August 21, 2014

Microtubules are known for their fascinating dynamics, but some cellular processes require a more stable microtubule cytoskeleton. Thankfully, these stable, acetylated microtubules are just as photogenic as their non-modified microtubule pals. Today’s image is from a paper describing the role of the protein paxillin in microtubule acetylation. 

Crawling cells require coordination of adhesive forces, cytoskeletal rearrangements, and cell polarization. Cell polarization helps to direct newly synthesized proteins to the leading edge of the crawling cell, relying on both a stable microtubule cytoskeleton and positioning of the Golgi apparatus in front of the nucleus. The stability of these long-lived microtubules is due to acetylation—a post-translational modification of α-tubulin. A recent study by Deakin and Turner uncovered a role for the focal adhesion scaffolding protein paxillin in regulating microtubule acetylation, which in turn regulates Golgi integrity and cell polarization. Paxillin modulates microtubule stability through its inhibition of HDAC6, an α-tubulin deacetylase, and does so in both normal and transformed cells. In the images above, depletion of paxillin (bottom) in malignant (left column) and normal (right column) cell types resulted in a drop of microtubule acetylation (yellow), compared to control cells (top).

Deakin, N., & Turner, C. (2014). Paxillin inhibits HDAC6 to regulate microtubule acetylation, Golgi structure, and polarized migration originally published in the Journal of Cell Biology, 206 (3), 395-413 DOI: 10.1083/jcb.201403039