SARS-CoV-2 accessory protein ORF8 is secreted extracellularly as a glycoprotein homodimer

Matsuoka, Katsunari; Imahashi, Nobuhiko; Ohno, Miki; Ode, Hirotaka; Nakata, Yoshihiro; Kubota, Mai; Sugimoto, Atsuko; Imahashi, Mayumi; Yokomaku, Yoshiyuki; Iwatani, Yoshinori

doi:10.1016/j.jbc.2022.101724

Cited by 37 publications

(42 citation statements)

References 70 publications

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“…This protein is largely secreted ( Fig. S2A ) as previously reported [ 14 ]. However, we did not observe mRNA splicing in the unoptimized ORF8 ( Fig.…”

Section: Resultssupporting

confidence: 69%

“…Very recently, it has been reported that upon transfection of ORF8 expression plasmid, the mRNA expressed in cells was unexpectedly spliced at cryptic splice sites, which should result in the production of a truncated ORF8 protein lacking 42-amino acid residues in the C-terminal region [ 14 ]. By comparing original ORF8 with codon-optimized ORF8, we found that codon-optimized ORF8 encodes a protein with larger molecular size ( Fig.…”

Section: Resultsmentioning

confidence: 99%

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SARS-CoV-2 ORF8 reshapes the ER through forming mixed disulfides with ER oxidoreductases

et al. 2022

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“…This protein is largely secreted ( Fig. S2A ) as previously reported [ 14 ]. However, we did not observe mRNA splicing in the unoptimized ORF8 ( Fig.…”

Section: Resultssupporting

confidence: 69%

Section: Resultsmentioning

confidence: 99%

SARS-CoV-2 ORF8 reshapes the ER through forming mixed disulfides with ER oxidoreductases

et al. 2022

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“…The protein encoded by the SARS-CoV-2 ORF8 gene is unique to SARS-CoV-2 containing a predicted Ig-like fold, which can interact with a variety of host proteins involved in ER-associated degradation. Caki-1 cells show a strong staining with no background in the uninfected cells, and we see a vesicular staining with a concentration towards the plasma membrane in agreement with the existing literature showing secretion of ORF8 (24). ORF9, the nucleocapsid protein (N), shows localization to the replication-transcription complex in the perinuclear space, where it aids packaging of the viral genome into a ribonucleoprotein particle.…”

Section: Resultssupporting

confidence: 92%

One for all – Human kidney Caki-1 cells are highly susceptible to infection with corona- and other respiratory viruses

Daniels

Fletcher

Kerr

et al. 2022

Preprint

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Despite the vast increase in research activity in the coronavirus field over the past two years, researchers are still heavily reliant on non-human cells, for example Vero E6, highly heterogeneous or not fully differentiated cells, such as Calu-3, or not naturally susceptible cell lines overexpressing receptor ACE2 and other accessory factors, such as TMPRSS2. Complex cell models, such as primary cell-derived air-liquid interface epithelial models are highly representative of human tissues but are expensive and time-consuming to develop and maintain and have limited suitability for high-throughput analysis. In vitro investigations of host-pathogen interactions of viruses is highly reliant on suitable cell and tissue culture models and results are only as good as the model they have been validated in. Here, we show the use of a highly characterized human kidney cell line, Caki-1, for infection with three human coronaviruses: Betacoronaviruses severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and Middle Eastern respiratory syndrome coronavirus (MERS-CoV) and Alphacoronavirus human coronavirus 229E (hCoV-229E). Caki-1 cells show equal or superior susceptibility to all three coronaviruses when compared to other commonly used cells lines for the cultivation of the respective virus. Furthermore, we used a panel of antibodies generated against 21 SARS-CoV-2-encoded proteins to identify their location in the infected Caki-1 cells using immunocytochemistry. Most importantly, Caki-1 cells are also susceptible to two other respiratory viruses, Influenza A virus and RSV, making them an ideal model for cross-comparison of not only a broad range of coronaviruses but respiratory viruses in general.

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“…Notably, presence of acetylated lysine within the ARKSAP motif is probably incompatible with dimerization of ORF8, which involves a hydrogen-bond interaction at this residue 24 , and thus suggests that ORF8 can exist as a monomer within cells. Finally, given that ORF8 promotes lysosomal degradation of another binding partner 30,38 , we examined whether ORF8 similarly affects chromatin-associated proteins. ORF8 expression resulted in a marked decrease in the abundance of KAT2A (Fig.…”

Section: Orf8 Contains a Histone H3 Mimicmentioning

confidence: 99%

SARS-CoV-2 disrupts host epigenetic regulation via histone mimicry

Kee

Thudium

Renner

et al. 2022

Nature

101

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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged at the end of 2019 and caused the devastating global pandemic of coronavirus disease 2019 (COVID-19), in part because of its ability to effectively suppress host cell responses 1 – 3 . In rare cases, viral proteins dampen antiviral responses by mimicking critical regions of human histone proteins 4 – 8 , particularly those containing post-translational modifications required for transcriptional regulation 9 – 11 . Recent work has demonstrated that SARS-CoV-2 markedly disrupts host cell epigenetic regulation 12 – 14 . However, how SARS-CoV-2 controls the host cell epigenome and whether it uses histone mimicry to do so remain unclear. Here we show that the SARS-CoV-2 protein encoded by ORF8 (ORF8) functions as a histone mimic of the ARKS motifs in histone H3 to disrupt host cell epigenetic regulation. ORF8 is associated with chromatin, disrupts regulation of critical histone post-translational modifications and promotes chromatin compaction. Deletion of either the ORF8 gene or the histone mimic site attenuates the ability of SARS-CoV-2 to disrupt host cell chromatin, affects the transcriptional response to infection and attenuates viral genome copy number. These findings demonstrate a new function of ORF8 and a mechanism through which SARS-CoV-2 disrupts host cell epigenetic regulation. Further, this work provides a molecular basis for the finding that SARS-CoV-2 lacking ORF8 is associated with decreased severity of COVID-19.

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SARS-CoV-2 accessory protein ORF8 is secreted extracellularly as a glycoprotein homodimer

Cited by 37 publications

References 70 publications

SARS-CoV-2 ORF8 reshapes the ER through forming mixed disulfides with ER oxidoreductases

SARS-CoV-2 ORF8 reshapes the ER through forming mixed disulfides with ER oxidoreductases

One for all – Human kidney Caki-1 cells are highly susceptible to infection with corona- and other respiratory viruses

SARS-CoV-2 disrupts host epigenetic regulation via histone mimicry

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