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Kaposi's sarcoma associated herpesvirus (KSHV)/human herpesvirus 8 (HHV-8) encodes an immediate early transcriptional activator, Rta, which mediates viral reactivation from latency and lytic viral replication. Here we report the purification and characterizations of HHV-8 Rta and its interaction with Rta-responsive DNA elements. The Rta response element(More)
Expression of the human T lymphotropic virus type I (HTLV-I) transactivator/oncoprotein, Tax, leads to faulty mitosis as reflected by chromosome aneuploidy, cytokinesis failure, and formation of micro- and multinucleated cells. Here we show that HTLV-I-transformed T cells progress through S/G(2)/M phases of the cell cycle with a delay. This delay is(More)
Potent activation of human T-cell leukemia virus type 1 (HTLV-1) gene expression is mediated by the virus-encoded transactivator protein Tax and three imperfect 21-bp repeats in the viral long terminal repeats. Each 21-bp repeat contains a cAMP-responsive-element core flanked by 5' G-rich and 3' C-rich sequences. Tax alone does not bind DNA. Rather, it(More)
Outer dense fiber 2 (Odf2) was initially identified as a major component of sperm tail cytoskeleton and later was suggested to be a widespread component of centrosomal scaffold that preferentially associates with the appendages of the mother centrioles in somatic cells. Here we report the identification of two Odf2-related centrosomal components, hCenexin1(More)
The human T-lymphotropic virus type 1 (HTLV-1) Tax binds the anaphase promoting complex (APC) and activates it ahead of schedule. Here, we show that APC activation by Tax induces rapid senescence (tax-IRS) independently of p53 and pRB. In response to tax, cyclin A, cyclin B1, securin, and Skp2 becomes polyubiquitinated and degraded starting in S phase. This(More)
The regulatory circuit for Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV-8) gene expression bears resemblance to that of Epstein-Barr virus (EBV), but with interesting differences. Based on protein sequence similarities and synteny to their EBV counterparts, two KSHV/HHV-8 viral regulatory factors, HHV-8 Rta and K-bZIP, encoded by(More)
Human T-lymphotropic virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia. The HTLV-1 transactivator, Tax, is implicated as the viral oncoprotein. Naïve cells expressing Tax for the first time develop severe cell cycle abnormalities that include increased DNA synthesis, mitotic arrest, appearance of convoluted nuclei with decondensed DNA,(More)
Human T-lymphotropic virus type I (HTLV-1) is the etiological agent of adult T-cell leukemia/lymphoma (ATL) and HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-1 viral transactivator/oncoprotein, Tax, activates viral transcription and usurps regulatory mechanisms that are critical for cell growth and division to facilitate viral(More)
I-kappa B kinase (IKK) is a serine/threonine kinase that phosphorylates I-kappa B alpha and I-kappa B beta and targets them for polyubiquitination and proteasome-mediated degradation. IKK consists of two highly related catalytic subunits, alpha and beta, and a regulatory gamma subunit, which becomes activated after serine phosphorylation of the activation(More)