Article

Different domains of C. elegans PAR-3 are required at different times in development.

Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
Developmental Biology (Impact Factor: 3.87). 08/2010; 344(2):745-57. DOI:10.1016/j.ydbio.2010.05.506
Source: PubMed

ABSTRACT Polarity is a fundamental cellular feature that is critical for generating cell diversity and maintaining organ functions during development. In C. elegans, the one-cell embryo is polarized via asymmetric localization of the PAR proteins, which in turn are required to establish the future anterior-posterior axis of the embryo. PAR-3, a conserved PDZ domain-containing protein, acts with PAR-6 and PKC-3 (atypical protein kinase; aPKC) to regulate cell polarity and junction formation in a variety of cell types. To understand how PAR-3 localizes and functions during C. elegans development, we produced targeted mutations and deletions of conserved domains of PAR-3 and examined the localization and function of the GFP-tagged proteins in C. elegans embryos and larvae. We find that CR1, the PAR-3 self-oligomerization domain, is required for PAR-3 cortical distribution and function only during early embryogenesis and that PDZ2 is required for PAR-3 to accumulate stably at the cell periphery in early embryos and at the apical surface in pharyngeal and intestinal epithelial cells. We also show that phosphorylation at S863 by PKC-3 is not essential in early embryogenesis, but is important in later development. 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.

0 0
 · 
0 Bookmarks
 · 
70 Views
  • [show abstract] [hide abstract]
    ABSTRACT: Par-3, the central organizer of the Par-3/Par-6/atypical protein kinase C complex, is a multimodular scaffold protein that is essential for cell polarity establishment and maintenance. The N-terminal domain (NTD) of Par-3 is capable of self-association to form filament-like structures, although the underlying mechanism is poorly understood. Here, we determined the crystal structure of Par-3 NTD and solved the filament structure by cryoelectron microscopy. We found that an intrinsic "front-to-back" interaction mode is important for Par-3 NTD self-association and that both the lateral and longitudinal packing within the filament are mediated by electrostatic interactions. Disruptions of the lateral or longitudinal packing significantly impaired Par-3 NTD self-association and thereby impacted the Par-3-mediated epithelial polarization. We finally demonstrated that a Par-3 NTD-like domain from histidine ammonia-lyase also harbors a similar self-association capacity. This work unequivocally provides the structural basis for Par-3 NTD self-association and characterizes one type of protein domain that can self-assemble via electrostatic interactions.
    Structure 04/2013; · 5.99 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: A hallmark of cell polarity in metazoans is the distribution of partitioning defective (PAR) proteins into two domains on the membrane. Domain boundaries are set by the collective integration of mechanical, biochemical and biophysical signals, and the resulting PAR domains define areas of cytosol specialization. However, the complexity of the signals acting on PAR proteins has been a barrier to uncovering the general principles of PAR polarity. We propose that physical studies, when combined with genetic data, provide new understanding of the mechanisms of polarity establishment in the Caenorhabditis elegans embryo and other organisms.
    Nature Reviews Molecular Cell Biology 04/2013; · 37.16 Impact Factor
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: Cell polarity is regulated by evolutionarily conserved polarity factors whose precise higher-order organization at the cell cortex is largely unknown. Here we image frontally the cortex of live fission yeast cells using time-lapse and super-resolution microscopy. Interestingly, we find that polarity factors are organized in discrete cortical clusters resolvable to ~50-100 nm in size, which can form and become cortically enriched by oligomerization. We show that forced co-localization of the polarity factors Tea1 and Tea3 results in polarity defects, suggesting that the maintenance of both factors in distinct clusters is required for polarity. However, during mitosis, their co-localization increases, and Tea3 helps to retain the cortical localization of the Tea1 growth landmark in preparation for growth reactivation following mitosis. Thus, regulated spatial segregation of polarity factor clusters provides a means to spatio-temporally control cell polarity at the cell cortex. We observe similar clusters in Saccharomyces cerevisiae and Caenorhabditis elegans cells, indicating this could be a universal regulatory feature.
    Nature Communications 05/2013; 4:1834. · 10.02 Impact Factor

Full-text (2 Sources)

View
9 Downloads
Available from
Oct 9, 2013