The overarching aim of this program is to develop small molecule tools for understanding ion channel protein function associated with the highly complex ionic mechanisms of electrical transmission in neuronal cells. Naturally occurring guanidinium poisons - tetrodotoxin, saxitoxin, gonyautoxin 2/3, and zetekitoxin AB - form the bedrock of these investigations. Despite evident differences in molecular size and topology, all four molecules are exquisitely potent blockers of voltage-gated sodium ion channels (NaV) that operate by occluding the extracellular mouth of the ion conductance pore (Site I). Studies of NaV structure, of which there exist ten mammalian isoforms, and function have been advanced with the availability from natural sources of tetrodotoxin, saxitoxin, and small number of structurally related forms. In the absence of crystallographic data, molecules such as gonyautoxin 2/3, zetekitoxin AB, and designed saxitoxin mimics in combination with protein mutagenesis experiments would enable current homology models of the channel pore to be challenged and refined. Knowledge accrued from these types of studies could lead to new chemical agents patterned after the guanidinium toxins that demonstrate NaV subtype specific activity. Such tools are desirable for mapping the spatial and temporal distribution of specific channel isoforms in developing or injured neurons. As NaV channels are considered lead actors in mechanisms for inflammation and neuropathic pain response, drugs that act on specific channel subtypes could represent next-generation therapies for the treatment of such ailments.

Public Health Relevance

We are interested in understanding at a molecular level how nerve cells conduct electricity and how the process of electrical signaling is affected when a nerve is injured. Chemical synthesis is the engine that drives our program and will make possible the preparation of selective reagents that can be used to investigate these complex biological phenomena. Results from these studies could help guide the development of new therapies for the treatment of acute and/or chronic pain.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS045684-08
Application #
7753181
Study Section
Synthetic and Biological Chemistry A Study Section (SBCA)
Program Officer
Stewart, Randall R
Project Start
2003-02-01
Project End
2012-01-31
Budget Start
2010-02-01
Budget End
2011-01-31
Support Year
8
Fiscal Year
2010
Total Cost
$378,417
Indirect Cost
Name
Stanford University
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305
Logan, Matthew M; Toma, Tatsuya; Thomas-Tran, Rhiannon et al. (2016) Asymmetric synthesis of batrachotoxin: Enantiomeric toxins show functional divergence against NaV. Science 354:865-869
Thomas-Tran, Rhiannon; Du Bois, J (2016) Mutant cycle analysis with modified saxitoxins reveals specific interactions critical to attaining high-affinity inhibition of hNaV1.7. Proc Natl Acad Sci U S A 113:5856-61
Mulcahy, John V; Walker, James R; Merit, Jeffrey E et al. (2016) Synthesis of the Paralytic Shellfish Poisons (+)-Gonyautoxin 2, (+)-Gonyautoxin 3, and (+)-11,11-Dihydroxysaxitoxin. J Am Chem Soc 138:5994-6001
Toma, Tatsuya; Logan, Matthew M; Menard, Frederic et al. (2016) Inhibition of Sodium Ion Channel Function with Truncated Forms of Batrachotoxin. ACS Chem Neurosci 7:1463-1468
Olson, David E; Su, Justin Y; Roberts, D Allen et al. (2014) Vicinal diamination of alkenes under Rh-catalysis. J Am Chem Soc 136:13506-9
Thottumkara, Arun P; Parsons, William H; Du Bois, J (2014) Saxitoxin. Angew Chem Int Ed Engl 53:5760-84
Eberlin, Livia S; Mulcahy, John V; Tzabazis, Alexander et al. (2014) Visualizing dermal permeation of sodium channel modulators by mass spectrometric imaging. J Am Chem Soc 136:6401-5
Devlin, A Sloan; Bois, J Du (2013) Modular Synthesis of the Pentacyclic Core of Batrachotoxin and Select Batrachotoxin Analogue Designs. Chem Sci 4:1059-1063
Hoehne, Aileen; Behera, Deepak; Parsons, William H et al. (2013) A 18F-labeled saxitoxin derivative for in vivo PET-MR imaging of voltage-gated sodium channel expression following nerve injury. J Am Chem Soc 135:18012-5
Parsons, William H; Du Bois, J (2013) Maleimide conjugates of saxitoxin as covalent inhibitors of voltage-gated sodium channels. J Am Chem Soc 135:10582-5

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