BILIARY EXCRETION OF LYSOSOMAL PROTEIN

Project: Research project

Description

Our OVERALL OBJECTIVES continue to be to understand how liver cells,
process exogenous and endogenous substances and to identify the physiologic
consequences of these processing activities. Our GENERAL HYPOTHESIS is
that cellular processing (internalization/transport/structural
modification/externalization) involves a coordinated series of anatomically
and temporally discrete events that are integral to and selectively coupled
with the absorptive, digestive, and secretory activities of hepatic
epithelia--namely, bile duct epithelial cells and hepatocytes. We will
employ current and complementary biochemical and quantitative morphological
techniques to define regulatory and mechanistic aspects of cell processing
by focusing on: (i) the role of exocytosis and endocytosis in regulating
secretion by intrahepatic bile duct epithelial cells (IBDEC); and (ii) the
role of lysosomal proteolysis and vesicular transport in regulating
digestion and secretion by hepatocytes. The proposal has two specific
aims. First, we will CHARACTERIZE THE PLASMA-MEMBRANE DEPENDENT COMPONENTS
OF CELLULAR PROCESSING (i.e., endocytosis/exocytosis) IN IBDEC by: (a)
testing the HYPOTHESIS that hormone-responsive ductular bile flow involves
the selective recycling by coupled exocytic/endocytic insertion and
retrieval of specific, transport-protein containing microdomains of the
apical plasma membrane of IBDEC; (b) testing the HYPOTHESIS that secretin
interacts with a receptor on IBDEC activating second messengers that
stimulate exocytosis by acidic organelles; and (c) developing and applying
additional novel technology (monoclonal antibodies, organelle isolation
methods, polar primary cultures) for IBDEC. Second, we will DETERMINE THE
MECHANISMS FOR THE CATALYTIC AND MOTILE COMPONENTS OF CELLULAR PROCESSING
(lysosomal digestion/vesicular transport) IN HEPATOCYTES by: (a) examining
lysosomal autophagy using an in vitro, cell-tree system of highly-purified,
subfractions of hepatocyte lysosomes; and (b) characterizing the dynamics
of lysosomal heterophage using both isolated hepatocytes and a liver-
derived, in vitro cell-free system containing purified endosomes, lysosomes
and cytoskeletal elements. The proposed studies are feasible now because
we have at our disposal new experimental models (isolated/short-term
cultured IBDEC and in vitro cell-free systems), novel biochemical methods
(fluorescence assays for both exocytosis and heterophagy), and advanced
cell biologic techniques (fluorescence spectroscopy, immunocytochemical and
freeze-fracture electron microscopy, and digitized video and confocal
microscopy). Our LONG-TERM GOALS are to define the biochemical basis for
and the physiologic consequences of cellular processing in hepatic
epithelia, to identify disturbances of the individual components of
cellular processing relevant to disease, and ultimately to develop
therapies for treatment of processing disorders of hepatic epithelia.
StatusFinished
Effective start/end date12/1/783/31/18

Funding

  • National Institutes of Health: $403,230.00
  • National Institutes of Health
  • National Institutes of Health: $502,208.00
  • National Institutes of Health: $412,603.00
  • National Institutes of Health
  • National Institutes of Health: $503,420.00
  • National Institutes of Health: $473,780.00
  • National Institutes of Health: $367,765.00
  • National Institutes of Health: $624,424.00
  • National Institutes of Health: $306,775.00
  • National Institutes of Health
  • National Institutes of Health: $616,490.00
  • National Institutes of Health: $473,780.00
  • National Institutes of Health
  • National Institutes of Health: $570,959.00
  • National Institutes of Health: $473,780.00
  • National Institutes of Health
  • National Institutes of Health: $183,039.00
  • National Institutes of Health: $499,835.00
  • National Institutes of Health: $432,203.00
  • National Institutes of Health
  • National Institutes of Health: $550,976.00
  • National Institutes of Health: $384,201.00
  • National Institutes of Health
  • National Institutes of Health: $335,919.00
  • National Institutes of Health: $485,275.00
  • National Institutes of Health
  • National Institutes of Health: $559,836.00
  • National Institutes of Health
  • National Institutes of Health: $422,258.00
  • National Institutes of Health: $502,732.00

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Epithelium
Liver
Bile
Intrahepatic Bile Ducts
Cilia
Aquaporins
Autosomal Recessive Polycystic Kidney
Epithelial Cells
Hepatocytes
Exocytosis
Cysts
Autosomal Dominant Polycystic Kidney
Autophagy
Lysosomes
Bile Ducts
MicroRNAs
Exosomes
Organelles
Animal Models
Cell-Free System

ASJC

  • Medicine(all)