Continuous hypoxic culturing of human embryonic stem cells enhances SSEA-3 and MYC levels.
Low oxygen tension (hypoxia) contributes critically to pluripotency of human embryonic stem cells (hESCs) by preventing spontaneous differentiation and supporting self-renewal. However, it is not well understood how hESCs respond to reduced oxygen availability and what are the molecular mechanisms maintaining pluripotency in these conditions. In this study we characterized the transcriptional and molecular responses of three hESC lines (H9, HS401 and HS360) on short (2 hours), intermediate (24 hours) and prolonged (7 days) exposure to low oxygen conditions (4% O2). In response to prolonged hypoxia the expression of pluripotency surface marker SSEA-3 was increased. Furthermore, the genome wide gene-expression analysis revealed that a substantial proportion (12%) of all hypoxia-regulated genes in hESCs, were directly linked to the mechanisms controlling pluripotency or differentiation. Moreover, transcription of MYC oncogene was induced in response to continuous hypoxia. At the protein level MYC was stabilized through phosphorylation already in response to a short hypoxic exposure. Total MYC protein levels remained elevated throughout all the time points studied. Further, MYC protein expression in hypoxia was affected by silencing HIF2α, but not HIF1α. Since MYC has a crucial role in regulating pluripotency we propose that induction of sustained MYC expression in hypoxia contributes to activation of transcriptional programs critical for hESC self-renewal and maintenance of enhanced pluripotent state.
Turku Centre for Biotechnology, Turku University and Åbo Akademi University, Turku, Finland.
Elisa
E
Närvä
Juha-Pekka
JP
Pursiheimo
Asta
A
Laiho
Nelly
N
Rahkonen
Maheswara Reddy
MR
Emani
Miro
M
Viitala
Kirsti
K
Laurila
Roosa
R
Sahla
Riikka
R
Lund
Harri
H
Lähdesmäki
Panu
P
Jaakkola
Riitta
R
Lahesmaa
D015295:Antigens, Tumor-Associated, Carbohydrate / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D015687:Cell Hypoxia; D049109:Cell Proliferation; D002478:Cells, Cultured; D053595:Embryonic Stem Cells / Q000502:physiology*; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3 / Q000235:genetics / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*; D055748:SOXB1 Transcription Factors / Q000235:genetics / Q000378:metabolism; D055746:Stage-Specific Embryonic Antigens / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D059467:Transcriptome
D015295:Antigens, Tumor-Associated, Carbohydrate; D018398:Homeodomain Proteins; C489427:MYC protein, human; C486780:NANOG protein, human; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; D016271:Proto-Oncogene Proteins c-myc; C527782:SOX2 protein, human; D055748:SOXB1 Transcription Factors; D055746:Stage-Specific Embryonic Antigens; C052924:stage-specific embryonic antigen-3