Specific Inhibitors of Mitochondrial Deacylase Sirtuin 4 Endowed with Cellular Activity

Sirtuins
are NAD+-dependent protein lysine deacylases
implicated in aging-related diseases. Mammalian Sirtuin 4 (Sirt4)
is located in mitochondria and a potential therapeutic target for
cancer and metabolic diseases, but no potent and selective Sirt4 inhibitors
have been reported. Here, we describe the identification of potent
Sirt4-specific small-molecule inhibitors. Testing hits from a target-based
virtual screen revealed 12 active compounds. A focused screen based
on two top compounds, followed by structure-assisted design of derivatives,
yielded four first-in-class potent Sirt4 inhibitors. Kinetic analyses
indicate compound competition with the acyl peptide substrate, consistent
with the docking models and implicating Sirt4’s unique acyl
binding site. The compounds indeed show preference for Sirt4 over
other isoforms, with one of them (69) being highly isoform
selective, and they are active in cells. Our results provide first
lead compounds and mechanistic insights for optimization toward Sirt4-specific
inhibitors useful as experimental tools and potential therapeutics.