EMP-1 is a junctional protein in a liver stem cell line and in the liver.
In an attempt to discover cell markers for liver stem cells, a cDNA microarray analysis was carried out to compare the gene expression profiles between an adult liver stem cell line, Lig-8, and mature hepatocytes. Several genes in the categories of extracellular matrix, cell membrane, cell adhesion, transcription factor, signal molecule, transporter, and metabolic enzyme were shown to be differentially expressed in Lig-8 cells. Among them, epithelial membrane protein (EMP)-1 has been previously implicated with stem cell phenotypes. Antiserum to EMP-1 was produced to localize its expression. On monolayers of Lig-8 cells, EMP-1 was expressed along the intercellular border. In the liver harboring proliferating oval cells, the liver progenitors, EMP-1 was localized as ribbon bands, a staining pattern for epithelial junctions, all the way through bile duct epithelia, oval cell ductules, and into peri-hepatocytic regions. These peri-hepatocytic regions were proved to be bile canaliculi by co-localization of EMP-1 and dipeptidyl peptidase IV, an enzyme located on bile canaliculi. This report is the first to indicate EMP-1 to be a junctional protein in the liver.
Lee
Hsuan-Shu
HS
Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University, College of Medicine, Taipei, Taiwan.
Sherley
James L
JL
Chen
Jeremy J W
JJ
Chiu
Chien-Chang
CC
Chiou
Ling-Ling
LL
Liang
Ja-Der
JD
Yang
Pan-Chyr
PC
Huang
Guan-Tarn
GT
Sheu
Jin-Chuan
JC
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002460:Cell Line; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D022781:Hepatocytes / Q000378:metabolism*; D007365:Intercellular Junctions / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008297:Male; D009363:Neoplasm Proteins / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013234:Stem Cells / Q000378:metabolism*; D014018:Tissue Distribution
D015415:Biomarkers; D009363:Neoplasm Proteins; D011956:Receptors, Cell Surface; C097051:epithelial membrane protein-1