Fatty acid synthesis promotes inflammasome activation through NLRP3 palmitoylation
Fatty acid synthesis promotes inflammasome activation through NLRP3 palmitoylation
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DOI：
10.1101/2023.10.30.564549
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发表时间：
2023-11
期刊：
影响因子：
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通讯作者：
Stuart Leishman;Najd M. Aljadeed;Liyunhe Qian;Shamshad Cockcroft;Jacques Behmoaras;P. Anand
中科院分区：
文献类型：
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作者：
Stuart Leishman;Najd M. Aljadeed;Liyunhe Qian;Shamshad Cockcroft;Jacques Behmoaras;P. Anand
炎性小体是由nod样受体（NLR）蛋白家族组装而成的多蛋白复合物，在感染性、炎症性和代谢性疾病中发挥重要作用。NLRP3炎症小体的组装是由传感器蛋白识别一个适宜的刺激触发的，导致通过适配器蛋白ASC与前caspase-1结合。炎性小体的激活导致细胞因子IL-1β和IL-18前体形式的成熟，以及caspase-1依赖性焦亡，这是一种促炎症的细胞死亡形式。新出现的证据表明脂质代谢参与炎性小体的激活；然而，脂质调节NLRP3炎性体的确切机制仍不清楚。脂肪酸合成酶（fatty acid synthase， FASN）是一种多酶蛋白，是脂质代谢的中枢调节因子，通过催化棕榈酸的产生，在脂肪酸生物合成途径中发挥重要作用。棕榈酸作为长链脂肪酸的前体，并通过棕榈酰化调节细胞功能，棕榈酰化是将棕榈酸可逆地添加到靶蛋白的半胱氨酸残基上，从而改变蛋白质的定位和功能的过程。在这里，我们采用药理学方法研究脂肪酸生物合成途径在NLRP3炎性体激活中的作用。我们的研究结果表明，抑制原代小鼠和人巨噬细胞中的FASN可消除NLRP3炎性小体的激活，导致caspase-1激活减弱。此外，这种现象依赖于蛋白棕榈酰化，因为在体外和体内去除棕榈酰化同样会降低NLRP3的激活，这可以通过在培养细胞中外源补充棕榈酸盐来恢复。因此，酰基生物素交换实验证实了NLRP3棕榈酰化。值得注意的是，当FASN或棕榈酰化被阻断时，感知AIM2炎症小体的dsDNA激活保持不变。因此，这些结果突出了FASN和棕榈酰化的关键作用，为NLRP3炎症小体的激活提供了新的机制见解。
Inflammasomes are multi-protein complexes assembled by NOD-like receptor (NLR) family of proteins, which play critical roles in infectious, inflammatory and metabolic diseases. The assembly of the NLRP3 inflammasome is triggered upon recognition of an apt stimulus by the sensor protein, resulting in binding to pro-caspase-1 via the adaptor protein ASC. Inflammasome activation results in the maturation of the precursor forms of cytokines IL-1β and IL-18, along with caspase-1-dependent pyroptosis, a pro-inflammatory form of cell death. Emerging evidence suggests the involvement of lipid metabolism in inflammasome activation; however, the precise mechanisms by which lipids regulate the NLRP3 inflammasome remain ambiguous. A multi-enzyme protein, fatty acid synthase (FASN) is a central regulator of lipid metabolism partaking an essential role in fatty acid biosynthesis pathway by catalysing the production of palmitic acid. Palmitic acid acts as a precursor to long-chain fatty acids and additionally regulates cellular functions by palmitoylation, a process in which palmitate is reversibly added to cysteine residues of target proteins, modifying protein localization and function. Here, we undertook a pharmacological approach to investigate the roles of fatty acid biosynthetic pathway in NLRP3 inflammasome activation. Our results demonstrated that inhibition of FASN in primary mouse and human macrophages abrogates the activation of the NLRP3 inflammasome, resulting in blunted caspase-1 activation. Furthermore, this phenomenon relied on protein palmitoylation as in vitro and in vivo abrogation of palmitoylation similarly reduced NLRP3 activation, which could be restored by exogenously supplementing palmitate in cultured cells. Consequently, an acyl biotin exchange assay corroborated NLRP3 palmitoylation. Notably, activation of the dsDNA sensing AIM2 inflammasome remained unaltered when either FASN or palmitoylation was blocked. These results therefore highlight the pivotal role of FASN and palmitoylation, shedding new mechanistic insights into the activation of the NLRP3 inflammasome.