The macroautophagy/autophagy and inflammasome pathways are linked through their roles in innate immunity and chronic inflammatory disease. Ceramide-1-phosphate (C1P) is a bioactive sphingolipid that regulates pro-inflammatory eicosanoid production. Whether C1P also regulates autophagy and inflammasome assembly/activation is not known. Here we show that CPTP (a protein that traffics C1P from its site of phosphorylation in the trans-Golgi to target membranes) regulates both autophagy and inflammasome activation. In human epithelial cells, knockdown of CPTP (but not GLTP [glycolipid transfer protein]) or expression of C1P binding-site point mutants, stimulated an 8- to 10-fold increase in autophagosomes and altered endogenous LC3-II and SQSTM1/p62 protein expression levels. CPTP depletion-induced autophagy elevated early markers of autophagosome formation (Golgi-derived ATG9A-vesicles, WIPI1), required key phagophore assembly and elongation factors (ATG5, ATG7, ULK1), and suppressed MTOR phosphorylation and that of its downstream target, RPS6KB1/p70S6K. Wild-type CPTP overexpression exerted a protective effect against starvation-induced autophagy. In THP-1 macrophage-like surveillance cells, CPTP knockdown induced not only autophagy but also elevated CASP1/caspase-1 levels, and strongly increased IL1B/interleukin-1β and IL18 release via a NLRP3 (but not NLRC4) inflammasome-based mechanism, while only moderately increasing inflammatory (pyroptotic) cell death. Inflammasome assembly and activation stimulated by CPTP depletion were autophagy dependent. Elevation of intracellular C1P by exogenous C1P treatment (instead of CPTP inhibition) also induced autophagy and IL1B release. Our findings identify human CPTP as an endogenous regulator of early-stage autophagosome assembly and inflammasome-driven, pro-inflammatory cytokine generation and release.

中文翻译：

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CPTP：一种鞘脂转移蛋白，调节自噬和炎症小体激活。


巨自噬/自噬和炎症小体途径通过它们在先天免疫和慢性炎症疾病中的作用而相互联系。 1-磷酸神经酰胺 (C1P) 是一种生物活性鞘脂，可调节促炎类二十烷酸的产生。 C1P 是否也调节自噬和炎性小体组装/激活尚不清楚。在这里，我们展示了 CPTP（一种将 C1P 从反式高尔基体中的磷酸化位点运输到靶膜的蛋白质）调节自噬和炎症小体激活。在人上皮细胞中，CPTP（但不是 GLTP [糖脂转移蛋白]）的敲低或 C1P 结合位点点突变体的表达，刺激自噬体增加 8 至 10 倍，并改变内源性 LC3-II 和 SQSTM1/p62 蛋白表达水平。 CPTP耗竭诱导的自噬升高了自噬体形成的早期标志物（高尔基体来源的 ATG9A 囊泡，WIPI1）、所需的关键吞噬细胞组装和延伸因子（ATG5、ATG7、ULK1），并抑制了 MTOR 磷酸化及其下游靶标 RPS6KB1/ p70S6K。野生型 CPTP 过表达对饥饿诱导的自噬发挥保护作用。在 THP-1 巨噬细胞样监视细胞中，CPTP 敲低不仅诱导自噬，还升高 CASP1/caspase-1 水平，并通过基于 NLRP3（但不是 NLRC4）炎性体的机制强烈增加 IL1B/interleukin-1β 和 IL18 释放，而仅适度增加炎症（焦亡）细胞死亡。 CPTP 消耗刺激的炎性体组装和激活是自噬依赖性的。外源性 C1P 处理（而不是 CPTP 抑制）导致细胞内 C1P 升高，也诱导自噬和 IL1B 释放。 我们的研究结果表明，人类 CPTP 是早期自噬体组装和炎症小体驱动的促炎细胞因子生成和释放的内源性调节因子。