PIADINE · Deciphering the role of PI(4,5)P2 and its modulators PPK-1 and CSNK-1 in nematode asymmetric division
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2020-10-01 → 2022-10-24
- EU contribution
- €191,149
- Participants
- 1
- Scheme
- MSCA-IF
Lines connect the coordinator with its partners.
Results in brief
Deciphering the role of PI(4,5)P2 and its modulators PPK-1 and CSNK-1 in nematode asymmetric division
Originally, the project was focused on spindle positioning during the first mitosis of one-cell stage C. elegans embryos. In agreement with all parts concerned, the project quickly steered towards a focus in cell polarity establishment, which happens a bit earlier in the cell cycle. We took this decision because we identified a role for CSNK-1 (one of the proteins at the center of the fellowship application) in this process. Since cell polarity is defining the following steps of the cell cycle, including mitotic spindle positioning, we decided to address this biological problem to start with. C. elegans zygote is a great model system to investigate cell polarity, which results in the establishment of the anterior-posterior body axis. This system is attractive because of its large dimensions (50x30µm), optical accessibility, and the evolutionary conservation of most of the molecular players, which can be targeted using genetics and functional genomics. Following fertilization of the oocyte by the sperm, the newly formed zygote exhibits homogenous actomyosin dependent cortical contractions, and the presence of anterior-PAR proteins throughout the cell cortex. The sperm derived centrosomes mature in the zygote, through the recruitment of dedicated proteins, including SPD-2 and AIR-1. Once mature, the centrosomes contact the embryonic cortex, thus initiating polarity establishment. The first visible event of polarity establishment is a cortical actomyosin flow that moves away from the point of contact made by the centrosomes. This flow displaces also the anterior-PAR proteins, leaving the cortex accessible to posterior-PAR proteins. Polarity establishment ends when the cortical flow has moved the anterior-PARs to one half of the embryo cortex (the anterior half) and the posterior-PARs are localized on the other half (the posterior one), defining in this manner the anterior-posterior axis of the animal. SPD-2 and AIR-1 depletion or inactivation were previously shown to impair centrosome maturation. In this condition, the embryo still undergoes polarity establishment, but in an aberrant manner since it usually harbors two posterior poles rather than one, each marked with PAR-2. CSNK-1 depletion was reported previously not to affect polarity establishment.
Data: CORDIS, © European Union
Project objective
The first embryonic division of Caenorhabditis elegans is a powerful system to dissect the mechanisms governing asymmetric division, which relies on PAR-proteins for cell polarity and on dynein-dependant forces for centrosome and spindle positioning. In contrast to the extensive knowledge regarding proteins regulating asymmetric division, the contribution of plasma membrane tension, as well as of PIP2 and its modulators PPK-1 and CSNK-1 is poorly understood. I propose to decipher these questions as follows:1) PIP2 is enriched in the embryo anterior in microdomains of the plasma membrane. I will test the contribution of PPK-1, the only kinase from the proteome converting PIP into PIP2 in formation of PIP2 microdomains distribution, cell polarity and pulling force. This will be achieved through ppk-1(RNAi) as well as two complementary optogenetic approaches to obtain acute spatiotemporal inactivation of PIP2.2) I will decipher how the casein kinase CSNK-1 interacts with and phosphorylates PPK-1, thereby presumably regulating PIP2 microdomain distribution and function, as well as identify and characterize up to three CSNK-1 phospho-substrates with. 3) I will test whether PIP2 undergoes phase separation driven by a decrease in plasma membrane tension, and, if so, investigate the consequences on asymmetric division. Moreover, I will study the relationship between membrane tension and cortex contractility.4) I will analyze asymmetric cell division in the one-cell Pristiochus pacificus embryo I will then use the knowledge acquired in C. elegans to conduct related experiments in P. pacificus, thus investigating potential conserved and divergent themes governing asymmetric division across nematode evolution.Overall, these experiments will shed critical light on the poorly understood contribution of PIP2 and its modulators to asymmetric division, an evolutionarily conserved process fundamental for development and stem cell lineages.
Original text from CORDIS.
Participants
- ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE · LausanneCoordinatorSwitzerland
Links
Data: CORDIS, © European Union