Voltage-gated Ca channels convert electrical signals into intracellular Ca signals that are paramount for a variety of cellular processes, including neurotransmitter release, muscle contraction and gene expression. Ca channels trigger these processes by opening in response to electrical stimulation, thus allowing Ca ions to flow into the cell where they act as signaling molecules that are detected by Ca binding proteins. L-type Ca channels, one subset of the Ca channel superfamily, are the target proteins for a number of drugs including the dihydropyridines (DHPs). DHPs are an important class of drugs, used extensively to treat angina, hypertension and stroke. DHPs modulate Ca channel gating, but the molecular details that link DHP binding to changes in Ca channel gating are not known. We have found that the DHP receptor site and a Ca binding site in the pore exhibit cooperativity and are allosterically coupled. Ca binding to the pore promotes the energetic coupling between two amino acid residues located in the pore and DHP antagonists disrupt this coupling. This finding is intriguing given that gating for several types of ion channels is linked to structural rearrangements in their respective pore regions. We hypothesize that conformational changes that occur upon DHP binding are transduced to the pore where gating is altered. By studying the allosteric interactions between Ca and DHP binding, we intend to identify important molecular interactions that link DHP binding to changes in channel gating. We are integrating several techniques, including whole-cell patch-clamp electrophysiology, kinetic modeling and radioligand binding to develop a deep understanding of how DHPs modulate the gating behavior of L-type Ca channels. Results from these studies are expected to facilitate the rational design of new classes of drugs that modulate the gating behavior of Ca channels. This application is divided into four Specific Aims: 1. Identify interacting amino acid pairs in the Ca channel pore. 2. Identify changes in gating that are dependent on Ca binding to the channel pore. 3. Clarify the relationship between Ca and DHP binding and channel block. 4. Develop an allosteric-kinetic scheme that links DHP- and Ca- binding to Ca channel gating. ? ?

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL074143-04
Application #
7326767
Study Section
Electrical Signaling, Ion Transport, and Arrhythmias Study Section (ESTA)
Program Officer
Przywara, Dennis
Project Start
2004-12-15
Project End
2009-11-30
Budget Start
2007-12-01
Budget End
2008-11-30
Support Year
4
Fiscal Year
2008
Total Cost
$343,248
Indirect Cost
Name
Pennsylvania State University
Department
Physiology
Type
Schools of Medicine
DUNS #
129348186
City
Hershey
State
PA
Country
United States
Zip Code
17033
Yarotskyy, Viktor; Gao, Guofeng; Peterson, Blaise Z et al. (2012) Domain III regulates N-type (CaV2.2) calcium channel closing kinetics. J Neurophysiol 107:1942-51
Li, Zhe; Wang, Xianming; Gao, Guofeng et al. (2010) A single amino acid change in Ca(v)1.2 channels eliminates the permeation and gating differences between Ca(2+) and Ba(2+). J Membr Biol 233:23-33
Wang, Xianming; Gao, Guofeng; Guo, Kai et al. (2010) Phospholemman modulates the gating of cardiac L-type calcium channels. Biophys J 98:1149-59
Yarotskyy, Viktor; Gao, Guofeng; Du, Lei et al. (2010) Roscovitine binds to novel L-channel (CaV1.2) sites that separately affect activation and inactivation. J Biol Chem 285:43-53
Guo, Kai; Wang, Xianming; Gao, Guofeng et al. (2010) Amino acid substitutions in the FXYD motif enhance phospholemman-induced modulation of cardiac L-type calcium channels. Am J Physiol Cell Physiol 299:C1203-11
Yarotskyy, Viktor; Gao, Guofeng; Peterson, Blaise Z et al. (2009) The Timothy syndrome mutation of cardiac CaV1.2 (L-type) channels: multiple altered gating mechanisms and pharmacological restoration of inactivation. J Physiol 587:551-65
Wang, Xianming; Du, Lei; Peterson, Blaise Z (2007) Calcicludine binding to the outer pore of L-type calcium channels is allosterically coupled to dihydropyridine binding. Biochemistry 46:7590-8
Peterson, Blaise Z; Catterall, William A (2006) Allosteric interactions required for high-affinity binding of dihydropyridine antagonists to Ca(V)1.1 Channels are modulated by calcium in the pore. Mol Pharmacol 70:667-75
Wang, Xianming; Ponoran, Tudor A; Rasmusson, Randall L et al. (2005) Amino acid substitutions in the pore of the Ca(V)1.2 calcium channel reduce barium currents without affecting calcium currents. Biophys J 89:1731-43