Transcriptome modulation of ventricles, cardiomyocytes and cardiac fibroblasts during postnatal mouse development

During development the fetal heart undergoes a rapid and dramatic transition to adult function through transcriptional and post-transcriptional mechanisms, including alternative splicing (AS). We performed deep RNA-sequencing for high-resolution analysis of transcriptome changes during postnatal mouse heart development using RNA from ventricles and freshly isolated cardiomyocytes (CM) and cardiac fibroblasts (CF). Extensive changes in gene expression and AS occur primarily between postnatal days 1 and 28. CM and CF showed reciprocal regulation of gene expression during postnatal development reflecting differences in proliferative capacity, cell adhesion functions, and mitochondrial metabolism. We found that AS plays a novel role in vesicular trafficking and membrane organization during postnatal CM development. Interestingly, these AS transitions are enriched among targets of two RNA-binding proteins, Celf1 and Mbnl1, which undergo developmentally regulated change in expression. Vesicular traffic genes affected by AS during normal development where Celf1 is down-regulated, showed a reversion to neonatal AS patterns when Celf1 was over-expressed in adults. RNA-seq was performed in RNA samples of ventricles, cardiomyocytes or cardiac fibroblast at different developmental stages; embryonic day 17, postnatal day (PN) 1, 10, 28 and 90 for ventricles, PN1-3, PN28 and PN60 for cardiac fibroblasts, and PN1-2, PN30, and PN67 for cardiomyocytes