Polarization restricts hepatitis C virus entry into HepG2 hepatoma cells.
The primary reservoir for hepatitis C virus (HCV) replication is believed to be hepatocytes, which are highly polarized with tight junctions (TJ) separating their basolateral and apical domains. HepG2 cells develop polarity over time, resulting in the formation and remodeling of bile canalicular (BC) structures. HepG2 cells expressing CD81 provide a model system to study the effects of hepatic polarity on HCV infection. We found an inverse association between HepG2-CD81 polarization and HCV pseudoparticle entry. As HepG2 cells polarize, discrete pools of claudin-1 (CLDN1) at the TJ and basal/lateral membranes develop, consistent with the pattern of receptor staining observed in liver tissue. The TJ and nonjunctional pools of CLDN1 show an altered association with CD81 and localization in response to the PKA antagonist Rp-8-Br-cyclic AMPs (cAMPs). Rp-8-Br-cAMPs reduced CLDN1 expression at the basal membrane and inhibited HCV infection, supporting a model where the nonjunctional pools of CLDN1 have a role in HCV entry. Treatment of HepG2 cells with proinflammatory cytokines, tumor necrosis factor alpha and gamma interferon, perturbed TJ integrity but had minimal effect(s) on cellular polarity and HCV infection, suggesting that TJ integrity does not limit HCV entry into polarized HepG2 cells. In contrast, activation of PKC with phorbol ester reduced TJ integrity, ablated HepG2 polarity, and stimulated HCV entry. Overall, these data show that complex hepatocyte-like polarity alters CLDN1 localization and limits HCV entry, suggesting that agents which disrupt hepatocyte polarity may promote HCV infection and transmission within the liver.
Hepatitis C Research Group, Division of Immunity and Infection, University of Birmingham, Birmingham, United Kingdom.
Christopher J
CJ
Mee
Helen J
HJ
Harris
Michelle J
MJ
Farquhar
Garrick
G
Wilson
Gary
G
Reynolds
Christopher
C
Davis
Sven C D
SC
van IJzendoorn
Peter
P
Balfe
Jane A
JA
McKeating
D015703:Antigens, CD / Q000378:metabolism; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity; D062445:Claudin-1; D000242:Cyclic AMP / Q000031:analogs & derivatives; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D016174:Hepacivirus / Q000378:metabolism / Q000502:physiology*; D006526:Hepatitis C / Q000821:virology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D010703:Phorbol Esters / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D060225:Tetraspanin 28; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism / Q000821:virology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D053586:Virus Internalization
D015703:Antigens, CD; C554798:CD81 protein, human; C568108:CLDN1 protein, human; D062445:Claudin-1; D008565:Membrane Proteins; D010703:Phorbol Esters; D060225:Tetraspanin 28; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C