title: A membrane microdomain-associated protein, Arabidopsis Flot1, is involved in a clathrin-independent endocytic pathway and is required for seedling development.
abstract: Endocytosis is essential for the maintenance of protein and lipid compositions in the plasma membrane and for the acquisition of materials from the extracellular space. Clathrin-dependent and -independent endocytic processes are well established in yeast and animals; however, endocytic pathways involved in cargo internalization and intracellular trafficking remain to be fully elucidated for plants. Here, we used transgenic green fluorescent protein-flotillin1 (GFP-Flot1) Arabidopsis thaliana plants in combination with confocal microscopy analysis and transmission electron microscopy immunogold labeling to study the spatial and dynamic aspects of GFP-Flot1-positive vesicle formation. Vesicle size, as outlined by the gold particles, was ∼100 nm, which is larger than the 30-nm size of clathrin-coated vesicles. GFP-Flot1 also did not colocalize with clathrin light chain-mOrange. Variable-angle total internal reflection fluorescence microscopy also revealed that the dynamic behavior of GFP-Flot1-positive puncta was different from that of clathrin light chain-mOrange puncta. Furthermore, disruption of membrane microdomains caused a significant alteration in the dynamics of Flot1-positive puncta. Analysis of artificial microRNA Flot1 transgenic Arabidopsis lines established that a reduction in Flot1 transcript levels gave rise to a reduction in shoot and root meristem size plus retardation in seedling growth. Taken together, these findings support the hypothesis that, in plant cells, Flot1 is involved in a clathrin-independent endocytic pathway and functions in seedling development.
authors.affiliation: Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Ruili
authors.initials: R
authors.lastname: Li
authors.forename: Peng
authors.initials: P
authors.lastname: Liu
authors.forename: Yinglang
authors.initials: Y
authors.lastname: Wan
authors.forename: Tong
authors.initials: T
authors.lastname: Chen
authors.forename: Qinli
authors.initials: Q
authors.lastname: Wang
authors.forename: Ursula
authors.initials: U
authors.lastname: Mettbach
authors.forename: Frantisek
authors.initials: F
authors.lastname: Baluska
authors.forename: Jozef
authors.initials: J
authors.lastname: Samaj
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Fang
authors.forename: William J
authors.initials: WJ
authors.lastname: Lucas
authors.forename: Jinxing
authors.initials: J
authors.lastname: Lin
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002966:Clathrin / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis / Q000235:genetics / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D036226:Seedlings / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D002966:Clathrin; D008565:Membrane Proteins