ATF4 Signaling in HIV Infection: Viral Subversion of a Stress Response Transcription Factor

Abstract

Cellular Integrated Stress Response (ISR), the mitochondrial Unfolded Protein Response (UP-Rmt) and the IFN signaling are associated with viral infections. The Activating transcription fac-tor 4 (ATF4) plays a pivotal role in these pathways and controls the expression of many genes involved in redox processes, amino acid metabolism, protein misfolding, autophagy and apop-tosis. The precise role of ATF4 during viral infection is unclear and depends on cell hosts, viral agents and models. Furthermore, ATF4 signaling can be hijacked by pathogens to favor viral in-fection and replication. In this review, we summarize the ATF4-mediated signaling pathways in response to viral infections, focusing on human immunodeficiency virus (HIV). We examine the consequences of ATF4 activation for HIV replication and reactivation. The role of ATF4 in au-tophagy and apoptosis is explored as in the context of HIV infection programmed cell deaths contribute to the depletion of CD4 T cells. Furthermore, ATF4 can also participate in the estab-lishment of innate and adaptive immunity that are essential for the host to control viral infec-tions. We finally discuss the putative role of the ATF4 paralogue, named ATF5, in HIV infection. This review underlines the role of ATF4 at the crossroads of multiple processes reflecting host-pathogen interactions.