KDAC6 alters cell morphology and motility through positive and negative modulation of F-actin distribution

Lysine deacetylase 6 (KDAC6 or HDAC6) has been associated with cell motility and deacetylation of cytoskeleton-related proteins. KDAC6 is the only human KDAC having three identified major domains, including two catalytic domains (CD). Defining the roles of KDAC6 in cell motility has been constrained by limited understanding of domain-specific contributions. Live and fixed cell imaging was used to characterize the effects of KDAC6 on F-actin distribution, cell morphology, and cell motility of genetically modified HT1080 cells containing KDAC6 with an inactivated CD or knockout. CD1 inactivation resulted in cells that migrated faster and had more concentrated cortical F-actin at the leading edge. Conversely, inactivation of CD2 resulted in slower migration, depleted cortical F-actin, more stress fibers with poor alignment, and larger, flatter cells. Loss of both CD1 and CD2 activity in the knockout cell line resulted in phenotypes that were most similar to wild-type cells. Hyperacetylation of α-tubulin alone was insufficient to explain the observed phenotypes of the cell line with inactive CD2, as the knockout cell line had similar hyperacetylation but lacked most of the phenotypic changes. Altered gene expression implicated actin-associated proteins as mediators of phenotypic effects. Although the cell lines exhibited variation in localization of putative KDAC6 targets cortactin and HSP90, these variations did not correlate with the observed phenotypes. Inactivation of CD2 resulted in more focal adhesions formed throughout cells, correlating with more stress fibers and reduced motility. Collectively, these results establish that each CD of KDAC6 has a distinctive and opposing role in F-actin regulation.