Protein Tyrosine Phosphatase SHP2 Suppresses Host Innate Immunity against Influenza A Virus by Regulating EGFR-Mediated Signaling

Abstract

Influenza A virus (IAV) emerges as a highly contagious pathogen, causing acute respiratory illnesses in human beings and animals and frequently giving rise to epidemic outbreaks. Evasion of IAV from host immunity facilitates viral replication and spread, which can be initiated through various mechanisms, including epidermal growth factor receptor (EGFR) activation. However, how EGFR mediates the suppression of antiviral systems remains unclear. Here, we examined host innate immune responses and their relevant signaling to EGFR upon IAV infection. IAV was found to induce the phosphorylation of EGFR and extracellular signal-regulated kinase (ERK) at an early stage of infection. Inhibition of EGFR or ERK suppressed the viral replication but increased the expression of type I and type III interferons (IFNs) and interferon-stimulated genes (ISGs), supporting that IAV escapes from antiviral innate immunity by activating the EGFR/ERK signaling. Meanwhile, IAV infection also induced the activation of Src homology region 2-containing protein tyrosine phosphatase 2 (SHP2). Pharmacological inhibition or siRNA-based silencing of SHP2 enhanced the IFN-dependent antiviral activity and reduced virion production. Furthermore, knockdown of SHP2 attenuated the EGFR-mediated ERK phosphorylation triggered by viral infection or EGF stimulation. Conversely, ectopic expression of constitutively active SHP2 remarkably promoted ERK activation and viral replication, concomitant with diminished immune function. Altogether, the results indicate that SHP2 is crucial for IAV-induced activation of the EGFR/ERK pathway to suppress host antiviral responses. IMPORTANCE Viral immune evasion is the most important strategy whereby viruses evolve for their survival. This work shows that influenza A virus (IAV) suppressed the antiviral innate immunity through downregulation of IFNs and ISGs by activating the EGFR/ERK signaling. Meanwhile, IAV also induced the activation of protein tyrosine phosphatase SHP2, which was found to be responsible for modulating the EGFR-mediated ERK activity and subsequent antiviral effectiveness both in vitro and in vivo. The results suggest that SHP2 is a key signal transducer between EGFR and ERK and plays a crucial role in suppressing host innate immunity during IAV infection. The finding enhances our understanding of influenza immune evasion and provides a new therapeutic approach to viral infection.

EGFR Activation Impairs Antiviral Activity of Interferon Signaling in Brain Microvascular Endothelial Cells During Japanese Encephalitis Virus Infection

“…Nevertheless, in the monolayer of hBMECs, there was no significant difference both in transcription and translation levels of EGFR at 12, 36, and 72 h post-infection (hpi) ( Supplementary Figure S1C ). Many viruses activate EGFR through phosphorylation at the early stage of infection, including ZIKV, PEDV, and IAV (Yang et al, 2018 ; Sabino et al, 2021 ; Wang et al, 2021 ). To figure out whether EGFR could be activated by JEV through phosphorylation, phosphorylation on tyrosine sites of EGFR in hBMECs at the early phase of JEV infection was examined.…”

“…Since EGFR does not affect JEV attachment and entry in hBMECs, how does EGFR facilitate JEV infection in hBMECs? It has been widely reported that EGFR participates in the regulation of host innate immunity during viral infection (Lupberger et al, 2013 ; Qiu et al, 2020 ; Wang et al, 2021 ). For example, respiratory virus (RSV) induced EGFR phosphorylation, which inhibited interferon regulatory factor 1 (IRF1)-regulate interferon-lambda (IFN-λ) production and breakdown of airway epithelium antiviral response (Kalinowski et al, 2018 ).…”

“…As a member of the tyrosine kinase family, the biological significance of EGFR has been well studied in tumorigenesis. In recent years, the activated EGFR also appeared in response to viral infection, including IAV, PEDV, ZIKV, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Yang et al, 2018 ; Klann et al, 2020 ; Sabino et al, 2021 ; Wang et al, 2021 ). The activation of EGFR might build a favorable cellular environment to prompt viral entry or replication (Oshiumi et al, 2015 ; Fukano et al, 2021 ).…”

I226R Protein of African Swine Fever Virus Is a Suppressor of Innate Antiviral Responses

“…The 3D4/21 cells were maintained in Roswell Park Memorial Institute 1640 Medium (Gibco, Thermo Fisher Scientific, Inc., Waltham, MA, USA), containing 10% FBS, 1% nonessential amino acids (Invitrogen, Carlsbad, CA, USA), 100 U/mL penicillin, and 100 μg/mL streptomycin. All cells were cultured at 37 °C under 5% CO 2 atmosphere, as previously described [ 34 ].…”

“…GAPDH was used as a reference housekeeping gene for internal standardization. For quantification, the 2-ΔΔCt methods were used to calculate the relative RNA levels against the GAPDH [ 34 ].…”