Project description:Objective/Hypothesis: To assess the efficacy and mechanism of action of a novel approach to mitigate acute and chronic radiation toxicity in a validated animal model. We propose that synthetic triterpenoid RTA-408, an Nrf2 activator, activates additional protective pathways which stabilize soft tissue during radiation, thereby reducing necrosis and improves surgical outcomes in a subsequently created axial rotational flap. Methods: Experimental animal study utilizing Sprague-Dawley rats were divided into 3 cohorts: (i) radiation + DMSO (inert vehicle), (ii) radiation + RTA-408 (therapeutic drug), and (iii) no radiation + DMSO. Two main groups of rats were utilized in these experiments: (i) rotational flap experiment (n=40) and (ii) transcriptome analysis (n=9). In the first experiment all animals in the radiation cohorts underwent 40 Gy of radiation to the soft tissue of the abdomen. Then all three cohorts underwent surgery with construction of an inferior epigastric axial rotational flap, which was performed 30 days after resolution of acute injury from radiation in the radiation groups. Percentage of flap necrosis, the primary endpoint, was calculated by standardized measurement of tissue necrosis by blinded observers and vascular density measured by CD31 staining. In a second experiment, an additional three cohorts, with identical treatment as described above underwent serial punch biopsies of the abdominal skin before, during, and after radiation and drug/vehicle control treatment. Transcriptome analysis utilizing gene set enrichment analysis and digital PCR were performed at the various timepoints. Results: In the first experiment, 40 rats were divided into the three groups and underwent treatment accordingly. The average flap necrosis was 20% (95% CI, 16-45%) in the radiation control group, 3% (95% CI, 0-11%) in the non-irradiated control, and 3% (95% CI, 0.2-10%) in the radiation group treated with RTA-408. Vascular density was preserved in the treatment group as compared to the radiated control. Nine rats were included in the second experiment, and transcriptome analyses in the treatment group revealed robust activation of antioxidant pathways with induced expression of genes associated with hypoxia and adipogenesis/angiogenesis. Conclusions: Administration of RTA-408 during radiation treatment in a rat model resulted in transcriptome changes which appear to mitigate the toxic effects of radiation, preserving capillary networks and improving flap survival and tissue healing after subsequent surgery. Such reductions in toxicity may have broad implications for functional outcomes and salvage surgery following therapeutic irradiation.
Project description:Lytic reactivation from latency is critical for the pathogenesis of KSHV. We previously demonstrated that the 691 amino acid KSHV Rta transcriptional transactivator is necessary and sufficient to reactivate the virus from latency. Viral lytic cycle genes, including those expressing additional transactivators and putative oncogenes, are induced in a cascade fashion following Rta expression. In this study, we sought to define Rta’s direct targets during reactivation by generating a conditionally nuclear variant of Rta. WT Rta protein is constitutively localized to cell nuclei, and contains two putative nuclear localization signals (NLSs). Only one NLS (NLS-2; aa 516-530) was required for nuclear localization of Rta, and relocalized eGFP exclusively to cell nuclei. Analyses of Rta NLS mutants demonstrated that proper nuclear localization of Rta was required for transactivation and stimulation of viral reactivation. Fusion of Rta_NLS-1,2 to the hormone binding domain of the murine estrogen receptor generated a variant of Rta whose nuclear localization and ability to transactivate and induce reactivation were tightly controlled post-translationally by the synthetic hormone tamoxifen. We used this strategy in KSHV-infected cells treated with protein synthesis inhibitors to identify direct transcriptional targets of Rta. Only eight KSHV genes were activated by Rta in the absence of de novo protein synthesis. These direct transcriptional targets of Rta were transactivated to different magnitudes, and included the genes nut-1/PAN, ORF57/Mta, ORF56/Primase, K2/vIL-6, ORF37/SOX, K14/vOX, K9/vIRF1, and ORF52. Our data suggest that induction of most of the KSHV lytic cycle genes requires additional protein expression post-Rta. Keywords: Comparative transcriptome analysis by oligonucleotide microarray
Project description:KSHV RTA (K-RTA) is a transcriptional activator that functions to disrupt KSHV latency and activates specific sets of viral promoters in the lytic cycle. Structure-function studies indicate that K-RTA possesses a very potent transactivation domain locating at the C-terminus. To further characterize the biological functions of K-RTA, we have established three doxycycline-inducible K-RTA 293 cell lines using RevTRE/Tet-On system (Clontech). Comparing to two control lines in which K-RTA was replaced with luciferase reporter, a total of 88 host genes were identified to be modulated by 24 h doxycycline-induced K-RTA synthesized in 293 cells. Designations for the three K-RTA inducible cell lines are KRta_92, KRta_116 and KRta_124; for the control line is RevTRE_Luc_1.
Project description:The objective of this study was to identify the binding sites of KSHV encoded imemdiate early protein, RTA and early protein, K8 on KSHV genome by chromatin immunoprecipitation assay and sequencing of the DNA bound to RTA and K8
Project description:Chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) analysis was performed during Kaposi's sarcoma-associated herpesvirus (KSHV) reactivation in KSHV+ recombinant primary effusion B-cell lymphoma cells (PEL). RTA binding sites were identified genome-wide in a recombinant PEL cell line called TRExBCBL1-3xFLAG-RTA cells at 12 hours post-induction (hpi) of RTA expression.