ASYMMETRIC CELL DIVISION IN C. ELEGANS EMBRYOS

Summary

Principal Investigator: K Kemphues
Abstract: DESCRIPTION: Asymmetric cell division, in which the two daughter cells adopt different fates, plays a key role in embryonic development and in tissue regeneration in adult life. The goal of this project is to obtain detailed molecular information about intrinsically asymmetric cell divisions using the nematode C. elegans as a model system. The research addresses two general questions: How are intracellular asymmetries established? How are mitotic spindles aligned along the axis of asymmetry? The research focuses on the six PAR proteins, which are required for a series of reproducible asymmetric divisions in the lineage leading to the C. elegans germline. Mutation of these proteins disrupts both polarized distributions of cellular components and proper alignment of mitotic spindles in the early embryo. Four of the PAR proteins and an interacting protein, PKC-3, are localized to the cell periphery at the poles of asymmetrically dividing cells, defining discrete cortical domains in the anterior (PAR-3, PAR-6 and PKC-3) and in the posterior (PAR1- and PAR-2). The proposed experiments address three broad and overlapping questions: How do the PAR proteins become localized? How do the PAR proteins influence the asymmetric distribution of other molecules? How do the PAR proteins contribute to spindle orientation? Specific aims include 1) Determination of the functional relationships between PAR-3, PAR-6, PKC-3 and two other proteins that influence their activity, PAR-5 and Cdc-42. In this aim a combination of in vitro binding studies and in vivo tests of mutations in binding domains will lead to insights into molecular mechanisms for PAR protein action. 2) Identification of additional components of the polarity system. 3) Identification of substrates of the PAR-1, PAR-4 and PKC-3 serine/threonine kinases. Because the PAR proteins are only a small part of the polarity system, understanding their mechanism of action requires the identification of proteins that influence their activities or which they influence. In these two aims, a combination of reverse genetics, protein interaction screens, biochemical fractionation and kinase assays will result in the discovery of some of these proteins. The recent discovery of broad conservation of PAR-1, PAR-3 and PAR-6 in polarity systems in flies and mammals indicates that our analysis of the PAR proteins will provide basic information that will be applicable to studies of human growth and development.
Funding Period: 1991-02-05 - 2006-03-31
more information: NIH RePORT

Top Publications

  1. pmc A genome-wide RNAi screen for enhancers of par mutants reveals new contributors to early embryonic polarity in Caenorhabditis elegans
    Diane G Morton
    Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
    Genetics 192:929-42. 2012
  2. pmc PAR-2, LGL-1 and the CDC-42 GAP CHIN-1 act in distinct pathways to maintain polarity in the C. elegans embryo
    Alexander Beatty
    Department of Molecular Biology and Genetics, Cornell University, 433 Biotechnology Building, Ithaca, NY 14853, USA
    Development 140:2005-14. 2013
  3. pmc Binding to PKC-3, but not to PAR-3 or to a conventional PDZ domain ligand, is required for PAR-6 function in C. elegans
    Jin Li
    Department of Molecular Biology and Genetics, 107 Biotechnology Building, Cornell University, Ithaca, NY 14853, USA
    Dev Biol 340:88-98. 2010
  4. pmc Different domains of C. elegans PAR-3 are required at different times in development
    Bingsi Li
    Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
    Dev Biol 344:745-57. 2010
  5. pmc The C. elegans homolog of Drosophila Lethal giant larvae functions redundantly with PAR-2 to maintain polarity in the early embryo
    Alexander Beatty
    Department of Molecular Biology and Genetics, Cornell University, 433 Biotechnology Building, Ithaca, NY 14850, USA
    Development 137:3995-4004. 2010
  6. pmc Nucleoporins NPP-1, NPP-3, NPP-4, NPP-11 and NPP-13 are required for proper spindle orientation in C. elegans
    Aaron Schetter
    Department of Molecular Biology and Genetics, Cornell University, 435 Biotechnology Building, Ithaca, NY 14853, USA
    Dev Biol 289:360-71. 2006
  7. ncbi Depletion of the co-chaperone CDC-37 reveals two modes of PAR-6 cortical association in C. elegans embryos
    Melissa Beers
    Department of Molecular Biology and Genetics, 101 Biotechnology Building, Cornell University, Ithaca, NY 14853, USA
    Development 133:3745-54. 2006
  8. pmc Interaction of PAR-6 with CDC-42 is required for maintenance but not establishment of PAR asymmetry in C. elegans
    Donato Aceto
    Department of Molecular Biology and Genetics, Cornell University, 435 Biotechnology Building, Ithaca, NY 14853, USA
    Dev Biol 299:386-97. 2006

