Characterisation of the outflow tract banded heart utilising RNA sequencing to direct functional analysis

Heart development is known to be influenced by haemodynamics, however the effects of abnormal load on gene expression are not clearly defined. To determine the hearts transcriptional response to stress, a model of haemodynamic alteration, outflow tract (OFT) banding, was employed in the chick embryo at HH21. Stereological and expression analysis were performed at HH29, with targeted expression studies at HH35. We defined a phenotype of left sided heart dilation and performed RNA sequencing on OFT-banded hearts compared to Sham controls. Globin transcripts were depleted in the RNA during library preparation, and 28 differentially expressed genes were identified. Expression appeared to represent a mechanism of cardioprotection with calcium sequestering, metabolic and developmental genes highlighted. Significant reductions in apoptosis were also seen. We have presented a model of left sided dilation in OFT-banded hearts and found differential expression of genes that may be associated with stress and maintaining cardiac output. Overall design: mRNA profiles of HH29 chick heart in 3 OFT-banded samples and 3 Sham samples were generated by DEEP Sequencing using the Illumina NextSeq500 platform