THE HARDIN LABZygotic loss of ZEN-4/MKLP1 results in disruption of epidermal morphogenesis in the C. elegans embryo
Jeff Hardin1,2,5 , Ryan King2, Christina Thomas-Virnig3,4, and William B. Raich2
1 Department of Zoology, 2 Program in Cellular and Molecular Biology, and 3 Department of Biomolecular Chemistry, University of Wisconsin Madison, WI 53706
4 Present address: Department of Pathology and Laboratory Medicine, University of Wisconsin Madison, WI 53706
5 Corresponding author
Supplemental material for the following paper:
Hardin, J., King, R., Thomas-Virnig, C., and Raich, W.B. (2008). Zygotic loss of ZEN-4/MKLP1 results in disruption of epidermal morphogenesis in the C. elegans embryo. Dev. Dyn. 237:830-6. PubMed
Summary
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Summary
ZEN-4/MKLP1 is required maternally for cytokinesis in C. elegans, but was originally identified in a screen for zygotic lethal, enclosure abnormal (Zen) mutants. We report that zen-4(w35) homozygotes exhibit stochastic failures in cytokinesis in multiple lineages. Remarkably, multinucleate epidermal cells show directional migration, even when there are as few as half the normal number of cells. Temperature shift experiments and analysis of zen-4::gfp expression confirm that the epidermal requirement for zen-4 function precedes morphogenesis. Driving expression of wild-type zen-4 via an epithelial-specific transgene can rescue many epidermal morphogenetic defects in zen-4 mutants. Early expression of unc-119 in epidermal precursors made this promoter unsuitable as a neuronal-specific driver in this context. Our results indicate that zygotic zen-4 function is required for correct division of epidermal precursors, and hence indirectly for normal morphogenesis, and that the epidermal morphogenetic program is surprisingly robust even in the absence of zen-4 function.
Supplemental Movies
Movie 1. Morphogenetic defects in a zen-4(w35) homozygote imaged via 4d Nomarski microscopy.
Single focal plane from a 4d Nomarski movie of a zen-4(w35) homozygote (left; anterior to the upper right) and a wild-type embryo (anterior at lower right). Both ventrolateral views. The mutant fails to elongate, and ruptures after ventral enclosure. Interval between frames = 360 sec.
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Movie 2. Dorsal intercalation imaged in wildtype using ajm-1::gfp.
A projection of from a 4d multiphoton movie of an embryo expressing ajm-1::gfp (dorsal view, anterior to left). At the beginning of the movie, the anterior region (far left) is not enclosed. 20 cells form a ladder-like array on the dorsal surface of the embryo as intercalation completes. Interval between frames = 360 sec.
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Movie 3. Dorsal intercalation imaged in a zen-4(w35) homozygote using ajm-1::gfp.
A projection of from a 4d multiphoton movie of an embryo expressing ajm-1::gfp (dorsal view, anterior to left). At the beginning of the movie, the anterior region (far left) is not enclosed. Approximately 10 cells are visible on the dorsal surface of the embryo. Interval between frames = 360 sec.
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Movie 4. Ventral enclosure imaged in wildtype using ajm-1::gfp.
A projection of from a 4d multiphoton movie of an embryo expressing ajm-1::gfp (ventral view, anterior to left). Leading cells and ventral pocket cells are clearly visible. Interval between frames = 360 sec.
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Movie 5. Ventral enclosure imaged in a zen-4(w35) homozygote using ajm-1::gfp.
A projection from a 4d multiphoton movie of an embryo expressing ajm-1::gfp (ventral view, anterior to left). Abnormally large cells, at the same position as leading and pocket cells found in wild-type embryos, are clearly visible. The anterior cells at the same position as leading cells in wild-type embryos make successful midline contact to enclose the embryo. An unenclosed hole is just visible in the posterior, at an anterior-posterior position appropriate to ventral pocket cells in a wild-type embryo. Interval between frames = 360 sec.
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Movie 6. unc-119::gfp expression occurs in neuronal and epidermal precursors during morphogenesis, and becomes restricted to neuronal cells later in development.
A brightest point projection from a spinning disc confocal movie of unc-119::gfp expression. Anterior to the left, dorsal view. At the beginning of the movie, expression is uniformly bright except for the C-derived dorsal epidermal cells, which express at lower levels, and can be seen a s dark patch at the posterior. As time proceeds, anterior dorsal retain signal as they intercalate, and lateral epidermal cells also express unc-119::gfp at high levels. Eventually, signal becomes restricted to neuronal cells, but only after epidermal morphogenesis is complete. Interval between frames = 180 sec.
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