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. 2007 Jul 4;27(27):7141–7153. doi: 10.1523/JNEUROSCI.4599-06.2007

Figure 10.

Figure 10.

Dominant-negative Rab5 blocks apoptosis caused by exogenous expression of either APP–BP1 or APP(V642I). A, Coexpression of a dominant-negative mutant of Rab5 (S34N) with either APP–BP1 or APP(V642I) inhibits the early endosome enlargement caused by expression of either of these proteins alone. Primary neurons were infected with HSV vectors expressing APP–BP1 and APP(V642I) alone or together with Rab5(S34N), fixed, and stained with the rabbit polyclonal anti-EEA1. Neurons coexpressing Rab5(S34N) did not show the increase in amount and size of early endosome staining that is observed in neurons expressing either APP–BP1 or APP(V642I) alone. Each panel presents endosomes in a single neuron. Scale bar, 5 μm. B, Coexpression of a dominant-negative mutant of Rab5, Rab5(S34N), with either APP–BP1 or APP(V642I) inhibits enhancement of receptor-mediated endocytosis that is caused by expression of either of these proteins alone. Primary neurons were infected with HSV vectors expressing APP–BP1 or APP(V642I), alone or together with Rab5(S34N), and incubated for 5 min with transferrin at 37°C. Cells coexpressing Rab5(S34N) present more membrane-bound transferrin and less uptake of transferrin than do cells expressing APP–BP1 or APP(V642I) alone. Each panel presents endosomes in a single neuron. Scale bar, 5 μm. C, Dominant-negative Rab5 blocks neuronal apoptosis caused by exogenous expression of either APP–BP1 or APP(V642I). Primary neurons were infected with HSV vectors expressing APP–BP1 or APP(V642I), alone or together with Rab5(S34N), Rab7(N125I), or Rab11(S27N), fixed, and stained with bisbenzimide to assess apoptosis. Apoptosis induced by exogenous expression of APP–BP1 or APP(V642I) was blocked by coexpression of Rab5(S34N) but not by coexpression of either Rab7(N125I) or Rab11(S27N). ANOVA for differences between expression of APP–BP1 alone or with the dominant-negative mutants by ANOVA revealed significant differences only between APP–BP1 versus APP–BP1/Rab5(S34N). The analysis for differences between expression of APP(V642I) alone or with the dominant-negative mutants showed a significant difference only between APP(V642I) versus APP(V642I)/Rab5(S34N). *p < 0.001. Inset shows bisbenzimide staining of condensed nuclei in representative fields for each condition.