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Constitutive activation of Epstein-Barr virus (EBV) nuclear antigen 1 gene transcription by IRF1 and IRF2 during restricted EBV latency.
Mol Cell Biol. 1997 Feb; 17(2):873-86.MC

Abstract

The Epstein-Barr virus (EBV) EBNA1 gene promoter active in the type I program of restricted viral latency was recently identified and shown to reside in the viral BamHI Q fragment. This promoter, Qp, is active in a wide variety of cell lines and has an architecture reminiscent of eukaryotic housekeeping gene promoters (B. C. Schaefer, J. L. Strominger, and S. H. Speck, Proc. Natl. Acad. Sci. USA 92:10565-10569, 1995; B. C. Schaefer, J. L. Strominger, and S. H. Speck, Mol. Cell. Biol. 17:364-377, 1997). Here we demonstrate by deletion analysis that the important cis-acting elements regulating Qp are clustered in a relatively small region (ca. 80 bp) surrounding the site of transcription initiation. Immediately upstream of the site of initiation is a region which is protected from DNase I digestion by crude nuclear extracts. Electrophoretic mobility shift analyses (EMSA) employing probes spanning this region demonstrated the presence of two major protein complexes. Deletion analysis of Qp demonstrated that at least one of these complexes plays an important role in Qp activity. Evidence that interferon response factor 2 (IRF2) is a major constituent of the most prominent EMSA complex and that IRF1 may be a minor component of this complex is presented. Transfections into IRF1-/-, IRF2-/-, and IRF1,2-/- fibroblasts demonstrated that absence of both IRF1 and IRF2 reduced Qp activity to approximately the same extent as mutation of the IRF-binding site in Qp, strongly implicating IRF2, and perhaps IRF1, in the regulation of Qp activity. Notably, transcription from Qp was not inducible by either alpha or gamma interferon in EBV-negative B cells but rather was shown to be constitutively activated by IRF1 and IRF2. This observation suggests that IRF1 and IRF2 have a previously unrecognized role as constitutive activators of specific genes. Additionally, data presented indicate that a protein complex containing the nonhistone architectural protein HMG-I(Y) binds to the region identified as the major transcription initiation site for Qp. This observation raises the possibility that HMG-I(Y)-induced DNA bending plays a role in the initiation of transcription from Qp.

Authors+Show Affiliations

Division of Tumor Virology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

9001242

Citation

Schaefer, B C., et al. "Constitutive Activation of Epstein-Barr Virus (EBV) Nuclear Antigen 1 Gene Transcription By IRF1 and IRF2 During Restricted EBV Latency." Molecular and Cellular Biology, vol. 17, no. 2, 1997, pp. 873-86.
Schaefer BC, Paulson E, Strominger JL, et al. Constitutive activation of Epstein-Barr virus (EBV) nuclear antigen 1 gene transcription by IRF1 and IRF2 during restricted EBV latency. Mol Cell Biol. 1997;17(2):873-86.
Schaefer, B. C., Paulson, E., Strominger, J. L., & Speck, S. H. (1997). Constitutive activation of Epstein-Barr virus (EBV) nuclear antigen 1 gene transcription by IRF1 and IRF2 during restricted EBV latency. Molecular and Cellular Biology, 17(2), 873-86.
Schaefer BC, et al. Constitutive Activation of Epstein-Barr Virus (EBV) Nuclear Antigen 1 Gene Transcription By IRF1 and IRF2 During Restricted EBV Latency. Mol Cell Biol. 1997;17(2):873-86. PubMed PMID: 9001242.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Constitutive activation of Epstein-Barr virus (EBV) nuclear antigen 1 gene transcription by IRF1 and IRF2 during restricted EBV latency. AU - Schaefer,B C, AU - Paulson,E, AU - Strominger,J L, AU - Speck,S H, PY - 1997/2/1/pubmed PY - 1997/2/1/medline PY - 1997/2/1/entrez SP - 873 EP - 86 JF - Molecular and cellular biology JO - Mol Cell Biol VL - 17 IS - 2 N2 - The Epstein-Barr virus (EBV) EBNA1 gene promoter active in the type I program of restricted viral latency was recently identified and shown to reside in the viral BamHI Q fragment. This promoter, Qp, is active in a wide variety of cell lines and has an architecture reminiscent of eukaryotic housekeeping gene promoters (B. C. Schaefer, J. L. Strominger, and S. H. Speck, Proc. Natl. Acad. Sci. USA 92:10565-10569, 1995; B. C. Schaefer, J. L. Strominger, and S. H. Speck, Mol. Cell. Biol. 17:364-377, 1997). Here we demonstrate by deletion analysis that the important cis-acting elements regulating Qp are clustered in a relatively small region (ca. 80 bp) surrounding the site of transcription initiation. Immediately upstream of the site of initiation is a region which is protected from DNase I digestion by crude nuclear extracts. Electrophoretic mobility shift analyses (EMSA) employing probes spanning this region demonstrated the presence of two major protein complexes. Deletion analysis of Qp demonstrated that at least one of these complexes plays an important role in Qp activity. Evidence that interferon response factor 2 (IRF2) is a major constituent of the most prominent EMSA complex and that IRF1 may be a minor component of this complex is presented. Transfections into IRF1-/-, IRF2-/-, and IRF1,2-/- fibroblasts demonstrated that absence of both IRF1 and IRF2 reduced Qp activity to approximately the same extent as mutation of the IRF-binding site in Qp, strongly implicating IRF2, and perhaps IRF1, in the regulation of Qp activity. Notably, transcription from Qp was not inducible by either alpha or gamma interferon in EBV-negative B cells but rather was shown to be constitutively activated by IRF1 and IRF2. This observation suggests that IRF1 and IRF2 have a previously unrecognized role as constitutive activators of specific genes. Additionally, data presented indicate that a protein complex containing the nonhistone architectural protein HMG-I(Y) binds to the region identified as the major transcription initiation site for Qp. This observation raises the possibility that HMG-I(Y)-induced DNA bending plays a role in the initiation of transcription from Qp. SN - 0270-7306 UR - https://www.unboundmedicine.com/medline/citation/9001242/Constitutive_activation_of_Epstein_Barr_virus__EBV__nuclear_antigen_1_gene_transcription_by_IRF1_and_IRF2_during_restricted_EBV_latency_ L2 - http://mcb.asm.org/cgi/pmidlookup?view=long&pmid=9001242 DB - PRIME DP - Unbound Medicine ER -