Aquaporin-5 water channel in lipid rafts of rat parotid glands

Ishikawa, Yasuko; Cho, Gota; Yuan, Zengqiang; Inoue, Naokazu; Nakae, Yoshiko

doi:10.1016/j.bbamem.2006.03.026

Cited by 44 publications

(39 citation statements)

References 60 publications

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“…In addition, the Brij 98 treatment dramatically increased the amount of AQP0 and AQP5 in the low-density fraction. Increasing evidence supports the lipid raft localization of AQP5, [29][30][31] whereas the localization of AQP0 in lipid rafts has been reported previously. 16,17 These results suggest that Brij 98 provides better yields of lipid raft marker proteins in the low-density fractions; therefore, further studies were performed only on DRM isolated after Brij 98 solubilization.…”

Section: Isolation Of Lipid Raft-like Drmsmentioning

confidence: 93%

Proteomic Analysis of Lipid Raft-Like Detergent-Resistant Membranes of Lens Fiber Cells

Wang

Schey

2015

Invest. Ophthalmol. Vis. Sci.

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Citation: Wang Z, Schey KL. Proteomic analysis of lipid raft-like detergentresistant membranes of lens fiber cells. Invest Ophthalmol Vis Sci. 2015;56:8349-8360. DOI:10.1167/ iovs.15-18273 PURPOSE. Plasma membranes of lens fiber cells have high levels of long-chain saturated fatty acids, cholesterol, and sphingolipids-key components of lipid rafts. Thus, lipid rafts are expected to constitute a significant portion of fiber cell membranes and play important roles in lens biology. The purpose of this study was to characterize the lens lipid raft proteome.METHODS. Quantitative proteomics, both label-free and iTRAQ methods, were used to characterize lens fiber cell lipid raft proteins. Detergent-resistant, lipid raft membrane (DRM) fractions were isolated by sucrose gradient centrifugation. To confirm protein localization to lipid rafts, protein sensitivity to cholesterol removal by methyl-b-cyclodextrin was quantified by iTRAQ analysis. RESULTS.A total of 506 proteins were identified in raft-like detergent-resistant membranes. Proteins identified support important functions of raft domains in fiber cells, including trafficking, signal transduction, and cytoskeletal organization. In cholesterol-sensitivity studies, 200 proteins were quantified and 71 proteins were strongly affected by cholesterol removal. Lipid raft markers flotillin-1 and flotillin-2 and a significant fraction of AQP0, MP20, and AQP5 were found in the DRM fraction and were highly sensitive to cholesterol removal. Connexins 46 and 50 were more abundant in nonraft fractions, but a small fraction of each was found in the DRM fraction and was strongly affected by cholesterol removal. Quantification of modified AQP0 confirmed that fatty acylation targeted this protein to membrane raft domains.CONCLUSIONS. These data represent the first comprehensive profile of the lipid raft proteome of lens fiber cells and provide information on membrane protein organization in these cells.

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Section: Isolation Of Lipid Raft-like Drmsmentioning

confidence: 93%

Proteomic Analysis of Lipid Raft-Like Detergent-Resistant Membranes of Lens Fiber Cells

Wang

Schey

2015

Invest. Ophthalmol. Vis. Sci.

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“…Although such a distribution is functionally important in potassium ion and water homeostasis, the mechanisms regulating the formation of these Kir4.1-and AQP4-enriched domains remain to be elucidated. AQP4 is associated with lipid raft-containing fractions in both brain and retina (27,35) as is another aquaporin, AQP5, that participates in fluid secretion in parotid gland cells (36). We therefore undertook a study to evaluate the role of lipid rafts in laminin-DG-dependent AQP4 clustering, and our data show that laminin induced a dramatic redistribution of GM1 into large cell surface clusters or macrodomains that colocalized extensively with ␤-DG and AQP4.…”

