Fig. 1

Targeted knock-down of Paxillin leads to heart failure in zebrafish.

(A-C) Co-immunostaining of Paxillin (A, red) and the known Z-disk protein Focal Adhesion Kinase (FAK) (B, green) on adult primary zebrafish cardiomyocytes revealed localization of Paxillin to sarcomeric Z-disks. Cell nuclei were counterstained with DAPI (C, blue). Scale bar 10 μm. (D-G) Lateral view of paxillin start MO (MO1-paxillin) (D) and paxillin 5bp-mismatch-MO (MO1-control) (E) injected embryos at 72 hpf. (F) 78% of embryos injected with 5.4 ng MO1-paxillin developed pericardial edema and blood congestion at the cardiac inflow tract (n = 3; *P<0.0001), whereas control-injected embryos developed no pathological phenotype. (G) Fractional shortening (FS) measurements of Paxillin morphant ventricles at 48, 72 and 96 hpf. FS of Paxillin morphant ventricles was slightly reduced to 69.6% ± 5.07% compared to corresponding 5bp-mismatch-MO injected embryos (FS: 71.6% ± 3.96%) at 48 hpf. At 72 hpf, FS in Paxillin morphants was reduced to 49.29% ± 4.39% compared to control morphants (FS: 69.3% ± 4.36%), whereas ventricular chambers of Paxillin morphants became almost silent (FS: 4.23% ± 6.17%) compared to controls (FS: 74% ± 4.96%) at 96 hpf (n = 6–8 individuals per time point). (H-K) Lateral view of MO2-paxillin (H) and MO2-paxillin+paxillin mRNA (I) injected embryos at 72 hpf. (J) Co-injection of 4.5 ng of MO2-paxillin and 1 ng wild-type paxillin mRNA rescued the Paxillin morphant heart failure phenotype (n = 3; *P = 0.0073). (K) Quantification of ventricular FS revealed that ectopic expression of paxillin mRNA significantly improved contractile function in Paxillin morphants at 72 hpf (n = 8–9 individuals; *P<0.0001). Error bars indicate s.d.