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Pancreatic and duodenal homeobox gene 1 (Pdx1) down-regulates hepatic transcription factor 1 alpha (HNF1?) expression during reprogramming of human hepatic cells into insulin-producing cells.

ABSTRACT: Ectopic expression of Pdx1 triggers rapid hepatocyte dedifferentiation by down-regulating liver-enriched transcription factors and liver-specific functional genes such as hepatic nuclear factor-1? (HNF1?), albumin, and AAT. However, the links between Pdx1 over-expression and hepatic gene down-regulation are incompletely understood. HNF1? and HNF4? are important transcription factors that establish and maintain the hepatocyte phenotype. The human HNF4? gene contains two promoters (P1 and P2) that drive expression of P1-(HNF4? 1-6) or P2-(HNF4? 7-9)-derived isoforms, which are used in different tissues and at different times during development. We hypothesized that the relative expression of HNF1? and HNF4? following ectopic Pdx1 expression may promote hepatic cell dedifferentiation and transdifferentiation toward pancreatic beta-cells. We produced lentiviruses expressing Pdx1, Pdx1-VP16, and Ngn3, along with dual-color reporter genes to indicate hepatic and pancreatic beta-cell phenotype changes. Using these PTF alone or in combinations, we demonstrated that Pdx1 not only activates specific beta-cell genes but down-regulates HNF1?. Pdx1-mediated reduction of HNF1? is accompanied by altered expression of its major activator, HNF4? isoforms, down-regulating hepatic genes ALB and AAT. Pdx1 up-regulates HNF4? via the P2 promoter. These P2-driven isoforms compete with P1-driven isoforms to suppress target gene transcription. In Huh7 cells, the AF-1 activation domain is more important for transactivation, whereas in INS1 cells, the F inhibitory domain is more important. The loss and gain of functional activity strongly suggests that Pdx1 plays a central role in reprogramming hepatocytes into beta-cells by suppressing the hepatic phenotype.

SUBMITTER: Donelan W

PROVIDER: S-EPMC4532734 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Pancreatic and duodenal homeobox gene 1 (Pdx1) down-regulates hepatic transcription factor 1 alpha (HNF1α) expression during reprogramming of human hepatic cells into insulin-producing cells.

Donelan William W Li Shiwu S Wang Hai H Lu Shun S Xie Chao C Tang Dongqi D Chang Lung-Ji LJ Yang Li-Jun LJ

American journal of translational research 20150615 6

Ectopic expression of Pdx1 triggers rapid hepatocyte dedifferentiation by down-regulating liver-enriched transcription factors and liver-specific functional genes such as hepatic nuclear factor-1α (HNF1α), albumin, and AAT. However, the links between Pdx1 over-expression and hepatic gene down-regulation are incompletely understood. HNF1α and HNF4α are important transcription factors that establish and maintain the hepatocyte phenotype. The human HNF4α gene contains two promoters (P1 and P2) that ...[more]

PMID: 26279745

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Project description:Adenovirus-mediated transient expression of the pancreatic duodenal homeobox transcription factor Pdx1 in mouse liver activates pancreatic endocrine and exocrine genes, the latter reportedly resulting in severe hepatitis. Expression of a super-active form of Pdx1 or Pdx1-VP16 selectively transdifferentiates hepatic WB cells into functional pancreatic beta-like insulin-producing cells, without evidence of exocrine differentiation. No study has systematically compared the transdifferentiation efficiency of Pdx1 and Pdx1-VP16 at the cellular and molecular level. Comparisons can be ambiguous when vectors harboring a transcription factor cDNA have differing extents and duration of gene expression. In view of the remarkable capacity of lentiviral vector (LV) for delivering and integrating transgene into both dividing and nondividing cells, we transduced rat hepatic stem cell-like WB cells with LV-Pdx1 or LV-Pdx1-VP16, and then used the limiting-dilution technique to clone single-cell-derived cell lines that stably express either Pdx1 or Pdx1-VP16. With these cell lines, we studied: (a) the expression of Pdx1 or Pdx1-VP16 protein by Western blotting and immunocytochemistry; (b) the repertoire of long-term expression of Pdx1- or Pdx1-VP16-induced pancreatic gene expression using RT-PCR methods; and (c) their capacity to serve as beta-cell surrogates in restoring euglycemia in streptozotocin-treated diabetic mice. We found that cell lines expressing either Pdx1 or Pdx1-VP16 long-term exhibited similar profiles for expression of genes related to pancreatic development and beta-cell function, and reversed hyperglycemia in diabetic mice. We also examined short-term expression of Pdx1 or Pdx1-VP16, and the results demonstrated that expression of Pdx1-VP16 is more efficient in initiating liver-to-endocrine pancreas transdifferentiation. Our findings demonstrate: (a) that the LV system is highly effective in producing persistent expression of Pdx1 or Pdx1-VP16 in WB hepatic cells; and (b) long-term, persistent expression of either Pdx1 or Pdx1-VP16 is similarly effective in converting hepatic stem cells into pancreatic endocrine precursor cells that, upon transplantation into diabetic mice, become functional insulin-producing cells and restore euglycemia.

