Professor of the Graduate School Division of Cell and Developmental BiologyLab Homepage: http://mcb.berkeley.edu/labs/machen/
The general goal is to determine how cytoplasmic and organellar Ca, pH and redox contribute to physiology and pathophysiology of secretory epithelial cells.
The Cystic Fibrosis Transmembrane conductance Regulator (CFTR) is an anion channel that conducts Cl, HCO3 and glutathione (GSH). This channel is normally located in the apical membrane of trachea and other secretory and absorptive epithelial cells. The genetic disease cystic fibrosis (CF) is caused by mutations in CFTR that lead to reduced function of CFTR, resulting in altered luminal ionic milieu, accumulation of viscous mucus with altered biochemical properties, reduced activities of anti-bacterial products secreted by epithelial cells and accumulation of bacteria and neutrophils in affected tissues.
Patch clamp and transepithelial electrophysiology are used to investigate the Cl and HCO3 permeability properties of the CFTR channel, which is key to determining the secretory and absorptive properties of epithelial cells in the lung airways.
To test the hypothesis that CFTR controls or modulates pH and redox of the airway surface liquid and organelles (ER, Golgi, and mucus secretory granules), we use digital imaging microscopy and genetic targeting of green fluorescent protein (GFP) and organic fluorescent dyes to determine how the channel affects the pH regulatory properties of organelles in intact, living cells.
Widefield and confocal microscopy coupled with measurements of are used to characterize the interactions between epithelial cells and bacteria in an attempt to determine the early events that precede inflammatory events like invasion by neutrophils. One of the key events in CF and other inflammatory diseases is that bacteria that accumulate in the airways induce neutrophils to migrate from the capillaries across the epithelial surface and into the airway lumen to attack the foreign invaders. The epithelilal cells appear to help orchestrate this event. Using imaging microscopy, quantitative PCR and ELISA we are testing the hypothesis that flagellin released from bacteria trigger apical toll-like receptors and NF-kappaB-related signaling in the epithelial cells, and this process is importantly modulated by epithelial cell [Ca].
CFTR and H+ permeability in regulation of Golgi pH. [T. E. Machen, G. Chandy, M. Wu, M. Grabe, and H-P. Moore (2001) Proceedings of the International Symposium on HC03- and Cystic Fibrosis, P.Quinton, ed. J. Pancreas, in press]
ENaC and CFTR dependent ion and fluid transport in mammary epithelia. [S. Blaug, K. Hybiske, J. Cohn, G. L. Firestone, T.E. Machen and S.S. Miller (2001) Amer. J. Physiol., in press]
Proton leak and CFTR in regulation of Golgi pH in airway epithelial cells [G. Chandy, M. Grabe, H-P. Moore and T. E. Machen (2001) Amer. J. Physiol. in press]
Studying organelle physiology using targeted avidin and fluorescein-biotin. [M. Wu, J. Llopis, S. Adams, J.M. McCaffery, K. Teter, M.S. Kulomaa, T.E. Machen, H-P. Moore and R.Y. Tsien (2000) Methods in Enzymology 327, 546-564]
Organelle pH studies using targeted avidin and fluorescein-biotin. [M. M. Wu, J. Llopis, S. Adams, J. M. McCaffery, M. S. Kuolomaa, T. E. Machen, H.-P. Moore, and R. Y. Tsien (2000) Chemistry and Biology 7, 197-209]
Airway epithelial tight junctions and binding and cytotoxicity of Pseudomonas aeruginosa. [A. Lee, D. Chow, W. Tseng, B. Haus, D. Evans, S. Fleiszig, G. Chandy, and T. E. Machen (1999) Amer. J. Physiol. Lung Cell and Molecular Biology 277, L204-L217]
Cellubrevin-targeted fluorescence uncovers heterogeneity in the recycling endosomes. [K. Teter, G. Chandy, B. Quiñones, K. Pereyra, T. E. Machen, and H-P. Moore (1998) J. Biol. Chem. 273, 19625-19633]
Regulation of apical CFTR by protein phosphatase 2B and protein kinase C. [H. Fischer, B. Illek, and T. E. Machen (1998) Pflug. Archiv., Eur. J. Physiol. 436, 175-181]
The actin filament disrupter cytochalisin D activates the recombinant CFTR Cl channel in 3T3 fibroblasts. [H. Fischer, B. Illek, and T. E. Machen (1996) J. Physiol. 489, 745-754]
Alternate stimulation of apical CFTR by genistein in epithelia. [B. Illek, H. Fischer, and T. E. Machen (1996) Am. J. Physiol. 270, C265-C275]
Spatial distribution and quantitation of free luminal [Ca] within the InsP3-sensitive internal store of individual BHK-21 cells. Ion dependence of InsP3-induced Ca release and reloading. [A. M. Hofer, W. R. Schlue, S. Curci, and T. E. Machen (1995) FASEB J. 9, 788-798]
Bicarbonate conductance and pH regulatory capability of CFTR. [J. H. Poulsen, H. Fischer, B. Illek, and T. E. Machen (1994) Proc.Natl. Acad. Sci. 91, 5340-5344]
Regulated Cl transport, K and Cl permeability, and exocytosis in T84 cells. [M. E. Huflejt, R. A. Blum, S. G. Miller, H.-P. Moore, and T. E. Machen (1994) J .Clin. Invest. 93, 1900-1910]
Photo credit: Mark Joseph Hanson of Mark Joseph Studio.
Last Updated 2005-08-25