Fig. 8

Expression of Pcdh1α-cytoplasmic domain attenuates neuronal apoptosis. (A) Morpholino-injected embryos exhibit a range of phenotypes that we have grouped into wild type/mild, moderate and severe, on the basis of density of apoptotic cells and embryo morphology. Shown are representative embryos for each group. (B) To assess the ability of the Pcdh1α cytoplasmic domain to attenuate the apoptosis observed in response to Pcdh1α disruption, we injected either Pcdh1αCD mRNA (200 pg), MO1.1 (2.5 ng), or both together. By itself, Pcdh1αCD mRNA resulted in a small increase in the number of embryos exhibiting moderate levels of apoptosis (n = 190). Injection of MO1.1 resulted in an increase in embryos exhibiting both moderate and severe levels of cell death (34% ± 6 moderate, 51% ± 7 severe; mean ± SEM; n = 214). When MO1.1 and Pcdh1αCD mRNA are co-injected, the percentage of embryos exhibiting a severe phenotype is dramatically decreased (51% ± 5 moderate, 27% ± 3 severe; mean ± SEM; n = 195; p < 0.05, Student's t-test), indicating a shift toward milder phenotypes. Thus, expression of the Pcdh1α cytoplasmic domain can attenuate the effects of morpholino injection. (C) In order to demonstrate the specificity of the myc-αCD mRNA effects, we determined the dose-dependence of the observed attenuation of cell death. Embryos were injected with 2 ng of MO1.1 along with 0, 50, 100 or 200 pg of myc-αCD mRNA. We found that 50 pg of mRNA had no discernible effect on the severity of cell death, but that 100 pg and 200 pg were increasingly effective in reducing the percentage of embryos exhibiting a severe phenotype (0 pg mRNA: 51%, n = 42; 50 pg: 52%, n = 52; 100 pg: 41%, n = 69; 200 pg: 27%, n = 195).