Fig. 5

Blood-Flow-Independent Expression of klf2a/b mRNA in ccm2^m201 Mutants

(A–C) The ccm2^m201 mutant cardiac ballooning phenotype is flow independent. Frontal views of 48 hrpf hearts of the myocardial reporter line Tg(myl7:GFP)^twu34 (Huang et al., 2003) show that cardiac expansion is not rescued in ccm2^m201 mutant; tnnt2a morphants that lack blood flow.

(D) The expression levels of klf2a and klf2b mRNA, as measured by qRT-PCR, are elevated in ccm2^m201 mutant; tnnt2a morphants that lack blood flow.

(E–G) Loss of Ccm2 results in overproliferation of the endocardium under no-flow conditions. (E) Quantifications of the ratio of proliferating versus nonproliferating endocardial cells between 33 and 53 hrpf in tnnt2a morphants compared with ccm2^m201 mutant;tnnt2a morphants based on SPIM recordings (n = 2). (F) The endocardium of tnnt2a morphants is not proliferative as indicated by the lack of color-coded proliferative cells (still image derived from Movie S1, which is based on SPIM time-lapse recordings of endocardial morphogenesis marked by Tg(kdrl:GFP)^s843 between 33 and53 hrpf). (G) The combined loss of Ccm2 and Tnnt2a is characterized by a high rate of proliferative events (indicated by uniquely colored daughter cells derived from proliferative events; still image derived from Movie S2). A, atrium; V, ventricle. Statistical data are means and SEM; ns, not significant; p < 0.05; p < 0.01; p < 0.001; p < 0.0001; see  Supplemental Experimental Procedures for details about statistical data analysis.