130. MICROARRAY ANALYSIS OF FOETAL MOUSE BRAIN FOLLOWING INDUCTION OF MITOCHONDRIAL DYSFUNCTION DURING PRE-IMPLANTATION EMBRYO DEVELOPMENT

Abstract

Environmental stress can disrupt mitochondrial function in the pre-implantation embryo, subsequently hindering embryo viability. Brain tissue is also sensitive to developmental perturbations, and we have previously discovered genes involved in neurological function and epigenetic modification are differentially expressed in blastocysts following mitochondrial dysfunction by amino-oxyacetate (AOA). In this study CBAxC57Bl6 2 cell stage mouse embryos were cultured in 5μM-AOA without pyruvate for 72h to induce mitochondrial dysfunction. Blastocyst stage embryos were then transferred to pseudopregnant recipients and the expression profile of day 18 foetal brains was interrogated using microarray. mRNA from mouse whole brain (4 per treatment) was extracted and analysed using an Affymetrix gene array. Ingenuity Pathway Analysis software identified persistent alterations in gene expression pathways in foetal brain after AOA treatment during embryo culture, that were subsequently confirmed by qPCR. Expression was significantly increased by both array and qPCR (>1.5 fold, p<0.05) for; 1) Eomes (1.9, 2.9 fold respectively), a T-box transcription factor involved in differentiation, cell death and development, 2) Nr4a3 (1.8, 2.2 fold respectively), a steroid hormone receptor and putative transcriptional activator and 3) Nola3 (1.7, 1.9 fold respectively), a small nucleolar ribonucleoprotein involved in rRNA processing. Neurological disease, behavioural disorders, carbohydrate metabolism, cellular growth and proliferation, cell death, DNA replication, recombination and repair pathways also showed altered gene expression (>1.25 fold). qPCR was performed on 28 genes exhibiting the greatest change in expression. 24/28 genes confirmed the array data, and of the 4 genes that did not; two had expression not detected by qPCR (Snhg1, Speer6-ps1), and two contradicted array results (Atp1b3 p=0.05, Stk38l p=0.06). This study links mitochondrial dysfunction during early embryo development and persistent molecular changes in the developing foetal brain. This indicates that insults incurred during early embryo development can cause permanent changes that we predict results from aberrant epigenetic modification.