Single-cell RNA sequencing of E13.5 and E15.5 epicardium and epicardium-derived cells from Wt1CreERT2;Srsf3+/+ and Wt1CreERT2; Srsf3fl/fl embryonic hearts

Background: The epicardium is a fundamental regulator of cardiac development, functioning to secrete essential growth factors and to produce epicardium-derived cells (EPDCs) that contribute most coronary vascular smooth muscle cells and cardiac fibroblasts. The molecular mechanisms that control epicardial formation and proliferation have not been fully elucidated. In this study, we found that the RNA-binding protein SRSF3 is highly expressed in the proepicardium and later in the epicardial layer during heart development. Methods: We performed scRNA-seq analyses on epicardial and epicardial-derived cells from E13.5 Wt1CreERT2;Srsf3+/+ (control), E13.5 Wt1CreERT2;Srsf3fl/fl (mutant) and E15.5 Wt1CreERT2;Srsf3fl/fl (mutant) embryonic hearts in order to elucidate the role of SRSF3 in the epicardial lineage. Results: Induction of SRSF3 deletion using Wt1CreERT2 resulted in impaired epicardial proliferation and EPDC formation at E13.5. Single-cell RNA-sequencing showed SRSF3-depleted epicardial cells were eliminated by E15.5 and the remaining non-recombined cells up-regulated Srsf3 to become hyperproliferative and compensate for the early deficit. This research identifies SRSF3 as a master regulator of epicardial cell proliferation. E15.5 control raw data already available under GSE145832 Overall design: 10x Genomics sequencing of E13.5 hearts containing tdTomato positive cells labelled with tamoxifen induction at E9.5 (1mg) and E11.5 (1mg) of Wt1CreERT2; Srsf3+/+ and Wt1CreERT2;Srsf3fl/fl, from 3 pooled C57BL/6 embryos and 2 pooled C57BL/6 embryos respectively. SMART-Seq2 sequencing of E15.5 heart tdTomato positive sorted cells labelled with tamoxifen induction at E9.5 (1mg) and E11.5 (1mg) of Wt1CreERT2; Srsf3fl/fl from 4 pooled C57BL/6 embryos.