Publications (2)4.65 Total impact
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Article: Time-response evaluation by transcriptomics of methylmercury effects on neural differentiation of murine embryonic stem cells.
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ABSTRACT: Current globally harmonized Organisation for Economic Co-operation and Development (OECD) animal test guidelines for developmental toxicity require high numbers of experimental animals. To reduce animal use in this field, alternative developmental toxicity assays are highly desirable. We previously developed a dynamic in vitro model for screening effects of possible neurodevelopmental toxicants, using neural cell differentiation of pluripotent murine embryonic stem cells. To further mechanistically characterize the mouse neural embryonic stem cell test (ESTn) and to improve detection of possible neurodevelopmental toxicants, gene expression patterns were studied describing neural cell differentiation over time, as well as the impact on gene expression of exposure to the well-known neurotoxicant methylmercury (MeHg). A transcriptomics study was performed to examine whole-genome expression changes during the first 7 days of the cell differentiation protocol. Specific gene clusters were identified and enrichment analysis of Gene Ontology (GO) terms and gene sets derived from literature was performed using DAVID and T-profiler. Over time, a decrease of blastocyst and trophectoderm GO terms was observed, which included well-characterized pluripotency genes. Furthermore, an increase in the range of neural development-related GO terms, such as neuron differentiation and the wnt pathway, was observed. Analysis of gene expression using principle component analysis showed a time-dependent track in untreated cells, describing the process of neural differentiation. Furthermore, MeHg was shown to induce deviation from the predefined differentiation track. The compound inhibited general development GO terms and induced neural GO terms over time. This system appears promising for studying compound effects on neural differentiation in a mechanistic approach.Toxicological Sciences 05/2011; 122(2):437-47. · 4.65 Impact Factor -
Article: Embryotoxicant-specific transcriptomic responses in rat postimplantation whole-embryo culture
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ABSTRACT: Rat postimplantation whole-embryo culture (WEC) is a promising alternative test for the assessment of developmental toxicity. Toxicogenomic-based approaches may improve the predictive ability of the WEC model by providing a means to identify compound-specific mechanistic responses associated with embryotoxicity in vivo. Furthermore, alterations in gene expression may serve as a sensitive, objective, and robust marker, which precedes the observation of classical developmental toxicity endpoints in time. In this study, in combination with morphological developmental assessments, we studied transcriptomic responses associated with four distinct teratogens (caffeine [CAF], methylmercury [MM], monobutyl phthalate, and methoxyacetic acid) after 4 h of exposure, well before apparent embryotoxicity in WEC. We evaluated gene expression changes associated with similar levels of induced morphological embryotoxicity for each teratogen (as determined by total morphological score), evaluating for functional enrichment and quantitative changes in response. Concentrations selected for each of the four teratogens used induced a number of common effects on embryonic development (neural tube closure and optic/otic system). Despite inducing common morphological effects, our analysis suggests limited overlap in terms of toxicogenomic response at the gene expression level and at the level of biological processes across all four test chemicals. Many unique responses associated with each chemical correlated with previously hypothesized modes of developmental toxicity. For example, alterations in developmental signaling and cholesterol metabolism were observed with MM and CAF, respectively. This initial study suggests that distinct chemically induced toxicogenomic responses precede morphological effects in WEC and that these responses are relevant with mechanisms of toxicity previously observed in vivo.
