We continue to test the hypothesis that exocytosis of lysosomal contents into biliary canaliculi is a major excretory route for hepatocyte lysosomes. We propose to: (1) Relate biliary excretion of lysosomal contents to turnover of lysosomal constituents by studying: a) turnover rates of hepatic lysosomal enzymes relative to their biliary excretion; b) amount of lysosomal enzymes released by isolated hepatocytes relative to their cellular content; c) effects of alterations in hepatic autophagy and heterophagy on biliary excretion of lysosomal enzymes. (2) Study regulation of hepatic lysosomal enzyme activities by measuring activity and content of lysosomal hydrolases by enzymatic assays and radioimmunoassays, respectively. (3) Study hepatic handling of chole-cystokinin (CCK) and renin, proteins that may be processed in hepatocyte lysosomes, by: a) determining hepatic sites of cellular and subcellular metabolism of labeled CCK peptides; b) purifying and labeling rat renal renin and studying hepatic processing of labeled ligand. (4) Characterize the role of hepatocyte lysosomes in biliary metal excretion using animal models of hepatic iron and copper overload by assessing: a) effects of lysosomotropic agents on biliary metal secretion; b) the form of iron and copper in bile; c) metal-induced changes in hepatic lysosomal enzyme content, lipid and protein composition of lysosomal membranes, and appearance of pericanalicular lysosomes; d) the fate of biliary iron in the intestine; and e) the effect on hepatic and biliary metal concentrations of chronic administration of agents which accelerate release of lysosomal contents into bile. (5) Explore the role of hepatocyte lysosomes in lipoprotein processing and in biliary excretion of lipids and apolipoproteins by: a) characterizing molecular forms of apolipoproteins B, A-I and A-II in human bile; b) studying the relationship between biliary lipid secretion and hepatic uptake of LDL; c) assessing binding to liver plasma membranes of labeled LDL and HDL3 after bile acid administration; and d) studying effects of lysosomotropic agents on biliary lipid secretion. We will utilize intact rats and isolated livers, cells, and organelles, and apply novel biochemical and morphologic techniques (radioimmunoassays, immunocytochemistry). Our long-term objectives are to define the physiological and biochemical bases for and the functional significance of the release of lysosomal contents into bile, identify disturbances of this pathway relevant to disease, and develop therapies which accelerate biliary excretion of toxic materials that accumulate in hepatocyte lysosomes.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK024031-10
Application #
3227259
Study Section
General Medicine A Subcommittee 2 (GMA)
Project Start
1978-12-01
Project End
1991-03-31
Budget Start
1988-04-01
Budget End
1989-03-31
Support Year
10
Fiscal Year
1988
Total Cost
Indirect Cost
Name
Mayo Clinic, Rochester
Department
Type
DUNS #
City
Rochester
State
MN
Country
United States
Zip Code
55905
Masyuk, Tatyana V; Masyuk, Anatoliy I; LaRusso, Nicholas F (2018) Polycystic liver disease: The interplay of genes causative for hepatic and renal cystogenesis. Hepatology 67:2462-2464
Masyuk, Anatoliy I; Masyuk, Tatyana V; Lorenzo Pisarello, Maria J et al. (2018) Cholangiocyte autophagy contributes to hepatic cystogenesis in polycystic liver disease and represents a potential therapeutic target. Hepatology 67:1088-1108
Banales, Jesus M; Marzioni, Marco; LaRusso, Nicholas F et al. (2018) Cholangiocytes in health and disease: From basic science to novel treatments. Biochim Biophys Acta Mol Basis Dis 1864:1217-1219
Mansini, Adrian P; Lorenzo Pisarello, Maria J; Thelen, Kristen M et al. (2018) MicroRNA (miR)-433 and miR-22 dysregulations induce histone-deacetylase-6 overexpression and ciliary loss in cholangiocarcinoma. Hepatology 68:561-573
Lorenzo Pisarello, Maria; Masyuk, Tatyana V; Gradilone, Sergio A et al. (2018) Combination of a Histone Deacetylase 6 Inhibitor and a Somatostatin Receptor Agonist Synergistically Reduces Hepatorenal Cystogenesis in an Animal Model of Polycystic Liver Disease. Am J Pathol 188:981-994
Cheung, Angela C; Lorenzo Pisarello, Maria J; LaRusso, Nicholas F (2018) Pathobiology of biliary epithelia. Biochim Biophys Acta Mol Basis Dis 1864:1220-1231
Loarca, Lorena; De Assuncao, Thiago M; Jalan-Sakrikar, Nidhi et al. (2017) Development and characterization of cholangioids from normal and diseased human cholangiocytes as an in vitro model to study primary sclerosing cholangitis. Lab Invest 97:1385-1396
Masyuk, Tatyana V; Masyuk, Anatoliy I; LaRusso, Nicholas F (2017) Therapeutic Targets in Polycystic Liver Disease. Curr Drug Targets 18:950-957
Masyuk, Tatyana V; Masyuk, Anatoliy I; Lorenzo Pisarello, Maria et al. (2017) TGR5 contributes to hepatic cystogenesis in rodents with polycystic liver diseases through cyclic adenosine monophosphate/G?s signaling. Hepatology 66:1197-1218
Holditch, Sara J; Schreiber, Claire A; Harris, Peter C et al. (2017) B-type natriuretic peptide overexpression ameliorates hepatorenal fibrocystic disease in a rat model of polycystic kidney disease. Kidney Int 92:657-668

Showing the most recent 10 out of 165 publications