Abstract

The innate antiviral response is integral in protecting the host against virus infection. Many proteins regulate these signaling pathways including ubiquitin enzymes. The ubiquitin-activating (E1), -conjugating (E2), and -ligating (E3) enzymes work together to link ubiquitin, a small protein, onto other ubiquitin molecules or target proteins to mediate various effector functions. The tripartite motif (TRIM) protein family is a group of E3 ligases implicated in the regulation of a variety of cellular functions including cell cycle progression, autophagy, and innate immunity. Many antiviral signaling pathways, including type-I interferon and NF-κB, are TRIM-regulated, thus influencing the course of infection. Additionally, several TRIMs directly restrict viral replication either through proteasome-mediated degradation of viral proteins or by interfering with different steps of the viral replication cycle. In addition, new studies suggest that TRIMs can exert their effector functions via the synthesis of unconventional polyubiquitin chains, including unanchored (non-covalently attached) polyubiquitin chains. TRIM-conferred viral inhibition has selected for viruses that encode direct and indirect TRIM antagonists. Furthermore, new evidence suggests that the same antagonists encoded by viruses may hijack TRIM proteins to directly promote virus replication. Here, we describe numerous virus–TRIM interactions and novel roles of TRIMs during virus infections.

Highlights

  • Eukaryotes are constantly exposed to a variety of pathogens, including viruses

  • This suggests that the association of TRIM21 with Ig-V complexes is important for triggering antiviral responses

  • Viral antagonism of tripartite motif (TRIM) exemplifies the importance of this protein family in antiviral responses

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Summary

Introduction

Eukaryotes are constantly exposed to a variety of pathogens, including viruses. As with other environmental signals, viral invasion triggers tightly regulated intracellular signaling cascades to optimally respond to infection. Mammals enact both an innate and an adaptive immune response to identify an infecting pathogen, to clear the foreign agent, and to protect against subsequent invasion. A primary mechanism for fine-tuning molecular pathways is utilization of post-translational modifications. Altering the functional proteome influences protein interactions, transcriptional programs, translation, secretion, and cytoskeletal arrangement. A variety of molecules, including phosphates, sugars, lipids, or proteins, can be attached or removed enzymatically to modulate protein function. Post-translational modifications enable rapid and reversible regulation

Ubiquitin
Introduction to Innate Antiviral Responses
Ubiquitin Protein
Regulation
TRIMs and STING Signaling
TRIMs and TLR Signaling
TRIMs and Cytokine Signaling
TRIMs and Adaptive Immunity
TRIM-Mediated Virus Inhibition
TRIM5α and Retroviruses
Other TRIMs and Retroviruses
TRIM21 and Antibody-Dependent Intracellular Neutralization of Viruses
TRIMs and Negative Sense RNA Viruses
TRIMs and Positive Sense RNA Viruses
TRIMs and DNA Viruses
Viral Antagonism of TRIMs
Antagonism of TRIMs by RNA Viruses
TRIM6 is targeted targeted by by Nipah
Antagonism of TRIMs by DNA Viruses
Potential Roles of TRIM-mediated Autophagy during Virus Infections
Conclusions and Future Perspectives
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