Abstract 14076: Class IIb HDAC6 Contributes to Angiogenesis and Endothelial Cell Function
Histone deacetylases (HDACs) act as modulators of gene expression by deacetylation of histone proteins as well as non-histone proteins. Previous studies identified HDAC5 and HDAC7 as regulators of angiogenesis. The cytoplasmic class IIb HDAC6 is the only HDAC that possesses two functional deacetylase domains, and is known to interact with the cytoskeleton, to be involved in cell migration and in cancer development. However, the function of HDAC6 in endothelial cells (EC) is unknown. Knockdown of HDAC6 with siRNA decreases EC sprouting from spheroids (42±7%, p<0.05), tube formation in matrigel assay (88±3%) and migration without affecting cell viability. To investigate the in vivo role of HDAC6 for vessel formation, we used morpholino (MO)—mediated knockdown of HDAC6 during zebrafish embryogenesis. Downregulation of HDAC6 with two unrelated MO significantly increases the number of defects in intersomitic vessel formation and in the alignment of the dorsal longitudinal anastomotic vessel per animal compared to a control MO. To confirm the role of HDAC6 in mammalian vessel formation, we performed a spheroid-based matrigel plug assay in mice. Knockdown of HDAC6 in the injected cells does not affect vessel density, but decreases the size (63±3%, p<0.01) and perfusion of vessels (p<0.01). Consistently, overexpression of HDAC6 wildtype in ECs increases sprouting (209±7%, p<0.05), indicating that HDAC6 is a positive regulator of angiogenesis. Further overexpression studies indicate that the pro-angiogenic effect of HDAC6 requires catalytic activity but is independent of ubiquitin binding and deacetylation of tubulin. In ECs, HDAC6 interacts with the actin remodeling protein cortactin. SiRNA mediated downregulation of cortactin impairs EC sprouting indicating that cortactin is a potential target of HDAC6 mediating its pro-angiogenic effect. In summary, we found that HDAC6 is necessary for in vitro angiogenesis as assessed by EC sprouting, tube formation and migration. Additionally, HDAC6 contributes to in vivo vessel formation in zebrafish and in a spheroid-based matrigel plug assay in mice. Mechanistically, the pro-angiogenic effect of HDAC6 in EC requires catalytic activity, but is independent of tubulin deacetylation and binding of ubiquitin.
- © 2010 by American Heart Association, Inc.