Centre International de Recherche en Infectiologie (CIRI), Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, 69100 Lyon, France.
Université Grenoble Alpes, INSERM, CEA, UA13 BGE, CNRS, CEA, 38000 Grenoble, France.
Viruses. 2023 Sep 26;15(10):1993. doi: 10.3390/v15101993.
IFITMs are a family of highly related interferon-induced transmembrane proteins that interfere with the processes of fusion between viral and cellular membranes and are thus endowed with broad antiviral properties. A number of studies have shown how the antiviral potency of IFITMs is highly dependent on their steady-state levels, their intracellular distribution and a complex pattern of post-translational modifications, parameters that are overall tributary of a number of cellular partners. In an effort to identify additional protein partners involved in the biology of IFITMs, we devised a proteomics-based approach based on the piggyback incorporation of IFITM3 partners into extracellular vesicles. MS analysis of the proteome of vesicles bearing or not bearing IFITM3 identified the NDFIP2 protein adaptor protein as an important regulator of IFITM3 levels. NDFIP2 is a membrane-anchored adaptor protein of the E3 ubiquitin ligases of the NEDD4 family that have already been found to be involved in IFITM3 regulation. We show here that NDFIP2 acts as a recruitment factor for both IFITM3 and NEDD4 and mediates their distribution in lysosomal vesicles. The genetic inactivation and overexpression of NDFIP2 drive, respectively, lower and higher levels of IFITM3 accumulation in the cell, overall suggesting that NDFIP2 locally competes with IFITM3 for NEDD4 binding. Given that NDFIP2 is itself tightly regulated and highly responsive to external cues, our study sheds light on a novel and likely dynamic layer of regulation of IFITM3.
IFITMs 是一类高度相关的干扰素诱导的跨膜蛋白，它们干扰病毒和细胞膜之间的融合过程，因此具有广泛的抗病毒特性。许多研究表明，IFITMs 的抗病毒效力高度依赖于其稳定状态水平、细胞内分布以及复杂的翻译后修饰模式，这些参数总体上受许多细胞伴侣的影响。为了鉴定参与 IFITM 生物学的其他蛋白质伴侣，我们设计了一种基于蛋白质组学的方法，该方法基于将 IFITM3 伴侣通过 piggyback 方式掺入细胞外囊泡中。对携带或不携带 IFITM3 的囊泡的蛋白质组进行 MS 分析，鉴定出 NDFIP2 蛋白衔接蛋白作为 IFITM3 水平的重要调节剂。NDFIP2 是一种膜锚定衔接蛋白，属于 NEDD4 家族的 E3 泛素连接酶，已经发现其参与 IFITM3 的调节。我们在这里表明，NDFIP2 作为 IFITM3 和 NEDD4 的募集因子，介导它们在溶酶体囊泡中的分布。NDFIP2 的遗传失活和过表达分别导致细胞中 IFITM3 积累的水平降低和升高，总体表明 NDFIP2 局部与 IFITM3 竞争与 NEDD4 的结合。鉴于 NDFIP2 本身受到严格调节且对外部信号高度敏感，我们的研究揭示了 IFITM3 调节的一个新的、可能动态的调控层。
