Zhiyuan Yang

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The cyclinT1/Cdk9 heterodimer that constitutes core P-TEFb is generally presumed to be the transcriptionally active form for stimulating RNA polymerase II elongation. About half of cellular P-TEFb also exists in an inactive complex with the 7SK snRNA and the HEXIM1 protein. Here, we show that the remaining half associates with the bromodomain protein Brd4.(More)
The pathway causing CD4 T-cell death in HIV-infected hosts remains poorly understood although apoptosis has been proposed as a key mechanism. We now show that caspase-3-mediated apoptosis accounts for the death of only a small fraction of CD4 T cells corresponding to those that are both activated and productively infected. The remaining over 95% of(More)
The mechanism by which CD4 T cells are depleted in HIV-infected hosts remains poorly understood. In ex vivo cultures of human tonsil tissue, CD4 T cells undergo a pronounced cytopathic response following HIV infection. Strikingly, >95% of these dying cells are not productively infected but instead correspond to bystander cells. We now show that the death of(More)
The positive transcription elongation factor b (P-TEFb), comprising CDK9 and cyclin T, stimulates transcription of cellular and viral genes by phosphorylating RNA polymerase II. A major portion of nuclear P-TEFb is sequestered and inactivated by the coordinated actions of the 7SK snRNA and the HEXIM1 protein, whose induced dissociation from P-TEFb is(More)
Brd4, a bromodomain protein capable of interacting with acetylated histones, is implicated in transmitting epigenetic memory through mitosis. It also functions as an associated factor and positive regulator of P-TEFb, a Cdk9-cyclin T1 heterodimer that stimulates transcriptional elongation by phosphorylating RNA polymerase II. In the present study,(More)
In order to find the immune-relevant factors responsible for the virus resistance in the WSSV-resistant shrimp, a suppression subtractive hybridization method was employed to identify differentially expressed genes and their expression profile in the hepatopancreas of the virus-resistant penaeid shrimp. Thirty five genes were identified from more than 400(More)
The progressive depletion of quiescent "bystander" CD4 T cells, which are nonpermissive to HIV infection, is a principal driver of the acquired immunodeficiency syndrome (AIDS). These cells undergo abortive infection characterized by the cytosolic accumulation of incomplete HIV reverse transcripts. These viral DNAs are sensed by an unidentified host sensor(More)
Long interspersed element-1 (LINE-1 or L1) retrotransposons account for nearly 17% of human genomic DNA and represent a major evolutionary force that has reshaped the structure and function of the human genome. However, questions remain concerning both the frequency and the developmental timing of L1 retrotransposition in vivo and whether the mobility of(More)
Human immunodeficiency virus type 1 (HIV-1) transcriptional transactivator (Tat) recruits the positive transcription elongation factor b (P-TEFb) to the viral promoter. Consisting of cyclin dependent kinase 9 (Cdk9) and cyclin T1, P-TEFb phosphorylates RNA polymerase II and the negative transcription elongation factor to stimulate the elongation of HIV-1(More)
The progressive depletion of CD4 T cells underlies clinical progression to AIDS in untreated HIV-infected subjects. Most dying CD4 T cells correspond to resting nonpermissive cells residing in lymphoid tissues. Death is due to an innate immune response against the incomplete cytosolic viral DNA intermediates accumulating in these cells. The viral DNA is(More)