Project description:AimTo investigate reprogramming of human adipose tissue derived stem cells into insulin producing cells using non-integrated lentivirus harboring PDX1 gene.MethodsIn this study, human adipose tissue derived stem cells (hADSCs) were obtained from abdominal adipose tissues by liposuction, selected by plastic adhesion, and characterized by flow cytometric analysis. Human ADSCs were differentiated into adipocytes and osteocytes using differentiating medium to confirm their multipotency. Non-integrated lentiviruses harboring PDX1 (Non-integrated LV-PDX1) were constructed using specific plasmids (pLV-HELP, pMD2G, LV-105-PDX1-1). Then, hADSCs were transduced with non-integrated LV-PDX1. After transduction, ADSCs(PDX1+) were cultured in high glucose DMEM medium supplement by B27, nicotinamide and βFGF for 21 d. Expressions of PDX1 and insulin were detected at protein level by immunofluorescence analysis. Expressions of PDX1, neurogenin3 (Ngn3), glucagon, glucose transporter2 (Glut2) and somatostatin as specific marker genes were investigated at mRNA level by quantitative RT-PCR. Insulin secretion of hADSCs(PDX1+) in the high-glucose medium was detected by electrochemiluminescence test. Human ADSCs(PDX1+) were implanted into hyperglycemic rats.ResultsHuman ADSCs exhibited their fibroblast-like morphology and made colonies after 7-10 d of culture. Determination of hADSCs identified by FACS analysis showed that hADSCs were positive for mesenchymal cell markers and negative for hematopoietic cell markers that guaranteed the lack of hematopoietic contamination. In vitro differentiation of hADSCs into osteocytes and adipocytes were detected by Alizarin red and Oil red O staining and confirmed their multilineage differentiation ability. Transduced hADSCs(+PDX1) became round and clusters in the differentiation medium. The appropriate expression of PDX1 and insulin proteins was confirmed using immunocytochemistry analysis. Significant expressions of PDX1, Ngn3, glucagon, Glut2 and somatostatin were detected by quantitative RT-PCR. hADSCs(PDX1+) revealed the glucose sensing ability by expressing Glut2 when they were cultured in the medium containing high glucose concentration. The insulin secretion of hADSCs(PDX1+) in the high glucose medium was 2.32 μU/mL. hADSCs(PDX1+) implantation into hyperglycemic rats cured it two days after injection by reducing blood glucose levels from 485 mg/dL to the normal level.ConclusionHuman ADSCs can differentiate into IPCs by non-integrated LV-PDX1 transduction and have the potential to be used as a resource in type 1 diabetes cell therapy.

Dataset Information

Pancreatic and duodenal homeobox gene 1 (Pdx1) down-regulates hepatic transcription factor 1 alpha (HNF1?) expression during reprogramming of human hepatic cells into insulin-producing cells.

Publications

Pancreatic and duodenal homeobox gene 1 (Pdx1) down-regulates hepatic transcription factor 1 alpha (HNF1α) expression during reprogramming of human hepatic cells into insulin-producing cells.

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