Planar Cell Polarity (PCP) signaling polarizes cells in epithelial sheets along an axis orthogonal to their apical- basal axis. Most of our mechanistic understanding of PCP signaling derives from work in Drosophila. However, a range of medically important developmental defects and physiological processes in vertebrates are under its control. PCP in vertebrates appears to conserve much or all of control of PCP signaling, including neural tube closure defects, polycystic kidneys, conotruncal heart defects, deafness and situs inversus. PCP polarizes skin and hair, and underlies directed migration during wound healing and invasion and metastasis of malignant cells the mechanism uncovered in flies, motivating considerable interest in studying PCP both in Drosophila. Studies in Drosophila reveal a modular system controlling PCP. A 'global' module comprising Fat(Ft), Dachsous(Ds) and Four-jointed(Fj) converts opposing tissue-level expression gradients of Fj and Ds into subcellular asymmetry of intercellular Ft-Ds heterodimers, and could therefore align PCP with the tissue axes. A 'core' module amplifies molecular asymmetry, localizing proximal (Van Gogh and Prickle) and distal (Frizzled, Dishevelled[Dsh]) proteins to opposite sides of the cell and coordinating polarity between neighboring cells. Morphological responses to the resulting molecular asymmetry are tissue specific. We have identified a mechanism linking these modules in series, and in so doing, revealed a fascinating cell biological mechanism. The global components Ft and Ds, via novel junctional ultrastructures, organize and tether arrays of polarized apical microtubules (MTs) that serve as substrates for directional trafficking of Dsh, thereby introducing a directional bias to the core module. Directional trafficking of Dsh breaks symmetry to bias core protein polarization. A paradox was the observation that the relationship between the direction of the global gradients and the direction of core module polarization is not conserved between tissues. We found that the predominance of the Prickle(Pk) or Spiny-legs(Sple) isoform of the core PCP component Pk controls gradient interpretation in these tissues by determining the direction of gradient dependent MTs, and thus the direction of MT dependent Dsh trafficking. These results raise a number of fascinating questions that we address in this proposal. How do the global components organize apical MTs? We hypothesize that Ft and Ds recruit proteins that capture and organize MTs. We will investigate how Pk-Sple controls Ft-Ds dependent MT orientation. Our data indicate that the Ft- Ds mechanism functions partially redundantly with a second signal originating at the wing margin. Preliminary data indicate that Wnt4 serves as this other signal, also by organizing polarized MTs. How does this other signal function? Once MTs are established, we wish to understand whether Dsh vesicle production is directly linked to these structures, and to study the signals for internalization and the control of molecular motors. Finally, we will study the E3 Ubiquitin ligase Cul1, which we have identified as a regulator of Pk function.

Public Health Relevance

Planar Cell Polarity (PCP) signaling polarizes cells in epithelial sheets along an axis orthogonal to their apical- basal axis. Most of our mechanistic understanding of PCP signaling derives from work in Drosophila, however, a range of medically important developmental defects and physiological processes in vertebrates are under control of PCP signaling, including neural tube closure defects, polycystic kidneys, conotruncal heart defects, deafness and situs inversus, polarization of skin and hair, and directed migration during wound healing and invasion and metastasis of malignant cells. In this project, we will harness the power of the Drosophila model system to investigate cell biological mechanisms underlying PCP, and thereby inform our understanding of PCP dependent vertebrate developmental (birth) defects and physiological processes.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37GM059823-18
Application #
9459910
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Hoodbhoy, Tanya
Project Start
2000-09-01
Project End
2019-03-31
Budget Start
2018-04-01
Budget End
2019-03-31
Support Year
18
Fiscal Year
2018
Total Cost
Indirect Cost
Name
Stanford University
Department
Pathology
Type
Schools of Medicine
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94304
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Kunimoto, Koshi; Bayly, Roy D; Vladar, Eszter K et al. (2017) Disruption of Core Planar Cell Polarity Signaling Regulates Renal Tubule Morphogenesis but Is Not Cystogenic. Curr Biol 27:3120-3131.e4
Cho, Bomsoo; Pierre-Louis, Gandhy; Sagner, Andreas et al. (2015) Clustering and negative feedback by endocytosis in planar cell polarity signaling is modulated by ubiquitinylation of prickle. PLoS Genet 11:e1005259
Matis, Maja; Russler-Germain, David A; Hu, Qie et al. (2014) Microtubules provide directional information for core PCP function. Elife 3:e02893
Olofsson, Jessica; Sharp, Katherine A; Matis, Maja et al. (2014) Prickle/spiny-legs isoforms control the polarity of the apical microtubule network in planar cell polarity. Development 141:2866-74
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Peng, Ying; Han, Chun; Axelrod, Jeffery D (2012) Planar polarized protrusions break the symmetry of EGFR signaling during Drosophila bract cell fate induction. Dev Cell 23:507-18