51. Modulation of the biliary expression of arylalkylamine N-acetyltransferase alters the autocrine proliferative responses of cholangiocytes in rats
- Author
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Romina Mancinelli, Kendal Jensen, Paolo Onori, Giuseppina Dusio, Heather Francis, Guido Carpino, Shannon Glaser, Mellanie White, Fanyin Meng, John Greene, Yuyan Han, Julie Venter, Anastasia Renzi, Gianfranco Alpini, Yoshiyuki Ueno, Sharon DeMorrow, Eugenio Gaudio, and Antonio Franchitto
- Subjects
Male ,medicine.medical_specialty ,AANAT ,SLC4A Proteins ,Anion Transport Proteins ,Apoptosis ,Arylalkylamine N-Acetyltransferase ,digestive system ,Antioxidants ,Antiporters ,Article ,Cholangiocyte ,Secretin ,Melatonin ,Mice ,Proliferating Cell Nuclear Antigen ,Internal medicine ,medicine ,Animals ,Autocrine signalling ,Cell Line, Transformed ,Cell Proliferation ,Cholestasis ,Hepatology ,biology ,Biliary hyperplasia ,Rats, Inbred F344 ,digestive system diseases ,Cystic fibrosis transmembrane conductance regulator ,Rats ,Autocrine Communication ,Bile Ducts, Intrahepatic ,Endocrinology ,Gene Knockdown Techniques ,Receptors, Serotonin ,biology.protein ,Secretin receptor ,hormones, hormone substitutes, and hormone antagonists ,medicine.drug - Abstract
Secretin stimulates ductal secretion by interacting with secretin receptor (SR) activating cyclic adenosine 3',5'-monophosphate/cystic fibrosis transmembrane conductance regulator/chloride bicarbonate anion exchanger 2 (cAMP⇒CFTR⇒Cl(-) /HCO 3- AE2) signaling that is elevated by biliary hyperplasia. Cholangiocytes secrete several neuroendocrine factors regulating biliary functions by autocrine mechanisms. Melatonin inhibits biliary growth and secretin-stimulated choleresis in cholestatic bile-duct-ligated (BDL) rats by interaction with melatonin type 1 (MT1) receptor through down-regulation of cAMP-dependent signaling. No data exist regarding the role of melatonin synthesized locally by cholangiocytes in the autocrine regulation of biliary growth and function. In this study, we evaluated the (1) expression of arylalkylamine N-acetyltransferase (AANAT; the rate-limiting enzyme for melatonin synthesis from serotonin) in cholangiocytes and (2) effect of local modulation of biliary AANAT expression on the autocrine proliferative/secretory responses of cholangiocytes. In the liver, cholangiocytes (and, to a lesser extent, BDL hepatocytes) expressed AANAT. AANAT expression and melatonin secretion (1) increased in BDL, compared to normal rats and BDL rats treated with melatonin, and (2) decreased in normal and BDL rats treated with AANAT Vivo-Morpholino, compared to controls. The decrease in AANAT expression, and subsequent lower melatonin secretion by cholangiocytes, was associated with increased biliary proliferation and increased SR, CFTR, and Cl(-) /HCO 3- AE2 expression. Overexpression of AANAT in cholangiocyte cell lines decreased the basal proliferative rate and expression of SR, CFTR, and Cl(-) /HCO 3- AE2 and ablated secretin-stimulated biliary secretion in these cells.Local modulation of melatonin synthesis may be important for management of the balance between biliary proliferation/damage that is typical of cholangiopathies. (HEPATOLOGY 2013).
- Published
- 2013