Human immunodeficiency virus-1 Nef protein interacts with Tat and enhances HIV-1 gene expression

AbstractThe human immunodeficiency virus (HIV-1) Nef protein is now regarded as a regulatory protein responsible not only for establishment of infection and increased pathogenesis but also for enhancement of viral replication. However, the mechanism of Nef-induced activation of viral replication remains to be clearly understood. Using transient transfection assay, co-immunoprecipitation and pull-down analysis, we demonstrate in this report that the HIV-1 Nef protein physically interacts with Tat, the principal transactivating protein of HIV-1. Our observations with single cycle replication experiments further indicate that this interaction results not only in enhancement of Tat-induced HIV-1 long terminal repeat-mediated gene expression but also in virus production

The cell death regulator GRIM-19 is involved in HIV-1 induced T-cell apoptosis

One of the hallmarks of Human Immunodeficiency Virus-1 (HIV-1) infection is progressive depletion of the infected and bystander CD4+ T-cells by apoptosis. Different mitochondrial proteins have been implicated in this apoptotic process; however, the role of different subunits of mitochondrial oxidative phosphorylation (OXPHOS) complexes in apoptosis is not clearly understood. Some of the OXPHOS complex subunits seem to perform other functions in addition to their primary role in energy generating process. GRIM-19 (gene associated with retinoid-interferon-induced-mortality-19), a subunit of mitochondrial complex-I was previously implicated in Interferon-β and retionoic acid induced apoptosis in many tumor cells. In this study we report, using differential gene expression analysis, that GRIM-19 is up-regulated in HIV-1 infected apoptotic T-cells. A temporal up regulation of this subunit was observed in different HIV-1 infected T-cell lines and human PBMC and the extent of increase correlated to increasing apoptosis and virus production. Moreover, silencing GRIM-19 in HIV-1 infected cells reduced apoptosis, indicating its involvement in HIV-1 induced T-cell death

Tat predominantly associates with host promoter elements in HIV-1-infected T-cells - regulatory basis of transcriptional repression of c-Rel

HIV-1 Tat is a multifunctional regulatory protein that, in addition to its primary function of transactivating viral transcription, also tends to modulate cellular gene expression, for which the molecular mechanism remains to be clarified. We have reported earlier nuclear factor kappa B (NFκB) enhancer binding activity of Tat and proposed this DNA binding activity as a possible molecular basis for Tat-mediated regulation of cellular gene expression in infected cells. In the present study, we analyzed the genome-wide occupancy of Tat protein on host cell chromatin in HIV-1-infected T-cells to investigate a potential role of Tat on cellular gene expression. The results obtained identify a spectrum of binding sites of Tat protein on the chromatin and reveal that Tat is also recruited on a number of cellular gene promoters in HIV-1-infected T-cells, indicating its possible involvement in the regulation of gene expression of such cellular genes. Tat was identified as a repressor of one such validated gene, c-Rel, because it downregulates the expression of c-Rel in both Tat expressing and HIV-1-infected T-cells. The results also show that Tat downregulates c-Rel promoter activity by interacting with specific NFκB sites on the c-Rel promoter, thus providing a molecular basis of Tat-mediated regulation of cellular gene expression. Thus, in the present study, we have not only identified recruitment sites of Tat on the chromatin in HIV-1-infected T-cells, but also report for the first time that c-Rel is downregulated in HIV-1-infected cells specifically by interaction of Tat with NFκB binding sites on the promoter

Glioblastoma-specific protein interaction network identifies PP1A and CSK21 as connecting molecules between cell cycle-associated genes

Glioblastoma (GBM; grade IV astrocytoma) is a very aggressive form of brain cancer with a poor survival and few qualified predictive markers. This study integrates experimentally validated genes that showed specific upregulation in GBM along with their protein-protein interaction information. A system level analysis was used to construct GBM-specific network. Computation of topological parameters of networks showed scale-free pattern and hierarchical organization. From the large network involving 1,447 proteins, we synthesized subnetworks and annotated them with highly enriched biological processes. A careful dissection of the functional modules, important nodes, and their connections identified two novel intermediary molecules CSK21 and protein phosphatase 1 α (PP1A) connecting the two subnetworks CDC2-PTEN-TOP2A-CAV1-P53 and CDC2-CAV1-RB-P53-PTEN, respectively. Real-time quantitative reverse transcription-PCR analysis revealed CSK21 to be moderately upregulated and PP1A to be overexpressed by 20-fold in GBM tumor samples. Immunohistochemical staining revealed nuclear expression of PP1A only in GBM samples. Thus, CSK21 and PP1A, whose functions are intimately associated with cell cycle regulation, might play key role in gliomagenesis

Glioblastoma-Specific Protein Interaction Network Identifies PP1A and CSK21 as Connecting Molecules between Cell Cycle-Associated Genes

