The Transient Receptor Potential Vanilloid 1 channel (TRPV1) is a key component of nociceptors and is also a mechanosensor in the urinary bladder and osmosensor in neurons. The water channel Aquaporin-4 (AQP-4) is found in glial cells in the CNS and is critical for water homeostasis in the brain. Although both TRPV1 and AQP-4 are important in normal body function and several pathological conditions, little is currently known about how the functions of these channels are modified by bilayer composition or their membrane microdomain locations. These are fundamental issues because the functions of many ion channels have been shown to be modified by specific membrane lipids such as phosphatidylinositol-4,5 bisphosphate (PIP2), as well as by membrane material properties controlled by the presence of cholesterol. Moreover, some channels are sequestered into cholesterol-rich plasma membrane microdomains called rafts. This application uses patch clamp electrophysiology and micropipette aspiration to measure the role of bilayer cholesterol concentration on the channel properties of TRPV1 and AQP-4, respectively. In addition, a variety of techniques, including confocal microscopy and freeze-fracture electron microscopy, will be employed to determine the microdomain locations of TRPV1 and AQP-4 and test possible mechanisms for the sequestering of channels into rafts. Our hypotheses are that: (1) specific protein-lipid and protein- protein interactions, including homo-oligomerization of the channels, are key factors in sorting channels between microdomains, (2) bilayer material properties (as controlled by phospholipid hydrocarbon chain composition and cholesterol content) modulate the function of both TRPV1 and AQP-4, and (3) acylated polybasic cytoplasmic proteins can sequester key regulatory lipids such as PIP2 into raft domains in the cytoplasmic leaflet of membrane bilayers.

Public Health Relevance

The water channel AQP-4 and the Transient Receptor Potential channel TRPV1 are critically important in normal body function and several pathological conditions. AQP-4, expressed in glial cells in the brain, is implicated in brain edema and a variety of cerebral disorders. TRPV1, found in many regions of the body including pain receptors, is implicated in bowel disease, contact dermatitis, as well as pain in general.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
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Biochemistry and Biophysics of Membranes Study Section (BBM)
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Chin, Jean
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Duke University
Anatomy/Cell Biology
Schools of Medicine
United States
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Tong, Jihong; Wu, Zhe; Briggs, Margaret M et al. (2016) The Water Permeability and Pore Entrance Structure of Aquaporin-4 Depend on Lipid Bilayer Thickness. Biophys J 111:90-9
McIntosh, Thomas J (2015) Stepping between membrane microdomains. Biophys J 108:783-4
Tong, Jihong; Canty, John T; Briggs, Margaret M et al. (2013) The water permeability of lens aquaporin-0 depends on its lipid bilayer environment. Exp Eye Res 113:32-40
Zhang, Xiao-Xiang; McIntosh, Thomas J; Grinstaff, Mark W (2012) Functional lipids and lipoplexes for improved gene delivery. Biochimie 94:42-58
Godeau, Guilhem; Navailles, Laurence; Nallet, Frédéric et al. (2012) From Brittle to Pliant Viscoelastic Materials with Solid State Linear Polyphosphonium - Carboxylate Assemblies. Macromolecules 45:2509-2513
LaManna, Caroline M; Lusic, Hrvoje; Camplo, Michel et al. (2012) Charge-reversal lipids, peptide-based lipids, and nucleoside-based lipids for gene delivery. Acc Chem Res 45:1026-38
Tong, Jihong; Briggs, Margaret M; McIntosh, Thomas J (2012) Water permeability of aquaporin-4 channel depends on bilayer composition, thickness, and elasticity. Biophys J 103:1899-908
Picazo-Juárez, Giovanni; Romero-Suárez, Silvina; Nieto-Posadas, Andrés et al. (2011) Identification of a binding motif in the S5 helix that confers cholesterol sensitivity to the TRPV1 ion channel. J Biol Chem 286:24966-76
Zhang, Xiao-Xiang; Prata, Carla A H; Berlin, Jason A et al. (2011) Synthesis, characterization, and in vitro transfection activity of charge-reversal amphiphiles for DNA delivery. Bioconjug Chem 22:690-9
Zhang, Xiao-Xiang; Prata, Carla A H; McIntosh, Thomas J et al. (2010) The effect of charge-reversal amphiphile spacer composition on DNA and siRNA delivery. Bioconjug Chem 21:988-93

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