title: ZASC1 stimulates HIV-1 transcription elongation by recruiting P-TEFb and TAT to the LTR promoter.
abstract: Transcription from the HIV-1 LTR promoter efficiently initiates but rapidly terminates because of a non-processive form of RNA polymerase II. This premature termination is overcome by assembly of an HIV-1 TAT/P-TEFb complex at the transactivation response region (TAR), a structured RNA element encoded by the first 59 nt of HIV-1 mRNA. Here we have identified a conserved DNA-binding element for the cellular transcription factor, ZASC1, in the HIV-1 core promoter immediately upstream of TAR. We show that ZASC1 interacts with TAT and P-TEFb, co-operating with TAT to regulate HIV-1 gene expression, and promoting HIV-1 transcriptional elongation. The importance of ZASC1 to HIV-1 transcription elongation was confirmed through mutagenesis of the ZASC1 binding sites in the LTR promoter, shRNAs targeting ZASC1 and expression of dominant negative ZASC1. Chromatin immunoprecipitation analysis revealed that ZASC1 recruits Tat and P-TEFb to the HIV-1 core promoter in a TAR-independent manner. Thus, we have identified ZASC1 as novel regulator of HIV-1 gene expression that functions through the DNA-dependent, RNA-independent recruitment of TAT/P-TEFb to the HIV-1 promoter.
authors.affiliation: Morgridge Institute for Research, Madison, Wisconsin, United States of America ; Institute for Molecular Virology, University of Wisconsin, Madison, Wisconsin, United States of America ; McArdle Laboratory for Cancer Research, University of Wisconsin, Madison, Wisconsin, United States of America.
authors.forename: James W
authors.initials: JW
authors.lastname: Bruce
authors.forename: Rachel
authors.initials: R
authors.lastname: Reddington
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Mathieu
authors.forename: Megan
authors.initials: M
authors.lastname: Bracken
authors.forename: John A T
authors.initials: JA
authors.lastname: Young
authors.forename: Paul
authors.initials: P
authors.lastname: Ahlquist
mesh_terms: D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015658:HIV Infections / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D042925:Positive Transcriptional Elongation Factor B / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D061805:Transcription Elongation, Genetic; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C479231:ZNF639 protein, human; D054322:tat Gene Products, Human Immunodeficiency Virus; D042925:Positive Transcriptional Elongation Factor B