Stem-loop binding protein is a multifaceted cellular regulator of HIV-1 replication
Ming Li, … , Michelle A. Lally, Bharat Ramratnam
Ming Li, … , Michelle A. Lally, Bharat Ramratnam
Published July 25, 2016
Citation Information: J Clin Invest. 2016;126(8):3117-3129. https://doi.org/10.1172/JCI82360.
View: Text | PDF
Research Article AIDS/HIV Article has an altmetric score of 3

Stem-loop binding protein is a multifaceted cellular regulator of HIV-1 replication

Abstract

A rare subset of HIV-1–infected individuals is able to maintain plasma viral load (VL) at low levels without antiretroviral treatment. Identifying the mechanisms underlying this atypical response to infection may lead to therapeutic advances for treating HIV-1. Here, we developed a proteomic analysis to compare peripheral blood cell proteomes in 20 HIV-1–infected individuals who maintained either high or low VL with the aim of identifying host factors that impact HIV-1 replication. We determined that the levels of multiple histone proteins were markedly decreased in cohorts of individuals with high VL. This reduction was correlated with lower levels of stem-loop binding protein (SLBP), which is known to control histone metabolism. Depletion of cellular SLBP increased promoter engagement with the chromatin structures of the host gene high mobility group protein A1 (HMGA1) and viral long terminal repeat (LTR), which led to higher levels of HIV-1 genomic integration and proviral transcription. Further, we determined that TNF-α regulates expression of SLBP and observed that plasma TNF-α levels in HIV-1–infected individuals correlated directly with VL levels and inversely with cellular SLBP levels. Our findings identify SLBP as a potentially important cellular regulator of HIV-1, thereby establishing a link between histone metabolism, inflammation, and HIV-1 infection.

Authors

Ming Li, Lynne D. Tucker, John M. Asara, Collins K. Cheruiyot, Huafei Lu, Zhijin J. Wu, Michael C. Newstein, Mark S. Dooner, Jennifer Friedman, Michelle A. Lally, Bharat Ramratnam

×

Figure 2

Identification of HIV-1–related host factors by a 2-phase β-gal reporter assay.

Options: View larger image (or click on image) Download as PowerPoint
Identification of HIV-1–related host factors by a 2-phase β-gal reporter...
(A) Schematic representation of siRNA screen to identify potential roles of the 23 host candidates in the HIV-1 life cycle. siRNAs against each candidate were transfected into TZM-bl cells. HIV-1NL4-3 was added at 24 hours after transfection. Forty-eight hours after infection, cells were subjected to phase I β-gal assay. For phase II, the culture supernatant was HIV-1 p24-adjusted and added to fresh TZM-bl cells. Twenty-four hours after the addition of supernatant, the fresh cells were subjected to β-gal quantification. (B) Phase I β-gal assay results revealed that depletion of 5 of 23 proteins (KPNA2, PGM2, H2AZ, H2B1N, and H4) led to a significant change in reporter activity. (C) No candidates impacted phase II β-gal assay results. In both phase I and II assays, nontarget siRNA control (negative control), siRNA against CD4 (positive control for phase I), and RABEK (positive control for phase II) were also used. For each candidate, analyses were performed in 3 biologic replicates, each associated with technical triplicate measurements. Student’s t test; *P < 0.05, **P < 0.01; error bars represent ± SD.