Expression of the subgenomic hepatitis C virus replicon alters iron homeostasis in Huh7 cells.
OBJECTIVE
Infection with hepatitis C virus (HCV) is associated with alterations in body iron homeostasis by poorly defined mechanisms. To seek for molecular links, we employed an established cell culture model for viral replication, and assessed how the expression of an HCV subgenomic replicon affects iron metabolism in host Huh7 hepatoma cells.


METHODS
The expression of iron metabolism genes and parameters defining the cellular iron status were analyzed and compared between parent and replicon Huh7 cells.


RESULTS
By using the IronChip microarray platform, we observed replicon-induced changes in expression profiles of iron metabolism genes. Notably, ceruloplasmin mRNA and protein expression were decreased in replicon cells. In addition, transferrin receptor 1 (TfR1) was also downregulated, while ferroportin levels were elevated, resulting in reduced iron uptake and increased iron release capacity of replicon cells. These responses were associated with an iron-deficient phenotype, manifested in decreased levels of the "labile iron pool" and concomitant induction of IRE-binding activity and IRP2 expression. Furthermore, hemin-treated replicon cells exhibited a defect in retaining iron. The clearance of the replicon by prolonged treatment with interferon-alpha only partially reversed the iron-deficient phenotype but almost completely restored the capacity of cured cells to retain iron.


CONCLUSIONS
We propose that Huh7 cells undergo genetic reprogramming to permit subgenomic viral replication that results in reduction of intracellular iron levels. This response may provide a mechanism to bypass iron-mediated inactivation of the viral RNA polymerase NS5B.
Fillebeen
Carine
C
Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, 3755 Cote-Ste-Catherine Road, Montreal, Que., Canada H3T 1E2.
Muckenthaler
Martina
M
Andriopoulos
Bill
B
Bisaillon
Martin
M
Mounir
Zineb
Z
Hentze
Matthias W
MW
Koromilas
Antonis E
AE
Pantopoulos
Kostas
K
D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D045744:Cell Line, Tumor; D002570:Ceruloplasmin / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D020869:Gene Expression Profiling; D016679:Genome, Viral; D006427:Hemin / Q000494:pharmacology; D016174:Hepacivirus / Q000235:genetics / Q000502:physiology*; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism* / Q000821:virology*; D006706:Homeostasis; D006801:Humans; D007501:Iron / Q000378:metabolism*; D011990:Receptors, Transferrin / Q000235:genetics / Q000378:metabolism; D012093:Replicon / Q000235:genetics; D014779:Virus Replication / Q000235:genetics*
D015703:Antigens, CD; C068126:CD71 antigen; D011990:Receptors, Transferrin; D006427:Hemin; D007501:Iron; D002570:Ceruloplasmin