The Interferon-induced Transmembrane Proteins, IFITM1, IFITM2, and IFITM3 Inhibit Hepatitis C Virus Entry

Narayana, Sumudu; Helbig, Karla J.; McCartney, Erin M.; Eyre, Nicholas S.; Bull, Rowena A.; Eltahla, Auda A.; Lloyd, Andrew R.; Beard, Michael R.

doi:10.1074/jbc.m115.657346

Cited by 137 publications

(143 citation statements)

References 47 publications

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“…S5 and S6). Our results are consistent with previous IFITM mutagenesis and antiviral activity studies (21,22,27,32,35), but demonstrates that antiviral activity is directly correlated to S-fatty acylation levels and that dually S-fatty acylated IFITM3 at Cys72 and Cys105 is likely the most active isoform in mammalian cells (Fig. S9).…”

Section: Discussionsupporting

confidence: 82%

“…4). Although previous studies have suggested that mutation of these conserved Cys residues may partially affect the localization or trafficking of IFITMs in mammalian cells (21,22,27,32), our quantitative immunofluorescence analysis suggest that site-specific S-fatty acylation may regulate more subtle functions of IFITM3 beyond lysosomal targeting (Figs. S7 and S8), such as protein-protein interactions (33,34) or membrane tethering, but which awaits more detailed biochemical or biophysical studies.…”

Section: Discussionmentioning

confidence: 93%

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Mass-tag labeling reveals site-specific and endogenous levels of protein S-fatty acylation

Percher

Ramakrishnan

Thinon

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

151

210

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Fatty acylation of cysteine residues provides spatial and temporal control of protein function in cells and regulates important biological pathways in eukaryotes. Although recent methods have improved the detection and proteomic analysis of cysteine fatty (S-fatty) acylated proteins, understanding how specific sites and quantitative levels of this posttranslational modification modulate cellular pathways are still challenging. To analyze the endogenous levels of protein S-fatty acylation in cells, we developed a mass-tag labeling method based on hydroxylamine-sensitivity of thioesters and selective maleimide-modification of cysteines, termed acyl-PEG exchange (APE). We demonstrate that APE enables sensitive detection of protein S-acylation levels and is broadly applicable to different classes of S-palmitoylated membrane proteins. Using APE, we show that endogenous interferoninduced transmembrane protein 3 is S-fatty acylated on three cysteine residues and site-specific modification of highly conserved cysteines are crucial for the antiviral activity of this IFN-stimulated immune effector. APE therefore provides a general and sensitive method for analyzing the endogenous levels of protein S-fatty acylation and should facilitate quantitative studies of this regulated and dynamic lipid modification in biological systems.fatty-acylation | palmitoylation | PEGylation | influenza virus | IFITM3 P rotein S-fatty acylation describes the covalent attachment of long-chain fatty acids to cysteine (Cys) residues through a thioester bond, which alters the hydrophobicity of diverse proteins and regulates their stability, trafficking, and activity in eukaryotic cells ( Fig. 1A) (1, 2). Cys residues are predominately acylated with palmitic acid (S-palmitoylation), but can also be modified with longer chain and unsaturated fatty acids, thus more generally described as S-fatty acylation (1, 3, 4). The fatty-acylation of Cys residues is regulated by the DHHC-family of protein acyltransferases (5, 6) and different classes of thioesterases (7,8) that are associated with a variety of important physiological pathways and diseases (1). Determining the precise levels of protein S-fatty acylation is therefore crucial for understanding how this dynamic lipid modification is regulated and quantitatively controls specific cellular pathways.Recent methods to detect and enrich S-fatty acylated proteins have facilitated the characterization of key regulatory mechanisms and discovery of new S-fatty acylated proteins (1, 2). For example, alkyne-modified fatty acid chemical reporters have enabled the fluorescent detection and enrichment of metabolically labeled proteins using bioorthogonal ligation methods (Fig. S1A) (9, 10). Alternatively, exploitation of thioester sensitivity to hydroxylamine (NH 2 OH) has enabled selective capture and analysis of S-acylated proteins by acyl-biotin exchange (ABE) (Fig. S1B) (11, 12) or acyl-resin capture (acyl-RAC) (Fig. S1C) (13). However, all of these methods do not readily reveal the fraction of unmodified...

