Youn Tae Kwak

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NF-kappaB, a key regulator of the cellular inflammatory and immune response, is activated by the HTLV-I transforming and transactivating protein Tax. We show that Tax binds to the amino terminus of the protein kinase MEKK1, a component of an IkappaB kinase complex, and stimulates MEKK1 kinase activity. Tax expression increases the activity of IkappaB kinase(More)
SPT5 and its binding partner SPT4 regulate transcriptional elongation by RNA polymerase II. SPT4 and SPT5 are involved in both 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB)-mediated transcriptional inhibition and the activation of transcriptional elongation by the human immunodeficiency virus type 1 (HIV-1) Tat protein. Recent data suggest that(More)
Heat shock protein 27 (Hsp27) is a ubiquitously expressed member of the heat shock protein family that has been implicated in various biological functions including the response to heat shock, oxidative stress, and cytokine treatment. Previous studies have demonstrated that heat shock proteins are involved in regulating signal transduction pathways(More)
Recent iPrEx clinical trial results provided evidence that systemic preexposure prophylaxis (PrEP) with emtricitabine (FTC) and tenofovir disoproxil fumarate (TDF) can partially prevent rectal HIV transmission in humans. Similarly, we have previously demonstrated that systemic administration of the same FTC-TDF combination efficiently prevented rectal(More)
Tat activates transcription from the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) by increasing the processivity of RNA polymerase II. Recently, it has been demonstrated that the cellular kinase CDK9 and its binding partner cyclin T1 are involved in regulating transcriptional elongation and tat-activation. Cyclin T1, CDK9 and Tat(More)
Successful antiretroviral pre-exposure prophylaxis (PrEP) for mucosal and intravenous HIV-1 transmission could reduce new infections among targeted high-risk populations including discordant couples, injection drug users, high-risk women and men who have sex with men. Targeted antiretroviral PrEP could be particularly effective at slowing the spread of(More)
The NF-kappaB pathway is important in the control of the immune and inflammatory response. One of the critical events in the activation of this pathway is the stimulation of the IkappaB kinases (IKKs) by cytokines such as tumor necrosis factor-alpha and interleukin-1. Although the mechanisms that modulate IKK activation have been studied in detail, much(More)
Human cyclin T1 markedly stimulates tat-activation in rodent cells which are normally poorly responsive to the effects of Tat. This result suggests that there are likely to be critical differences in the murine and human cyclin T1 proteins. Here, we analyzed the role of the murine and human cyclin T1 proteins in addition to the human cyclin T2a and T2b(More)
SPT5 and its binding partner SPT4 function in both positively and negatively regulating transcriptional elongation. The demonstration that SPT5 and RNA polymerase II are targets for phosphorylation by CDK9/cyclin T1 indicates that posttranslational modifications of these factors are important in regulating the elongation process. In this study, we utilized(More)
IKKgamma/NEMO is an essential regulatory component of the IkappaB kinase complex that is required for NF-kappaB activation in response to various stimuli including tumor necrosis factor-alpha and interleukin-1beta. To investigate the mechanism by which IKKgamma/NEMO regulates the IKK complex, we examined the ability of IKKgamma/NEMO to recruit the IkappaB(More)