Abstract
In the one-cell C. elegans embryo, polarity is maintained by mutual antagonism between the anterior cortical proteins PAR-3, PKC-3, PAR-6 and CDC-42, and the posterior cortical proteins PAR-2 and LGL-1 on the posterior cortex. The mechanisms by which these proteins interact to maintain polarity are incompletely understood. In this study, we investigate the interplay among PAR-2, LGL-1, myosin, the anterior PAR proteins and CDC-42. We find that PAR-2 and LGL-1 affect cortical myosin accumulation by different mechanisms. LGL-1 does not directly antagonize the accumulation of cortical myosin and instead plays a role in regulating PAR-6 levels. By contrast, PAR-2 likely has separate roles in regulating cortical myosin accumulation and preventing the expansion of the anterior cortical domain. We also provide evidence that asymmetry of active CDC-42 can be maintained independently of LGL-1 and PAR-2 by a redundant pathway that includes the CDC-42 GAP CHIN-1. Finally, we show that, in addition to its primary role in regulating the size of the anterior cortical domain via its binding to PAR-6, CDC-42 has a secondary role in regulating cortical myosin that is not dependent on PAR-6.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Animals
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Caenorhabditis elegans / embryology*
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Caenorhabditis elegans / genetics
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Caenorhabditis elegans / metabolism
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Caenorhabditis elegans Proteins / genetics
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Caenorhabditis elegans Proteins / metabolism*
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism
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Cell Polarity*
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Cytoplasm / genetics
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Cytoplasm / metabolism
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Embryo, Nonmammalian / cytology
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Embryo, Nonmammalian / metabolism
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Embryonic Development
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GTP-Binding Proteins / genetics
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GTP-Binding Proteins / metabolism
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GTPase-Activating Proteins / genetics
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GTPase-Activating Proteins / metabolism
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Gene Expression Regulation, Developmental
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Guanine Nucleotide Exchange Factors / genetics
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Guanine Nucleotide Exchange Factors / metabolism
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Immunohistochemistry
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Mutation
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Myosins / metabolism
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Protein Binding
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Protein Interaction Mapping
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Protein Transport
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RNA Interference
Substances
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CGEF-1 protein, C elegans
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CHIN-1 protein, C elegans
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Caenorhabditis elegans Proteins
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Cell Cycle Proteins
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GTPase-Activating Proteins
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Guanine Nucleotide Exchange Factors
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LGL-1 protein, C elegans
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cdc-42 protein, C elegans
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par-2 protein, C elegans
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par-6 protein, C elegans
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GTP-Binding Proteins
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Myosins