Detail Information

Publications8

  1. pmc A genome-wide RNAi screen for enhancers of par mutants reveals new contributors to early embryonic polarity in Caenorhabditis elegans
    Diane G Morton
    Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
    Genetics 192:929-42. 2012
    ..Further studies of these genes should give mechanistic insight into pathways regulating establishment and maintenance of cell polarity...
  2. pmc PAR-2, LGL-1 and the CDC-42 GAP CHIN-1 act in distinct pathways to maintain polarity in the C. elegans embryo
    Alexander Beatty
    Department of Molecular Biology and Genetics, Cornell University, 433 Biotechnology Building, Ithaca, NY 14853, USA
    Development 140:2005-14. 2013
    ..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...
  3. pmc Binding to PKC-3, but not to PAR-3 or to a conventional PDZ domain ligand, is required for PAR-6 function in C. elegans
    Jin Li
    Department of Molecular Biology and Genetics, 107 Biotechnology Building, Cornell University, Ithaca, NY 14853, USA
    Dev Biol 340:88-98. 2010
    ..We conclude that PAR-6 binding to PKC-3, but not to PAR-3 nor to a conventional PDZ ligand, is required for PAR-6 cortical localization and function in C. elegans...
  4. pmc Different domains of C. elegans PAR-3 are required at different times in development
    Bingsi Li
    Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
    Dev Biol 344:745-57. 2010
    ..Surprisingly neither PDZ1 nor PDZ3 are essential for localization or function. Our results indicate that the different domains and phosphorylated forms of PAR-3 can have different roles during C. elegans development...
  5. pmc The C. elegans homolog of Drosophila Lethal giant larvae functions redundantly with PAR-2 to maintain polarity in the early embryo
    Alexander Beatty
    Department of Molecular Biology and Genetics, Cornell University, 433 Biotechnology Building, Ithaca, NY 14850, USA
    Development 137:3995-4004. 2010
    ..LGL-1 negatively regulates the accumulation of myosin (NMY-2) on the posterior cortex, representing a possible mechanism by which LGL-1 might contribute to polarity maintenance...
  6. pmc Nucleoporins NPP-1, NPP-3, NPP-4, NPP-11 and NPP-13 are required for proper spindle orientation in C. elegans
    Aaron Schetter
    Department of Molecular Biology and Genetics, Cornell University, 435 Biotechnology Building, Ithaca, NY 14853, USA
    Dev Biol 289:360-71. 2006
    ..These findings raise the possibility that these nucleoporins may have direct roles in orienting the mitotic spindle and the maintenance of cell polarity...
  7. ncbi Depletion of the co-chaperone CDC-37 reveals two modes of PAR-6 cortical association in C. elegans embryos
    Melissa Beers
    Department of Molecular Biology and Genetics, 101 Biotechnology Building, Cornell University, Ithaca, NY 14853, USA
    Development 133:3745-54. 2006
    ..We propose that, in wild-type embryos, CDC-37-mediated inhibition of the CDC-42-dependent binding site and PAR-3-mediated release of this inhibition provide a key mechanism for the anterior accumulation of PAR-6...
  8. pmc Interaction of PAR-6 with CDC-42 is required for maintenance but not establishment of PAR asymmetry in C. elegans
    Donato Aceto
    Department of Molecular Biology and Genetics, Cornell University, 435 Biotechnology Building, Ithaca, NY 14853, USA
    Dev Biol 299:386-97. 2006
    ..We conclude that the CDC-42 interaction with PAR-6 is not required for the initial establishment of asymmetry but is required for maximal cortical accumulation of PAR-6 and to maintain its asymmetry...