Novel regulation of aquaporins during osmotic stress

• Published in: Plant physiology (Bethesda) Vol. 135; no. 4; pp. 2318 - 2329
• Main Authors: Vera-Estrella, R, Barkla, B.J, Bohnert, H.J, Pantoja, O
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01.08.2004; American Society of Plant Physiologists
• Subjects: Antibodies; Aquaporins; Aquaporins - physiology; Biological and medical sciences; Cell membranes; Cell physiology; cyclic AMP; DNA, Plant - genetics; Environmental Stress and Adaptation; Fundamental and applied biological sciences. Psychology; Gene expression regulation; Glycosylation; Mesembryanthemum - physiology; Mesembryanthemum crystallinum; Oocytes; Osmolar Concentration; Osmoregulation; osmotic stress; Plant cells; Plant Leaves - physiology; Plant physiology and development; plant proteins; Plant Proteins - metabolism; Plant Proteins - physiology; Plant Roots - physiology; plant stress; Plants; Plasma membrane and permeation; polypeptides; protein synthesis; Proteins; RNA Caps - genetics; RNA, Plant - genetics; signal transduction; Transcription, Genetic; transgenes; Water channels; Xenopus laevis; Cyclic AMP; Aizoaceae; Glycosylation; Osmotic shock; Mesembryanthemum crystallinum; Signal transduction; Regulation(control); Cytochalasin; Dynamics; Dicotyledones; Angiospermae; Plasma membrane; Spermatophyta; Aquaporin
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.104.044891

Aquaporin protein regulation and redistribution in response to osmotic stress was investigated. Ice plant (Mesembryanthemum crystallinum) McTIP1;2 (McMIPF) mediated water flux when expressed in Xenopus leavis oocytes. Mannitol-induced water imbalance resulted in increased protein amounts in tonoplast fractions and a shift in protein distribution to other membrane fractions, suggesting aquaporin relocalization. Indirect immunofluorescence labeling also supports a change in membrane distribution for McTIP1;2 and the appearance of a unique compartment where McTIP1;2 is expressed. Mannitol-induced redistribution of McTIP1;2 was arrested by pretreatment with brefeldin A, wortmannin, and cytochalasin D, inhibitors of vesicle trafficking-related processes. Evidence suggests a role for glycosylation and involvement of a cAMP-dependent signaling pathway in McTIP1;2 redistribution. McTIP1;2 redistribution to endosomal compartments may be part of a homeostatic process to restore and maintain cellular osmolarity under osmotic-stress conditions.