Proteomic analyses uncover a new function and mode of action for mouse homolog of Diaphanous 2 (mDia2)

Mol Cell Proteomics. 2015 Apr;14(4):1064-78. doi: 10.1074/mcp.M114.043885. Epub 2015 Feb 14.


mDia2 is an auto-inhibited Formin influencing actin dynamics upon conversion to the active conformation. mDia2 regulates actin-based protrusions and cell invasion, cell differentiation, vesicle trafficking, and cytokinesis. However, whether mDia2 has additional functions and how its action is functionally specified remain unknown. Here we draw the interactome of auto-inhibited and constitutively active mDia2 to address these issues. We embed mDia2 in protein networks accounting for its attributed functions and unexpectedly link it to the Ubiquitin Proteasome System. Taking FBXO3 as a test case, we show that mDia2 binds FBXO3 and p53, and regulates p53 transcriptional activity in an actin-nucleation-independent and conformation-insensitive manner. Increased mDia2 and FBXO3 levels elevate p53 activity and expression thereby sensitizing cells to p53-dependent apoptosis, whereas their decrease produces opposite effects. Thus, we discover a new role of mDia2 in p53 regulation suggesting that the closed conformation is biologically active and an FBXO3-based mechanism to functionally specify mDia2's activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Chromatography, Affinity
  • DNA Damage
  • F-Box Proteins / metabolism
  • Fetal Proteins / metabolism
  • Formins
  • Gene Knockdown Techniques
  • HeLa Cells
  • Humans
  • Mass Spectrometry
  • Mice
  • Microfilament Proteins / metabolism
  • Microtubule-Associated Proteins / metabolism*
  • NADPH Dehydrogenase / metabolism*
  • Nuclear Proteins / metabolism
  • Protein Binding
  • Protein Conformation
  • Protein Interaction Maps
  • Proteomics / methods*
  • Reproducibility of Results
  • Sequence Homology, Amino Acid*
  • Tumor Suppressor Protein p53 / metabolism


  • F-Box Proteins
  • Fbxo3 protein, mouse
  • Fetal Proteins
  • Formins
  • Microfilament Proteins
  • Microtubule-Associated Proteins
  • Nuclear Proteins
  • Tumor Suppressor Protein p53
  • Dia2 protein, mouse
  • NADPH Dehydrogenase