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The effects of nuclear reprogramming on mitochondrial DNA replication
journal contribution
posted on 2013-02-01, 00:00 authored by Richard D W Kelly, Huseyin Sumer, Matthew McKenzieMatthew McKenzie, Joao Facucho-Oliveira, Ian A Trounce, Paul J Verma, Justin C St JohnUndifferentiated mouse embryonic stem cells (ESCs) possess low numbers of mitochondrial DNA (mtDNA), which encodes key subunits associated with the generation of ATP through oxidative phosphorylation (OXPHOS). As ESCs differentiate, mtDNA copy number is regulated by the nuclear-encoded mtDNA replication factors, which initiate a major replication event on Day 6 of differentiation. Here, we examined mtDNA replication events in somatic cells reprogrammed to pluripotency, namely somatic cell-ES (SC-ES), somatic cell nuclear transfer ES (NT-ES) and induced pluripotent stem (iPS) cells, all at low-passage. MtDNA copy number in undifferentiated iPS cells was similar to ESCs whilst SC-ES and NT-ES cells had significantly increased levels, which correlated positively and negatively with Nanog and Sox2 expression, respectively. During pluripotency and differentiation, the expression of the mtDNA-specific replication factors, PolgA and Peo1, were differentially expressed in iPS and SC-ES cells when compared to ESCs. Throughout differentiation, reprogrammed somatic cells were unable to accumulate mtDNA copy number, characteristic of ESCs, especially on Day 6. In addition, iPS and SC-ES cells were also unable to regulate ATP content in a manner similar to differentiating ESCs prior to Day 14. The treatment of reprogrammed somatic cells with an inhibitor of de novo DNA methylation, 5-Azacytidine, prior to differentiation enabled iPS cells, but not SC-ES and NT-ES cells, to accumulate mtDNA copies per cell in a manner similar to ESCs. These data demonstrate that the reprogramming process disrupts the regulation of mtDNA replication during pluripotency but this can be re-established through the use of epigenetic modifiers.
History
Journal
Stem cell reviews and reportsVolume
9Issue
1Pagination
1 - 15Publisher
SpringerLocation
Cham, SwitzerlandPublisher DOI
ISSN
1550-8943eISSN
1558-6804Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
2011, Springer Science+Business Media, LLCUsage metrics
Categories
Keywords
mitochondrial DNA (mtDNA)PluripotencyReprogrammingmtDNA replicationScience & TechnologyLife Sciences & BiomedicineCell & Tissue EngineeringCell BiologyMedicine, Research & ExperimentalResearch & Experimental MedicinePLURIPOTENT STEM-CELLSTRANSCRIPTION FACTORNEURAL DIFFERENTIATIONCOMPLEX IMETHYLATIONNANOGEXPRESSIONREDUCTIONCYTOSINEEMBRYO