Recycling, clustering, and endocytosis jointly maintain PIN auxin carrier polarity at the plasma membrane.
Cell polarity reflected by asymmetric distribution of proteins at the plasma membrane is a fundamental feature of unicellular and multicellular organisms. It remains conceptually unclear how cell polarity is kept in cell wall-encapsulated plant cells. We have used super-resolution and semi-quantitative live-cell imaging in combination with pharmacological, genetic, and computational approaches to reveal insights into the mechanism of cell polarity maintenance in Arabidopsis thaliana. We show that polar-competent PIN transporters for the phytohormone auxin are delivered to the center of polar domains by super-polar recycling. Within the plasma membrane, PINs are recruited into non-mobile membrane clusters and their lateral diffusion is dramatically reduced, which ensures longer polar retention. At the circumventing edges of the polar domain, spatially defined internalization of escaped cargos occurs by clathrin-dependent endocytosis. Computer simulations confirm that the combination of these processes provides a robust mechanism for polarity maintenance in plant cells. Moreover, our study suggests that the regulation of lateral diffusion and spatially defined endocytosis, but not super-polar exocytosis have primary importance for PIN polarity maintenance.
Department of Plant Systems Biology, VIB, Universiteit Gent, Gent, Belgium.
Jürgen
J
Kleine-Vehn
Krzysztof
K
Wabnik
Alexandre
A
Martinière
Łukasz
Ł
Łangowski
Katrin
K
Willig
Satoshi
S
Naramoto
Johannes
J
Leitner
Hirokazu
H
Tanaka
Stefan
S
Jakobs
Stéphanie
S
Robert
Christian
C
Luschnig
Willy
W
Govaerts
Stefan W
SW
Hell
John
J
Runions
Jiří
J
Friml
D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity; D002473:Cell Wall / Q000378:metabolism; D002966:Clathrin / Q000378:metabolism; D003198:Computer Simulation; D004058:Diffusion; D004705:Endocytosis; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D021381:Protein Transport
D029681:Arabidopsis Proteins; D002966:Clathrin; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; C116363:PIN1 protein, Arabidopsis; C117013:AT5G57090 protein, Arabidopsis