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Summary: Phenobarbital responsiveness as a uniquely sensitive indicator
of hepatocyte differentiation status: requirement of dexamethasone
and extracellular matrix in establishing the functional integrity of
cultured primary rat hepatocytes
Jaspreet S. Sidhu,a
Fei Liu,a
and Curtis J. Omiecinskib,*
a
Department of Environmental Health, University of Washington, Seattle, WA 98105, USA
b
Center for Molecular Toxicology and Carcinogenesis, Department of Veterinary Science, The Pennsylvania State University,
University Park, PA 16802, USA
Received 8 July 2003
Abstract
We used a serum-free, highly defined primary hepatocyte culture model to investigate the mechanisms whereby dexamethasone (Dex) and
extracellular matrix (ECM) coordinate cell differentiation and transcriptional responsiveness to the inducer, phenobarbital (PB). Low
nanomolar levels of Dex and dilute concentrations of ECM overlay were essential in the maintenance of normal hepatocyte physiology, as
assessed by cell morphology, LDH release, expression of the hepatic nuclear factors C/EBPa, -h, -g, HNF-1a, -1h, -4a, and RXRa,
expression of prototypical hepatic marker genes, including albumin and transferrin, and ultimately, cellular capacity to respond to PB. The
loss of hepatocyte integrity produced by deficiency of these components correlated with the activation of several stress signaling pathways
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