A Coreceptor for HIV-1 Entry CXCR4, Suppresses, the Promoter Activity Of
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USF/c-Myc Enhances, While Yin-Yang 1 Suppresses, the Promoter Activity of CXCR4, a Coreceptor for HIV-1 Entry This information is current as Masako Moriuchi, Hiroyuki Moriuchi, David M. Margolis of September 23, 2021. and Anthony S. Fauci J Immunol 1999; 162:5986-5992; ; http://www.jimmunol.org/content/162/10/5986 Downloaded from References This article cites 41 articles, 26 of which you can access for free at: http://www.jimmunol.org/content/162/10/5986.full#ref-list-1 Why The JI? Submit online. http://www.jimmunol.org/ • Rapid Reviews! 30 days* from submission to initial decision • No Triage! Every submission reviewed by practicing scientists • Fast Publication! 4 weeks from acceptance to publication *average by guest on September 23, 2021 Subscription Information about subscribing to The Journal of Immunology is online at: http://jimmunol.org/subscription Permissions Submit copyright permission requests at: http://www.aai.org/About/Publications/JI/copyright.html Email Alerts Receive free email-alerts when new articles cite this article. Sign up at: http://jimmunol.org/alerts The Journal of Immunology is published twice each month by The American Association of Immunologists, Inc., 1451 Rockville Pike, Suite 650, Rockville, MD 20852 Copyright © 1999 by The American Association of Immunologists All rights reserved. Print ISSN: 0022-1767 Online ISSN: 1550-6606. USF/c-Myc Enhances, While Yin-Yang 1 Suppresses, the Promoter Activity of CXCR4, a Coreceptor for HIV-1 Entry Masako Moriuchi,1* Hiroyuki Moriuchi,1,2* David M. Margolis,† and Anthony S. Fauci* Transcription factors USF1 and USF2 up-regulate gene expression (i.e., HIV-1 long terminal repeats) via interaction with an E box on their target promoters, which is also a binding site for c-Myc. The c-Myc oncoprotein is important in control of cellular proliferation and differentiation, while Yin-Yang 1 (YY1) has been shown to control the expression of a number of cellular and viral genes. These two proteins physically interact with each other and mutually inhibit their respective biological functions. In this study, we show that USF/c-Myc up-regulates, while YY1 down-regulates the promoter activity of CXCR4, a coreceptor for T cell-tropic HIV-1 entry. We have identified an E box around 2260 and a YY1 binding site around 2300 relative to the transcription start site. Mutation of the E box abolished USF/c-Myc-mediated up-regulation of CXCR4 promoter activity, and mutation of the YY1 binding site was associated with unresponsiveness to YY1-mediated inhibition. These data suggest that Downloaded from USF/c-Myc and YY1 may play an important role in the HIV-1-replicative cycle, by modulating both the viral fusion/entry process and viral expression. The Journal of Immunology, 1999, 162: 5986–5992. number of cellular factors of the host have been shown monocytes has also been shown to be down-regulated upon dif- to modulate replication of HIV-1 at various steps of the ferentiation of these cells into mature macrophages (25). viral replication cycle (1). At the level of viral expres- In this study, we characterize the further upstream region of the A http://www.jimmunol.org/ sion, numerous cellular transcription factors regulate transcription CXCR4 promoter. We report that USF/c-Myc and YY1 bind to the from the long terminal repeat (LTR),3 the promoter of HIV-1. upstream region of the CXCR4 promoter, and positively or nega- While many of these factors (i.e., nuclear factor-kB/Rel family tively regulate the CXCR4 promoter, respectively. Involvement of proteins (2), C/EBP (NF-IL6) (3, 4), Sp1 (5), or USF (6)) enhance USF and YY1 at two critical steps of HIV-1 replication, viral LTR activity (reviewed in Ref. 7), a few factors have been shown fusion/entry and expression, suggests that these transcription fac- to directly reduce HIV expression at the promoter level. YY1, a tors may play a role in the pathogenesis of HIV disease. multifunctional transcription factor, has been shown to repress a number of cellular and viral gene promoters (reviewed in Ref. 8), Materials and Methods including the HIV-1 LTR (9, 10). Plasmids by guest on September 23, 2021 Host cell factors also affect HIV at earlier steps in its replication Plasmid pGL-CXCR4(2357) contains the CXCR4 upstream sequence be- cycle. HIV-1 entry into cells requires the CD4 molecule as well as tween 2357 and 151 relative to the transcription start site (TSS), followed a fusion/entry cofactor (11–18). Several chemokine receptors serve by the luciferase gene (24). Plasmids pGL-CXCR4DE box and pGL- D as fusion/entry cofactors, among which CXCR4, a receptor for CXCR4 YY1 were constructed by PCR-based site-directed mutagenesis (26) to generate mutations on an E box around 2260 and on a YY1 binding CXC chemokine stromal-derived factor (SDF-1) (19, 20), is a ma- site around 2300 relative to the TSS, respectively (see Table I and Fig. 1). jor fusion/entry cofactor for T