Hedgehog-YAP Signaling Pathway Regulates Glutaminolysis to Control Activation of Hepatic Stellate Cells
| Autor: | Steve S. Choi, Jeongeun Hyun, Marzena Swiderska-Syn, Richard T. Premont, Youngmi Jung, Anna Mae Diehl, Bahar Salimian Rizi, George D. Dalton, Kuo Du, Gregory A. Michelotti, Eric Thelen |
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| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
Liver Cirrhosis Time Factors Glutamine Cell Cycle Proteins Mitochondria Liver Liver Cirrhosis Experimental chemistry.chemical_compound Myofibroblasts Cells Cultured YAP1 Mice Knockout Chemistry Transdifferentiation Gastroenterology Cellular Reprogramming Smoothened Receptor Hedgehog signaling pathway Phenotype Editorial Liver Ketoglutaric Acids RNA Interference Signal Transduction Cyclopamine Transfection 03 medical and health sciences Glutaminase Hepatic Stellate Cells Animals Humans Hedgehog Proteins Hedgehog Adaptor Proteins Signal Transducing Cell Proliferation Glutaminolysis Hepatology YAP-Signaling Proteins Phosphoproteins Rats Mice Inbred C57BL 030104 developmental biology Gene Expression Regulation Case-Control Studies Cell Transdifferentiation Cancer research Hepatic stellate cell Smoothened Energy Metabolism Transcription Factors |
| Zdroj: | Cellular and Molecular Gastroenterology and Hepatology |
| ISSN: | 1528-0012 |
| Popis: | Background & Aims Cirrhosis results from accumulation of myofibroblasts derived from quiescent hepatic stellate cells (Q-HSCs); it regresses when myofibroblastic HSCs are depleted. Hedgehog signaling promotes transdifferentiation of HSCs by activating Yes-associated protein 1 (YAP1 or YAP) and inducing aerobic glycolysis. However, increased aerobic glycolysis alone cannot meet the high metabolic demands of myofibroblastic HSCs. Determining the metabolic processes of these cells could lead to strategies to prevent progressive liver fibrosis, so we investigated whether glutaminolysis (conversion of glutamine to alpha-ketoglutarate) sustains energy metabolism and permits anabolism when Q-HSCs become myofibroblastic, and whether this is controlled by hedgehog signaling to YAP. Methods Primary HSCs were isolated from C57BL/6 or Smo flox/flox mice; we also performed studies with rat and human myofibroblastic HSCs. We measured changes of glutaminolytic genes during culture-induced primary HSC transdifferentiation. Glutaminolysis was disrupted in cells by glutamine deprivation or pathway inhibitors (bis-2-[5-phenylacetamido-1,2,4-thiadiazol-2-yl] ethyl sulfide, CB-839, epigallocatechin gallate, and aminooxyacetic acid), and effects on mitochondrial respiration, cell growth and migration, and fibrogenesis were measured. Hedgehog signaling to YAP was disrupted in cells by adenovirus expression of Cre-recombinase or by small hairpin RNA knockdown of YAP. Hedgehog and YAP activity were inhibited by incubation of cells with cyclopamine or verteporfin, and effects on glutaminolysis were measured. Acute and chronic liver fibrosis were induced in mice by intraperitoneal injection of CCl 4 or methionine choline-deficient diet. Some mice were then given injections of bis-2-[5-phenylacetamido-1,2,4-thiadiazol-2-yl] ethyl sulfide to inhibit glutaminolysis, and myofibroblast accumulation was measured. We also performed messenger RNA and immunohistochemical analyses of percutaneous liver biopsies from healthy human and 4 patients with no fibrosis, 6 patients with mild fibrosis, and 3 patients with severe fibrosis. Results Expression of genes that regulate glutaminolysis increased during transdifferentiation of primary Q-HSCs into myofibroblastic HSCs, and inhibition of glutaminolysis disrupted transdifferentiation. Blocking glutaminolysis in myofibroblastic HSCs suppressed mitochondrial respiration, cell growth and migration, and fibrogenesis; replenishing glutaminolysis metabolites to these cells restored these activities. Knockout of the hedgehog signaling intermediate smoothened or knockdown of YAP inhibited expression of glutaminase, the rate-limiting enzyme in glutaminolysis. Hedgehog and YAP inhibitors blocked glutaminolysis and suppressed myofibroblastic activities in HSCs. In livers of patients and of mice with acute or chronic fibrosis, glutaminolysis was induced in myofibroblastic HSCs. In mice with liver fibrosis, inhibition of glutaminase blocked accumulation of myofibroblasts and fibrosis progression. Conclusions Glutaminolysis controls accumulation of myofibroblast HSCs in mice and might be a therapeutic target for cirrhosis. |
| Databáze: | OpenAIRE |
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