Dataset Information

E3 Ubiquitin Ligase NEDD4 Promotes Influenza Virus Infection by Decreasing Levels of the Antiviral Protein IFITM3.

ABSTRACT: Interferon (IFN)-induced transmembrane protein 3 (IFITM3) is a cell-intrinsic factor that limits influenza virus infections. We previously showed that IFITM3 degradation is increased by its ubiquitination, though the ubiquitin ligase responsible for this modification remained elusive. Here, we demonstrate that the E3 ubiquitin ligase NEDD4 ubiquitinates IFITM3 in cells and in vitro. This IFITM3 ubiquitination is dependent upon the presence of a PPxY motif within IFITM3 and the WW domain-containing region of NEDD4. In NEDD4 knockout mouse embryonic fibroblasts, we observed defective IFITM3 ubiquitination and accumulation of high levels of basal IFITM3 as compared to wild type cells. Heightened IFITM3 levels significantly protected NEDD4 knockout cells from infection by influenza A and B viruses. Similarly, knockdown of NEDD4 in human lung cells resulted in an increase in steady state IFITM3 and a decrease in influenza virus infection, demonstrating a conservation of this NEDD4-dependent IFITM3 regulatory mechanism in mouse and human cells. Consistent with the known association of NEDD4 with lysosomes, we demonstrate for the first time that steady state turnover of IFITM3 occurs through the lysosomal degradation pathway. Overall, this work identifies the enzyme NEDD4 as a new therapeutic target for the prevention of influenza virus infections, and introduces a new paradigm for up-regulating cellular levels of IFITM3 independently of IFN or infection.

SUBMITTER: Chesarino NM

PROVIDER: S-EPMC4532365 | biostudies-other | 2015 Aug

REPOSITORIES: biostudies-other

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E3 Ubiquitin Ligase NEDD4 Promotes Influenza Virus Infection by Decreasing Levels of the Antiviral Protein IFITM3.

Chesarino Nicholas M NM McMichael Temet M TM Yount Jacob S JS

PLoS pathogens 20150811 8

Interferon (IFN)-induced transmembrane protein 3 (IFITM3) is a cell-intrinsic factor that limits influenza virus infections. We previously showed that IFITM3 degradation is increased by its ubiquitination, though the ubiquitin ligase responsible for this modification remained elusive. Here, we demonstrate that the E3 ubiquitin ligase NEDD4 ubiquitinates IFITM3 in cells and in vitro. This IFITM3 ubiquitination is dependent upon the presence of a PPxY motif within IFITM3 and the WW domain-containi ...[more]

PMID: 26263374

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Project description:Commissural axons initially respond to attractive signals at the midline, but once they cross, they become sensitive to repulsive cues. In insects and mammals, negative regulation of the surface expression of Roundabout (Robo) receptors prevents premature response to Slit. We previously identified two mammalian Nedd4 interacting proteins, Ndfip1 and Ndfip2, that act analogously to Drosophila Commissureless (Comm) to recruit mammalian Robo1 to late endosomes. However, whether Nedd4 E3 ubiquitin ligases are required for Ndfip-mediated Robo1 regulation and midline axon crossing in vivo is not known. Here, we show using in vitro biochemical techniques and genetic analysis using embryonic mice of either sex that Nedd4-1 and Nedd4-2 are specifically required for Robo1 regulation and spinal commissural axon guidance. Biochemical data indicate that Robo1, Ndfip and Nedd4 form a ternary protein complex that depends on the presence of Ndfip, and these interactions are required for Robo1 endosomal sorting, ubiquitylation and degradation. Nedd4-1 and Nedd4-2 are expressed in commissural neurons in the developing spinal cord, and conditional deletion of Nedd4-1 or Nedd4-2 results in dose-dependent defects in midline crossing. We propose that Nedd4 E3 Ubiquitin ligases and their adaptor proteins Ndfip1 and Ndfip2 constitute a vital intracellular trafficking pathway required to downregulate Robo1 and promote midline crossing of commissural axons.SIGNIFICANCE STATEMENT During the development of the nervous system, many neurons extend their axons across the midline to establish circuits that are important for sensory, motor and cognitive functions. In order to cross the midline, axon responses to midline-derived cues must be precisely regulated. Here, we characterize an important intracellular trafficking pathway that regulates the membrane expression of the conserved Roundabout (Robo) axon guidance receptor- the receptor for the midline repellant Slit. We show that Nedd4 E3 Ubiquitin ligases and their Ndfip adapter proteins inhibit premature responses to Slit by promoting Robo degradation in precrossing commissural neurons in the developing spinal cord.

Dataset Information

E3 Ubiquitin Ligase NEDD4 Promotes Influenza Virus Infection by Decreasing Levels of the Antiviral Protein IFITM3.

Publications

E3 Ubiquitin Ligase NEDD4 Promotes Influenza Virus Infection by Decreasing Levels of the Antiviral Protein IFITM3.

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