title: Short-time gene expression response to valproic acid and valproic acid analogs in mouse embryonic stem cells.
abstract: Prediction of developmental toxicity in vitro could be based on short-time toxicogenomic endpoints in embryo-derived cell lines. Microarray studies in P19 mouse embryocarcinoma cells and mouse embryos have indicated that valproic acid (VPA), an inducer of neural tube defects, deregulates the expression of many genes, including those critically involved in neural tube development. In this study, we exposed undifferentiated R1 mouse embryonic stem cells to VPA and VPA analogs for 6 h and used CodeLink whole-genome expression microarrays to define VPA-responsive genes correlating with teratogenicity. Compared with the nonteratogenic analog 2-ethyl-4-methylpentanoic acid, VPA and the teratogenic VPA analog (S)-2-pentyl-4-pentynoic acid deregulated a much larger number of genes. Five genes (of ∼2500 array probes correlating with the separation) were sufficient to effectively separate teratogens from nonteratogens. A large fraction of the target genes correlating with teratogenicity are functionally related to embryonic development and morphogenesis, including neural tube formation and closure. Similar responses in R1 were found for most genes previously identified as VPA responsive in P19 and embryos. A subset of target genes was evaluated as candidate markers predictive of potential teratogenicity against a range of known teratogens using TaqMan expression arrays. These marker genes showed a positive predictive value for the teratogens butyrate and trichostatin A, which like VPA and (S)-2-pentyl-4-pentynoic acid are known histone deacetylase (HDAC) inhibitors but not for compounds that are likely to act by other mechanisms. This indicates that HDAC inhibition may be a major mechanism by which VPA induces gene deregulation and possibly teratogenicity.
authors.affiliation: Department of Pharmaceutical Biosciences, Uppsala University, Uppsala SE-751 24, Sweden. mans.jergil@farmbio.uu.se
authors.forename: Måns
authors.initials: M
authors.lastname: Jergil
authors.forename: Maud
authors.initials: M
authors.lastname: Forsberg
authors.forename: Hugh
authors.initials: H
authors.lastname: Salter
authors.forename: Kenneth
authors.initials: K
authors.lastname: Stockling
authors.forename: Anne-Lee
authors.initials: AL
authors.lastname: Gustafson
authors.forename: Lennart
authors.initials: L
authors.lastname: Dencker
authors.forename: Michael
authors.initials: M
authors.lastname: Stigson
mesh_terms: D000014:Abnormalities, Drug-Induced / Q000235:genetics; D000818:Animals; D002087:Butyrates / Q000633:toxicity; D002460:Cell Line; D047108:Embryonic Development / Q000235:genetics; D053595:Embryonic Stem Cells / Q000187:drug effects* / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000633:toxicity*; D018507:Gene Expression Regulation, Developmental; D056726:Genetic Association Studies; D005819:Genetic Markers; D056572:Histone Deacetylase Inhibitors / Q000378:metabolism; D006877:Hydroxamic Acids / Q000633:toxicity; D051379:Mice; D046228:Microarray Analysis; D009436:Neural Tube Defects / Q000139:chemically induced / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013723:Teratogens / Q000633:toxicity; D043922:Toxicogenetics; D014635:Valproic Acid / Q000031:analogs & derivatives* / Q000633:toxicity
chemical_list: C551393:2-pentyl-4-pentynoic acid; D002087:Butyrates; D005231:Fatty Acids, Unsaturated; D005819:Genetic Markers; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D012333:RNA, Messenger; D013723:Teratogens; C513636:pentyl-4-pentynoic acid; C012589:trichostatin A; D014635:Valproic Acid