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Exploring Transcriptional Response toValproic Acid and Valproic Acid Analogs in Human Embryonic Stem Cells
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Toxicology. (Lennart Dencker)
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, The Linnaeus Centre for Bioinformatics.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Toxicology. (Lennart Dencker)
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(English)Manuscript (preprint) (Other (popular science, discussion, etc.))
Abstract [en]

Developmental toxicity is a major concern for manufacturers of new pharmaceuticals,and current testing requires many laboratory animals. Human embryonic stem (hES)cells, potentially being close in function to cells in the developing embryo, mayprovide a technology for classification of candidate drugs in the early phase of toxicityevaluation. Altered gene expression in such system may be predictive of teratogenicproperties of a substance if important gene regulatory pathways are affected, and mayhence be used as appropriate endpoint. In the present study we used the pluripotenthES cell line SA002 (Cellartis AB), and microarrays to profile the response tovalproic acid (VPA), a known human teratogen causing increased risk of e.g. spinabifida and cognitive disorders in exposed embryos We also investigated three closelyrelated VPA analogs with differing in vivo teratogenicity in mice as well as histonedeacetylase (HDAC) inhibition, a proposed teratogenic mechanism of VPA. hEScells in an undifferentiated state were exposed for 24 h to either 1 mM VPA, 0.25mM or 0.5 mM (S)-2-pentyl-4-pentynoic acid a more potent teratogen and HDACinhibitor than VPA, 1 mM 3-propyl-heptanoic acid, a potent teratogen but not anHDAC inhibitor, 1 mM 2-ethyl-4-methyl-pentanoic acid, a non-teratogen and non-HDAC inhibitor, or 0.1% DMSO. Gene expression was subsequently profiled usingCodelink Human Whole Genome BioArrays. We found the HDAC inhibitors tostrongly deregulate largely the same genes. Further, a concordance of altered geneontology groups, predominantly neurogenic processes, was evident between all theteratogenic substances. Also, comparison with mouse ES cells showed an overlap ofderegulated genes as well as species specific gene to be deregulated.

Keyword [en]
Gene ontology; human embryonic stem cell; in vitro toxicology; microarray;neural tube defects; teratogen; toxicogenomics; valproic acid;
URN: urn:nbn:se:uu:diva-110248OAI: oai:DiVA.org:uu-110248DiVA: diva2:275576
Available from: 2009-11-06 Created: 2009-11-06 Last updated: 2010-01-14
In thesis
1. Pluripotent Stem Cells of Embryonic Origin: Applications in Developmental Toxicology
Open this publication in new window or tab >>Pluripotent Stem Cells of Embryonic Origin: Applications in Developmental Toxicology
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

General toxicity evaluation and risk assessment for human exposure is essential when developing new pharmaceuticals and chemicals. Developmental toxicology is an important part of this risk assessment which consumes large resources and many laboratory animals. The prediction of developmental toxicity could potentially be assessed in vitro using embryo-derived pluripotent stem cells for lead characterization and optimization.

This thesis explored the potential of short-time assays with pluripotent stem cells of embryonic origin using toxicogenomics. Three established pluripotent stem cell lines; P19 mouse embryonal carcinoma (EC) cells, R1 mouse embryonic stem (mES) cells, and SA002 human embryonic stem (hES) cells were used in the studies.

Valproic acid (VPA), an antiepileptic drug which can cause the neural tube defects spina bifida in human and exencephaly in mouse, was used together with microarrays to investigate the global transcriptional response in pluripotent stem cells using short-time exposures (1.5 - 24 h). In addition to VPA, three closely related VPA analogs were tested, one of which was not teratogenic in mice. These analogs also differed in their ability to inhibit histone deacetylase (HDAC) allowing this potential mechanism of VPA teratogenicity to be investigated. The results in EC cells indicated a large number of genes to be putative VPA targets, many of which are known to be involved in neural tube morphogenesis. When compared with data generated in mouse embryos, a number of genes emerged as candidate in vitro markers of VPA-induced teratogenicity. VPA and its teratogenic HDAC inhibiting analog induced major and often overlapping deregulation of genes in mES cells and hES cells. On the other hand, the two non-HDAC inhibiting analogs (one teratogenic and one not) had only minor effects on gene expression. This indicated that HDAC inhibition is likely to be the major mechanism of gene deregulation induced by VPA. In addition, a comparison between human and mouse ES cells revealed an overlap of deregulated genes as well as species specific deregulated genes.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 54 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy, ISSN 1651-6192 ; 116
Embryonic stem cell, Microarray, Toxicogenomics, Valproic acid, Developmental toxicology, Teratogenicity, Neural tube defects, Histone deacetylase inhibitor, In vitro toxicology
National Category
Pharmacology and Toxicology
Research subject
urn:nbn:se:uu:diva-109946 (URN)978-91-554-7660-1 (ISBN)
Public defence
2009-12-18, B21, BMC, Husargatan 3, Uppsala, Uppsala, 09:15 (English)
Available from: 2009-11-27 Created: 2009-11-01 Last updated: 2011-05-11Bibliographically approved

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