Global gene expression profiling reveals a key role of CD44 in hepatic oval-cell reaction after 2-AAF/CCl4 injury in rodents.
Liver progenitors, so-called oval cells, proliferate remarkably from periportal areas after severe liver injury when hepatocyte regeneration is compromised. These cells invade far into the liver parenchyma. Molecular mechanisms underlying these behaviors of oval cells remain poorly understood. In this study, we treated rats with 2-acetylaminofluorene/carbon tetrachloride to induce hepatic oval cells. By expression microarray analysis, we investigated global gene expression profiles in liver tissue, with an emphasis on adhesion molecules, extracellular matrix proteins, matrix metalloproteinases (MMPs), growth factors/cytokines, and receptors that might contribute to the distinct behaviors of oval cells. Genes upregulated at least twofold were selected. We then performed immunostaining to verify the microarray results and identified expression of MMP-7 and CD44 in oval cells. Staining of cytokeratin (CK)-19, an oval-cell marker, was similar between oval cells located next to periportal areas and those located far within the parenchyma. In contrast, CD44 staining was more intense in the parenchyma than in periportal areas, suggesting a role of CD44 in oval-cell invasion. Moreover, newly differentiated CK-19+ hepatocytes within foci did not show CD44 staining, suggesting that CD44 is related to the undifferentiated oval-cell phenotype. We then investigated oval-cell reactivity in CD44-deficient mice fed an oval cell-inducing diet of 3,5-diethoxycarbonyl-1,4-dihydrocollidine. Results showed significantly reduced oval-cell reactivity in CD44-deficient mice. Thus, oval cells express MMP-7 and CD44, and CD44 appears to play critical roles in the proliferation, invasion, and differentiation of hepatic oval cells in rodents.
Chiu
Chien-Chang
CC
The Graduate Institute of Applied Science and Engineering, Fu-Jen Catholic University, and National Taiwan University Hospital, Taipei, Taiwan.
Sheu
Jin-Chuan
JC
Chen
Chien-Hung
CH
Lee
Cha-Ze
CZ
Chiou
Ling-Ling
LL
Chou
Shiu-Huey
SH
Huang
Guan-Tarn
GT
Lee
Hsuan-Shu
HS
D015073:2-Acetylaminofluorene / Q000008:administration & dosage / Q000494:pharmacology*; D000284:Administration, Oral; D000818:Animals; D002251:Carbon Tetrachloride / Q000008:administration & dosage / Q000494:pharmacology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D018960:Hyaluronan Receptors / Q000235:genetics / Q000378:metabolism*; D007120:Immunochemistry; D008099:Liver / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D008115:Liver Regeneration / Q000187:drug effects; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D020133:Reverse Transcriptase Polymerase Chain Reaction
D018960:Hyaluronan Receptors; D015073:2-Acetylaminofluorene; D002251:Carbon Tetrachloride