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Microscopy Using Fluorescent Drug Biosensors for "Inside-Out Pharmacology"

Muthusamy, Anand K. and Shivange, Amol V. and Nichols, Aaron L. and Kamajaya, Aron and Jeon, Janice and Borden, Philip M. and Marvin, Jonathan S. and Unger, Elizabeth K. and Bao, Huan and Chapman, Edwin R. and Tian, Lin and Looger, Loren L. and Lester, Henry A. (2018) Microscopy Using Fluorescent Drug Biosensors for "Inside-Out Pharmacology". Biophysical Journal, 114 (3). 358A. ISSN 0006-3495. doi:10.1016/j.bpj.2017.11.1990.

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Neuropharmacology offers many tools for connecting molecular to acute behavioral phenomena but has few tools to explain effects of chronic drugs. In the biophysically based “inside-out” approach to neuropharmacology, drugs bind to their nascent targets within the endoplasmic reticulum (ER) (i.e. pharmacological chaperoning). Now we visualize, quantify, and time the first steps: drugs entering the cell and entering organelles. Our fluorescent biosensors are built on an OpuBC-GFP fusion scaffold. OpuBC is a bacterial periplasmic binding protein with two key features: a cation-π box, favorable for binding amines well represented in drugs, and a binding-induced “Venus fly-trap” conformational change. The suitably mutated OpuBC domain is connected, at the hinge regions, to a circularly permuted “superfolder” GFP (cpGFP). Aided by structural information, we use directed evolution to create a family of drug-sensing biosensors meeting the criterion of ΔF/F0 > 1 at 1 μM drug. Our proof of principle study concerns nicotine entering the ER, as measured by an “intensity-based nicotine-sensing fluorescent reporter” (iNicSnFR). Previous data demonstrated that exposure to nicotine causes changes in number and stoichiometry of nicotinic receptors by chaperoning within the ER; however nicotine itself entering the ER had not yet been measured. In live cell imaging of an iNicSnFR targeted to the ER, we found that nicotine enters the ER within 10 s of application at concentrations experienced by a cigarette smoker. Moreover, we found that varenicline, a smoking cessation drug, enters the ER almost as rapidly as nicotine, helping to explain varenicline's biochemical and behavioral effects. We are currently developing other “iDrugSnFRs” for antidepressants, antipsychotics, and opioids. These tools to study subcellular pharmacokinetics will help to clarify chronic effects of several families of neural drugs. Support: DA037161, GM123582, NARSAD, California TRDRP, and HHMI.

Item Type:Article
Related URLs:
URLURL TypeDescription
Muthusamy, Anand K.0000-0003-1041-914X
Nichols, Aaron L.0000-0001-9341-0049
Jeon, Janice0000-0002-8483-586X
Marvin, Jonathan S.0000-0003-2294-4515
Chapman, Edwin R.0000-0001-9787-8140
Tian, Lin0000-0001-7012-6926
Lester, Henry A.0000-0002-5470-5255
Additional Information:© 2018 Biophysical Society. Available online 6 February 2018.
Funding AgencyGrant Number
National Alliance for Research on Schizophrenia and Depression (NARSAD)UNSPECIFIED
California Tobacco-Related Disease Research ProgramUNSPECIFIED
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
Issue or Number:3
Record Number:CaltechAUTHORS:20180523-150441864
Persistent URL:
Official Citation:Anand K. Muthusamy, Amol V. Shivange, Aaron L. Nichols, Aron Kamajaya, Janice Jeon, Philip M. Borden, Jonathan S. Marvin, Elizabeth K. Unger, Huan Bao, Edwin R. Chapman, Lin Tian, Loren L. Looger, Henry A. Lester, Microscopy Using Fluorescent Drug Biosensors for “Inside-Out Pharmacology”, Biophysical Journal, Volume 114, Issue 3, Supplement 1, 2018, Page 358a, ISSN 0006-3495, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86577
Deposited By: Tony Diaz
Deposited On:24 May 2018 16:29
Last Modified:15 Nov 2021 20:40

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