Epigenetic changes and disturbed neural development in a human embryonic stem cell-based model relating to the fetal valproate syndrome.
Exposure to the antiepileptic drug valproic acid (VPA) during gestation causes neurofunctional and anatomic deficits in later life. At present, there are little human data on how early neural development is affected by chemicals. We used human embryonic stem cells, differentiating to neuroectodermal precursors, as a model to investigate the modes of action of VPA. Microarray expression profiling, qPCR of specific marker genes, immunostaining and the expression of green fluorescent protein under the control of the promoter of the canonical neural precursor cell marker HES5 were used as readouts. Exposure to VPA resulted in distorted marker gene expression, characterized by a relative increase in NANOG and OCT4 and a reduction in PAX6. A similar response pattern was observed with trichostatin A, a potent and specific histone deacetylase inhibitor (HDACi), but not with several other toxicants. Differentiation markers were disturbed by prolonged, but not by acute treatment with HDACi, and the strongest disturbance of differentiation was observed by toxicant exposure during early neural fate decision. The increased acetylation of histones observed in the presence of HDACi may explain the up-regulation of some genes. However, to understand the down-regulation of PAX6 and the overall complex transcript changes, we examined further epigenetic markers. Alterations in the methylation of lysines 4 and 27 of histone H3 were detected in the promoter region of PAX6 and OCT4. The changes in these activating and silencing histone marks provide a more general mechanistic rational for the regulation of developmentally important genes at non-cytotoxic drug concentrations.
Doerenkamp-Zbinden Chair for In Vitro Toxicology and Biomedicine, University of Konstanz, D-78457 Konstanz, Germany.
Nina V
NV
Balmer
Matthias K
MK
Weng
Bastian
B
Zimmer
Violeta N
VN
Ivanova
Stuart M
SM
Chambers
Elena
E
Nikolaeva
Smita
S
Jagtap
Agapios
A
Sachinidis
Jürgen
J
Hescheler
Tanja
T
Waldmann
Marcel
M
Leist
D000014:Abnormalities, Drug-Induced / Q000235:genetics* / Q000473:pathology; D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D053595:Embryonic Stem Cells / Q000378:metabolism* / Q000502:physiology; D044127:Epigenesis, Genetic / Q000187:drug effects*; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006657:Histones / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D008745:Methylation; D000071317:Nanog Homeobox Protein; D054258:Neural Plate / Q000196:embryology* / Q000473:pathology; D058953:Neural Stem Cells / Q000378:metabolism / Q000502:physiology; D046569:Neuroepithelial Cells / Q000378:metabolism / Q000502:physiology; D050814:Octamer Transcription Factor-3 / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics / Q000378:metabolism; D025341:Principal Component Analysis; D011401:Promoter Regions, Genetic; D011499:Protein Processing, Post-Translational; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D059467:Transcriptome; D014635:Valproic Acid / Q000009:adverse effects
D000943:Antigens, Differentiation; D051792:Basic Helix-Loop-Helix Proteins; D005136:Eye Proteins; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D018398:Homeodomain Proteins; D006877:Hydroxamic Acids; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D012097:Repressor Proteins; D014635:Valproic Acid; C486780:NANOG protein, human; C000605730:PAX6 protein, human; C494173:POU5F1 protein, human; C077478:HES5 protein, human; C012589:trichostatin A