RESUMO
Graves' disease (GD) is a kind of autoimmune diseases. The development of GD is closely related to the imbalance of Th1/Th2 generated by the differentiation of CD4+ T cells. This study was sought to clarify the role of lncRNA RUNX1-IT1 and explore the mechanism of its function. The expressions of RUNX1-IT1 and Neural cell adhesion molecule (NrCAM) in the peripheral blood of GD patients were detected by qRT-PCR and Western blot. We performed RNA pull down, RIP, and ChIP experiments to verify the correlation between p53 and RUNX1-IT1, p53 and NrCAM. The levels of Th1 cells differentiation markers were detected by Flow cytometry assay and ELISA. The expressions of lncRNA RUNX1-IT1 and NrCAM were most significantly up-regulated in CD4+ T cells of GD patients, and NrCAM expression was significantly positively correlated with RUNX1-IT1 expression. Furthermore, p53 was a potential transcription factor of NrCAM, which could interact with NrCAM. NrCAM level was up-regulated after the overexpression of p53 in CD4+ T cells, while knockdown of RUNX1-IT1 reversed this effect. Down-regulation of NrCAM and RUNX1-IT1 could decrease the mRNA and protein levels of transcriptional regulator T-bet and CXC chemokine ligand 10 (CXCL10) in CD4+ T cells. Our results suggested that RUNX1-IT1 regulated the expressions of the important Th1 factor T-bet, CXCL10, and interferon γ (IFN-γ) by regulating NrCAM transcription, thus participating in the occurrence and development of specific autoimmune disease GD.
Assuntos
Moléculas de Adesão Celular , Doença de Graves , RNA Longo não Codificante , Células Th1 , Moléculas de Adesão Celular/biossíntese , Moléculas de Adesão Celular/genética , Moléculas de Adesão Celular/metabolismo , Quimiocinas CXC/metabolismo , Subunidade alfa 2 de Fator de Ligação ao Core/genética , Subunidade alfa 2 de Fator de Ligação ao Core/metabolismo , Doença de Graves/genética , Doença de Graves/imunologia , Doença de Graves/metabolismo , Doença de Graves/patologia , Humanos , Moléculas de Adesão de Célula Nervosa/metabolismo , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , Células Th1/imunologia , Células Th1/patologia , Células Th2/imunologia , Células Th2/patologia , Transcrição Gênica , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
In the status of obesity, the glucagon-like peptide-1 (GLP-1) level usually declines and results in metabolic syndrome. This study aimed to investigate the intracellular mechanism of GLP-1 synthesis in L cells from the perspective of microRNA (miRNA). In the present study, we found that GLP-1 level was down-regulated in the plasma and ileum tissues of obese mice, while the ileac miR-194 expression was up-regulated. In vitro experiments indicated that miR-194 overexpression down-regulated GLP-1 level, mRNA levels of proglucagon gene (gcg) and prohormone convertase 1/3 gene (pcsk1), and the nuclear protein level of beta-catenin (ß-catenin). Further investigation confirmed that ß-catenin could promote gcg transcription through binding to transcription factor 7-like 2 (TCF7L2). miR-194 suppressed gcg mRNA level via negatively regulating TCF7L2 expression. What's more, forkhead box a1 (Foxa1) could bind to the promoter of pcsk1 and enhanced its transcription. miR-194 suppressed pcsk1 transcription through targeting Foxa1. Besides, the interference of miR-194 reduced palmitate (PA)-induced cell apoptosis and the anti-apoptosis effect of miR-194 inhibitor was abolished by TCF7L2 knockdown. Finally, in HFD-induced obese mice, the silence of miR-194 significantly elevated GLP-1 level and improved the metabolic symptoms caused by GLP-1 deficiency. To sum up, our study found that miR-194 suppressed GLP-1 synthesis in L cells via inhibiting TCF7L2-mediated gcg transcription and Foxa1-mediated pcsk1 transcription. Meanwhile, miR-194 took part in the PA-induced apoptosis of L cells.
Assuntos
Células Enteroendócrinas/metabolismo , Peptídeo 1 Semelhante ao Glucagon/biossíntese , MicroRNAs/metabolismo , Obesidade/metabolismo , Animais , Peptídeo 1 Semelhante ao Glucagon/genética , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Células L , Masculino , Camundongos , MicroRNAs/genética , Obesidade/genética , TransfecçãoRESUMO
Lipopolysaccharide (LPS) as a component of the outer structure of cell wall of gram-negative bacteria, could induce apoptosis in the intestinal endocrine cell line STC-1. However, the signaling cascades involved in this process have not been elucidated. Hence, we investigated the mechanism of cell apoptosis and hyposecretion of glucagon-like peptide 1 (GLP-1) induced by LPS in the GLUTag enteroendocrine cell line. LPS decreased the cell viability of GLUTag cells, up-regulated the TNF-α level, induced the apoptosis and down-regulated the mRNA and protein levels of GLP-1. In addition, TNF-α promoted LPS-induced apoptosis of GLUTag cells through mediating the formation of the RIP1/RIP3 necrosome. RIP1 and RIP3 knockdown increased cell viability, the mRNA and protein levels of GLP-1 and the mTOR signaling pathway-related proteins (p-mTOR and p-S6), and decreased the relative caspase 3/7 activity, cell apoptosis and ROS production. Further studies showed that ROS inhibited the mTOR signaling pathway. Moreover, the antioxidant N-acetyl-l-cysteine increased cell viability, GLP-1 expressions and the mTOR signaling pathway-related proteins, and inhibited the ROS production. However, the mTOR specific inhibitor (Rapa) reversed all these above effects. Taken together, our result revealed that LPS induced the apoptosis of GLUTag cells and GLP-1 hyposecretion through the RIP/ROS/mTOR pathway.
