Human haematopoietic stem cells express Oct4 pseudogenes and lack the ability to initiate Oct4 promoter-driven gene expression.
The transcription factor Oct4 is well defined as a key regulator of embryonic stem (ES) cell pluripotency. In recent years, the role of Oct4 has purportedly extended to the self renewal and maintenance of multipotency in adult stem cell (ASC) populations. This profile has arisen mainly from reports utilising reverse transcription-polymerase chain reaction (RT-PCR) based methodologies and has since come under scrutiny following the discovery that many developmental genes have multiple pseudogenes associated with them. Six known pseudogenes exist for Oct4, all of which exhibit very high sequence homology (three >97%), and for this reason the generation of artefacts may have contributed to false identification of Oct4 in somatic cell populations. While ASC lack a molecular blueprint of transcription factors proposed to be involved with 'stemness' as described for ES cells, it is not unreasonable to assume that similar gene patterns may exist. The focus of this work was to corroborate reports that Oct4 is involved in the regulation of ASC self-renewal and differentiation, using a combination of methodologies to rule out pseudogene interference. Haematopoietic stem cells (HSC) derived from human umbilical cord blood (UCB) and various differentiated cell lines underwent RT-PCR, product sequencing and transfection studies using an Oct4 promoter-driven reporter. In summary, only the positive control expressed Oct4, with all other cell types expressing a variety of Oct4 pseudogenes. Somatic cells were incapable of utilising an exogenous Oct4 promoter construct, leading to the conclusion that Oct4 does not appear involved in the multipotency of human HSC from UCB.
Redshaw
Zoe
Z
School of Veterinary Medicine and Science, The University of Nottingham, Sutton Bonington Campus Sutton Bonington, Leicestershire, LE12 5RD, UK. zoe.redshaw@nottingham.ac.uk
Strain
Alastair J
AJ
D016477:Artifacts; D001483:Base Sequence; D002460:Cell Line / Q000378:metabolism; D004274:DNA, Recombinant / Q000235:genetics; D005189:False Positive Reactions; D005312:Fetal Blood / Q000166:cytology*; D018507:Gene Expression Regulation, Developmental; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D007231:Infant, Newborn; D008969:Molecular Sequence Data; D039902:Multipotent Stem Cells / Q000378:metabolism*; D050814:Octamer Transcription Factor-3 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011544:Pseudogenes; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D014162:Transfection
D004274:DNA, Recombinant; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human