NF-κB-Repressing Factor Inhibits Elongation of Human Immunodeficiency Virus Type 1 Transcription by DRB Sensitivity-Inducing Factor

Abstract

Human immunodeficiency virus type 1 (HIV-1) is able to establish a latent infection during which the integrated provirus remains transcriptionally silent. In response to specific stimuli, the HIV-1 long terminal repeat (LTR) is highly activated, enhancing both transcriptional initiation and elongation. Here, we have identified a specific binding sequence of the nuclear NF-B-repressing factor (NRF) within the HIV-1 LTR. The aim of this work was to define the role of NRF in regulating the LTR. Our data show that the endogenous NRF is required for transcriptional activation of the HIV-1 LTR in stimulated cells. In unstimulated cells, however, NRF inhibits HIV-1 LTR activity at the level of transcription elongation. Binding of NRF to the LTR in unstimulated cells prevents recruitment of elongation factor DRB sensitivity-inducing factor and formation of processive elongation complexes by hyperphosphorylated RNA polymerase II. Our data suggest that NRF interrupts the regulatory coupling of LTR binding factors and transcription elongation events. This inhibitory mechanism might contribute to transcriptional quiescence of integrated HIV-1 provirus.

Neutrophil Elastase Represses IL-8/CXCL8 Synthesis in Human Airway Smooth Muscle Cells through Induction of NF-κB Repressing Factor

“…In agreement with this, we found that p65 and NRF were both recruited to the IL-8/CXCL8 promoter in hASM cells following NE stimulation. This NRF-NF-B protein-protein interaction has been suggested to prevent recruitment of elongation factor DRB sensitivity-inducing factor and hence to interrupt the transcriptional elongation for the HIV-1 LTR reporter (26). However, such an observation was made on a synthesized promoter, where the condition of nucleosome assembled may be different from that at the native promoters or the DNA may be naked, therefore effects via the chromatin would be ignored.…”

“…Studies using a HIV-1 LTR reporter showed that NRF was constitutively binding to LTR and inhibiting its transcription activity. However, NRF seems to become required for transcriptional activation of the HIV-1 LTR upon stimulation with PMA and ionomycin (26), in which the level of NRF binding to the LTR is not changed. It is therefore suggested that endogenous NRF plays a dual role in gene transcription (24).…”

“…Using anti-sense RNA, endogenous NRF has been reported to be implicated in the basal silencing of specific NF-B targeting genes, including IFN-␤, IL-8/CXCL8, iNOS, and HIV type 1 (HIV-1) long terminal repeat (LTR) (23)(24)(25)(26). This silencing effect is mediated by NRF binding to negative regulatory elements, or NREs, in their promoters (23)(24)(25)(26). NRF binding to DNA specifically abolishes the transcriptional activity of the bordering NF-B binding sites by a noncompeting, distance, and position-independent mechanism (23).…”

Human NF-κB repressing factor acts as a stress-regulated switch for ribosomal RNA processing and nucleolar homeostasis surveillance

“…NKRF is known to bind specific DNA sequences in several NF-κB-regulated genes and to interact with NF-κB/p65, differentially controlling NF-κB-driven transcription under basal and/or stimulated conditions (10)(11)(12)(13)(14). Therefore, proteotoxic stress-induced NKRF expression and dynamic nucleolar-nuclear movement may contribute to NF-κB-driven transcription regulation, with important implications in inflammation and cancer.…”

Transcriptional Repression of Human Immunodeficiency Virus Type 1 by AP-4

“…8A, the newly raised anti-AP-4 antibody could specifically precipitate AP-4. Although the nature and/or the extent of chromatin formation on transiently transfected DNA templates likely differ from that of chromosomal genes, previous reports of ChIP assays using plasmids containing HIV-1 LTR have validated ChIP studies in transiently transfected cells (32)(33)(34)(35). In Fig.…”