title: Temporal gene expression during differentiation of human embryonic stem cells and embryoid bodies.
abstract: BACKGROUND
  The aim of this study was to characterize human embryonic stem (ES) cells at the molecular level by performing large-scale complementary DNA (cDNA) analysis using DNA micro-arrays.
  
  
  METHODS
  The transcription profile of human ES cells was determined by comparing it to 2, 10 and 30-day old embryoid bodies (EBs) using Affymetrix Genechip human micro-arrays (U133).
  
  
  RESULTS
  According to this analysis we demonstrate that two human ES cell lines are more close to each other than to their differentiated derivatives. We also show the spectrum of cytokine receptors that they express, and demonstrate the presence of five genes that are highly specific to human ES cells and to germ cells. Moreover, by profiling different stages in the differentiation of human embryoid bodies, we illustrate the clustering of five sets of temporally expressed genes, which could be related to the sequential stages of embryonic development. Among them are known genes that are involved in early pattern formation.
  
  
  CONCLUSIONS
  The present study provides a molecular basis for the identity of human ES cells and demonstrates that during their in vitro differentiation they express embryonic specific genes in a stage specific manner.
authors.affiliation: Department of Genetics, The Institute of Life Sciences, The Hebrew University, Jerusalem 91904, Israel.
authors.forename: Tamar
authors.initials: T
authors.lastname: Dvash
authors.forename: Yoav
authors.initials: Y
authors.lastname: Mayshar
authors.forename: Henia
authors.initials: H
authors.lastname: Darr
authors.forename: Michael
authors.initials: M
authors.lastname: McElhaney
authors.forename: Douglas
authors.initials: D
authors.lastname: Barker
authors.forename: Ofra
authors.initials: O
authors.lastname: Yanuka
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Kotkow
authors.forename: Lee L
authors.initials: LL
authors.lastname: Rubin
authors.forename: Nissim
authors.initials: N
authors.lastname: Benvenisty
authors.forename: Rachel
authors.initials: R
authors.lastname: Eiges
mesh_terms: D002454:Cell Differentiation / Q000235:genetics*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics; D004622:Embryo, Mammalian / Q000166:cytology*; D015870:Gene Expression; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D055458:Left-Right Determination Factors; D055457:Nodal Protein; D050814:Octamer Transcription Factor-3; D020411:Oligonucleotide Array Sequence Analysis; D037663:Pulmonary Surfactant-Associated Protein D / Q000235:genetics; D013234:Stem Cells / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000235:genetics; D000509:alpha-Fetoproteins / Q000235:genetics; D000097577:Homeobox Protein PITX2
chemical_list: D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D055458:Left-Right Determination Factors; D055457:Nodal Protein; D050814:Octamer Transcription Factor-3; D037663:Pulmonary Surfactant-Associated Protein D; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D000509:alpha-Fetoproteins; D000097577:Homeobox Protein PITX2; C526161:LEFTY1 protein, human; C526007:NODAL protein, human; C494173:POU5F1 protein, human