This proposal remains focused on applications of novel fluorescence methods to measure solute mobility and interactions in living cells and tissues. The central goal of this research is to utilize information about solute dynamics to generate a realistic picture of the intracellular milieu and tissue extracellular spaces that cannot be deduced from static measurements such as electron micrographs. The current proposal utilizes new methodologies (microfiberoptic photobleaching, quantum dot single particle tracking, two-color and polarization fluorescence cross-correlation microscopies) to study molecular diffusion in cell culture and in vivo (mouse) systems.
Aim 1 will measure diffusion in the extracellular space (ECS) of tumor and brain tissues to test the hypothesis that ECS matrix composition and tortuosity restrict macromolecule diffusion. A microfiberoptic epifluorescence photobleaching (MFEP) method will be used to measure diffusion deep in tumor and brain tissue in vivo to quantify the contributions of extracellular matrix composition vs. geometric factors.
Aim 2 will measure plasma membrane diffusion of individual G-protein coupled receptors (GPCRs) to test the hypothesis that cytoskeletal and intrinsic membrane barriers restrict GPCR diffusion. High- resolution tracking of individual, quantum dot (QD)-labeled beta-2 and vasopressin-2 receptors, together with mutagenesis and pharmacological maneuvers, will be used to identify the determinants of receptor diffusion.
Aim 3 will measure protein interactions and rotational dynamics by fluorescence cross-correlation spectroscopy to test the hypotheses that mitochondrial matrix enzymes and membrane CFTR chloride channels form multi-molecular complexes. Following on from extensive preliminary data about the biology of mitochondrial matrix enzymes of the tricarboxylic acid cycle, and CFTR chloride channels, we will use cross- correlation microscopy to define the degree of complexation of mitochondrial matrix enzymes, and role of C- terminus PDZ interactions in restricting CFTR rotational mobility.

National Institute of Health (NIH)
National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Method to Extend Research in Time (MERIT) Award (R37)
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Biochemistry and Biophysics of Membranes Study Section (BBM)
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Zhang, Yantian
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University of California San Francisco
Internal Medicine/Medicine
Schools of Medicine
San Francisco
United States
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Smith, Alex J; Verkman, Alan S (2018) The ""glymphatic"" mechanism for solute clearance in Alzheimer's disease: game changer or unproven speculation? FASEB J 32:543-551
Duan, Tianjiao; Smith, Alex J; Verkman, Alan S (2018) Complement-dependent bystander injury to neurons in AQP4-IgG seropositive neuromyelitis optica. J Neuroinflammation 15:294
Lee, Sujin; Cil, Onur; Diez-Cecilia, Elena et al. (2018) Nanomolar-Potency 1,2,4-Triazoloquinoxaline Inhibitors of the Kidney Urea Transporter UT-A1. J Med Chem 61:3209-3217
Tradtrantip, Lukmanee; Felix, Christian M; Spirig, Rolf et al. (2018) Recombinant IgG1 Fc hexamers block cytotoxicity and pathological changes in experimental in vitro and rat models of neuromyelitis optica. Neuropharmacology 133:345-353
Phuan, Puay-Wah; Veit, Guido; Tan, Joseph-Anthony et al. (2018) ?F508-CFTR Modulator Screen Based on Cell Surface Targeting of a Chimeric Nucleotide Binding Domain 1 Reporter. SLAS Discov 23:823-831
Verkman, Alan S; Yao, Xiaoming; Smith, Alex J (2018) The evolving mystery of why skeletal muscle is spared in seropositive neuromyelitis optica. J Cell Mol Med 22:2039-2040
Verkman, Alan S; Smith, Alex J; Phuan, Puay-Wah et al. (2017) The aquaporin-4 water channel as a potential drug target in neurological disorders. Expert Opin Ther Targets 21:1161-1170
Yao, Xiaoming; Verkman, Alan S (2017) Marked central nervous system pathology in CD59 knockout rats following passive transfer of Neuromyelitis optica immunoglobulin G. Acta Neuropathol Commun 5:15
Lee, Sujin; Phuan, Puay-Wah; Felix, Christian M et al. (2017) Nanomolar-Potency Aminophenyl-1,3,5-triazine Activators of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Chloride Channel for Prosecretory Therapy of Dry Eye Diseases. J Med Chem 60:1210-1218
Verkman, Alan S; Tradtrantip, Lukmanee; Smith, Alex J et al. (2017) Aquaporin Water Channels and Hydrocephalus. Pediatr Neurosurg 52:409-416

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