Interaction between the cellular E3 ubiquitin ligase SIAH-1 and the viral immediate-early protein ICP0 enables efficient replication of Herpes Simplex Virus type 2 in vivo

Abstract

Herpes Simplex Virus type 2 (HSV-2) is a neurotropic human pathogen. Upon de novo infection, the viral infected cell protein 0 (ICP0) is immediately expressed and interacts with various cellular components during the viral replication cycle. ICP0 is a multifunctional regulatory protein that has been shown to be important for both efficient viral replication and virus reactivation from latency. In particular, as previously demonstrated in transfected tissue culture models, ICP0 interacts with the cellular E3 ubiquitin ligase SIAH-1, which targets ICP0 for proteasomal degradation. However, the consequence of this virus-host interaction during the establishment of HSV-2 infection in vivo has not yet been elucidated. Here we confirmed that ICP0 of HSV-2 interacts with SIAH-1 via two conserved PxAxVxP amino acid binding motifs. We also demonstrate in vitro that a SIAH-1 binding-deficient HSV-2 strain, constructed by homologous recombination technology, exhibits an attenuated growth curve and impaired DNA and protein synthesis. This attenuated phenotype was also confirmed in an in vivo ocular infection mouse model. Specifically, viral load of the SIAH-1 binding-deficient HSV-2 mutant was significantly reduced in the trigeminal ganglia and brain stem at day 5 and 7 post infection. Our findings indicate that the interplay between ICP0 and SIAH-1 is important for efficient HSV-2 replication in vivo, thereby affecting viral dissemination kinetics in newly infected organisms, and possibly revealing novel targets for antiviral therapy.

Inhibition of the Super Elongation Complex Suppresses Herpes Simplex Virus Immediate Early Gene Expression, Lytic Infection, and Reactivation from Latency

“…Strikingly, levels of AFF4 protein were induced in cells infected with HSV, suggesting that a virus-mediated mechanism might enhance SEC levels for HSV gene expression. Interestingly, reports from the Hauber laboratory have shown that the ICP0 viral IE protein interacts with SIAH1 through SIAH1-binding consensus motifs and that viruses with mutations in these motifs are defective for growth in culture and in vivo (56,57). The authors propose several models, including one in which ICP0 functions to sequester SIAH1, thus blocking SIAH1's interactions with its targets.…”

“…Interestingly, previous studies identified SIAH1 as an interaction partner for the HSV IE protein ICP0 and demonstrated that a recombinant virus with a mutant ICP0 that did not interact with SIAH1 was defective in growth in vitro and in vivo (56,57). Therefore, to determine if ICP0 was involved in the regulation of AFF4 protein levels upon infection, cells were infected with wild-type (WT) HSV or a recombinant lacking ICP0 (ΔICP0 [58,59]).…”

The HSV-1 ubiquitin ligase ICP0: Modifying the cellular proteome to promote infection

“…SLSs 1-7 (aa 164-167, 176-179, 331-334, 362-363, 651-654, 664-667 and 678-681, respectively) are indicated with black vertical half-moons ( Boutell et al, 2011 ); SLS4 and aa 634-719 influence PML-NB localization (highlighted grey; ( Everett et al, 2014 )). SIAH binding motif (aa 401-410; ( Czechowicz et al, 2018 )), a NLS (aa 500-506), and USP7 binding motif (aa 620-624) are indicated with vertical rectangles. ICP0 regions of SUMO2/3 (aa 241-388, highlighted orange) and SUMO1 (aa 594-775, highlighted red) binding shown ( Boutell et al, 2011 ; Everett et al, 2014 ).…”

Siah1 in cancer and nervous system diseases (Review)

“…The characteristics of the SIPs have also been studied (13). A consensus Pro-X-Ala-X-Val-X-Pro (VxP, core sequence; where X is not conserved) motif is common to a family of SIPs (Table I) (11,14,21,(23)(24)(25)(26). Some SIPs are also substrates of Siah1 and are targeted by Siah1 for degradation or functional modification.…”