The ability to induce microtubule acetylation is a general feature of formin proteins

PLoS One. 2012;7(10):e48041. doi: 10.1371/journal.pone.0048041. Epub 2012 Oct 24.

Abstract

Cytoplasmic microtubules exist as distinct dynamic and stable populations within the cell. Stable microtubules direct and maintain cell polarity and it is thought that their stabilization is dependent on coordinative organization between the microtubule network and the actin cytoskeleton. A growing body of work suggests that some members of the formin family of actin remodeling proteins also regulate microtubule organization and stability. For example, we showed previously that expression of the novel formin INF1 is sufficient to induce microtubule stabilization and tubulin acetylation, but not tubulin detyrosination. An important issue with respect to the relationship between formins and microtubules is the determination of which formin domains mediate microtubule stabilization. INF1 has a distinct microtubule-binding domain at its C-terminus and the endogenous INF1 protein is associated with the microtubule network. Surprisingly, the INF1 microtubule-binding domain is not essential for INF1-induced microtubule acetylation. We show here that expression of the isolated FH1 + FH2 functional unit of INF1 is sufficient to induce microtubule acetylation independent of the INF1 microtubule-binding domain. It is not yet clear whether or not microtubule stabilization is a general property of all mammalian formins; therefore we expressed constitutively active derivatives of thirteen of the fifteen mammalian formin proteins in HeLa and NIH3T3 cells and measured their effects on stress fiber formation, MT organization and MT acetylation. We found that expression of the FH1 + FH2 unit of the majority of mammalian formins is sufficient to induce microtubule acetylation. Our results suggest that the regulation of microtubule acetylation is likely a general formin activity and that the FH2 should be thought of as a dual-function domain capable of regulating both actin and microtubule networks.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylation
  • Animals
  • Fetal Proteins / genetics
  • Fetal Proteins / metabolism*
  • Fluorescent Antibody Technique
  • Formins
  • HeLa Cells
  • Humans
  • Immunoblotting
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Mice
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism*
  • Microtubules / metabolism*
  • NIH 3T3 Cells
  • Nerve Tissue Proteins
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Proteins / genetics
  • Proteins / metabolism
  • Stress Fibers / metabolism
  • Transfection

Substances

  • FMNL3 protein, mouse
  • Fetal Proteins
  • Fhod3 protein, mouse
  • Fmnl1 protein, mouse
  • Formins
  • INF2 protein, mouse
  • Intracellular Signaling Peptides and Proteins
  • Microfilament Proteins
  • Nerve Tissue Proteins
  • Nuclear Proteins
  • Proteins
  • formin 2 protein, mouse

Grant support

This work was supported by grant T6317 from the Heart and Stroke Foundation of Canada awarded to John Copeland. http://www.hsf.ca/research/en/home. Work in Jonathan Lee's laboratory is supported by an Natural Sciences and Engineering Research Council of Canada Discovery Grant. http://www.nserc-crsng.gc.ca/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.