Identification of a Novel Glucocorticoid Response Element within the Genome of the Human Immunodeficiency Virus Type 1

Abstract

We have shown that (HIV-1) replication can be regulated by interaction between glucocorticoid hormones and the viral genome; treatment of acutely infected lymphoid and monocytoid cell lines with cortisol and dexamethasone increased HIV-1 production in culture. The magnitude of this response correlated with glucocorticoid receptor (GR) and GR message in responder and non-responder cell lines. Furthermore, treatment of each of two HIV-infected cell lines with glucocorticoids led to enhancement of HIV-1 gene expression. We have identified a novel intragenic glucocorticoid response element (GRE) within the genome of HIV-1 at position +5002 in the vif open reading frame, as well as a second potential GRE, previously identified by other researchers at position -257 in the HIV-1 negative regulatory element (LTR-NRE). Our data indicate that only the motif at position +5002 represents a true GRE that confers glucocorticoid inducibility to a MMTV-luciferase reporter gene construct. The GRE located at -257 lacked significant functional activity in its native configuration in that it could bind GR but did not transactivate reporter gene constructs. However, this sequence was able to impart glucocorticoid inducibility when inverted or dimerized. These results suggest that as in the case of other retroviruses, HIV-1 has evolved to interface with the GR signal transduction pathway to gain replicative advantage in target cells.