Subunit-dependent inhibition of recombinant rodent N-methyl-D-aspartate receptors by a HIV-1 glycoprotein 120 derived peptide.
Considerable evidence suggests that low (picomolar) concentrations of the HIV-1 envelope glycoprotein gp120 induce neuronal cell death by stimulating the release of microglial toxins, which in turn activate N-methyl-D-aspartate (NMDA) receptors. Conversely, high (micromolar) concentrations of gp120 have been reported to directly inhibit NMDA receptor-mediated currents and do not induce neurotoxicity. Here we show that micromolar concentrations of a synthetic peptide corresponding to the V3-loop of gp120 (V3-pep) inhibited agonist responses of recombinant heteromeric rodent NMDA receptors expressed in Xenopus laevis oocytes by decreasing their apparent glycine affinity. Different combinations of NMDA receptor subunits displayed differential sensitivities to inhibition by V3-pep, with a potency rank order of NR1/2B > NR1/2D > NR1/2C > or = NR1/2A. Our observations may provide an explanation for the reduced neurotoxicity of high doses of gp120 in cell cultures and may be useful for the pharmacological discrimination of NMDA receptor subtypes.
Wittekindt
B
B
Department of Neurochemistry, Max-Planck-Institute for Brain Research, Deutschordenstrasse 46, 60528, Frankfurt, Germany.
Betz
H
H
Laube
B
B
D000595:Amino Acid Sequence; D000818:Animals; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005260:Female; D018698:Glutamic Acid / Q000494:pharmacology; D005998:Glycine / Q000494:pharmacology; D015699:HIV Envelope Protein gp120 / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D008969:Molecular Sequence Data; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D018408:Patch-Clamp Techniques; D010446:Peptide Fragments / Q000494:pharmacology*; D020033:Protein Isoforms / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D018075:RNA, Complementary / Q000235:genetics; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D014982:Xenopus laevis
D018690:Excitatory Amino Acid Agonists; D015699:HIV Envelope Protein gp120; D010446:Peptide Fragments; D020033:Protein Isoforms; D018075:RNA, Complementary; D016194:Receptors, N-Methyl-D-Aspartate; D011994:Recombinant Proteins; D018698:Glutamic Acid; D005998:Glycine