application) Dr. Hallows is currently conducting his research fellowship in the laboratory of Dr. Foskett at the University of Pennsylvania. His career goals for the period of this grant are to further develop both the technical expertise (e.g., in molecular, biochemical and electrophysiological methodologies) and the creative skills necessary for a successful independent investigative career. After another 1-2 years of mentored research fellowship training, he plans to make the transition to a tenure-track faculty position within a renal division. Long-term career goals are to become a fully independent academic investigator performing basic research in an environment where bench results could be applied to important clinical problems within the broad fields of nephrology and cellular transport physiology; especially, the regulation and coordination of epithelial transport systems. The basis for this research project is a novel interaction that was discovered in our laboratory between CFTR, the ATP-regulated Cl-channel which is defective in cystic fibrosis, and the metabolic sensor AMP-activated protein kinase (AMPK). Using both yeast two-hybrid and biochemical assays, the C-terminal regulatory domain of the alpha (catalytic) subunit of AMPK was shown to bind to the CFTR C-terminal tail. AMPK co-localized in an apical distribution with CFTR in rat epithelial tissues and phosphorylated CFTR in vitro. Moreover, AMPK co-expression with CFTR in Xenopus oocytes inhibited cAMP-activated CFTR whole-cell conductance by up to 50 percent. Because AMPK responds to changes in cellular ATP, this inhibition of CFTR by AMPK may serve as a mechanism for inhibition of CFTR under conditions of metabolic stress, which suggests a novel paradigm for the coupling of ion transport to cellular metabolism. The goals of this research project are to determine the mechanisms for AMPK-dependent CFTR inhibition. The effects of AMPK activation on single-channel properties (Po) and surface expression (N) of CFTR will be determined in CFTR-expressing epithelial cells. Because both binding of alpha-AMPK to CFTR and its kinase activity appear to be required to confer this inhibition, further goals are to investigate the molecular details of how these phenomena translate into CFTR inhibition within the context of the macromolecular complex at the CFTR C-terminus. A final goal is to extend the search for functional effects of AMPK to transport systems that are closely associated with and modulated by CFTR.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Clinical Investigator Award (CIA) (K08)
Project #
1K08DK059477-01
Application #
6322644
Study Section
Diabetes, Endocrinology and Metabolic Diseases B Subcommittee (DDK)
Program Officer
Hyde, James F
Project Start
2001-07-01
Project End
2002-06-30
Budget Start
2001-07-01
Budget End
2002-06-30
Support Year
1
Fiscal Year
2001
Total Cost
$124,794
Indirect Cost
Name
University of Pennsylvania
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Myerburg, Michael M; King Jr, J Darwin; Oyster, Nicholas M et al. (2010) AMPK agonists ameliorate sodium and fluid transport and inflammation in cystic fibrosis airway epithelial cells. Am J Respir Cell Mol Biol 42:676-84
King Jr, J Darwin; Fitch, Adam C; Lee, Jeffrey K et al. (2009) AMP-activated protein kinase phosphorylation of the R domain inhibits PKA stimulation of CFTR. Am J Physiol Cell Physiol 297:C94-101
Hallows, Kenneth R; Fitch, Adam C; Richardson, Christine A et al. (2006) Up-regulation of AMP-activated kinase by dysfunctional cystic fibrosis transmembrane conductance regulator in cystic fibrosis airway epithelial cells mitigates excessive inflammation. J Biol Chem 281:4231-41
Bhalla, Vivek; Oyster, Nicholas M; Fitch, Adam C et al. (2006) AMP-activated kinase inhibits the epithelial Na+ channel through functional regulation of the ubiquitin ligase Nedd4-2. J Biol Chem 281:26159-69
Hallows, Kenneth R (2005) Emerging role of AMP-activated protein kinase in coupling membrane transport to cellular metabolism. Curr Opin Nephrol Hypertens 14:464-71
Carattino, Marcelo D; Edinger, Robert S; Grieser, Heather J et al. (2005) Epithelial sodium channel inhibition by AMP-activated protein kinase in oocytes and polarized renal epithelial cells. J Biol Chem 280:17608-16
Hallows, Kenneth R; McCane, Jill E; Kemp, Bruce E et al. (2003) Regulation of channel gating by AMP-activated protein kinase modulates cystic fibrosis transmembrane conductance regulator activity in lung submucosal cells. J Biol Chem 278:998-1004
Hallows, Kenneth R; Kobinger, Gary P; Wilson, James M et al. (2003) Physiological modulation of CFTR activity by AMP-activated protein kinase in polarized T84 cells. Am J Physiol Cell Physiol 284:C1297-308