The transactivating response element （TAR） structure of the nascent HIV-1 transcript is critically involved in the recruitment of inactive positive transcription elongation factor b （P-TEFb） to the promoter proxim...The transactivating response element （TAR） structure of the nascent HIV-1 transcript is critically involved in the recruitment of inactive positive transcription elongation factor b （P-TEFb） to the promoter proximal paused RNA polymerase II. The viral transactivator Tat is responsible for subsequent P-TEFb activation in order to start efficient viral transcription elongation. In the absence of the viral transactivator of transcription （Tat）, e.g., during latency or in early stages of HIV tran- scription, TAR mediates an interaction of P-TEFb with its inhibitor hexamethylene bis-aeetamide- inducible protein 1 （HEXIM1）, keeping P-TEFb in its inactive form. In this study, we address the function of HIV-1 TAR in the absence of Tat by analyzing consequences of HIV-1 TAR overexpres- sion on host cellular gene expression. An RNA chimera consisting of Epstein-Barr virus-expressed RNA 2 （EBER2） and HIV-1 TAR was developed to assure robust overexpression of TAR in HEK293 cells. The overexpression results in differential expression of more than 800 human genes. A significant proportion of these genes is involved in the suppression of cellular immune responses, including a significant set of 7SK-responsive P-TEFb target genes. Our findings identify a novel role for HIV-1 TAR in the absence of Tat, involving the interference with host cellular immune responses by targeting 7SK RNA-mediated gene expression and P-TEFb inactivation.展开更多
基金supported by funds from the Genopole Evrythe Institut des Hautes ètudes Scientifiquesthe Centre National de la Recherche Scientifique (CNRS),France,awarded to AGB
文摘The transactivating response element （TAR） structure of the nascent HIV-1 transcript is critically involved in the recruitment of inactive positive transcription elongation factor b （P-TEFb） to the promoter proximal paused RNA polymerase II. The viral transactivator Tat is responsible for subsequent P-TEFb activation in order to start efficient viral transcription elongation. In the absence of the viral transactivator of transcription （Tat）, e.g., during latency or in early stages of HIV tran- scription, TAR mediates an interaction of P-TEFb with its inhibitor hexamethylene bis-aeetamide- inducible protein 1 （HEXIM1）, keeping P-TEFb in its inactive form. In this study, we address the function of HIV-1 TAR in the absence of Tat by analyzing consequences of HIV-1 TAR overexpres- sion on host cellular gene expression. An RNA chimera consisting of Epstein-Barr virus-expressed RNA 2 （EBER2） and HIV-1 TAR was developed to assure robust overexpression of TAR in HEK293 cells. The overexpression results in differential expression of more than 800 human genes. A significant proportion of these genes is involved in the suppression of cellular immune responses, including a significant set of 7SK-responsive P-TEFb target genes. Our findings identify a novel role for HIV-1 TAR in the absence of Tat, involving the interference with host cellular immune responses by targeting 7SK RNA-mediated gene expression and P-TEFb inactivation.
