Fig. 4

inhbaa GOF promotes CM proliferation independently of ErbB2 signaling and competes with mstnb GOF. a Experimental setup of EdU treatment, followed by fixation. b, c Tg(myl7:nlsDsRedExpress) hearts of wild-type sibling and inhbaa OE larvae at 120 hpf; ?-DsRed (red), EdU (green). White arrowheads point to proliferating CMs (EdU⁺/DsRed⁺). d Quantification of CM proliferation in wild-type sibling (n?=?6) and inhbaa OE (n?=?6) ventricles at 120 hpf. e Experimental setup of injections, EdU exposure, followed by fixation. f, g Tg(myl7:nlsDsRedExpress) hearts of myl7:H2B-EGFP and myl7:inhbaa-2A-H2B-EGFP(inhbaa OE) injected erbb ^?/? larvae at 120 hpf; ?-DsRed (red), ?-GFP (blue), EdU (green). White arrowheads point to proliferating CMs (EdU⁺/DsRed⁺/GFP⁺). h Quantification of CM proliferation in myl7:H2B-EGFP (n?=?7) and inhbaa OE (n?=?7) injected ventricles at 120 hpf. i Experimental setup of EdU treatment, followed by fixation. j?m Tg(myl7:nlsDsRedExpress) hearts of wild-type sibling, inhbaa OE, nrg2a OE, and nrg2a OE/inhbaa OE larvae at 120 hpf; ?-DsRed (red), EdU (green). White arrowheads point to proliferating CMs (EdU⁺/DsRed⁺). n Quantification of CM proliferation in wild-type sibling (n?=?4), inhbaa OE (n?=?4), nrg2a OE (n?=?4), and nrg2a OE/inhbaa OE (n?=?5) ventricles at 120 hpf. o?r Tg(myl7:nlsDsRedExpress) hearts of wild-type sibling, inhbaa OE, mstnb OE, and mstnb OE/inhbaa OE larvae at 120 hpf; ?-DsRed (red), EdU (green). s Quantification of CM proliferation in wild-type sibling (n?=?5), inhbaa OE (n?=?4), mstnb OE (n?=?6), and mstnb OE/inhbaa OE (n?=?6) ventricles at 120 hpf. All cell counts were performed on non-overlapping confocal planes (thickness, 1?µm) (data are mean?±?s.e.m., ns: no significant changes observed, *P???0.05, **P???0.01, ***P???0.001 and ****P???0.0001?Student?s t test, two-tailed). Scale bars, 20?µm. vent., ventricle; atr., atrium