title: Activation of membrane receptors by a neurotransmitter conjugate designed for surface attachment.
abstract: The derivatization of surfaces with bioactive molecules is a research area of growing importance for cell and tissue engineering. Tetherable molecules used in such applications must contain an anchoring moiety as well as the biofunctional group, typically along with a spacer to prevent steric clashes between the target molecule and the tethering surface. Post-synaptic membrane receptors at chemical synapses in neural tissue mediate signaling to the post-synaptic neuron and are activated by the binding of diffusible neurotransmitter molecules released by the pre-synaptic neuron. However, little attention has been directed at developing neurotransmitter analogs that might retain functionality when tethered to a surface that could be interfaced with post-synaptic receptor proteins. Muscimol (5-aminomethyl-3-hydroxyisoxazole), an analog of GABA (gamma-aminobutryic acid), is a known potent agonist of GABA(A) and GABA(C) post-synaptic receptors found in retina and other central nervous system tissue. The present paper reports experiments testing the electrophysiological activity of "muscimol-biotin" on cloned GABA receptors expressed in Xenopus oocytes. This compound, which is potentially suitable for tethering at avidin-coated surfaces, consists of muscimol conjugated through an N-acyl linkage to a 6-aminohexanoyl chain that is distally terminated by biotin. We find that muscimol-biotin, as well as a structurally similar compound (muscimol-BODIPY) containing a bulky fluorophore at the distal end of the aminohexanoyl chain, exhibits substantial agonist activity at GABA(A) and GABA(C) receptors. Muscimol-biotin and other similarly biotinylated neurotransmitter analogs, in combination with surface functionalization using avidin-biotin technology, may be useful in applications involving the controlled activation of neuronal post-synaptic receptors by surface-attached molecules.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Lions of Illinois Eye Research Institute, University of Illinois at Chicago, 1855 W. Taylor St., Chicago, IL 60612, USA. taniavu@bu.edu
authors.forename: Tania Q
authors.initials: TQ
authors.lastname: Vu
authors.forename: Sarwat
authors.initials: S
authors.lastname: Chowdhury
authors.forename: Niraj J
authors.initials: NJ
authors.lastname: Muni
authors.forename: Haohua
authors.initials: H
authors.lastname: Qian
authors.forename: Robert F
authors.initials: RF
authors.lastname: Standaert
authors.forename: David R
authors.initials: DR
authors.lastname: Pepperberg
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D020099:Coated Materials, Biocompatible / Q000494:pharmacology; D058785:GABA-A Receptor Agonists; D058786:GABA-B Receptor Agonists; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D009118:Muscimol / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000819:agonists / Q000378:metabolism; D011963:Receptors, GABA-A / Q000378:metabolism*; D018080:Receptors, GABA-B / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: D020099:Coated Materials, Biocompatible; D058785:GABA-A Receptor Agonists; D058786:GABA-B Receptor Agonists; D018377:Neurotransmitter Agents; D011956:Receptors, Cell Surface; D011963:Receptors, GABA-A; D018080:Receptors, GABA-B; D011994:Recombinant Proteins; D009118:Muscimol