title: Neurosteroid binding to the amino terminal and glutamate binding domains of ionotropic glutamate receptors.
abstract: The endogenous neurosteroids, pregnenolone sulfate (PS) and 3α-hydroxy-5β-pregnan-20-one sulfate (PREGAS), have been shown to differentially regulate the ionotropic glutamate receptor (iGluR) family of ligand-gated ion channels. Upon binding to these receptors, PREGAS decreases current flow through the channels. Upon binding to non-NMDA or NMDA receptors containing an GluN2C or GluN2D subunit, PS also decreases current flow through the channels, however, upon binding to NMDA receptors containing an GluN2A or GluN2B subunit, flow through the channels increases. To begin to understand this differential regulation, we have cloned the S1S2 and amino terminal domains (ATD) of the NMDA GluN2B and GluN2D and AMPA GluA2 subunits. Here we present results that show that PS and PREGAS bind to different sites in the ATD of the GluA2 subunit, which when combined with previous results from our lab, now identifies two binding domains for each neurosteroid. We also show both neurosteroids bind only to the ATD of the GluN2D subunit, suggesting that this binding is distinct from that of the AMPA GluA2 subunit, with both leading to iGluR inhibition. Finally, we provide evidence that both PS and PREGAS bind to the S1S2 domain of the NMDA GluN2B subunit. Neurosteroid binding to the S1S2 domain of NMDA subunits responsible for potentiation of iGluRs and to the ATD of NMDA subunits responsible for inhibition of iGluRs, provides an interesting option for therapeutic design.
authors.affiliation: Department of Chemistry, University of Richmond, 28 Westhampton Way, Richmond, VA 23173, USA.
authors.forename: Krasnodara
authors.initials: K
authors.lastname: Cameron
authors.forename: Emily
authors.initials: E
authors.lastname: Bartle
authors.forename: Ryan
authors.initials: R
authors.lastname: Roark
authors.forename: David
authors.initials: D
authors.lastname: Fanelli
authors.forename: Melissa
authors.initials: M
authors.lastname: Pham
authors.forename: Beth
authors.initials: B
authors.lastname: Pollard
authors.forename: Brian
authors.initials: B
authors.lastname: Borkowski
authors.forename: Sarah
authors.initials: S
authors.lastname: Rhoads
authors.forename: Joon
authors.initials: J
authors.lastname: Kim
authors.forename: Monica
authors.initials: M
authors.lastname: Rocha
authors.forename: Martha
authors.initials: M
authors.lastname: Kahlson
authors.forename: Melinda
authors.initials: M
authors.lastname: Kangala
authors.forename: Lisa
authors.initials: L
authors.lastname: Gentile
mesh_terms: D001665:Binding Sites; D003001:Cloning, Molecular; D008958:Models, Molecular; D018377:Neurotransmitter Agents / Q000378:metabolism*; D011280:Pregnanolone / Q000031:analogs & derivatives* / Q000378:metabolism; D011284:Pregnenolone / Q000378:metabolism*; D058468:Receptors, Ionotropic Glutamate / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D018377:Neurotransmitter Agents; D058468:Receptors, Ionotropic Glutamate; C018370:pregnenolone sulfate; D011284:Pregnenolone; C019427:3-hydroxypregnan-3-one 3-sulfate; D011280:Pregnanolone