Cyclic nucleotide-gated (CNG) ion channels play important roles in vision and olfaction and have recently been identified in neurons and cardiac muscle. These channels are likely to be involved in disease, including retinal degeneration, and are potential targets for therapeutic drugs. The long-term goals of this project are to understand the molecular mechanism of channel of channel activation gating. This proposal investigates how cyclic nucleotide binding leads to the opening of the CNG channels, building upon the previous identification of two domains important for ligand gating: the C-helix of the carboxyl terminus ligand-binding domain and an amino terminus gating domain (N-S2 domain). Activation can be described by the Monod-Wyman-Changeyx (MWC) model in which the N-S2 domain participates in the concerted allosteric transition which mediates channel opening. The C-helix is important for enhanced binding of ligand to the open channel, thus stabilizing the open state. This hypothesis will be tested by investigating three specific questions: 1. What is the functional stoichiometry of ligan-gating? How many ligands must bind to activate the channel? Does the MWC model adequately describe gating? The properties of channels will be investigated in which the binding to zero to three of the channel's four subunits has been inactivated using point mutations of deletions in the binding site. These experiments will provide information as to whether ligand binding is cooperative or independent. They will revieal how much free energy for activation each binding site contributes. Finally they may suggest alternative schemes for channel activation gating other than the MWC model. 2. How does the C helix participate in activation gating? Does the C helix act to selectively stabilize cyclic mucleotide binding to the open channel? Does this stabilization require the formation of intrasubunit bonds? 3. What is the role of the N-S2 domain in subunit assembly? Does the allosteric gating transition involve a change in subunit-subunit interactions? This hypothesis is based on the fact that regions homologous to the N-S2 domain mediate subunit assembly in voltage-gated K channels. It is our hypothesis that the N-S2 domain contributes to subunit assembly of CNG channels. These experiments will thus provide a powerful means of exploring both the basic mechanism of CNG channel gating as well as a test of the role of two domains of the channel in activation gating. Such information will be important for understanding how the structure of this family of channels underlies the unique physiological roles of different types of CNG channels in sensory information processing.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
1R01NS036658-01A1
Application #
2622985
Study Section
Physiology Study Section (PHY)
Program Officer
Baughman, Robert W
Project Start
1998-04-01
Project End
2003-02-28
Budget Start
1998-04-01
Budget End
1999-02-28
Support Year
1
Fiscal Year
1998
Total Cost
Indirect Cost
Name
Columbia University (N.Y.)
Department
Neurosciences
Type
Schools of Medicine
DUNS #
167204994
City
New York
State
NY
Country
United States
Zip Code
10032
Saponaro, Andrea; Cantini, Francesca; Porro, Alessandro et al. (2018) A synthetic peptide that prevents cAMP regulation in mammalian hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. Elife 7:
Gross, Christine; Saponaro, Andrea; Santoro, Bina et al. (2018) Mechanical transduction of cytoplasmic-to-transmembrane-domain movements in a hyperpolarization-activated cyclic nucleotide-gated cation channel. J Biol Chem 293:12908-12918
Srinivas, Kalyan V; Buss, Eric W; Sun, Qian et al. (2017) The Dendrites of CA2 and CA1 Pyramidal Neurons Differentially Regulate Information Flow in the Cortico-Hippocampal Circuit. J Neurosci 37:3276-3293
Masurkar, Arjun V; Srinivas, Kalyan V; Brann, David H et al. (2017) Medial and Lateral Entorhinal Cortex Differentially Excite Deep versus Superficial CA1 Pyramidal Neurons. Cell Rep 18:148-160
Basu, Jayeeta; Zaremba, Jeffrey D; Cheung, Stephanie K et al. (2016) Gating of hippocampal activity, plasticity, and memory by entorhinal cortex long-range inhibition. Science 351:aaa5694
Kupferman, Justine V; Basu, Jayeeta; Russo, Marco J et al. (2014) Reelin signaling specifies the molecular identity of the pyramidal neuron distal dendritic compartment. Cell 158:1335-1347
Saponaro, Andrea; Pauleta, Sofia R; Cantini, Francesca et al. (2014) Structural basis for the mutual antagonism of cAMP and TRIP8b in regulating HCN channel function. Proc Natl Acad Sci U S A 111:14577-82
Hu, Lei; Santoro, Bina; Saponaro, Andrea et al. (2013) Binding of the auxiliary subunit TRIP8b to HCN channels shifts the mode of action of cAMP. J Gen Physiol 142:599-612
Piskorowski, Rebecca; Santoro, Bina; Siegelbaum, Steven A (2011) TRIP8b splice forms act in concert to regulate the localization and expression of HCN1 channels in CA1 pyramidal neurons. Neuron 70:495-509
Santoro, Bina; Hu, Lei; Liu, Haiying et al. (2011) TRIP8b regulates HCN1 channel trafficking and gating through two distinct C-terminal interaction sites. J Neurosci 31:4074-86

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