title: The Arabidopsis abiotic stress-induced TSPO-related protein reduces cell-surface expression of the aquaporin PIP2;7 through protein-protein interactions and autophagic degradation.
abstract: The Arabidopsis thaliana multi-stress regulator TSPO is transiently induced by abiotic stresses. The final destination of this polytopic membrane protein is the Golgi apparatus, where its accumulation is strictly regulated, and TSPO is downregulated through a selective autophagic pathway. TSPO-related proteins regulate the physiology of the cell by generating functional protein complexes. A split-ubiquitin screen for potential TSPO interacting partners uncovered a plasma membrane aquaporin, PIP2;7. Pull-down assays and fluorescence imaging approaches revealed that TSPO physically interacts with PIP2;7 at the endoplasmic reticulum and Golgi membranes in planta. Intriguingly, constitutive expression of fluorescently tagged PIP2;7 in TSPO-overexpressing transgenic lines resulted in patchy distribution of the fluorescence, reminiscent of the pattern of constitutively expressed yellow fluorescent protein-TSPO in Arabidopsis. Mutational stabilization of TSPO or pharmacological inhibition of the autophagic pathway affected concomitantly the detected levels of PIP2;7, suggesting that the complex containing both proteins is degraded through the autophagic pathway. Coexpression of TSPO and PIP2;7 resulted in decreased levels of PIP2;7 in the plasma membrane and abolished the membrane water permeability mediated by transgenic PIP2;7. Taken together, these data support a physiological role for TSPO in regulating the cell-surface expression of PIP2;7 during abiotic stress conditions through protein-protein interaction and demonstrate an aquaporin regulatory mechanism involving TSPO.
authors.affiliation: Institut des Sciences de la Vie, Université Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium.
authors.forename: Charles
authors.initials: C
authors.lastname: Hachez
authors.affiliation: Institut des Sciences de la Vie, Université Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium.
authors.forename: Vasko
authors.initials: V
authors.lastname: Veljanovski
authors.affiliation: Institut des Sciences de la Vie, Université Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium.
authors.forename: Hagen
authors.initials: H
authors.lastname: Reinhardt
authors.affiliation: Institut des Sciences de la Vie, Université Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium.
authors.forename: Damien
authors.initials: D
authors.lastname: Guillaumot
authors.affiliation: Institut des Sciences de la Vie, Université Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium.
authors.forename: Celine
authors.initials: C
authors.lastname: Vanhee
authors.affiliation: Institut des Sciences de la Vie, Université Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium.
authors.forename: François
authors.initials: F
authors.lastname: Chaumont
authors.affiliation: Institut des Sciences de la Vie, Université Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium henri.batoko@uclouvain.be.
authors.forename: Henri
authors.identifier: http://orcid.org/0000-0002-8256-519X
authors.initials: H
authors.lastname: Batoko
mesh_terms: D020346:Aquaporins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D001343:Autophagy; D004721:Endoplasmic Reticulum / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006056:Golgi Apparatus / Q000378:metabolism; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000378:metabolism
chemical_list: D020346:Aquaporins; D029681:Arabidopsis Proteins; D008565:Membrane Proteins; C550345:TSPO-related protein, Arabidopsis