FIGURE 6

FIGURE 6

Myocardium-specific smarce1 overexpression reduces ventricular CM proliferation in the embryonic heart of Tg (myl7:Tet-On-smarce1/AcGFP). (A) Illustration of Tet-On system structure. The protein of rtTA-Adv is specifically expressed in the myocardium by the myl7 promotor. Under doxycycline treatment, smarce1 and AcGFP are bi-directionally induced in the myocardium. (B–D) Lateral view of wt and Tg(myl7:Tet-On-smarce1/AcGFP) embryos with or without doxycycline (dox) treatment at 96 hpf. (B′–D′) Confocal images of dissected hearts from Tg(myl7:mCherry.nls) and Tg(myl7:Tet-On-smarce1/AcGFP) × Tg(myl7:mCherry.nls) with or without dox treatment at 96 hpf. (E) Transcriptional level of smarce1 in the hearts of wt or Tg (myl7:Tet-On-smarce1/AcGFP) embryos showing dox-induced smarce1 overexpression at 96 hpf. (F) Confocal IF images of wt and Tg (myl7:Tet-On-smarce1/AcGFP) embryonic hearts with CM nuclei (myl7:mCherry.nls) and EdU incorporation at 96 hpf (scale bar: 50 µm). (G–I) Quantitative analyses of ventricular CM numbers, EdU⁺ ventricular CMs, and the mitotic index in wt or smarce1-overexpressed developing hearts at 96 hpf (n = 10). (J) IF images of the hearts from Tg (myl7:mCherry.nls) and Tg (myl7:Tet-ON-smarce1/AcGFP) × Tg(myl7:mCherry.nls) embryos stained with pH3 (scale bar: 50 µm). (K–M) Quantitative analyses of ventricular CM numbers, pH3⁺ ventricular CMs, and the mitotic index at 96 hpf (n = 10). v, ventricle; a, atrium; ventr., ventricular.