PgmNr W432: Unraveling cell polarity dynamics with single-cell biochemistry.

Authors:
Daniel J. Dickinson; Bob Goldstein


Institutes
Department of Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC.


Keyword: Cell polarization

Abstract:

Cell polarity is a fundamental feature of eukaryotic cells and plays a major role in many developmental processes. The conserved PAR protein system mediates polarization in a wide variety of animal cell types including epithelia, neurons and stem cells. PAR proteins localize asymmetrically within a cell and direct the polarization of downstream cellular processes. Although some in vitro binding interactions between PAR proteins are known, a fundamental unanswered question is how PAR proteins are organized biochemically into a signaling network that can mediate cell polarization. To address this question, we have developed a method to quantify protein-protein interactions at the single-molecule level, and with temporal resolution, in single cells. We are applying this approach to the C. elegans zygote, a single cell that polarizes in a defined manner with known and reproducible timing. We have identified PAR protein complexes that are specifically up- or down-regulated as the zygote polarizes. In particular, our data identify PAR-3 oligomerization as a key regulatory node for controlling cell polarization: PAR-3 forms large oligomers during polarity establishment, but these oligomers are absent in both stably polarized and non-polarized cells. Quantitative live imaging experiments suggest that PAR-3 oligomerization may contribute to polarity establishment by facilitating redistribution of the PAR-3/PAR-6/aPKC complex to the anterior half of the zygote. Ongoing experiments that combine single-cell biochemistry, quantitative live cell imaging, CRISPR/Cas9-induced targeted mutations and computational modeling in this simple system will reveal how regulated interactions between PAR proteins contribute to the establishment and maintenance of cell polarity.



Wormbase Genetic Index
1. par-3
2. par-6
3. pkc-3
4. cdc-42