Epithelial Protein Lost in Neoplasm alpha (Eplin-alpha) is transcriptionally regulated by G-actin and MAL/MRTF coactivators

Mol Cancer. 2010 Mar 17:9:60. doi: 10.1186/1476-4598-9-60.

Abstract

Epithelial Protein Lost in Neoplasm alpha is a novel cytoskeleton-associated tumor suppressor whose expression inversely correlates with cell growth, motility, invasion and cancer mortality. Here we show that Eplin-alpha transcription is regulated by actin-MAL-SRF signalling. Upon signal induction, the coactivator MAL/MRTF is released from a repressive complex with monomeric actin, binds the transcription factor SRF and activates target gene expression. In a transcriptome analysis with a combination of actin binding drugs which specifically and differentially interfere with the actin-MAL complex (Descot et al., 2009), we identified Eplin to be primarily controlled by monomeric actin. Further analysis revealed that induction of the Eplin-alpha mRNA and its promoter was sensitive to drugs and mutant actins which stabilise the repressive actin-MAL complex. In contrast, the Eplin-beta isoform remained unaffected. Knockdown of MRTFs or dominant negative MAL which inhibits SRF-mediated transcription impaired Eplin-alpha expression. Conversely, constitutively active mutant actins and MAL induced Eplin-alpha. MAL and SRF were bound to a consensus SRF binding site of the Eplin-alpha promoter; the recruitment of MAL to this region was enhanced severalfold upon induction. The tumor suppressor Eplin-alpha is thus a novel cytoskeletal target gene transcriptionally regulated by the actin-MAL-SRF pathway, which supports a role in cancer biology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism*
  • Animals
  • Cytoskeletal Proteins / genetics*
  • Gene Expression Regulation*
  • Mice
  • Mutation / genetics
  • NIH 3T3 Cells
  • Promoter Regions, Genetic / genetics
  • Protein Binding
  • Serum Response Factor / metabolism
  • Signal Transduction
  • Trans-Activators / metabolism*
  • Transcription, Genetic*

Substances

  • Actins
  • Cytoskeletal Proteins
  • D15Ertd366e protein, mouse
  • Mrtfa protein, mouse
  • Serum Response Factor
  • Trans-Activators