Identification of a novel cis-acting element for fibroblast-specific transcription of the FSP1 gene

Am J Physiol. 1998 Aug;275(2):F306-14. doi: 10.1152/ajprenal.1998.275.2.F306.


The FSP1 gene encodes a filament-binding S100 protein with paired EF hands that is specifically expressed in fibroblasts. This led us to look for cis-acting elements in the FSP1 promoter that might engage nuclear transcription factors unique to fibroblasts. The first exon of FSP1 is noncoding, therefore, a series of luciferase reporter minigenes were created containing varying lengths of 5'-flanking sequence, the first intron, and the noncoding region of the second exon. A position and promoter-dependent proximal element between -187 and -88 bp was shown to be active in fibroblasts but not in epithelium. Sequence in the first intron from +777 to +964 had an enhancing effect that was not cell type specific. Hsv TK reporter constructs driven by this promoter/intron cassette in transgenic mice were coexpressed appropriately with FSP1 in tissue fibroblasts. Gel mobility shift competitor assays identified a novel domain, FTS-1 (fibroblast transcription site-1; TTGAT from -177 to -173 bp), that specifically interacts with nuclear extracts from fibroblasts. The necessity of this binding site was confirmed by site-specific mutagenesis. Database searches also turned up putative FTS-1 sites in the early promoter regions of other fibroblast expressed proteins, including the alpha1 and alpha2(I), and alpha1(III) collagens and the alphaSM-actin gene. We hypothesize that the selective engagement of FTS-1 elements may contribute to the mesenchymal phenotype of fibroblasts and perhaps other dedifferentiated cells.

Publication types

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

MeSH terms

  • 3T3 Cells
  • Animals
  • Base Sequence
  • Calcium-Binding Proteins / biosynthesis
  • Calcium-Binding Proteins / genetics*
  • Cell Line
  • DNA Methylation
  • Epithelial Cells
  • Fibroblasts / drug effects
  • Fibroblasts / metabolism
  • Intermediate Filament Proteins / biosynthesis
  • Intermediate Filament Proteins / genetics
  • Introns
  • Kidney Tubules
  • Kidney Tubules, Proximal
  • Luciferases / biosynthesis
  • Luciferases / genetics
  • Mice
  • Mice, Transgenic
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Oligodeoxyribonucleotides
  • Promoter Regions, Genetic*
  • Recombinant Fusion Proteins / biosynthesis
  • Regulatory Sequences, Nucleic Acid*
  • S100 Calcium-Binding Protein A4
  • S100 Proteins
  • Thymidine Kinase / biosynthesis
  • Transcription, Genetic*
  • Transfection


  • Calcium-Binding Proteins
  • Intermediate Filament Proteins
  • Oligodeoxyribonucleotides
  • Recombinant Fusion Proteins
  • S100 Calcium-Binding Protein A4
  • S100 Proteins
  • S100a4 protein, mouse
  • Luciferases
  • Thymidine Kinase