Palmitoylome profiling reveals S-palmitoylation-dependent antiviral activity of IFITM3

The Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, New York, New York, USA.
Nature Chemical Biology (Impact Factor: 13). 08/2010; 6(8):610-4. DOI: 10.1038/nchembio.405
Source: PubMed


Identification of immune effectors and the post-translational modifications that control their activity is essential for dissecting mechanisms of immunity. Here we demonstrate that the antiviral activity of interferon-induced transmembrane protein 3 (IFITM3) is post-translationally regulated by S-palmitoylation. Large-scale profiling of palmitoylated proteins in a dendritic cell line using a chemical reporter strategy revealed over 150 lipid-modified proteins with diverse cellular functions, including innate immunity. We discovered that S-palmitoylation of IFITM3 on membrane-proximal cysteines controls its clustering in membrane compartments and its antiviral activity against influenza virus. The sites of S-palmitoylation are highly conserved among the IFITM family of proteins in vertebrates, which suggests that S-palmitoylation of these immune effectors may be an ancient post-translational modification that is crucial for host resistance to viral infections. The S-palmitoylation and clustering of IFITM3 will be important for elucidating its mechanism of action and for the design of antiviral therapeutics.

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    • "The role of LCK acylation is not restricted to a membranebinding function, since a variant that localizes to the plasma membrane through a transmembrane domain instead of palmitoylation is unable to efficiently reconstitute T-cell receptor signaling (Kabouridis et al., 1997). Interferon-induced transmembrane protein 3 (IFITM3) is involved in innate responses to flu, dengue fever, and West Nile virus (Brass et al., 2009), and it has recently been shown that S-palmitoylation of IFITM3 controls clustering in membrane compartments and its antiviral activity (Yount et al., 2010). Analysis of the family suggests that S-palmitoylation may be an ancient post-translational modification that is crucial for host resistance to viral infections. "
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    • "However, recent evidence also supports the cytoplasmic localization of the N-terminus (Bailey et al., 2013; Yount et al., 2012). In addition to the plasma membrane, IFITM proteins are also observed in the endoplasmic reticulum (ER) and endosomes (Alber and Staeheli, 1996; Brass et al., 2009; Feeley et al., 2011; Jia et al., 2012; Lu et al., 2011; Yang et al., 2007; Yount et al., 2010; Zucchi et al., 2004). The localization of IFITM3 in late endosomes is important for inhibiting IAV infection, because ectopic expression of IFITM3, or its induced expression by interferon, causes expansion of late endosomes and lysosomes and results in the sequestration of endocytosed IAV particles in these acidic membrane compartments (Feeley et al., 2011; Huang et al., 2011). "
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    ABSTRACT: Interferon-induced transmembrane (IFITM) proteins inhibit the infection of a wide range of viruses including human immunodeficiency virus type 1 (HIV-1). At present, little is known about how viruses overcome IFITM restriction. In this study, we have utilized HIV-1 as a model and selected IFITM1-resistant viruses after multiple passages of HIV-1 in IFITM1-expressing SupT1 cells. Sequencing the entire viral genome revealed several mutations in the vpu and envelope genes, among which mutations Vpu34 and EnvG367E together enable efficient HIV-1 replication in IFITM1-expressing cells. Vpu34 introduces a stop codon at amino acid position 35 of Vpu, whereas EnvG367E changes the G367 residue at the CD4-binding site of gp120. These two mutations do not appear to overcome the downregulation of viral p24 expression caused by IFITM1, but rather enhance HIV-1 replication by promoting cell-to-cell virus transmission. Altogether, our data demonstrate that HIV-1 can mutate to evade IFITM1 restriction by increasing cell-to-cell transmission.
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    • "Previous studies showed that IFITM3 belongs to a family of murine genes [9], which are short, 2-transmembrane-domain proteins (5-18 kDa) with high core sequence similarity but divergent N- and C-termini. The human homologues (IFITM1, IFITM2, and IFITM3) are clustered on chromosome 11 within an 18-kb genomic sequence [7,10,11], and mediates cellular processes, including cell adhesion, immune-cell regulation, germ-cell homing and maturation, and bone mineralization [8,11-16]. "
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