DSH-2
Supplemental material for the following paper:
Walston, T, Tuskey, C., Edgar, E., Hawkins, N., Ellis, G., Bowerman, B., Wood, W., and Hardin, J. (2004). Multiple Wnt signaling pathways converge to orient the mitotic spindle in early C. elegans embryos. Dev Cell7, 831-841. PubMed
Summary
How cells integrate the input of multiple polarizing signals during division is poorly understood. We demonstrate that two distinct Caenorhabditis elegans Wnt pathways contribute to the polarization of the ABar blastomere by differentially regulating its duplicated centrosomes. Contact with the C blastomere orients the ABar spindle through a non-transcriptional Wnt spindle alignment pathway, while a Wnt/b-catenin pathway controls the timing of ABar spindle rotation. The three C. elegans Dishevelled homologs contribute to these processes in different ways, suggesting that functional distinctions may exist among them. We also find that CKI (KIN-19) not only plays a role in the Wnt/b-catenin pathway, but in the Wnt spindle orientation pathway as well. Based on these findings, we establish a model for the coordination of cell-cell interactions and distinct Wnt signaling pathways that ensures the robust timing and orientation of spindle rotation during a developmentally regulated cell division event.
Video sequence 1: Spindle misalignment and delayed rotation phenotypes in the ABar blastomere
Confocal movie of ABar spindle alignment visualized using TBB-2/b-tubulin::GFP. In wild-type embryos (left), the ABar spindle rotates quickly into the proper position perpendicular to that of ABpr, while wrm-1(RNAi) embryos (middle) display a delay in spindle rotation. The ABar spindle in dsh-2(RNAi); mig-5(RNAi) embryos (right) fails to rotate into the proper position. All embryos are shown in right-hand views with anterior to the right and dorsal at the top. Time points are 1 minute apart. Scale bar = 10 um.
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Video sequence 2: ABar orientation in a wild-type embryo
Nomarski movie of ABar spindle alignment (right-hand view; anterior to the right and dorsal at the top; movie courtesy of Tim Walston). In wild-type embryos, the ABar spindle rotates quickly into the proper position perpendicular to that of ABpr (spindle orientations are shown as black lines).
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Video sequence 3: ABar misalignment in a Dsh mutant embryo
Nomarski movie of ABar spindle misalignment in a dsh-2(or302);mig-5(RNAi);dsh-1(RNAi) embryo (right-hand view; anterior to the right and dorsal at the top; movie courtesy of Tim Walston). The ABar spindle in fails to rotate into the proper position (spindle orientations are shown as black lines).
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Video sequence 4: ABar alignment is induced by contact with C
Two different focal planes from a 4d Nomarski movie show the orientation of ABar (right) relative to time of contact with C (left). In wild-type embryos, the ABar spindle rotates quickly into the proper position perpendicular to that of ABpr (spindle orientation is shown as black lines). This coincides with contact by C; the edges of C (blue) and ABar (green) are shown.
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