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The maintenance and generation of membrane polarity in hepatocytes
Author(s) -
Wang Lin,
Boyer James L.
Publication year - 2004
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.20039
Subject(s) - microbiology and biotechnology , hepatocyte , secretion , polarity (international relations) , epithelial polarity , cell polarity , biology , membrane protein , cholestasis , transport protein , golgi apparatus , secretory pathway , membrane , biochemistry , cell , endoplasmic reticulum , endocrinology , in vitro
Hepatocytes, the major epithelial cells in the liver, are highly polarized. Their plasma membranes are separated by tight junctions into sinusoidal– basolateral and canalicular–apical domains, which contain distinct sets of proteins and lipids. A normal membrane polarity is vital for hepatocytes to perform many diverse functions, such as canalicular bile secretion and simultaneous sinusoidal secretion of large quantities of serum proteins into blood. Hepatocyte polarity is lost in many diseases like cholestasis. A complete understanding of the molecular mechanisms involved in hepatocyte polarity therefore is of considerable significance to both liver cell biology and the pathogenesis of liver diseases. To maintain the distinct distribution of proteins and lipids in the canalicular and sinusoidal membranes, hepatocytes have developed complex polarized trafficking and retention mechanisms. The establishment of membrane polarity in hepatocytes begins during liver embryogenesis. During hepatocyte differentiation, specific routes and mechanisms are defined for the delivery of plasma membrane proteins. How this polarity is maintained in adult hepatocytes and is generated during development are two major unanswered questions in this field. In this review, we first give an overview of the current knowledge about how membrane polarity is maintained in hepatocytes with the focus on recent developments in polarized protein trafficking.We then present a hypothetical model about how membrane polarity may be generated during liver development, and finally, we present an example of how membrane polarity is altered in cholestasis. Readers are directed to recent reviews for discussion of lipid trafficking in hepatocytes.1,2