PROJECTS

The research activities of the laboratory are directed to three principal areas:  

1.   Mechanisms of water transport across cell membranes

            Water transport across many cell plasma membranes is facilitated by molecular water channels.   A major focus of the lab is analysis of water transporting mechanisms, the identification and cellular processing of molecular water channels (aquaporins), and the generation and phenotype analysis of transgenic mouse models of aquaporin deficiency and mutation.   Optical methods have been developed to measure water permeability and applied to cells and intact epithelia / organs.   Key questions of ongoing interest include the physiological role of water channels (in kidney, central nervous system, eye, lung and GI tract), vesicle targeting mechanisms of vasopressin-sensitive water transport, and development of new therapies for conditions of water imbalance such as nephrogenic diabetes insipidus, congestive heart failure and glaucoma.   Methods/reagents include cell and transgenic mouse models of aquaporins, optical measurements of water permeability and aquaporin processing, mouse physiology, drug discovery, and analysis of GFP-aquaporin chimeras.

2.   Biophysics of molecular diffusion and interactions in living cells

            The motion of small and macromolecule-size solutes in cellular aqueous compartments is important in metabolism, signaling, growth and locomotion.   A goal of the research is to construct an accurate picture of the cell interior based on measurements of solute mobility and interactions, rather than static electron micrographs.   A series of biophysical approaches were developed to study these processes in living cells, including anisotropy imaging, picosecond microfluorimetry, single photon radioluminescence, 3-d single particle tracking, microsecond photobleaching recovery (FRAP), fluorescence correlation spectroscopy, total internal reflection FRAP (TIR-FRAP), and quantitative multi-angle TIR imaging.   Problems under investigation include measurements of macromolecule (proteins, DNA) mobility in cells, organelles, and intact tissues in vivo, mathematical modeling of diffusion, and development of new applications of fluorescence correlation microscopy.

3.   Drug discovery and lung disease mechanisms in Cystic Fibrosis

            After identification of the Cystic Fibrosis (CF) gene in 1989, there has been dramatic progress in Cystic Fibrosis research.   The Cystic Fibrosis gene product is a large protein (Cystic Fibrosis Transmembrane conductance Regulator, CFTR) that functions as a cAMP-stimulated chloride channel and possibly as a regulator of multiple intracellular processes.   Active work in the laboratory is directed at the identification of cellular abnormalities in CF that could account for the lung pathology, including studies of the airway surface fluid layer and submucosal glands.   A major focus of research is discovery of new drugs for CFTR inhibition (as antidiarrheals and to create CF animal models) and activation of mutant CFTRs (including ?F508-CFTR) that cause CF.   Resources for drug discovery include high-throughput screening, a large collection of small drug-like molecules, rodent pharmacology and efficacy testing, and synthetic/medicinal chemistry.