Fluorescence Polarization-Based Competition Assays to Evaluate Histone Deacetylase 6 Inhibitors.

Histone deacetylase 6 (HDAC6) is an emerging clinical target for the treatment of several hematological cancers and central nervous system disorders. HDAC6 catalyzes the deacetylation of lysine residues on substrates such as tubulin, with profound implications in key cellular processes, including cellular motility and migration. This critical deacetylation activity occurs at the catalytic domain 2 (CD2) of HDAC6, and small molecule inhibitors of HDAC6 are designed to target CD2. We briefly highlight previously reported strategies for recombinant bacterial expression and purification of the HDAC6 CD2. We aim to discuss competition assays that have been used to evaluate the potency of potential HDAC6 inhibitors against CD2 via displacement of pre-bound fluorescent HDAC-probes. Moreover, we elaborate on previous protocols that have been employed in inhibitor screening and present an HDAC6-selective probe that also enables rapid and reliable high-throughput screening of new chemical entities designed to target the HDAC6 CD2.