Dynamic methylation and expression of Oct4 in early neural stem cells.
Neural stem cells are a multipotent population of tissue-specific stem cells with a broad but limited differentiation potential. However, recent studies have shown that over-expression of the pluripotency gene, Oct4, alone is sufficient to initiate a process by which these can form 'induced pluripotent stem cells' (iPS cells) with the same broad potential as embryonic stem cells. This led us to examine the expression of Oct4 in endogenous neural stem cells, as data regarding its expression in neural stem cells in vivo are contradictory and incomplete. In this study we have therefore analysed the expression of Oct4 and other genes associated with pluripotency throughout development of the mouse CNS and in neural stem cells grown in vitro. We find that Oct4 is still expressed in the CNS by E8.5, but that this expression declines rapidly until it is undetectable by E15.5. This decline is coincident with the gradual methylation of the Oct4 promoter and proximal enhancer. Immunostaining suggests that the Oct4 protein is predominantly cytoplasmic in location. We also found that neural stem cells from all ages expressed the pluripotency associated genes, Sox2, c-Myc, Klf4 and Nanog. These data provide an explanation for the varying behaviour of cells from the early neuroepithelium at different stages of development. The expression of these genes also provides an indication of why Oct4 alone is sufficient to induce iPS formation in neural stem cells at later stages.
Lee
Shih-Han
SH
Children's Brain Tumour Research Centre, Institute of Genetics, University of Nottingham, Queen's Medical Centre, Nottingham, UK.
Jeyapalan
Jennie N
JN
Appleby
Vanessa
V
Mohamed Noor
Dzul Azri
DA
Sottile
Virginie
V
Scotting
Paul J
PJ
D000818:Animals; D001921:Brain / Q000196:embryology* / Q000378:metabolism; D002478:Cells, Cultured; D019175:DNA Methylation; D053595:Embryonic Stem Cells / Q000378:metabolism*; D015870:Gene Expression; D018398:Homeodomain Proteins / Q000378:metabolism; D000090062:Kruppel-Like Factor 4; D051379:Mice; D008815:Mice, Inbred Strains; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3 / Q000096:biosynthesis* / Q000235:genetics; D039904:Pluripotent Stem Cells / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods
D018398:Homeodomain Proteins; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D000071317:Nanog Homeobox Protein; C475540:Nanog protein, mouse; D050814:Octamer Transcription Factor-3; C494174:Pou5f1 protein, mouse