Expression of E-caddCR4h results in misoriented spindle in mitotic GSCs.
(A) Examples of GSCs with misoriented spindles upon expression of E-caddCR4h. Phospho-histone H3 (mitotic chromosomes). (B) An example of a GSC with an oriented spindle in an E-cadDEFL-expressing testis. (C) Quantification of GSC centrosome orientation (% misoriented centrosomes/total interphase GSCs) and spindle misorientation (% misoriented spindles/total mitotic GSCs). The fold difference (centrosome misorientation frequency/spindle misorientation frequency) is shown at the top of graph. n>250 GSCs per data point for centrosome orientation. n>30 mitotic GSCs per data point for spindle orientation. For apc2 and cnn mutants, heterozygous siblings from the same cross served as controls. (D) Model for E-cadherin function in multiple stem cell behaviors. The E-cadherin-based adherens junction serves as a polarity cue for stem cell orientation and also maintains stem cells in the niche. The intracellular domain of E-cadherin recruits Apc2 (directly or indirectly) and factor(s) that participate in the centrosome orientation checkpoint.