Histone deacetylase 6-mediated deacetylation of α-tubulin coordinates cytoskeletal and signaling events during platelet activation

Abstract

Aslan JE, Phillips KG, Healy LD, Itakura A, Pang J, McCarty OJ. Histone deacetylase 6-mediated deacetylation of ␣-tubulin coordinates cytoskeletal and signaling events during platelet activation. Am J Physiol Cell Physiol 149: C1230 -C1239, 2013. First published September 11, 2013; doi:10.1152/ajpcell.00053.2013.-The tubulin cytoskeleton plays a key role in maintaining the characteristic quiescent discoid shape of resting platelets. Upon activation, platelets undergo a dramatic change in shape; however, little is known of how the microtubule system contributes to regulating platelet shape and function. Here we investigated the role of the covalent modification of ␣-tubulin by acetylation in the regulation of platelet physiology during activation. Superresolution microscopy analysis of the platelet tubulin cytoskeleton showed that the marginal band together with an interconnected web of finer tubulin structures collapsed upon platelet activation with the glycoprotein VI (GPVI)-agonist collagen-related peptide (CRP). Western blot analysis revealed that ␣-tubulin was acetylated in resting platelets and deacetylated during platelet activation. Tubacin, a specific inhibitor of the tubulin deacetylase HDAC6, prevented tubulin deacetylation upon platelet activation with CRP. Inhibition of HDAC6 upregulated tubulin acetylation and disrupted the organization of the platelet microtubule marginal band without significantly affecting platelet volume changes in response to CRP stimulation. HDAC6 inhibitors also inhibited platelet aggregation in response to CRP and blocked platelet signaling events upstream of platelet Rho GTPase activation. Together, these findings support a role for acetylation signaling in controlling the resting structure of the platelet tubulin marginal band as well as in the coordination of signaling systems that drive platelet cytoskeletal changes and aggregation. acetylation; HDAC6; platelets; tubulin PLATELETS ARE THE PRIMARY cellular mediators of hemostasis (13,18,32). As discoid cellular fragments formed from the appendages of megakaryocytes, platelets patrol the circulation as guardians of vascular integrity. When platelets detect signals of vessel damage, they adhere to subendothelial matrix proteins, activate and aggregate with other platelets to potentiate thrombus formation to stem the leakage of blood. During this process, platelets change shape from discs to irregularly shaped spheres with finger-like pseudopods and form lamellipodial sheets to facilitate spreading. The characterization of the molecular and cellular regulators of platelet cytoskeletal organization will provide a better understanding of the role that changes in platelet morphology upon activation play in platelet physiology and function.The discoid shape of quiescent platelets is maintained by a circumferential marginal band of microtubules that scaffolds the platelet inner periphery (44). This marginal band is made up of multiple dynamic, continually polymerizing tubulin coils of mixed polarity (31). During platelet activati...

The histone deacetylase sirtuin 2 is a new player in the regulation of platelet function

“…It was recently demonstrated that HDAC inhibitors used clinically for the treatment of leukemia could be responsible for the observed reduction in the formation of new platelets from megakaryocytes [24]. Moreover, several recent reports have demonstrated that acetylation of a-tubulin, which is regulated by HDAC6 [8,9], affects some aspects of platelet function, albeit only at low concentrations of platelet agonists. In this study, we examined the role of SIRTs, which constitute a subtype of HDACs, in platelet responses.…”

Lysine acetyltransfer supports platelet function

“…We recently demonstrated that, in platelets, the cytoskeletal protein α‐tubulin is acetylated and specifically deacetylated upon platelet activation, suggesting a role for lysine acetyltransfer in platelet function . Although > 4500 proteins are modified by lysine acetylation in other mammalian cell types , the presence and regulation of lysine‐acetylated proteins in platelets beyond α‐tubulin remain largely unexamined.…”

Expression and significance of cortactin and HDAC6 in human prostatic foamy gland carcinoma

“…Cortactin is a cytoplasmic substrate of histone deacetylase (HDAC6) (Zuo et al 2012), and changes in cortactin acetylation status are involved in mobility and invasion of tumour cells (Daly 2004;Soe et al 2013). Inhibition of HDAC6 leads to hyperacetylation of cortactin, prevents its translocation to the cell periphery, blocks its association with F-actin and impairs cell motility (Saji et al 2005;Namdar et al 2010;Aslan et al 2013).…”