title: Dynamic status of REST in the mouse ESC pluripotency network.
abstract: BACKGROUND
  REST is abundantly expressed in mouse embryonic stem cells (ESCs). Many genome-wide analyses have found REST to be an integral part of the ESC pluripotency network. However, experimental systems have produced contradictory findings: (1) REST is required for the maintenance of ESC pluripotency and loss of REST causes increased expression of differentiation markers, (2) REST is not required for the maintenance of ESC pluripotency and loss of REST does not change expression of differentiation markers, and (3) REST is not required for the maintenance of ESC pluripotency but loss of REST causes decreased expression of differentiation markers. These reports highlight gaps in our knowledge of the ESC network.
  
  
  METHODS
  Employing biochemical and genome-wide analyses of various culture conditions and ESC lines, we have attempted to resolve some of the discrepancies in the literature.
  
  
  RESULTS
  We show that Rest+/- and Rest-/- AB-1 mutant ESCs, which did not exhibit a role of REST in ESC pluripotency when cultured in the presence of feeder cells, did show impaired self-renewal when compared with the parental cells under feeder-free culture conditions, but only in early passage cells. In late passage cells, both Rest+/- and Rest-/- AB-1 ESCs restored pluripotency, suggesting a passage and culture condition-dependent response. Genome-wide analysis followed by biochemical validation supported this response and further indicated that the restoration of pluripotency was associated by increased expression of the ESC pluripotency factors. E14Tg2a.4 ESCs with REST-knockdown, which earlier showed a REST-dependent pluripotency when cultured under feeder-free conditions, as well as Rest-/- AB-1 ESCs, showed no REST-dependent pluripotency when cultured in the presence of either feeder cells or laminin, indicating that extracellular matrix components can rescue REST's role in ESC pluripotency.
  
  
  CONCLUSIONS
  REST regulates ESC pluripotency in culture condition- and ESC line-dependent fashion and ESC pluripotency needs to be evaluated in a context dependent manner.
authors.affiliation: Department of Genetics, The University of Texas M D Anderson Cancer Center, Houston, Texas, United States of America. ssinghk@gmail.com
authors.forename: Sanjay K
authors.initials: SK
authors.lastname: Singh
authors.forename: Bethany L
authors.initials: BL
authors.lastname: Veo
authors.forename: Mohamedi N
authors.initials: MN
authors.lastname: Kagalwala
authors.forename: Weiwei
authors.initials: W
authors.lastname: Shi
authors.forename: Shoudan
authors.initials: S
authors.lastname: Liang
authors.forename: Sadhan
authors.initials: S
authors.lastname: Majumder
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D018929:Cell Culture Techniques; D054337:Cell Dedifferentiation; D002454:Cell Differentiation; D002460:Cell Line; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D023281:Genomics; D051379:Mice; D039904:Pluripotent Stem Cells / Q000166:cytology* / Q000378:metabolism*; D012097:Repressor Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D000099229:RE1-Silencing Transcription Factor
chemical_list: D015415:Biomarkers; D012097:Repressor Proteins; D000099229:RE1-Silencing Transcription Factor