title: The dynamics of mammalian P body transport, assembly, and disassembly in vivo.
abstract: Exported mRNAs are targeted for translation or can undergo degradation by several decay mechanisms. The 5'-->3' degradation machinery localizes to cytoplasmic P bodies (PBs). We followed the dynamic properties of PBs in vivo and investigated the mechanism by which PBs scan the cytoplasm. Using proteins of the decapping machinery, we asked whether PBs actively scan the cytoplasm or whether a diffusion-based mechanism is sufficient. Live-cell imaging showed that PBs were anchored mainly to microtubules. Quantitative single-particle tracking demonstrated that most PBs exhibited spatially confined motion dependent on microtubule motion, whereas stationary PB pairs were identified at the centrosome. Some PBs translocated in long-range movements on microtubules. PB mobility was compared with mitochondria, endoplasmic reticulum, peroxisomes, SMN bodies, and stress granules, and diffusion coefficients were calculated. Disruption of the microtubule network caused a significant reduction in PB mobility together with an induction of PB assembly. However, FRAP measurements showed that the dynamic flux of assembled PB components was not affected by such treatments. FRAP analysis showed that the decapping enzyme Dcp2 is a nondynamic PB core protein, whereas Dcp1 proteins continuously exchanged with the cytoplasm. This study reveals the mechanism of PB transport, and it demonstrates how PB assembly and disassembly integrate with the presence of an intact cytoskeleton.
authors.affiliation: The Mina and Everard Goodman Faculty of Life Sciences and Institute of Nanotechnology, Bar-Ilan University, Ramat Gan 52900, Israel.
authors.forename: Adva
authors.initials: A
authors.lastname: Aizer
authors.forename: Yehuda
authors.initials: Y
authors.lastname: Brody
authors.forename: Lian Wee
authors.initials: LW
authors.lastname: Ler
authors.forename: Nahum
authors.initials: N
authors.lastname: Sonenberg
authors.forename: Robert H
authors.initials: RH
authors.lastname: Singer
authors.forename: Yaron
authors.initials: Y
authors.lastname: Shav-Tal
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000502:physiology; D045744:Cell Line, Tumor; D018385:Centrosome / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D004058:Diffusion; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008322:Mammals / Q000502:physiology*; D008870:Microtubules / Q000378:metabolism; D008954:Models, Biological; D021381:Protein Transport; D020871:RNA Stability
chemical_list: D049452:Green Fluorescent Proteins