Igf signaling is required for contribution of<i>gata4:EGFP</i> positive cardiomyocytes to the regenerating area.

<p><i>gata4:EGFP</i> fish were treated with the Igf1r inhibitor NVP-AEW541 from 2–14 dpa (n = 12) (B, D) and 7–10 dpa (n = 5) (F, H). DMSO was used as a control (14dpa: n = 10; 10 dpa: n = 6) (A, C, E, G). Whole mount confocal microscopy from the view of the apex (A, B, E, F) and frozen sections (C, D, G, H) were performed at 14 and 10 dpa to determine the contribution of the EGFP positive population. BrdU (red) and Gata4 (green) double positive cells indicate proliferating <i>gata4:EGFP</i> positive cardiomyocytes (G, G’, H, H’). G’, and H’ are the higher magnification images of the dashed boxes in G and H. BrdU staining (red) and <i>gata4:EGFP</i> (green) were shown as separated channel images. The dashed line marks the regenerating area. Scale bar: (B, D, F, H) = 50 µm; (H’) = 20 µm. ia: injured area, v: ventricle. (I) Quantification of BrdU and <i>gata4:EGFP</i> double positive cells/<i>gata4:EGFP</i> area ± S.E. A significant decrease (*<i>p</i><0.05) in <i>gata4:EGFP</i> positive cell proliferation was detected in fish treated with Igf1r inhibitor NVP-AEW541 from 7–10dpa.</p

Igf signaling is required for proper cardiomyocyte number in zebrafish embryonic hearts.

<p>The number of ventricular cardiomyocytes (area encircled by dotted line) number decreased in embryos when Igf1r signaling was blocked. (A) <i>Tg(myl7:nDsRed)</i> single transgenic and (C) <i>Tg(hsp:dnigf1ra-GFP; myl7:nDsRed)</i> double transgenic embryos (n = 16) were heat shocked at 40°C for 30 min around 48 and 72 hpf and observed at 76 hpf. <i>dnigf1ra</i> embryos can be identified by GFP expression (C’ inset). <i>Tg(myl7:nDsRed)</i> single transgenic siblings (n = 16) were used as controls. <i>myl7:nDsRed</i> embryos were treated with Igf1r inhibitor (D) (n = 20) and DMSO as a control (B) (n = 20) from 48 to 72 hpf and observed at 76 hpf. a: atrium, v: ventricle. Scale bar = 20 µm. (E, F) Quantification of mean ventricular cardiomyocyte number ± S.E. (***<i>p</i><0.0001; **<i>p</i><0.001). Fewer ventricular cardiomyocytes were observed around 76 hpf after Igf1r signaling was blocked.</p

Chemical inhibition of Igf signaling suppresses cardiomyocyte proliferation during zebrafish heart regeneration.

<p>Wild type fish were treated with DMSO as a control (A, A’ and A’’) (n = 5) and the Igf1r inhibitor NVP-AEW541 (B, B’ and B’’) (n = 5) from 2–14 dpa. BrdU (green) and Mef2 (red) double positive cells indicate proliferating cardiomyocytes (A, A’, B, B’). A’ and B’ are the higher magnification images of the dashed boxes in A and B. A’’ and B’’ are the higher magnification images of the dashed boxes in A’ and B’. The yellow box indicates the wound area and cardiomyocytes were counted in this region. (A’’ and B’’), BrdU (green) and Mef2 (red) staining were shown as black and white or merged color images. Scale bar: (B, B’) = 100 µm, (B’’) = 20 µm. ia: injured area, v: ventricle. (C) Quantification of BrdU positive cardiomyocytes (Mef2 positive) ± S.E. A significant decrease (*<i>p</i><0.01) in cardiomyocyte proliferation was detected in fish treated with Igf1r inhibitor NVP-AEW541.</p

Igf signaling is required for cardiomyocyte proliferation during zebrafish heart development.

<p>Wild type fish were treated with DMSO as a control (n = 5) (A and A’) and the Igf1r inhibitor NVP-AEW541 (n = 7) (B and B’) from 48–72 hpf. BrdU was added for the same time period. BrdU (green) and Mef2 (red) double positive cells indicate proliferating cardiomyocytes (A, A’, B, B’). A’ and B’ are images of the dashed boxes in A and B. (A’ and B’), BrdU (green) and Mef2 (red) staining were shown as black and white or merged color images. Scale bar: (B) = 50 µm, (B’) = 20 µm. v: ventricle. (C) Quantification of BrdU positive cardiomyocytes (Mef2 positive) ± S. E. A significant decrease (***<i>p</i><0.0001) in cardiomyocyte proliferation was detected in embryos treated with NVP-AEW541.</p

Igf signaling is required for heart regeneration.

<p>Wild type fish were treated DMSO (A) (n = 6) or the Igf1r inhibitor NVP-AEW541 (n = 7) (B and C) from 2–30 dpa. AFOG staining was performed at 30 dpa to detect collagen (blue) and fibrin (red) deposition. The dashed line marks the regenerating area. Scale bar = 100 µm. ia: injured area. (D) Quantification of scar area normalized to ventricle area in DMSO and NVP-AEW541 treated hearts. A significant increase (*<i>p</i><0.05) in scar/ventricular area ratio was detected in NVP-AEW541 treated hearts.</p