Glioblastoma (GBM; grade IV astrocytoma) is a very aggressive form of brain cancer with a poor survival and few qualified predictive markers. This study integrates experimentally validated genes that showed specific upregulation in GBM along with their protein-protein interaction information. A system level analysis was used to construct GBM-specific network. Computation of topological parameters of networks showed scale-free pattern and hierarchical organization. From the large network involving 1,447 proteins, we synthesized subnetworks and annotated them with highly enriched biological processes. A careful dissection of the functional modules, important nodes, and their connections identified two novel intermediary molecules CSK21 and protein phosphatase 1 alpha (PP1A) connecting the two subnetworks CDC2-PTEN-TOP2A-CAV1-P53 and CDC2-CAV1-RB-P53-PTEN, respectively. Real-time quantitative reverse transcription-PCR analysis revealed CSK21 to be moderately upregulated and PP1A to be overexpressed by 20-fold in GBM tumor samples. Immunohistochemical staining revealed nuclear expression of PP1A only in GBM samples. Thus, CSK21 and PP1A, whose functions are intimately associated with cell cycle regulation, might play key role in gliomagenesis. Cancer Res; 70(16); 6437-47. (C)2010 AACR

The surgical safety checklist and patient outcomes after surgery: a prospective observational cohort study, systematic review and meta-analysis

© 2017 British Journal of Anaesthesia Background: The surgical safety checklist is widely used to improve the quality of perioperative care. However, clinicians continue to debate the clinical effectiveness of this tool. Methods: Prospective analysis of data from the International Surgical Outcomes Study (ISOS), an international observational study of elective in-patient surgery, accompanied by a systematic review and meta-analysis of published literature. The exposure was surgical safety checklist use. The primary outcome was in-hospital mortality and the secondary outcome was postoperative complications. In the ISOS cohort, a multivariable multi-level generalized linear model was used to test associations. To further contextualise these findings, we included the results from the ISOS cohort in a meta-analysis. Results are reported as odds ratios (OR) with 95% confidence intervals. Results: We included 44 814 patients from 497 hospitals in 27 countries in the ISOS analysis. There were 40 245 (89.8%) patients exposed to the checklist, whilst 7508 (16.8%) sustained ≥1 postoperative complications and 207 (0.5%) died before hospital discharge. Checklist exposure was associated with reduced mortality [odds ratio (OR) 0.49 (0.32–0.77); P\u3c0.01], but no difference in complication rates [OR 1.02 (0.88–1.19); P=0.75]. In a systematic review, we screened 3732 records and identified 11 eligible studies of 453 292 patients including the ISOS cohort. Checklist exposure was associated with both reduced postoperative mortality [OR 0.75 (0.62–0.92); P\u3c0.01; I2=87%] and reduced complication rates [OR 0.73 (0.61–0.88); P\u3c0.01; I2=89%). Conclusions: Patients exposed to a surgical safety checklist experience better postoperative outcomes, but this could simply reflect wider quality of care in hospitals where checklist use is routine

Prospective observational cohort study on grading the severity of postoperative complications in global surgery research

Background The Clavien–Dindo classification is perhaps the most widely used approach for reporting postoperative complications in clinical trials. This system classifies complication severity by the treatment provided. However, it is unclear whether the Clavien–Dindo system can be used internationally in studies across differing healthcare systems in high- (HICs) and low- and middle-income countries (LMICs). Methods This was a secondary analysis of the International Surgical Outcomes Study (ISOS), a prospective observational cohort study of elective surgery in adults. Data collection occurred over a 7-day period. Severity of complications was graded using Clavien–Dindo and the simpler ISOS grading (mild, moderate or severe, based on guided investigator judgement). Severity grading was compared using the intraclass correlation coefficient (ICC). Data are presented as frequencies and ICC values (with 95 per cent c.i.). The analysis was stratified by income status of the country, comparing HICs with LMICs. Results A total of 44 814 patients were recruited from 474 hospitals in 27 countries (19 HICs and 8 LMICs). Some 7508 patients (16·8 per cent) experienced at least one postoperative complication, equivalent to 11 664 complications in total. Using the ISOS classification, 5504 of 11 664 complications (47·2 per cent) were graded as mild, 4244 (36·4 per cent) as moderate and 1916 (16·4 per cent) as severe. Using Clavien–Dindo, 6781 of 11 664 complications (58·1 per cent) were graded as I or II, 1740 (14·9 per cent) as III, 2408 (20·6 per cent) as IV and 735 (6·3 per cent) as V. Agreement between classification systems was poor overall (ICC 0·41, 95 per cent c.i. 0·20 to 0·55), and in LMICs (ICC 0·23, 0·05 to 0·38) and HICs (ICC 0·46, 0·25 to 0·59). Conclusion Caution is recommended when using a treatment approach to grade complications in global surgery studies, as this may introduce bias unintentionally

Critical care admission following elective surgery was not associated with survival benefit: prospective analysis of data from 27 countries

This was an investigator initiated study funded by Nestle Health Sciences through an unrestricted research grant, and by a National Institute for Health Research (UK) Professorship held by RP. The study was sponsored by Queen Mary University of London