Transcriptional Networks in Cardiac Development

Cardiac development results from a variety of regulatory processes. The Harvard-Children-Cornell (HCC) Cardiogenetics Research Center, designed as a unit of the NHLBI Cardiac Development Consortium, is focused on defining the transcriptional regulatory network that controls cardiac formation. Regulation of RNA transcription is critical for normal organogenesis. Definition of the full repertoire of transcriptional regulators and the genes these target, and knowledge of interactive signals, are essential to understanding heart development. While many cardiac transcription factors that participate in development have been identified, the regulatory network through which they govern specific stages in heart formation remains largely undefined. We are employing novel genomic and genetic methods to define the network of transcription factors that regulate development, beginning with cell commitment and continuing through cardiac chamber morphogenesis. We will delineate this network through the comprehensive study of RNA expression, definition of molecules and pathways regulated by transcription proteins, and assessment of molecular and pathway connectivity. Collectively, these studies will establish the transcriptional network or blueprint for cardiac development, information that is expected to provide new insights into structural malformations and functional deficits that underpin human heart disease. In concert with data obtained through Consortium-wide activities, we will expect that the full range of regulatory mechanisms, transcriptional and post-transcriptional (e.g. micro RNAs, protein phosphorylation), will be defined. We will take advantage of novel technologies to define the regulatory network that governs the temporal and spatial patterns of RNA transcription at key developmental stages: primary and secondary heart fields, crescent and linear heart tube formation, looping, and septation. Three different novel technologies will be employed to define RNA profiles in each tissue at critical stages of development: Deep Sequence Analyses of Gene Expression, massively parallel RNA sequencing, and genome-wide location analysis of biotin-tagged transcription factors (termed bioChIP-seq). Taken together, this information will delineate regulatory networks that control RNA transcription in the developing heart. We will functionally validate the roles of critical molecules in this network by analyzing cardiac development using transgenic conditional RNA interference in mouse embryos, and assessing molecular and phenotypic consequences.