圆柱瘤蛋白相互作用蛋白SPATA2调控TNFR介导的炎症应答和细胞死亡

Regulation of TNFR-mediated inflammatory response and cell death by cylindromatosis-interacting protein SPATA2

去泛素化酶(deubiquitinase,DUB)圆柱瘤蛋白(cylindromatosis,CYLD)是肿瘤坏死因子受体(tumor necrosis factor receptor,TNFR)介导的炎症反应和细胞死亡的重要调节因子,然而CYLD特异性识别底物的机制尚不清楚。本研究通过生物识别(BioID)筛选得到CYLD的相互作用蛋白--精子发生相关蛋白2(spermatogenesis associated 2,SPATA2),并利用免疫沉淀法(immunoprecipitation,IP)和双分子荧光互补技术(bimolecular fluorescence complementation,BiFC)证实了CYLD与SPATA2的相互作用。SPATA2敲降或敲除抑制了TNF-α诱导的细胞凋亡和程序性死亡,增强了炎症相关基因的表达。机制研究发现,响应TNF-α刺激,SPATA2促进CYLD向肿瘤坏死因子受体信号复合物(tumor necrosis factor receptor signaling complex,TNFRSC)招募和催化受体相互作用蛋白1(receptor-interacting protein 1,RIP1)去泛素化,进而将TNF-α信号的效果由促炎反应向细胞死亡转变。小鼠模型研究发现,SPATA2敲除小鼠在从出生到成年过程中其生长发育和生殖方面均无明显异常。然而对12~15个月龄小鼠器官的苏木精-伊红(hematoxylin-eosin,HE)染色和病理形态学分析发现,SPATA2敲除小鼠的结肠和肺部较野生型小鼠出现更为严重的自发性炎症反应,说明SPATA2在体内也具有抑制炎症的功能。本研究揭示了SPATA2通过调控CYLD抑制炎症反应、促进细胞死亡的作用和分子机制,为炎症性相关疾病的治疗提供了新的潜在靶点。

Deubiquitinase(DUB)cylindromatosis(CYLD)is a critical regulator for tumor necrosis factor receptor(TNFR)-mediated cell death and inflammatory response.However,the molecular mechanism by which CYLD specifically recognizes its substrates is largely unknown.In this study,we identified spermatogenesis associated 2(SPATA2)as one of CYLD-interacting proteins by BioID and validated SPATA2-CYLD interaction by immunoprecipitation(IP)and bimolecular fluorescence com-plementation(BiFC).Knockdown or knockout of SPATA2 suppressed TNF-α-induced apoptosis and necroptosis and enhanced induction of proinflammatory cytokines.Mechanistically,in response to TNF-αstimulation,SPATA2 promoted the recruitment of CYLD to the tumor necrosis factor receptor signaling complex(TNFRSC)for the deubiquitination of receptor-inter-acting protein 1(RIP1),thereby promoting the transition of TNF-αsignaling from proinflammatory response to cell death.Furthermore,our in vivo study showed that SPATA2 knockout mice were born at expected Mendelian ratios and displayed no obvious abnormalities in growth and survival from birth to adulthood.Nevertheless,histological examination of different organs from 12-15-month old mice identified evidence of severer autoinflammatory responses in the colon and liver from SPATA2 knockout mice,suggesting an important role for SPATA2 in suppressing inflammation in vivo.Our data reveals the regulatory function and molecular mechanism of SPATA2 as a CYLD adaptor in controlling cell death and inflammatory response and provides another therapeutic target for treating inflammatory diseases.