Project description:Human ß cell dedifferentiation as a potent mechanism of diabetes is gaining prominence. Several data suggest an upregulation of the transcription factor SOX9, a progenitor and duct cell marker during ß cell dedifferentiation. However, its targets in such cells need more understanding. Here, we overexpressed SOX9 and a constitutively active mutant (VP16-SOX9∆TAD) in Human pancreatic beta EndoC-ßH1 cells in order to understand its targets.
Project description:Type 1 diabetes (T1D) is a chronic disease characterized by an autoimmune-mediated destruction of insulin-producing pancreatic β cells. Environmental factors such as viruses play an important role in the onset of T1D and interact with predisposing genes. Recent data suggest that viral infection of human islets leads to a decrease in insulin production rather than β cell death, suggesting loss of β cell identity. We undertook this study to examine whether viral infection could induce human ß cell dedifferentiation. Using the functional human β cell line EndoC-βH1, we demonstrate that polyinosinic-polycitidilic acid (PolyI:C), a synthetic double-stranded RNA that mimics a by-product of viral replication induces a decrease in β cell-specific gene expression. In parallel to this loss, the expression of progenitor-like genes such as SOX9 was activated following PolyI:C treatment or enteroviral infection. SOX9 was induced by the NF-kB pathway and also in a paracrine non-cell autonomous fashion through the secretion of IFNA. Finally, we identified new SOX9 targets in human β cells as new markers of dedifferentiation in T1D. These findings reveal that inflammatory signaling has clear implications in human β cell dedifferentiation.
Project description:EndoC-BH1 cells were plated in normal media and forward transfected with lipofectamine 3000 (2ug cDNA) of empty, OAS1, OAS2, or OAS3 plasmids from Vector builder
Project description:The HASTER promoter region is a cis-regulatory element that stabilizes the transcription HNF1A. If HASTER is deleted after beta cells have been formed and HNF1A is already stably expressed, HASTER is not required to maintain HNF1A activity, and is only required to provide negative feedback on HNF1A. HNF1A binding to the HASTER promoter mediates the repression of the HNF1A gene itself. To determine whether HNF1A binding to the HASTER promoter remodels 3D chromatin interactions of the HNF1A promoter, we performed UMI-4C experiments in wild type and HASTER-promoter KO EndoC-betaH3 cells with or without doxycycline-induced HNF1A overexpression using the HNF1A promoter as viewpoint.
Project description:Sorafenib is a multi-kinase blocker and one of the few suggested drug treatments for aggressive hepatocellular carcinoma (HCC) patients. However, drug resistance to sorafenib may often occur over time and cause further tumor aggression. Recently, cancer stem cells were found in HCC and were speculated to be involved in tumor progression. SOX9 is highly expressed in HCC cancer stem cells and promotes cell proliferation and self-renewal. Meanwhile, HCC patients with higher SOX9 expression show poorer prognosis [1]. Whether SOX9 is involved in sorafenib resistance in HCC is still unclear. Here, we found that sorafenib treatment increased SOX9 expression in HCC cell lines. Overexpression of exogenous SOX9 in HCC increased sorafenib resistance both in vitro and in vivo, whereas down-regulation led to inhibition of sorafenib resistance. Knock-down of SOX9 by RNA interference caused down-regulation of downstream genes, including ATP binding cassette subfamily G member 2 (ABCG2). The drug resistance to sorafenib caused by SOX9 overexpression could be ameliorated by overexpression of SOX9 in combination withby ABCG2 inhibition in HCC cell lines. In the cohort of patients resistant to sorafenib, we found that patients with lower SOX9 expression had more prolonged overall survival (OS) and progression-free survival (PFS). Cox analysis shows that SOX9 expression exerts as an independent risk factor for HCC, and logistic regression analysis reveals that SOX9 expression, tumor capsule deficiency, tumor diameters, and microvascular invasion are risk factors for poor prognosis of HCC patients. These findings demonstrate that SOX9 enhances sorafenib resistance and may regulate this process by modulating ABCG2 expression.