Consecutive Inhibition of ISG15 Expression and ISGylation by Cytomegalovirus Regulators

Kim YJ, Kim ET, Kim YE, Lee MK, Kwon KM, Kim KI, Stamminger T, Ahn JH (2016)

Publication Type: Journal article

Publication year: 2016

Journal

PLoS Pathogens Public Library of Science

Book Volume: 12

Pages Range: e1005850

Journal Issue: 8

DOI: 10.1371/journal.ppat.1005850

Abstract

Interferon-stimulated gene 15 (ISG15) encodes an ubiquitin-like protein that covalently conjugates protein. Protein modification by ISG15 (ISGylation) is known to inhibit the replication of many viruses. However, studies on the viral targets and viral strategies to regulate ISGylation-mediated antiviral responses are limited. In this study, we show that human cytomegalovirus (HCMV) replication is inhibited by ISGylation, but the virus has evolved multiple countermeasures. HCMV-induced ISG15 expression was mitigated by IE1, a viral inhibitor of interferon signaling, however, ISGylation was still strongly upregulated during virus infection. RNA interference of UBE1L (E1), UbcH8 (E2), Herc5 (E3), and UBP43 (ISG15 protease) revealed that ISGylation inhibits HCMV growth by downregulating viral gene expression and virion release in a manner that is more prominent at low multiplicity of infection. A viral regulator pUL26 was found to interact with ISG15, UBE1L, and Herc5, and be ISGylated. ISGylation of pUL26 regulated its stability and inhibited its activities to suppress NF-?B signaling and complement the growth of UL26-null mutant virus. Moreover, pUL26 reciprocally suppressed virus-induced ISGylation independent of its own ISGylation. Consistently, ISGylation was more pronounced in infections with the UL26-deleted mutant virus, whose growth was more sensitive to IFN? treatment than that of the wild-type virus. Therefore, pUL26 is a viral ISG15 target that also counteracts ISGylation. Our results demonstrate that ISGylation inhibits HCMV growth at multiple steps and that HCMV has evolved countermeasures to suppress ISG15 transcription and protein ISGylation, highlighting the importance of the interplay between virus and ISGylation in productive viral infection.

Authors with CRIS profile

Thomas Stamminger Professur für Virologie

Involved external institutions

Sungkyunkwan University (SKKU) KR Korea, Republic of (KR) Sookmyung Women's University KR Korea, Republic of (KR)

How to cite

APA:

Kim, Y.J., Kim, E.T., Kim, Y.-E., Lee, M.K., Kwon, K.M., Kim, K.I.,... Ahn, J.-H. (2016). Consecutive Inhibition of ISG15 Expression and ISGylation by Cytomegalovirus Regulators. PLoS Pathogens, 12(8), e1005850. https://doi.org/10.1371/journal.ppat.1005850

MLA:

Kim, Ye Ji, et al. "Consecutive Inhibition of ISG15 Expression and ISGylation by Cytomegalovirus Regulators." PLoS Pathogens 12.8 (2016): e1005850.

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