Viral apoptosis evasion via the MAPK pathway by use of a host long noncoding RNA

Abstract

An emerging realisation of infectious disease is the high incidence of genetic instability resulting from pathogen-induced DNA lesions, often leading to classical hallmarks of cancer such as evasion of apoptosis. The Human Immunodeficiency Virus type 1 (HIV-1) induces apoptosis in CD4+ T cells but is largely non-cytopathic in macrophages, thereby leading to long-term dissemination of the pathogen specifically by these host cells. Apoptosis is triggered by double-strand breaks (DSBs), such as those induced by integrating retroviruses, and is coordinated by the p53-regulated long noncoding RNA lincRNA-p21, in a complex with its protein binding partners HuR and hnRNP-K. Here, we monitor the cellular response to infection to determine how HIV-1 induces DSBs in macrophages yet evades apoptosis in these cells. We show that the virus does so by securing the pro-survival MAP2K1/ERK2 cascade early upon entry, in a gp120-dependent manner, to orchestrate a complex dysregulation of lincRNA-p21. By sequestering HuR in the nucleus, HIV-1 enables lincRNA-p21 degradation. Simultaneously, the virus permits transcription of pro-survival genes by sequestering hnRNP-K in the cytoplasm via the MAP2K1/ERK2 pathway. Notably, this pro-survival cascade is unavailable for similar viral manipulation in CD4+ T cells. The introduction of MAP2K1, ERK2 or HDM2 inhibitors in HIV-infected macrophages results in apoptosis providing strong evidence that the viral-mediated apoptotic block can be released, specifically by restoring the nuclear interaction of lincRNA-p21 and hnRNP-K. These results reveal pathogenic control of apoptosis and DNA damage via a host long noncoding RNA, and present MAP2K1/ERK2 inhibitors as a novel therapeutic intervention strategy for HIV-1 infection in macrophages.