Fig. 9

A Schematic illustrating the Tg(hsp70l:loxP-EGFP-loxP-mmp14b-P2A-tagBFPHA); Tg(myl7:Cre-ERT2) line and experimental scheme to induce CM-specific overexpression of mmp14b. Created in BioRender. Beisaw, A. (2025) https://BioRender.com/ifqm2g8. B RT-qPCR of mmp14b-P2A-tagBFP (left) and mmp14b (right) in control (n = 7 ventricles) and CM:mmp14b OE (n = 8 ventricles) zebrafish at 10 dpci. Data are presented as mean ± SD. P-values were calculated using unpaired two-sided t-test (mmp14b) or a two-sided Mann–Whitney test (mmp14b-tagBFP). Source data are presented in the Source Data file. C Phalloidin staining of F-actin in thick cryosections of control and CM:mmp14b OE zebrafish ventricles at 10 dpci. D Quantification of the number of CM protrusions per 100 microns of wound border and length of CM protrusions from thick cryosections of control (n = 814 CM protrusions from 7 ventricles) and CM:mmp14b OE (n = 1431 CM protrusions from 9 ventricles) zebrafish at 10 dpci. Data are presented as mean ± SD (number of CM protrusions) and violin plots of all points with solid gray lines indicating the median and dotted gray lines indicating 25th and 75th percentile (CM protrusion length). P-values were calculated using an unpaired two-sided t-test (number of CM protrusions) and a two-sided Mann–Whitney test (CM protrusion length). Source data are presented in the Source Data file. E Myosin heavy chain immunostaining of control and CM:mmp14b OE ventricles at 21 dpci. White dashed lines denote the wound apex and yellow lines denote cortical CMs that have migrated over the wound apex. F Quantification of cortical CM coverage (% wound apex) in control (n = 7 ventricles) and CM:mmp14b OE (n = 7 ventricles) at 21 dpci. Data are presented as mean ± SD. P-value was calculated using an unpaired two-sided t-test. Source data are presented in the Source Data file. G Schematic illustrating the experimental set-up to overexpress mmp14b in CMs and ablate macrophages with clodronate liposomes. Created in BioRender. Beisaw, A. (2025) https://BioRender.com/sdatdc8. H Phalloidin staining of F-actin in thick cryosections of ventricles from CM:mmp14b OE zebrafish injected with PBS control liposomes or clodronate liposomes (CL) at 10 dpci (left). Quantification of the length of CM protrusions from thick cryosections of CM:mmp14b OE zebrafish injected with PBS control liposomes (n = 598 CM protrusions from 5 ventricles) or clodronate liposomes (CL, n = 458 CM protrusions from 3 ventricles)) at 10 dpci (right). Data are presented as violin plots of all points with solid gray lines indicating the median and dotted gray lines indicating 25th and 75th percentile. P-values were calculated using a two-sided Mann–Whitney test. Source data are presented in the Source Data file. I Myosin heavy chain (MHC) immunostaining of ventricles from control zebrafish injected with PBS liposomes and CM:mmp14b OE zebrafish injected with PBS liposomes and clodronate liposomes (CL) at 21 dpci (left). White dashed lines denote the wound apex and yellow lines denote cortical CMs that have migrated over the wound apex. Quantification of cortical CM coverage (% wound apex) in ventricles from control zebrafish injected with PBS liposomes (n = 4 ventricles) and CM:mmp14b OE zebrafish injected with PBS liposomes (n = 4 ventricles) and clodronate liposomes (CL, n = 5 ventricles) at 21 dpci (right). Data are presented as mean ± SD. P-values were calculated using ordinary one-way ANOVA and Tukey’s multiple comparisons test. Source data are presented in the Source Data file. Scale bars: 100 μm.