Figure 7.
Membrane hyperpolarization represses Wnt signaling and drives the developmental progression in daughter neuron identity.
(A) AP hyperpolarization decreases canonical Wnt pathway activity. Arrowheads show example of 2 cells with active Wnt signaling as revealed by IUE of a Wnt reporter construct.
(B) Blocking canonical Wnt signaling by overexpressing the dominant negative form of TCF4 replicates the effect of Kir2.1-mediated hyperpolarization on neuronal output. Inducing canonical Wnt signaling by β-catenin overexpression rescues hyperpolarization-mediated reduction in neuronal output. Control and Kir2.1 values have been reported from Figure 6A for comparison.
(C) E14.5 AP-targeted repression of Wnt signaling using an inducible DN-TCF4 construct causes a forward shift in their laminar identity. Compare with Fig. 1A.
(D) Molecular expression is congruent with laminar location in single neurons following E14.5 AP Wnt signaling repression.
Data are represented as mean ± SEM, except scatter plots represented as means ± SD. (A), (B): one-way ANOVA; (C), two-way ANOVA for bin distribution analysis (statistically significantly different bins indicated in darker shades); Student’s t test for scatter plot (comparing average cell position). Individual biological replicates are distinguished by color and aligned from left to right. (D), Student’s t test. *: P<0.05; **: P<10−2; ***: P<10−3; ****: P<10−4.
DN-TCF4: dominant negative TCF4; ND2: NEUROD2.