The long-term goal of our studies is to understand the role of biliary epithelium in the repair and regeneration of the liver after damage. Inherited cholangiopathies with identified genetic defects serve as model diseases to elucidate the fundamental pathophysiological mechanisms. The previously funded proposal focused on polycystic liver disease associated to Adult Dominant Polycystic Kidney Disease (PLD-ADPKD) as a paradigm for the role of angiogenic signaling in biliary diseases. We uncovered mechanisms that may be relevant for the pathogenesis of other congenital and acquired liver diseases. In fact, using mice models with inducible defects of polycystins, we found that: 1) the cystic epithelium produces VEGF and expresses its cognate receptor VEGFR2;2) VEGF-mediated stimulation of VEGFR2 results in increased ERK1/2-dependent proliferation of the cystic epithelium, 3) PC2-defective cystic cholangiocytes, altered cellular Ca2+ homeostasis and a cAMP- dependent increase in PKA/Ras/Raf/ERK signaling results in mTOR/HIF-1?-mediated stimulation of VEGF production, 4) in response to stimuli able to deplete ER Ca2+ stores, PC2 participates in store-operated Ca2+ entry (SOCE);5) if PC2 is defective, an alternative pathway is activated (store-operated cAMP production - SOcAMP), leading to an inappropriate overproduction of cAMP;6) VEGF/VEGFR2 play a key role on cyst growth and expansion through paracrine effects on pericystic vascular cells, and autocrine stimulation of the cystic epithelium proliferation. These findings are the basis of this new proposal which main hypothesis is that the mechanism linking PC2 to VEGF secretion and VEGFR2 expression identified in PLD-ADPKD is of general relevance in biliary pathophysiology. We will address this hypothesis through three specific aims: 1) to better understand the interactions between PC2 function store-operated Ca2+ entry and inappropriate production of cAMP, 2) to study if PC2 expression in WT cholangiocytes can be modulated by cell stressors, thereby reproducing the changes seen in PC2-defective cells;3) to study the mechanisms leading to VEGFR2 expression in cystic and reactive cholangiocytes, and to elucidate the role of VEGF in the branching morphogenesis of the biliary epithelium during liver repair. These studies will address the novel idea that PC2 play a pivotal role in the regulation of cholangiocyte response to biliary damage acquired cholangiopathies, and that VEGF secreted by reactive cholangiocytes is a major factor in liver repair. Furthermore, our studies will increase understanding of VEGF/VEGFR2 signaling in epithelia and will address a fundamental mechanism in congenital and acquired cholangiopathies. Understanding the pathophysiology of cholangiopathies is a fundamental step for preserving liver function and prolonging the survival of patients

Public Health Relevance

Cholangiopathies are a group of genetic and acquired liver diseases responsible for significant morbidity and mortality among liver patients. In this proposal we will test the novel idea that Polycystin-2 (PC2), the protein mutated in ADPKD, can be modulated in response to biliary damage/repair and stimulate reparative VEGF secretion and VEGFR2 expression. Understanding of VEGF/VEGFR2 signaling in epithelia addresses a fundamental mechanism in congenital and acquired cholangiopathies.

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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Doo, Edward
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Yale University
Internal Medicine/Medicine
Schools of Medicine
New Haven
United States
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Kaffe, Eleanna; Fiorotto, Romina; Pellegrino, Francesca et al. (2018) ?-Catenin and interleukin-1?-dependent chemokine (C-X-C motif) ligand 10 production drives progression of disease in a mouse model of congenital hepatic fibrosis. Hepatology 67:1903-1919
Cadamuro, Massimiliano; Stecca, Tommaso; Brivio, Simone et al. (2018) The deleterious interplay between tumor epithelia and stroma in cholangiocarcinoma. Biochim Biophys Acta Mol Basis Dis 1864:1435-1443
Strazzabosco, Mario; Fiorotto, Romina; Cadamuro, Massimiliano et al. (2018) Pathophysiologic implications of innate immunity and autoinflammation in the biliary epithelium. Biochim Biophys Acta Mol Basis Dis 1864:1374-1379
Mariotti, Valeria; Strazzabosco, Mario; Fabris, Luca et al. (2018) Animal models of biliary injury and altered bile acid metabolism. Biochim Biophys Acta Mol Basis Dis 1864:1254-1261
Brivio, Simone; Cadamuro, Massimiliano; Fabris, Luca et al. (2018) Molecular Mechanisms Driving Cholangiocarcinoma Invasiveness: An Overview. Gene Expr 18:31-50
Cadamuro, Massimiliano; Brivio, Simone; Spirli, Carlo et al. (2017) Autocrine and Paracrine Mechanisms Promoting Chemoresistance in Cholangiocarcinoma. Int J Mol Sci 18:
Morell, Carola M; Fiorotto, Romina; Meroni, Marica et al. (2017) Notch signaling and progenitor/ductular reaction in steatohepatitis. PLoS One 12:e0187384
Spirli, Carlo; Mariotti, Valeria; Villani, Ambra et al. (2017) Adenylyl cyclase 5 links changes in calcium homeostasis to cAMP-dependent cyst growth in polycystic liver disease. J Hepatol 66:571-580
Cadamuro, Massimiliano; Spagnuolo, Gaia; Sambado, Luisa et al. (2016) Low-Dose Paclitaxel Reduces S100A4 Nuclear Import to Inhibit Invasion and Hematogenous Metastasis of Cholangiocarcinoma. Cancer Res 76:4775-84
Fiorotto, Romina; Villani, Ambra; Kourtidis, Antonis et al. (2016) The cystic fibrosis transmembrane conductance regulator controls biliary epithelial inflammation and permeability by regulating Src tyrosine kinase activity. Hepatology 64:2118-2134

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