title: Immunohistochemical analysis of cytokeratin 7 expression in resting and proliferating biliary structures of rat liver.
abstract: Cytokeratins are the largest subfamily of intermediate filament proteins and include more than 20 different gene products, which are expressed in an epithelial tissue-specific manner. We studied by immunohistochemistry and confocal microscopy the distribution of cytokeratin subtypes in the biliary system of adult rat liver. A cytokeratin (CK)19+/7- cholangiocyte population was observed in the smaller branches of the biliary tree including the canals of Hering. They proliferated after 2-acetaminofluorene (AAF) administration, although later the typical oval cells expressed CK7. This observation suggests that cholangiocytes with this cytokeratin phenotype may harbor adult hepatic stem cells. The CK19+/7- cholangiocytes were not present in the rat liver at birth, but developed postnatally. Similar cell populations were not observed in human livers. In conclusion, we propose that the CK19+/7- phenotype may be characteristic for adult hepatic stem cells in rat liver and that these cells are generated de novo after birth.
authors.affiliation: Department of Molecular Pathology, Joint Research Organization of the Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary.
authors.forename: Sándor
authors.initials: S
authors.lastname: Paku
authors.forename: Katalin
authors.initials: K
authors.lastname: Dezso
authors.forename: László
authors.initials: L
authors.lastname: Kopper
authors.forename: Peter
authors.initials: P
authors.lastname: Nagy
mesh_terms: D015073:2-Acetylaminofluorene / Q000031:analogs & derivatives / Q000494:pharmacology; D000367:Age Factors; D000818:Animals; D001653:Bile Ducts, Intrahepatic / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D053552:Keratin-7; D007633:Keratins / Q000378:metabolism*; D008099:Liver / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism*; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism
chemical_list: D015415:Biomarkers; C507497:KRT7 protein, human; D053552:Keratin-7; D007633:Keratins; D015073:2-Acetylaminofluorene