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Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 93%

Mass-tag labeling reveals site-specific and endogenous levels of protein S-fatty acylation

Percher

Ramakrishnan

Thinon

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

151

210

View full text Add to dashboard Cite

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“…Unexpectedly, preS1 treatment also induced the expression of genes involved in innate immunity, such as IFNα responses and the Jak/Stat-signaling pathway (Table 1; Figure 4A). Interestingly, IFITM2 and IFITM3 , which encode two restriction factors targeting HCV entry (Narayana et al., 2015), were among the preS1-induced genes (Figure 4B).…”

Section: Resultsmentioning

confidence: 99%

Solute Carrier NTCP Regulates Innate Antiviral Immune Responses Targeting Hepatitis C Virus Infection of Hepatocytes

et al. 2016

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SummaryChronic hepatitis B, C, and D virus (HBV, HCV, and HDV) infections are the leading causes of liver disease and cancer worldwide. Recently, the solute carrier and sodium taurocholate co-transporter NTCP has been identified as a receptor for HBV and HDV. Here, we uncover NTCP as a host factor regulating HCV infection. Using gain- and loss-of-function studies, we show that NTCP mediates HCV infection of hepatocytes and is relevant for cell-to-cell transmission. NTCP regulates HCV infection by augmenting the bile-acid-mediated repression of interferon-stimulated genes (ISGs), including IFITM3. In conclusion, our results uncover NTCP as a mediator of innate antiviral immune responses in the liver, and they establish a role for NTCP in the infection process of multiple viruses via distinct mechanisms. Collectively, our findings suggest a role for solute carriers in the regulation of innate antiviral responses, and they have potential implications for virus-host interactions and antiviral therapies.

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“…23 IFITM proteins have been reported to be regulated by palmitoylation and ubiquitination, for example. 24, 25 This might explain our finding that the increase in IFITM1 protein both in control and S100A6 knockdown cells is partially overcome by short-term VEGF-A treatment. To test the impact of increased IFITM1 protein levels, we conducted a dual S100A6/IFITM1 siRNA-mediated knockdown in HUVECs.…”

Section: Resultsmentioning

confidence: 86%

S100A6 Regulates Endothelial Cell Cycle Progression by Attenuating Antiproliferative Signal Transducers and Activators of Transcription 1 Signaling

Lerchenmüller

Heissenberg

Damilano

et al. 2016

ATVB

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Objective S100A6, a member of the S100-protein family, has been described as relevant for cell cycle entry and progression in endothelial cells (ECs). The molecular mechanism conferring S100A6’s proliferative actions, however, remained elusive. Approach and Results Originating from the clinically relevant observation of enhanced S100A6 protein expression in proliferating ECs in remodeling coronary and carotid arteries, our study unveiled S100A6 as a suppressor of antiproliferative signal transducers and activators of transcription 1 (STAT1) signaling. Discovery of the molecular liaison was enabled by combining gene expression time series analysis with bioinformatic pathway modeling in S100A6 silenced human ECs stimulated with vascular endothelial growth factor A (VEGF-A). This unbiased approach led to successful identification and experimental validation of interferon-inducible transmembrane protein 1 (IFITM1) and protein inhibitors of activated STAT (PIAS) as key components of the link between S100A6 and STAT1. Conclusions Given the important role of coordinated EC cell cycle activity for integrity and reconstitution of the inner lining of arterial blood vessels in health and disease, STAT1 suppression by S100A6 may represent a promising therapeutic target to facilitate reendothelialization in damaged vessels.

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The Interferon-induced Transmembrane Proteins, IFITM1, IFITM2, and IFITM3 Inhibit Hepatitis C Virus Entry

Cited by 137 publications

References 47 publications

Mass-tag labeling reveals site-specific and endogenous levels of protein S-fatty acylation

Mass-tag labeling reveals site-specific and endogenous levels of protein S-fatty acylation

Solute Carrier NTCP Regulates Innate Antiviral Immune Responses Targeting Hepatitis C Virus Infection of Hepatocytes

S100A6 Regulates Endothelial Cell Cycle Progression by Attenuating Antiproliferative Signal Transducers and Activators of Transcription 1 Signaling

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