Transcriptional Cofactor CA150 Regulates RNA Polymerase II Elongation in a TATA-Box-Dependent Manner

Abstract

Tat protein strongly activates transcription from the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) by enhancing the elongation efficiency of RNA polymerase II complexes. Tat-mediated transcriptional activation requires cellular cofactors and specific cis-acting elements within the HIV-1 promoter, among them a functional TATA box. Here, we have investigated the mechanism by which one of these cofactors, termed CA150, regulates HIV-1 transcription in vivo. We present a series of functional assays that demonstrate that the regulation of the HIV-1 LTR by CA150 has the same functional requirements as the activation by Tat. We found that CA150 affects elongation of transcription complexes assembled on the HIV-1 promoter in a TATA-box-dependent manner. We discuss the data in terms of the involvement of CA150 in the regulation of Tat-activated HIV-1 gene expression. In addition, we also provide evidence suggesting a role for CA150 in the regulation of cellular transcriptional processes.

ACKNOWLEDGMENTS

We thank C. Hernández-Munain and members of the M. A. Garcia-Blanco laboratory for their help during the course of this work. We also thank P. Bohjanen, R. Carstens, A. Goldstrohm, C. Hernández-Munain, and Y. Liu for critical review of the manuscript. We also thank K.-T. Jeang for HIV-1 promoter constructs, A. Postigo for α4 integrin promoter constructs, and W. Tansey for pCGNTBP.

This research was supported by a grant from the NIH to M.A.G.-B. C.S. is supported by the NIAID Research Training Program in AIDS to the Division of Infectious Diseases at Duke University Medical Center. We also acknowledge the Keck Foundation for support to the Levine Science Research Center.