Chronic exposure to nicotine is a crosscutting phenomenon, leading to nicotine dependence as well as to inadvertent therapeutic effects such as protection against Parkinson's disease. The project tests the novel suggestion that effects of chronic nicotine exposure depend on intracellular nicotine-not on conventional signal transduction via receptors at the plasma membrane. It is known that nicotine passively enters cells and recent studies suggest that nicotine also enters organelles such as endoplasmic reticulum (ER). In ER, nicotine may pharmacologically chaperone nascent nicotinic acetylcholine receptors (nAChRs), "matchmaking" subunits as pentameric receptors assemble. Other studies suggest additional potential sequelae of intracellular nicotine-nAChR interactions: decreasing unfolded protein responses, "escorting" other proteins from ER, or "abducting" proteins to abnormal pathways. The proposed mechanism is "inside-out", because it begins in the ER rather than on the plasma membrane. Nicotine's sustained inside-out effects proceed at concentrations much lower than its transient activation of plasma membrane nAChR channels. The project will invent new techniques to measure and control the initial steps in "inside-out" nicotinic pharmacology. We will develop NanoSIMS for measuring drug binding, and we will develop compartmentalized nicotinic ligands. We will also employ other state-of-the-art techniques: reconstitution of COPII vesicle budding, and FRET. Sub-Approach A invents tools measuring the compartmentalization of nicotine action. Sub-Approach B invents tools for confining pharmacology to the ER, both for nicotine and for the clinically important alpha4beta2 nAChR-selective ligand, varenicline. Sub-Approach C tests for interactions between nAChRs and "candidate genes" discovered by previous experiments. Inside-out pharmacology is a transformative concept that may reveal new therapeutic targets for addiction and neurodegeneration.

Public Health Relevance

Nicotine dependence and neurodegenerative disease are devastating problems and require better therapeutic drugs. The project attempts to understand what happens in the brain of a person chronically exposed to nicotine. The project suggests a new, inside-out mechanism of action, and this mechanism may reveal new therapeutic targets for addiction, neurodegeneration, and psychiatry.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
5R01DA037161-02
Application #
8728795
Study Section
Special Emphasis Panel (ZDA1)
Program Officer
Bough, Kristopher J
Project Start
Project End
Budget Start
Budget End
Support Year
2
Fiscal Year
2014
Total Cost
Indirect Cost
Name
California Institute of Technology
Department
None
Type
Schools of Arts and Sciences
DUNS #
009584210
City
Pasadena
State
CA
Country
United States
Zip Code
91125