cell-tropic HIV-1. Functional ex- Plasmid pBpuro-c-myc-ER (a generous gift of T. D. Littlewood, Imperical pression of CXCR4 is influenced by other host cell factors. SDF-1, Cancer Research Fund, London, U.K.) encodes human c-Myc fused to the a ligand of CXCR4, regulates cell surface expression of CXCR4 hormone-binding domain of the mutant murine estrogen receptor. Func- (21, 22), whereas IL-2 regulates the steady-state level of CXCR4 tional expression of a c-Myc fusion protein by the transfected plasmid is induced by 4-hydroxytamoxifen (10 nM; Sigma, St. Louis, MO) (27). Plas- mRNA (23). We have recently cloned and analyzed the promoter mids pCMV-Myc and pCMV-Max were gifts of D. Ayer (University of region of CXCR4 (24), and found that two transcription factors, Utah, Salt Lake City, UT) (28) and used for in vitro synthesis of c-Myc and nuclear respiratory factor-1 (NRF-1) and Sp1, interact with the Max proteins. USF expression plasmids pSV-USF1 and pSV-USF2 were proximal region of the CXCR4 promoter, and that the former is kindly provided by M. Sawadogo (University of Texas M. D. Anderson Can- cer Center, Houston, TX) (29), and a YY1 expression plasmid pCMV-YY1 critical for CXCR4 promoter activity. CXCR4 expression on was a generous gift of T. Shenk (Princeton University, Princeton, NJ) (30). Cells *Laboratory of Immunoregulation, National Institute of Allergy and Infectious Dis- eases, National Institutes of Health, Bethesda, MD 20892; and †Institute of Human PBMC were obtained from healthy volunteers, as described previously (31). Virology, University of Maryland, Baltimore, MD 21201 A3.01 human CD41 T cells were propagated as described previously (24, 32). Received for publication October 2, 1998. Accepted for publication February b 16, 1999. Transfection, and luciferase and -galactosidase assays The costs of publication of this article were defrayed in part by the payment of page Transient expression and luciferase and b-galactosidase assays were per- charges. This article must therefore be hereby marked advertisement in accordance formed as described previously (32, 33). with 18 U.S.C. Section 1734 solely to indicate this fact. DNase I footprinting 1 M.M. and H.M. contributed equally to this project. 2 Address correspondence and reprint requests to Dr. H. Moriuchi, Department of DNase I footprinting was performed as described previously (34). Probes Pediatrics, Nagasaki University School of Medicine, 1-7-1 Sakamoto, Nagasaki 852- used for DNase I footprinting were prepared as follows: a MluI-SacI frag- 8501, Japan. ment and a MluI-SphI fragment of pGL-CXCR4(2357) were labeled with 32 3 Abbreviations used in this paper: LTR, long terminal repeat; bHLHZip, basic re- [ P]dCTP using Klenow enzyme and gel purified. These fragments span gion-helix-loop-helix-zipper; CyPA, cyclophilin A; NRF-1, nuclear respiratory fac- the CXCR4 promoter sequence between 2357 and 2277, and between tor-1; SDF-1, stromal-derived factor-1; TSS, transcription start site; YY1, Yin-Yang 1. 2283 and 246, respectively, relative to the TSS. Furthermore, the CXCR4 Copyright © 1999 by The American Association of Immunologists 0022-1767/99/$02.00 The Journal of Immunology 5987 Table I. Oligonucleotides used for gel mobility shift assays and Biotechnology), anti-USF-1, or anti-USF2 rabbit polyclonal Ab (provided site-directed mutagenesisa by M. Sawadogo). Oligonucleotide Sequence Results L-E box 59-TGCTAGCTTCCCACCTGTCTTCAGGCGCATC-39 ACGATCGAAGGGTGGACAGAAGTCCGCGTAG Identification of putative cis-acting elements in the upstream L-E box-m 59-TGCTAGCTTCCTGTCTGTCTTCAGGCGCATC-39 region of the CXCR4 promoter ACGATCGAAGGACAGACAGAAGTCCGCGTAG E box 59-GGAAGCAGACCACGTGGTCTGCTTCC-39 First, we assessed the binding of cellular transcription factors to the CCTTCGTCTGGTGCACCAGACGAAGG CXCR4 promoter region between 2350 and 2150 relative to the TSS L-YY1 59-TAGCAAGGATGGACGCGCCACAGAGAGAC-39 in DNase I footprinting analysis. Among areas protected from DNase ATCGTTCCTACCTGCGCGGTGTCTCTCTG I digestion (Figs. 1 and 2), regions around 2260 (FP-5) and 2300 L-YY1-m1 59-TAGCAAGGATCCACGCGCCACAGAGAGAC-39 ATCGTTCCTAGGTGCGCGGTGTCTCTCTG (FP-6) were found to share homology to an E box (a binding site for L-YY1-m2 59-TAGCAAGGATGGACGCGCCACCTAGAGAC-39 basic region-helix-loop-helix-leucine zipper (bHLHZip) family pro- ATCGTTCCTACCTGCGCGGTGGATCTCTG teins (35)) and a YY1 binding site (8), respectively. YY1 59-CGCTCCGCGGCCATCTTGGCGGCTGGT-39 GCGAGGCGCCGGTAGAACCGCCGACCA GATA 59-CACTTGATAACAGAAAGTGATAACTCT-39 GTGAACTATTGTCTTTCACTATTGAGA bHLHZip proteins c-Myc, USF-1, and USF-2 bind to the STAT 59-GTATTTCCCAGAAAAGGAAC-39 CXCR4 promoter Downloaded from CATAAAGGGTCTTTTCCTTG To demonstrate that the putative E box in the CXCR4 promoter a Sequences corresponding to cis-acting elements are underlined. Mutated nucle- region actually serves as a binding site for bHLHZip family of otides are shown in bold letters. Oligonucleotides E box, YY1, GATA, and STAT transcription factors, gel-mobility shift assays were performed us- were purchased from Santa Cruz Biotechnology.