Regulation of microtubule dynamics by inhibition of the tubulin deacetylase HDAC6

Abstract

We studied the role of a class II histone deacetylase, HDAC6, known to function as a potent alpha-tubulin deacetylase, in the regulation of microtubule dynamics. Treatment of cells with the class I and II histone deacetylase inhibitor TSA, as well as the selective HDAC6 inhibitor tubacin, increased microtubule acetylation and significantly reduced velocities of microtubule growth and shrinkage. siRNA-mediated knockdown of HDAC6 also increased microtubule acetylation but, surprisingly, had no effect on microtubule growth velocity. At the same time, HDAC6 knockdown abolished the effect of tubacin on microtubule growth, demonstrating that tubacin influences microtubule dynamics via specific inhibition of HDAC6. Thus, the physical presence of HDAC6 with impaired catalytic activity, rather than tubulin acetylation per se, is the factor responsible for the alteration of microtubule growth velocity in HDAC6 inhibitor-treated cells. In support of this notion, HDAC6 mutants bearing inactivating point mutations in either of the two catalytic domains mimicked the effect of HDAC6 inhibitors on microtubule growth velocity. In addition, HDAC6 was found to be physically associated with the microtubule end-tracking protein EB1 and a dynactin core component, Arp1, both of which accumulate at the tips of growing microtubules. We hypothesize that inhibition of HDAC6 catalytic activity may affect microtubule dynamics by promoting the interaction of HDAC6 with tubulin and/or with other microtubule regulatory proteins

HDAC6 and RhoA are novel players in Abeta-driven disruption of neuronal polarity

“…Here we provide evidence that maintenance of polarized axonal identity is disrupted by Ab in an HDAC6-dependent manner. Importantly, overexpression of HDAC6 was sufficient to prevent the effect of Ab, and, together, with a decrease in ac-tub and tau, a function of HDAC6 as a MAP 20,22 may be implicated in the maintenance of stabilized MT in the AIS. Neuron polarization consists of morphological polarization that involve preferential elongation of the axon; sorting of proteins in different compartments; and functional polarization, in which the AIS barrier is also involved.…”

“…The maintenance of neuronal polarity depends on the AIS region in which proteins are stabilized and organized by ankyrin G (ankG). In the AIS, MTs are stabilized by the binding of the MT plus-end-binding protein 3 (EB3) to ankG 21 , and HDAC6, as a MT-capping protein, may contribute to MT stability 22 . It is thus important to establish the possible link between the increased acetylation found in AD, the activity of HDAC6 and Ab.…”

Microtubule-associated deacetylase HDAC6 promotes angiogenesis by regulating cell migration in an EB1-dependent manner

“…The microtubule-tip associated protein EB1 plays an essential role in cell polarization and migration (Lansbergen and Akhmanova, 2006), and has recently been shown to interact with HDAC6 and implicated in HDAC6-mediated activities (Zilberman et al, 2009). We therefore hypothesized that HDAC6 might promote cell migration and angiogenesis through interacting with EB1.…”

Inhibition of HDAC6 Deacetylase Activity Increases Its Binding with Microtubules and Suppresses Microtubule Dynamic Instability in MCF-7 Cells

“…The enzyme was inhibited using three different approaches: trichostatin A (TSA, a nonspecific inhibitor of HDAC6), tubastatin A (a specific inhibitor of HDAC6), and siRNA. TSA has been used previously to elucidate the functions of HDAC6 (25,27,29) but has a disadvantage in that it is a general inhibitor of class I and II HDACs. Tubastatin A, a hydroxamic acid-based inhibitor, exhibits ϳ1000-fold more selectivity against almost all HDAC isozymes compared with tubacin, making it one of the most selective HDAC6 inhibitors known (30).…”