Figure 3

Full-length or ΔN VCAP1X2 or human VCAM1 mRNA rescue decreased fractional shortening and cardiomyocyte proliferation in VCAP1X2 mutants. (A) Amino acid sequence and various domains of VCAP1X2 are shown. (B) A diagram shows various VCAP1X2 variants. (C) Ventricular fractional shortening (FS) was significantly lower in VCAP1X2 mutant (mut) than in WT and the defect was rescued by injection with full-length (FL) VCAP1X2 or human VCAM1 mRNA (hVCAM1) but not with SP VCAP1X2 mRNA at 48 hpf (n = 20 per condition, N = 3). (D) At 72 hpf, the FS defect was still observed in mutants and was rescued by injection with ΔN, FL VCAP1X2, or hVCAM1 mRNA, but not with LacZ, SP, ΔN Y2F or Y2F VCAP1X2 mRNA (n = 20 per condition, N = 3). (E,F) Ventricular cardiomyocyte (CM) number was significantly decreased in VCAP1X2 mutant at 72 hpf (E) and 96 hpf (F) compared to WT. Injection of ΔN or FL VCAP1X2 or hVCAM1 mRNA but not SP, ΔN Y2F or Y2F VCAP1X2 mRNA could restore CM number in VCAP1X2 mutant embryos (n = 20 per condition, N = 3). (G,H) A substantially reduced percentage of ventricular PCNA⁺ cardiomyocytes was detected in VCAP1X2 mutant at 72 hpf (G) and 96 hpf (H) compared to WT. Injection of ΔN or FL VCAP1X2 or hVCAM1 mRNA but not SP, ΔN Y2F or Y2F VCAP1X2 mRNA could restore the decreased percentage of ventricular PCNA⁺ cardiomyocytes in VCAP1X2 mutant embryos at 72 hpf. However, at 96 hpf, only injection of FL, but not ΔN or hVCAM1, significantly restored percentage of ventricular PCNA⁺ cardiomyocytes in VCAP1X2 mutants (n = 20 per condition, N = 3). Error bars indicate standard error. Quantitative data were analyzed by ANOVA with Bonferroni multiple comparisons. Treatments that are not statistically different (α = 0.05) from each other are labeled with the same letter.