Figure 5.

Overactivation of glucocorticoid signaling induced cardiac phenotypes in αB-crystallin mutant embryos. A, αBb^−/− embryos showed pericardial edema when treated with GR agonists, dexamethasone (50 μm) and hydrocortisone (50 μm). B, percentage of αBb^−/− embryos showing pericardial edema when treated with dexamethasone and hydrocortisone. C, immunofluorescence with MF20 and S46 antibodies allowed visualization of the ventricle (red) and atrium (green) in WT and αBb^−/− embryos at 2 dpf (panels a and b). The TUNEL staining revealed no significant increase of apoptosis in the heart (dotted circle area) of 2-dpf αBb^−/− embryos subjected to crowding compared with control αBb^−/− embryos (panels c and d). The cardiac chambers of 4 dpf αBb^−/− embryos were dilated after treating with dexamethasone (Dex) (panels e and f). D, upper panel, heart rates of WT, αBb^−/− embryos (1 and 4 dpf), and αBb^−/− embryos treated with dexamethasone (4 dpf). Lower panel, ventricular shortening fraction of WT, αBb^−/− embryos (2 and 4 dpf), and αBb^−/− embryos treated with dexamethasone (4 dpf).