Simultaneous Inhibition of SIRT2 Deacetylase and Defatty-Acylase Activities via a PROTAC Strategy.
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ABSTRACT:
SUBMITTER: Hong JY
PROVIDER: S-EPMC7667848 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:SIRT2 is a member of the human sirtuin family of proteins and possesses NAD+-dependent lysine deacetylase/deacylase activity. SIRT2 has been implicated in carcinogenesis in various cancers including leukaemia and is considered an attractive target for cancer therapy. Here, we identified NPD11033, a selective small-molecule SIRT2 inhibitor, by a high-throughput screen using the RIKEN NPDepo chemical library. NPD11033 was largely inactive against other sirtuins and zinc-dependent deacetylases. Crystallographic analysis revealed a unique mode of action, in which NPD11033 creates a hydrophobic cavity behind the substrate-binding pocket after a conformational change of the Zn-binding small domain of SIRT2. Furthermore, it forms a hydrogen bond to the active site histidine residue. In addition, NPD11033 inhibited cell growth of human pancreatic cancer PANC-1 cells with a concomitant increase in the acetylation of eukaryotic translation initiation factor 5A, a physiological substrate of SIRT2. Importantly, NPD11033 failed to inhibit defatty-acylase activity of SIRT2, despite its potent inhibitory effect on its deacetylase activity. Thus, NPD11033 will serve as a useful tool for both developing novel anti-cancer agents and elucidating the role of SIRT2 in various cellular biological processes.This article is part of a discussion meeting issue 'Frontiers in epigenetic chemical biology'.
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Project description:Human sirtuins (SIRT1-7) regulate not only deacetylation but also deacylation of fatty acid-derived acyl moieties (defatty-acylation) at the ε-amino group of lysine residues. SIRT-subtype-specific defatty-acylase activity modulators are needed for detailed investigation of the biological roles of these enzymes, and to find suitable small molecules, we require appropriate screening systems. Here, we designed and synthesized a set of SIRT defatty-acylase activity probes with various quencher moieties and peptide sequences based on our previously developed one-step FRET-based SIRT probe SFP3, using improved methodology. Scanning of this set of probes with SIRT isozymes revealed that certain probe/isozyme combinations showed especially high responses. To illustrate the utility of the combinations thus identified, we applied compound 18/SIRT2 for inhibitor screening of a large chemical library. This enabled us to discover a new small molecule SIRT2-specific defatty-acylase inhibitor.
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Project description:Autoacetylation of the p300 histone acetyltransferase controls the transition between VP16-mediated chromatin acetylation and preinitiation complex (PIC) assembly. Currently, it is unknown if and how autoacetylated p300 is deacetylated. We found that the NAD(+)-dependent histone deacetylase SIRT2 deacetylates p300 in vitro and in cells. SIRT2 deacetylates lysine residues in the catalytic domain of p300 and restores binding of p300 to the PIC. RNAi-mediated depletion or chemical inhibition of SIRT2 in cells results in accumulation of acetylated p300. The altered ac-p300/p300 ratio in SIRT2-depleted cells results in decreased p300 recruitment to an integrated VP16-responsive gene and inhibition of transcription. We conclude that p300 undergoes a dynamic cycle of autoacetylation and deacetylation.
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Project description:Sirtuin inhibitors have attracted much interest due to the involvement of sirtuins in various biological processes. Several SIRT2-selective inhibitors have been developed, and some exhibit anticancer activities. To facilitate the choice of inhibitors in future studies and the development of better inhibitors, we directly compared several reported SIRT2-selective inhibitors: AGK2, SirReal2, Tenovin-6, and TM. In vitro, TM is the most potent and selective inhibitor, and only TM could inhibit the demyristoylation activity of SIRT2. SirReal2, Tenovin-6, and TM all showed cytotoxicity in cancer cell lines, with Tenovin-6 being the most potent, but only TM showed cancer-cell-specific toxicity. All four compounds inhibited the anchorage-independent growth of HCT116 cells, but the effect of TM was most significantly affected by SIRT2 overexpression, suggesting that the anticancer effect of TM depends more on SIRT2 inhibition. These results not only provide useful guidance about choosing the right SIRT2 inhibitor in future studies, but also suggest general practices that should be followed for small-molecule inhibitor development activities.
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Project description:Although the number of proteins effectively targeted for posttranslational degradation by PROTAC has grown steadily, the number of E3 ligases successfully exploited to accomplish this has been limited to the few for which small-molecule ligands have been discovered. Although the E3 ligase MDM2 is bound by the nutlin class of small-molecule ligands, there are few nutlin-based PROTAC. Because a nutlin-based PROTAC should both knockdown its target protein and upregulate the tumor suppressor p53, we examined the ability of such a PROTAC to decrease cancer cell viability. A nutlin-based, BRD4-degrading PROTAC, A1874, was able to degrade its target protein by 98% with nanomolar potency. Given the complementary ability of A1874 to stabilize p53, we discovered that the nutlin-based PROTAC was more effective in inhibiting proliferation of many cancer cell lines with wild-type p53 than was a corresponding VHL-utilizing PROTAC with similar potency and efficacy to degrade BRD4. This is the first report of a PROTAC in which the E3 ligase ligand and targeting warhead combine to exert a synergistic antiproliferative effect. Our study highlights the untapped potential that may be unlocked by expanding the repertoire of E3 ligases that can be recruited by PROTAC. SIGNIFICANCE: These findings present the first BRD4-targeting MDM2-based PROTAC that possesses potent, distinct, and synergistic biological activities associated with both ends of this heterobifunctional molecule.
