Maternal Diabetes alters Transcriptional Programs in the Developing Embryo

Diabetic embryopathy can affect any developing organ system, although cardiovascular malformations, neural tube defects and caudal dysgenesis syndrome are the most prominent congenital malformations. We hypothesize that the metabolic imbalance occurring in diabetic pregnancy de-regulates tissue specific gene expression programs in the developing embryo. In order to identify genes whose expression is affected by maternal diabetes, we analyzed gene expression profiles of diabetes-exposed mouse embryos by using Affymetrix microarrays. We identified 129 genes with altered expression levels; 21 genes had increased and 108 genes had decreased expression levels in diabetes-exposed embryos relative to controls. A substantial fraction of these genes (35) are essential for normal embryonic development as shown by functional studies in mouse models. The largest fraction of diabetes-affected genes was in transcription factor and DNA-binding/chromatin remodeling functional categories (19%), which directly affect transcription. These findings suggest that transcriptional regulation in the developing embryos is perturbed by maternal diabetes and that transcriptional regulation plays a major role in the responses of embryos to intrauterine exposure to diabetic conditions. Interestingly, we found the expression of hypoxia-inducible factor 1 (Hif1) deregulated in the embryos exposed to the conditions of maternal diabetes. Since hypoxic stress is associated with the complications of diabetic pregnancy, we performed a post-hoc analysis of our microarray data with a specific focus on known HIF1 target genes. Of 39 genes detected in our microarrays, the expression changes of 22 genes (20 were increased and two genes were decreased in diabetes-exposed embryos) were statistically significant. These results indicate that HIF1-regulated pathways are affected in diabetes-exposed embryos. These results strongly suggest that de-regulation of hypoxia/HIF1 activated pathways could be the one of the key molecular events associated with the exposure to the teratogenic intrauterine environment of a diabetic mother.

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Pavlinkova G, Salbaum JM, Kappen C