05-P005 Ddc, a candidate developmental gene in heart and its role in disease

Dopa Decarboxylase (Ddc) is an enzyme that plays a fundamental role in the biosynthesis of catecholamine neurotransmitters and serotonin. A short form transcriptional variant of Ddc called Ddc_exon1a which originates from an alternative promoter at exon 1a, is highly expressed in the trabecular cardiomyocytes during development of pre-natal heart and is progressively silenced during post natal development. Ddc_exon1a has recently been shown by our group to be epigenetically regulated via genomic imprinting in mouse heart in a tightly regulated tissue-specific and transcriptional variant-specific manner. Ddc and Ddc_exon1a show bi-allelic expression in all other tissues. We aim to show by analysing Ddc and Ddc knockout mice how ablation of Ddc_exon1a affects heart-specific development. We also will look at downstream target genes using microarray analysis. We predict that the knockout may affect compaction of the myocardium during mid-gestation, which could lead to cardiomyopathies in adults. It has recently been shown that Ddc imprinting is controlled by epigenetic mechanisms via a differentially methylated region located in CGI2 of adjacent Grb10, another gene imprinted in development, CGI2 contains a putative CTCF binding site. We present our current findings looking at expression patterns of Ddc_exon1a and Grb10 in the mouse embryo using immunohistochemistry, insitu hybridization and qPCR. Furthermore we look at the role of the insulator protein CTCF using ChIP analysis and RNAi knockdown, to assay binding and function of this protein at this gene locus.