The outcomes of liver injury are dictated by the success or failure of repair. Current gaps in knowledge about how the liver regenerates limit prevention and treatment of cirrhosis and liver cancer, which are outcomes of dysfunctional regeneration (mis-repair).Thus, the ultimate goal of our research program is to delineate mechanisms that control liver regeneration. The present application seeks competitive renewal of a project that is evaluating the general hypothesis that the Hedgehog (Hh) pathway is one of the key regulators of liver regeneration. Thus far, we've discovered that the Hh pathway is activated during all types of liver injury, regulates multiple facets of regeneration, and that hepatic stellate cells (HSC) are critical targets of Hh signaling. We showed that acute injury transiently activates Hh signaling and proved this is required for regeneration. Conversely, we found that chronic injury provokes sustained Hh signaling that perpetuates phases of wound healing that necessitate mesenchymal cell enrichment and hence, fibrogenesis and liver cancer. The present application is built upon provocative evidence that HSC variably exhibit features of multipotent progenitors, liver epithelial cells, and myofibroblasts, and that Hh ligands modulate HSC fate decisions (i.e., reprogramming). Our latest data indicate that HSC reprogramming involves a Hh-regulated metabolic switch that induces glycolysis, and suggest that glycolytic end-products may modulate HSC fate. We will evaluate the SPECIFIC HYPOTHESIS that adult HSC retain sufficient plasticity to be reprogrammed to other lineages, and that Hh orchestrates liver regeneration by crafting a microenvironment that favors such reprogramming.
Our Aims are to answer these questions: 1) What is the role of the Hh signaling intermediate, Smoothened (Smo), in HSC reprogramming? 2) How do changes in intermediatry metabolism regulate Smo- mediated HSC reprogramming? 3) How do Hh-regulated changes in HSC phenotype impact liver regeneration and mis-repair. We will use transgenic mice that permit conditional deletion of Smo in quiescent or myofibroblastic-HSC before, during, and after liver injury.Preliminary data support the feasibility of this approach and link canonical Hh signaling with metabolic events that regulate HSC reprogramming.

Public Health Relevance

Liver cirrhosis and cancer are important causes of human suffering and death worldwide. Our work has identified previously-unsuspected mechanisms that control the development of these problems. These discoveries pave the way for new strategies to prevent and treat cirrhosis and liver cancer, which are the major bad outcomes of all types of chronic liver disease.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Project (R01)
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Hepatobiliary Pathophysiology Study Section (HBPP)
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Serrano, Jose
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Duke University
Internal Medicine/Medicine
Schools of Medicine
United States
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Machado, Mariana Verdelho; Diehl, Anna Mae (2018) Hedgehog signalling in liver pathophysiology. J Hepatol 68:550-562
Chen, Kai-Yuan; Shen, Xiling; Diehl, Anna Mae (2018) Prometheus revisited. J Clin Invest 128:2192-2193
Castro, Rui E; Diehl, Anna Mae (2018) Towards a definite mouse model of NAFLD. J Hepatol 69:272-274
Du, Kuo; Hyun, Jeongeun; Premont, Richard T et al. (2018) Hedgehog-YAP Signaling Pathway Regulates Glutaminolysis to Control Activation of Hepatic Stellate Cells. Gastroenterology 154:1465-1479.e13
Oh, Seh-Hoon; Swiderska-Syn, Marzena; Jewell, Mark L et al. (2018) Liver regeneration requires Yap1-TGF?-dependent epithelial-mesenchymal transition in hepatocytes. J Hepatol 69:359-367
Verdelho Machado, Mariana; Diehl, Anna Mae (2018) The hedgehog pathway in nonalcoholic fatty liver disease. Crit Rev Biochem Mol Biol 53:264-278
Chen, Jiamei; Chen, Long; Zern, Mark A et al. (2017) The diversity and plasticity of adult hepatic progenitor cells and their niche. Liver Int 37:1260-1271
Xie, Guanhua; Swiderska-Syn, Marzena; Jewell, Mark L et al. (2017) Loss of pericyte smoothened activity in mice with genetic deficiency of leptin. BMC Cell Biol 18:20
Machado, M V; Michelotti, G A; Jewell, M L et al. (2016) Caspase-2 promotes obesity, the metabolic syndrome and nonalcoholic fatty liver disease. Cell Death Dis 7:e2096
Swiderska-Syn, Marzena; Xie, Guanhua; Michelotti, Gregory A et al. (2016) Hedgehog regulates yes-associated protein 1 in regenerating mouse liver. Hepatology 64:232-44

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