RESUMO
After integration to the human genome as a provirus, human T-cell leukemia virus type 1 (HTLV-1) utilizes host T cell gene expression machinery for viral replication. The viral RNA-binding protein, Rex, is known to transport unspliced/incompletely spliced viral mRNAs encoding viral structural proteins out of the nucleus to enhance virus particle formation. However, the detailed mechanism of how Rex avoids extra splicing of unspliced/incompletely spliced viral mRNAs and stabilizes them for effective translation is still unclear. To elucidate the underlying molecular mechanism of Rex function, we comprehensively analyzed the changes in gene expression and splicing patterns in Rex-overexpressing T cells. In addition, we identified 81 human proteins interacting with Rex, involved in transcription, splicing, translation, and mRNA quality control. In particular, Rex interacts with NONO and SFPQ, which play important roles in the regulation of transcription and splicing. Accordingly, expression profiles and splicing patterns of a wide variety of genes are significantly changed in Rex-expressing T cells. Especially, the level of vPD-L1 mRNA that lacks the part of exon 4, thus encodes soluble PD-L1 was significantly increased in Rex-expressing cells. Overall, by integrated analysis of these three datasets, we showed for the first time that Rex intervenes the host gene expression machinery throughout the pathway, probably to escort viral unstable mRNAs from transcription (start) to translation (end). Upon exerting its function, Rex may alter the expression level and splicing patterns of various genes, thus influencing the phenotype of the host cell.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Produtos do Gene rex/metabolismo , Infecções por HTLV-I/metabolismo , Vírus Linfotrópico T Tipo 1 Humano/genética , Proteínas de Ligação a RNA/metabolismo , Replicação Viral/genética , Antígeno B7-H1/metabolismo , Linhagem Celular , Núcleo Celular/metabolismo , Proteínas de Ligação a DNA/genética , Regulação Viral da Expressão Gênica , Humanos , Fator de Processamento Associado a PTB/metabolismo , Splicing de RNA , RNA Mensageiro , Proteínas de Ligação a RNA/genéticaRESUMO
Accumulating evidence indicates that cell death triggers sterile inflammation and that impaired clearance of dead cells causes nonresolving inflammation; however, the underlying mechanisms are still unclear. Here, we show that macrophage-inducible C-type lectin (Mincle) senses renal tubular cell death to induce sustained inflammation after acute kidney injury in mice. Mincle-deficient mice were protected against tissue damage and subsequent atrophy of the kidney after ischemia-reperfusion injury. Using lipophilic extract from the injured kidney, we identified ß-glucosylceramide as an endogenous Mincle ligand. Notably, free cholesterol markedly enhanced the agonistic effect of ß-glucosylceramide on Mincle. Moreover, ß-glucosylceramide and free cholesterol accumulated in dead renal tubules in proximity to Mincle-expressing macrophages, where Mincle was supposed to inhibit clearance of dead cells and increase proinflammatory cytokine production. This study demonstrates that ß-glucosylceramide in combination with free cholesterol acts on Mincle as an endogenous ligand to induce cell death-triggered, sustained inflammation after acute kidney injury.
Assuntos
Injúria Renal Aguda/metabolismo , Morte Celular/genética , Lectinas Tipo C/metabolismo , Proteínas de Membrana/metabolismo , Injúria Renal Aguda/imunologia , Animais , Citocinas/metabolismo , Modelos Animais de Doenças , Feminino , Glucosilceramidase/metabolismo , Proteínas de Fluorescência Verde/genética , Inflamação/metabolismo , Lectinas Tipo C/deficiência , Lectinas Tipo C/genética , Ligantes , Macrófagos/imunologia , Macrófagos/metabolismo , Masculino , Proteínas de Membrana/deficiência , Proteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Transdução de Sinais/genética , Transdução de Sinais/imunologiaRESUMO
transResveratrol (Rsv) is a natural compound contained in red wine and grape skins that has various beneficial effects for organisms such as lengthening of their life span. Rsv induces expression of the human TP53 and HELB genes, which are involved in the regulation of DNA maintenance. In the present study, a luciferase expression vector containing 309 bp of the 5' upstream end of the human MCM4 gene was transfected into HeLa S3 cells. A luciferase assay revealed that Rsv treatment increased the minichromosome maintenance 4 (MCM4) gene promoter activity by GCbox and GGAA (TTCC) motifs. Electro phoretic mobility shift assay revealed that the specific binding factor (complex) contains PU.1 (SPI1). Quantitative reverse transcriptionpolymerase chain reaction analysis indicated that MCM4 gene expression was transiently induced by Rsv. Moreover, western blotting revealed that the SP1/PU.1 ratio markedly increased after Rsv treatment, indicating that a balance or profile of these transcription factors may control Rsvinducible initiation of transcription. These observations indicated that the beneficial effects of Rsv can be attributed to induction of the chromosomal DNA maintenance factor encoding gene expression.
Assuntos
Componente 4 do Complexo de Manutenção de Minicromossomo/genética , Proteínas Proto-Oncogênicas/metabolismo , Resveratrol/farmacologia , Transativadores/metabolismo , Linhagem Celular Tumoral , Células HL-60 , Humanos , Componente 4 do Complexo de Manutenção de Minicromossomo/metabolismo , Regiões Promotoras Genéticas , Transcrição Gênica/efeitos dos fármacos , TransfecçãoRESUMO
Nonalcoholic steatohepatitis (NASH) is a hepatic phenotype of the metabolic syndrome, and increases the risk of cirrhosis and hepatocellular carcinoma (HCC). Although increasing evidence points to the therapeutic implications of certain types of anti-diabetic agents in NASH, it remains to be elucidated whether their effects on NASH are independent of their effects on diabetes. Genetically obese melanocortin 4 receptor-deficient (MC4R-KO) mice fed Western diet are a murine model that sequentially develops hepatic steatosis, NASH, and HCC in the presence of obesity and insulin resistance. In this study, we investigated the effect of the dipeptidyl peptidase-4 (DPP-4) inhibitor anagliptin on NASH and HCC development in MC4R-KO mice. Anagliptin treatment effectively prevented inflammation, fibrosis, and carcinogenesis in the liver of MC4R-KO mice. Interestingly, anagliptin only marginally affected body weight, systemic glucose and lipid metabolism, and hepatic steatosis. Histological data and gene expression analysis suggest that anagliptin treatment targets macrophage activation in the liver during the progression from simple steatosis to NASH. As a molecular mechanism underlying anagliptin action, we showed that glucagon-like peptide-1 suppressed proinflammatory and profibrotic phenotypes of macrophages in vitro. This study highlights the glucose metabolism-independent effects of anagliptin on NASH and HCC development.