title: Demarcation of stable subpopulations within the pluripotent hESC compartment.
abstract: Heterogeneity is a feature of stem cell populations, resulting from innate cellular hierarchies that govern differentiation capability. How heterogeneity impacts human pluripotent stem cell populations is directly relevant to their efficacious use in regenerative medicine applications. The control of pluripotency is asserted by a core transcription factor network, of which Oct4 is a necessary member. In mouse embryonic stem cells (ESCs), the zinc finger transcription factor Rex1 (Zfp42) closely tracks the undifferentiated state and is capable of segregating Oct4 positive mESCs into metastable populations expressing or lacking Rex1 that are inter-convertible. However, little is currently understood about the extent or function of heterogeneous populations in the human pluripotent compartment. Human ESCs express REX1 transcripts but the distribution and properties of REX1 expressing cells have yet to be described. To address these questions, we used gene targeting in human ESCs to insert the fluorescent protein Venus and an antibiotic selection marker under the control of the endogenous REX1 transcription regulatory elements, generating a sensitive, selectable reporter of pluripotency. REX1 is co-expressed in OCT4 and TRA-1-60 positive hESCs and rapidly lost upon differentiation. Importantly, REX1 expression reveals significant heterogeneity within seemingly homogenous populations of OCT4 and TRA-1-60 hESCs. REX1 expression is extinguished before OCT4 during differentiation, but, in contrast to the mouse, loss of REX1 expression demarcates a stable, OCT4 positive lineage-primed state in pluripotent hESCs that does not revert back to REX1 positivity under normal conditions. We show that loss of REX1 expression correlates with altered patterns of DNA methylation at the REX1 locus, implying that epigenetic mechanisms may interfere with the metastable phenotype commonly found in murine pluripotency.
authors: McMaster Stem Cell and Cancer Research Institute, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.
authors: Sonam
authors: S
authors: Bhatia
authors: Carlos
authors: C
authors: Pilquil
authors: Ivana
authors: I
authors: Roth-Albin
authors: Jonathan S
authors: JS
authors: Draper
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000235:genetics* / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002135:Calcium-Binding Proteins; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D019070:Cell Lineage / Q000235:genetics*; D019175:DNA Methylation; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000378:metabolism; D044127:Epigenesis, Genetic; D017930:Genes, Reporter; D018740:Genetic Heterogeneity; D049452:Green Fluorescent Proteins; D006801:Humans; D051741:Kruppel-Like Transcription Factors / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D050814:Octamer Transcription Factor-3 / Q000235:genetics* / Q000378:metabolism; D039904:Pluripotent Stem Cells / Q000166:cytology* / Q000378:metabolism; D011509:Proteoglycans / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D050436:Regulatory Elements, Transcriptional
chemical_list: D000954:Antigens, Surface; D015415:Biomarkers; D002135:Calcium-Binding Proteins; D051741:Kruppel-Like Transcription Factors; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; D011509:Proteoglycans; D011993:Recombinant Fusion Proteins; C107064:TRA-1-60 antigen, human; C503160:VC6.1 cameleon protein, recombinant; C507976:ZFP42 protein, human; D049452:Green Fluorescent Proteins