, and SPC) and the Clara cell 10-kDa protein (CC10) contain potential binding sites for FREAC-1 and FREAC-2. DNaseI footprinting verified that FREAC proteins bind to the predicted sites in the CC10 and SPB promoters. While an SPB promoter construct could be transactivated by both FREAC-1 and FREAC-2, CC10 was only activated by FREAC-1. Efficient activation of CC10 by FREAC-1 is shown to be specific for a lung cell line with Clara cell characteristics (H441) and to involve a region of the FREAC-1 protein unable to activate in other cell types.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Binding Sites
  • Cell Line
  • Cloning, Molecular
  • DNA-Binding Proteins / biosynthesis*
  • DNA-Binding Proteins / metabolism
  • Female
  • Forkhead Transcription Factors
  • Gene Expression Regulation*
  • Gene Library
  • Humans
  • Insect Hormones / biosynthesis
  • Luciferases / biosynthesis
  • Lung / metabolism*
  • Mice
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Nuclear Proteins / biosynthesis
  • Placenta / metabolism
  • Pregnancy
  • Promoter Regions, Genetic*
  • Rabbits
  • Rats
  • Recombinant Fusion Proteins / biosynthesis
  • Sequence Homology, Nucleic Acid
  • Trans-Activators / biosynthesis*
  • Trans-Activators / metabolism
  • Transcription Factors / biosynthesis*
  • Transcription Factors / metabolism

Substances

  • DNA-Binding Proteins
  • FOXF1 protein, human
  • FOXF2 protein, human
  • Forkhead Transcription Factors
  • Foxf1 protein, mouse
  • Foxf2 protein, mouse
  • Insect Hormones
  • LUN protein, vertebrate
  • Nuclear Proteins
  • Recombinant Fusion Proteins
  • Trans-Activators
  • Transcription Factors
  • Luciferases

Associated data

  • GENBANK/U13219
  • GENBANK/U13220
  • GENBANK/U42556