Nitro-fatty acids as activators of hSIRT6 deacetylase activity.
Nitro-fatty acids as activators of hSIRT6 deacetylase activity.
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DOI：
10.1074/jbc.ra120.014883
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发表时间：
2020-12-25
期刊：
影响因子：
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通讯作者：
Denicola A
中科院分区：
文献类型：
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作者：
Carreño M;Bresque M;Machado MR;Santos L;Durán R;Vitturi DA;Escande C;Denicola A
SIRT6对葡萄糖和脂质稳态至关重要，并参与在氧化DNA损伤条件下维持基因组稳定性，例如在与年龄相关的疾病中观察到的情况。人们对SIRT6活性调节剂进行了激烈的研究，然而，没有许多特定的激活剂被报道。长酰基链脂肪酸已被证明可以增加体外弱的SIRT6去乙酰酶活性，但这种作用充其量是适度的。在这里，我们报道了亲电的硝基脂肪酸（硝基油酸和硝基共轭亚油酸）能有效激活SIRT6。硝基脂肪酸与SIRT6活性位点的疏水缝隙结合，产生适度的激活（20 μm处2倍），与之前报道的非硝化脂肪酸相似。然而，与Cys-18形成的共价Michael加合物（Cys-18存在于SIRT6的N端，但在其他同工异构体中不存在）诱导了构象变化，导致了更强的激活（在20 μm处40倍）。由此产生的Michael加合物的分子模型表明，共底物和酰基结合环的稳定可能是硝基脂肪酸激活SIRT6的另一种机制。重要的是，用硝基油酸处理细胞促进了H3K9的去乙酰化，而油酸没有影响。总之，我们的研究结果表明，硝化脂肪酸可以被认为是特异性SIRT6激活的有价值的工具，SIRT6应该被认为是这些抗炎硝基脂质的体内作用的分子靶点。
Sirtuin 6, SIRT6, is critical for both glucose and lipid homeostasis and is involved in maintaining genomic stability under conditions of oxidative DNA damage such as those observed in age-related diseases. There is an intense search for modulators of SIRT6 activity, however, not many specific activators have been reported. Long acyl-chain fatty acids have been shown to increase the weak in vitro deacetylase activity of SIRT6 but this effect is modest at best. Herein we report that electrophilic nitro-fatty acids (nitro-oleic acid and nitro-conjugated linoleic acid) potently activate SIRT6. Binding of the nitro-fatty acid to the hydrophobic crevice of the SIRT6 active site exerted a moderate activation (2-fold at 20 μm), similar to that previously reported for non-nitrated fatty acids. However, covalent Michael adduct formation with Cys-18, a residue present at the N terminus of SIRT6 but absent from other isoforms, induced a conformational change that resulted in a much stronger activation (40-fold at 20 μm). Molecular modeling of the resulting Michael adduct suggested stabilization of the co-substrate and acyl-binding loops as a possible additional mechanism of SIRT6 activation by the nitro-fatty acid. Importantly, treatment of cells with nitro-oleic acid promoted H3K9 deacetylation, whereas oleic acid had no effect. Altogether, our results show that nitrated fatty acids can be considered a valuable tool for specific SIRT6 activation, and that SIRT6 should be considered as a molecular target for in vivo actions of these anti-inflammatory nitro-lipids.