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Project description:meta-Azi-propofol (AziPm) is a photoactive analog of the general anesthetic propofol. We photolabeled a myelin-enriched fraction from rat brain with [(3)H]AziPm and identified the sirtuin deacetylase SIRT2 as a target of the anesthetic. AziPm photolabeled three SIRT2 residues (Tyr(139), Phe(190), and Met(206)) that are located in a single allosteric protein site, and propofol inhibited [(3)H]AziPm photolabeling of this site in myelin SIRT2. Structural modeling and in vitro experiments with recombinant human SIRT2 determined that propofol and [(3)H]AziPm only bind specifically and competitively to the enzyme when co-equilibrated with other substrates, which suggests that the anesthetic site is either created or stabilized in enzymatic conformations that are induced by substrate binding. In contrast to SIRT2, specific binding of [(3)H]AziPm or propofol to recombinant human SIRT1 was not observed. Residues that line the propofol binding site on SIRT2 contact the sirtuin co-substrate NAD(+) during enzymatic catalysis, and assays that measured SIRT2 deacetylation of acetylated ?-tubulin revealed that propofol inhibits enzymatic function. We conclude that propofol inhibits the mammalian deacetylase SIRT2 through a conformation-specific, allosteric protein site that is unique from the previously described binding sites of other inhibitors. This suggests that propofol might influence cellular events that are regulated by protein acetylation state.
| S-EPMC4375505 | biostudies-literature
Project description:BACKGROUND:Pathological cardiac hypertrophy induced by stresses such as aging and neurohumoral activation is an independent risk factor for heart failure and is considered a target for the treatment of heart failure. However, the mechanisms underlying pathological cardiac hypertrophy remain largely unknown. We aimed to investigate the roles of SIRT2 in aging-related and angiotensin II (Ang II)-induced pathological cardiac hypertrophy. METHODS:Male C57BL/6J wild-type and Sirt2 knockout mice were subjected to the investigation of aging-related cardiac hypertrophy. Cardiac hypertrophy was also induced by Ang II (1.3 mg/kg/d for 4 weeks) in male C57BL/6J Sirt2 knockout mice, cardiac-specific SIRT2 transgenic (SIRT2-Tg) mice, and their respective littermates (8 to ?12 weeks old). Metformin (200 mg/kg/d) was used to treat wild-type and Sirt2 knockout mice infused with Ang II. Cardiac hypertrophy, fibrosis, and cardiac function were examined in these mice. RESULTS:SIRT2 protein expression levels were downregulated in hypertrophic hearts from mice. Sirt2 knockout markedly exaggerated cardiac hypertrophy and fibrosis and decreased cardiac ejection fraction and fractional shortening in aged (24-month-old) mice and Ang II-infused mice. Conversely, cardiac-specific SIRT2 overexpression protected the hearts against Ang II-induced cardiac hypertrophy and fibrosis and rescued cardiac function. Mechanistically, SIRT2 maintained the activity of AMP-activated protein kinase (AMPK) in aged and Ang II-induced hypertrophic hearts in vivo as well as in cardiomyocytes in vitro. We identified the liver kinase B1 (LKB1), the major upstream kinase of AMPK, as the direct target of SIRT2. SIRT2 bound to LKB1 and deacetylated it at lysine 48, which promoted the phosphorylation of LKB1 and the subsequent activation of LKB1-AMPK signaling. Remarkably, the loss of SIRT2 blunted the response of AMPK to metformin treatment in mice infused with Ang II and repressed the metformin-mediated reduction of cardiac hypertrophy and protection of cardiac function. CONCLUSIONS:SIRT2 promotes AMPK activation by deacetylating the kinase LKB1. Loss of SIRT2 reduces AMPK activation, promotes aging-related and Ang II-induced cardiac hypertrophy, and blunts metformin-mediated cardioprotective effects. These findings indicate that SIRT2 will be a potential target for therapeutic interventions in aging- and stress-induced cardiac hypertrophy.
| S-EPMC5698109 | biostudies-literature
Project description:We have identified a proteolysis targeting chimera (PROTAC) of class I HDACs 1, 2 and 3. The most active degrader consists of a benzamide HDAC inhibitor, an alkyl linker, and the von Hippel-Lindau E3 ligand. Our PROTAC increased histone acetylation levels and compromised colon cancer HCT116 cell viability, establishing a degradation strategy as an alternative to class I HDAC inhibition.
| S-EPMC7610821 | biostudies-literature