Section: Discussionmentioning

confidence: 99%

Interdependence of Laminin-mediated Clustering of Lipid Rafts and the Dystrophin Complex in Astrocytes

Noël

Tham

Moukhles

2009

Journal of Biological Chemistry

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Astrocyte endfeet surrounding blood vessels are active domains involved in water and potassium ion transport crucial to the maintenance of water and potassium ion homeostasis in brain. A growing body of evidence points to a role for dystroglycan and its interaction with perivascular laminin in the targeting of the dystrophin complex and the water-permeable channel, aquaporin 4 (AQP4), at astrocyte endfeet. However, the mechanisms underlying such compartmentalization remain poorly understood. In the present study we found that AQP4 resided in Triton X-100-insoluble fraction, whereas dystroglycan was recovered in the soluble fraction in astrocytes. Cholesterol depletion resulted in the translocation of a pool of AQP4 to the soluble fraction indicating that its distribution is indeed associated with cholesterol-rich membrane domains. Upon laminin treatment AQP4 and the dystrophin complex, including dystroglycan, reorganized into laminin-associated clusters enriched for the lipid raft markers GM1 and flotillin-1 but not caveolin-1. Reduced diffusion rates of GM1 in the laminin-induced clusters were indicative of the reorganization of raft components in these domains. In addition, both cholesterol depletion and dystroglycan silencing reduced the number and area of laminininduced clusters of GM1, AQP4, and dystroglycan. These findings demonstrate the interdependence between laminin binding to dystroglycan and GM1-containing lipid raft reorganization and provide novel insight into the dystrophin complex regulation of AQP4 polarization in astrocytes.The basement membrane is a specialized extracellular matrix (ECM) 2 composed of collagen, fibronectin, perlecan, agrin, and laminin. Several studies have focused on the involvement of these ECM molecules in the formation and maturation of neuromuscular junctions (1-4) and interneuronal synapses (5). More recently, much effort has been made by our group and others to understand the role of these molecules at the interface of astroglia and blood vessels (6 -8). Laminin is highly expressed at the perivascular ECM, and the laminin receptor, dystroglycan (␣-DG), together with many other components of the dystrophin-associated protein (DAP) complex, is particularly enriched at astrocyte endfeet abutting the blood vessels (9 -11). The binding of laminin to ␣-DG at these specialized astrocyte domains in brain plays a key role in the polarized distribution of components of the DAP complex (6, 12).Multiple lines of evidence indicate that the DAP complex is crucial for the functional distribution both of the water-permeable channel, AQP4, and the inwardly rectifying potassium channel, Kir4

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“…In vivo experiments using confocal microscopy revealed that in the parotid gland under unstimulated conditions, AQP5 is located in lipid rafts that contain flotillins and prototypical ganglioside GM1 with a diffuse pattern in apical cytoplasm in duct cells. The activation of M 3 -and M 1 -mAChRs induces the rapid translocation of AQP5, together with lipid rafts, from the apical cytoplasm to the APM by enhancement of [Ca 2+ ]i [10,11]. AQP5 and lipid rafts are then released into saliva [12].…”

Section: Introductionmentioning

confidence: 99%

Activation of muscarinic receptors in rat parotid acinar cells induces AQP5 trafficking to nuclei and apical plasma membrane

Cho

Bragiel

Wang

et al. 2015

Biochimica et Biophysica Acta (BBA) - General Subjects

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Aquaporin-5 water channel in lipid rafts of rat parotid glands

Cited by 44 publications

References 60 publications

Proteomic Analysis of Lipid Raft-Like Detergent-Resistant Membranes of Lens Fiber Cells

Proteomic Analysis of Lipid Raft-Like Detergent-Resistant Membranes of Lens Fiber Cells

Interdependence of Laminin-mediated Clustering of Lipid Rafts and the Dystrophin Complex in Astrocytes

Activation of muscarinic receptors in rat parotid acinar cells induces AQP5 trafficking to nuclei and apical plasma membrane

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