This MERIT extension remains focused on the development and application of novel fluorescence methods to measure solute mobility and interactions in live cells and tissues.
The aims of the research are a direct extension of ongoing work to understand the determinants of extracellular space (ECS) diffusion and volume (Aim 1), plasma membrane protein diffusion (Aim 2) and protein-protein interactions (Aim 3).
In Aim 1, novel optical methods will be applied to study regulated ECS diffusion, volume and ionic homeostasis in brain and tumor. We will apply microfiberoptic methods, polarization correlation microscopy, and K'^-sensing fluorescent indicators to study ECS regulation in brain and tumor, addressing questions regarding the microviscosity of the extracellular matrix, the dynamic changes in ECS volume and [K*] during neural signal transduction, and the influence of cellular crowding on macromolecule diffusion in the ECS.
In Aim 2, single-molecule fiuorescence methods will be applied to investigate the determinants of membrane protein translational and rotational diffusion. Building on quantum dot-single particle tracking (SPT) studies of aquaporin-4 (AQP4) water channels, we will use multi-color SPT and quantum rod polarization correlation microscopy to investigate the determinants of AQP4 translational and rotation diffusion in live cells, and to study AQP diffusion in lamellipodia of migrating cells and the determinants of AQP4 supramolecular assembly.
In Aim 3, single-molecule fluorescence methods will be applied to investigate protein-protein interactions of membrane water and ion transporters. We have implemented methodology to quantify protein-protein interactions in live cells, including multicolor SPT, two-color FCS, and super-resolution microscopy. Building on our recent studies of AQP water channels and CFTR Cl' channels, we will investigate the size and dynamics of AQP4 supramolecular assembly, and the cytoskeletal and other interacting proteins of AQP4 and CFTR. These data will provide molecular-level information about the mechanisms and biological consequences of AQP4 and CFTR protein-protein interactions. In addition, the proposed studies will establish novel and widely applicable methodology to measure protein dynamics and interactions in cell plasma membrane and in the extracellular space.

Public Health Relevance

Our research involves the development and application of novel microscopy methods to study protein dynamics and interactions in live cells. The research addresses basic mechanistic questions about the extracellular space in brain and tumor, and how water and ion channels are regulated and assembled at cell membranes.

Agency
National Institute of Health (NIH)
Institute
National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
4R37EB000415-20
Application #
8210242
Study Section
Special Emphasis Panel (NSS)
Program Officer
Conroy, Richard
Project Start
2012-04-01
Project End
2017-03-31
Budget Start
2012-04-01
Budget End
2013-03-31
Support Year
20
Fiscal Year
2012
Total Cost
$466,875
Indirect Cost
$149,875
Name
University of California San Francisco
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
094878337
City
San Francisco
State
CA
Country
United States
Zip Code
94143
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
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Tradtrantip, Lukmanee; Jin, Bjung-Ju; Yao, Xiaoming et al. (2017) Aquaporin-Targeted Therapeutics: State-of-the-Field. Adv Exp Med Biol 969:239-250
Cil, Onur; Phuan, Puay-Wah; Son, Jung-Ho et al. (2017) Phenylquinoxalinone CFTR activator as potential prosecretory therapy for constipation. Transl Res 182:14-26.e4
Jin, Byung-Ju; Verkman, A S (2017) Microfluidic platform for rapid measurement of transepithelial water transport. Lab Chip 17:887-895
Felix, Christian M; Lee, Sujin; Levin, Marc H et al. (2017) Pro-Secretory Activity and Pharmacology in Rabbits of an Aminophenyl-1,3,5-Triazine CFTR Activator for Dry Eye Disorders. Invest Ophthalmol Vis Sci 58:4506-4513

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