title: Human telomerase activity, telomerase and telomeric template expression in hepatic stem cells and in livers from fetal and postnatal donors.
abstract: BACKGROUND
  Although telomerase activity has been analyzed in various normal and malignant tissues, including liver, it is still unknown to what extent telomerase can be associated with specific maturational lineage stages.
  
  
  METHODS
  We assessed human telomerase activity, protein and gene expression for the telomerase reverse transcriptase, as well as expression of the telomeric template RNA hTER in hepatic stem cells and in various developmental stages of the liver from fetal to adult. In addition, the effect of growth factors on telomerase activity was analyzed in hepatic stem cells in vitro.
  
  
  RESULTS
  Telomerase was found to be highly active in fetal liver cells and was significantly higher than in hepatic stem cells, correlating with gene and protein expression levels. Activity in postnatal livers from all donor ages varied considerably and did not correlate with age or gene expression levels. The hter expression could be detected throughout the development. A short stimulation by growth factors of cultured hepatic stem cells did not increase telomerase activity.
  
  
  CONCLUSIONS
  Telomerase is considerably active in fetal liver and variably in postnatal livers. Although telomerase protein is present at varying levels in liver cells of all donor ages, gene expression is solely associated with fetal liver cells.
authors.affiliation: Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA. schmelzere@upmc.edu
authors.forename: Eva
authors.initials: E
authors.lastname: Schmelzer
authors.forename: Lola M
authors.initials: LM
authors.lastname: Reid
mesh_terms: D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D005333:Fetus / Q000201:enzymology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology; D006133:Growth Substances / Q000494:pharmacology; D022781:Hepatocytes / Q000166:cytology / Q000201:enzymology*; D006801:Humans; D008099:Liver / Q000166:cytology / Q000196:embryology / Q000201:enzymology*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013234:Stem Cells / Q000201:enzymology*; D019098:Telomerase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D016615:Telomere / Q000201:enzymology
chemical_list: D006133:Growth Substances; C509186:TERT protein, human; D019098:Telomerase