Identification of Tcf21 downstream genes in the epicardial cells and cardiomyocytes by transcriptomic analysis

Purpose: Studying the epicardium-myocardium crosstalk in the zebrafish larval heart. To do so, we aimed to identify, with RNA-seq, the genes dysregulated following the loss of the epicardial marker gene tcf21 in sorted epicardial cells and cardiomyocytes. Results: We first analyzed the transcriptome of epicardial and myocardial WT cells and identified cell-type specific/enriched genes. Then, we identified several differential expressed genes in tcf21 mutants, including several ligand-receptor couples known to mediate the epicardium-myocardium crosstalk. Hearts were manually extracted from 96 hpf Tg(myl7:mcherry), TgBAC(tcf21:nls-EGFP) tcf21+/+ and tcf21-/- zebrafish larvae. Hearts were dissociated into single-cell suspensions and FACS was performed to sort epicardial and myocardial cells based on the fluorescence signal.