Loss of VHL confers hypoxia-inducible factor (HIF)-dependent resistance to vesicular stomatitis virus: role of HIF in antiviral response.

Hypoxia-inducible factor (HIF) is a central regulator of cellular responses to hypoxia, and under normal oxygen tension the catalytic alpha subunit of HIF is targeted for ubiquitin-mediated destruction via the VHL-containing E3 ubiquitin ligase complex. Principally known for its association with oncogenesis, HIF has been documented to have a role in the antibacterial response. Interferons, cytokines with antiviral functions, have been shown to upregulate the expression of HIF-1alpha, but the significance of HIF in the antiviral response has not been established. Here, using renal carcinoma cells devoid of VHL or reconstituted with functional wild-type VHL or VHL mutants with various abilities to negatively regulate HIF as an ideal model system of HIF activity, we show that elevated HIF activity confers dramatically enhanced resistance to vesicular stomatitis virus (VSV)-mediated cytotoxicity. Inhibition of HIF activity using a small-molecule inhibitor, chetomin, enhanced cellular sensitivity to VSV, while treatment with hypoxia mimetic CoCl2 promoted resistance. Similarly, targeting HIF-2alpha by RNA interference also enhanced susceptibility to VSV. Expression profiling studies show that upon VSV infection, the induction of genes with known antiviral activity, such as that encoding beta interferon (IFN-beta), is significantly enhanced by HIF. These results reveal a previously unrecognized role of HIF in the antiviral response by promoting the expression of the IFN-beta gene and other genes with antiviral activity upon viral infection.