The norbornenyl moiety of cyclothiazide determines the preference for flip-flop variants of AMPA receptor subunits.
Cyclothiazide and two analogs in which the norbornenyl part was replaced with a cyclohexyl or a cyclohexenyl moiety were examined with regard to their preference for flop vs. flip splice variants of the (+/-)-alphaamino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor subunits GluR2, 3 and 4. The studies were carried out by measuring the effects of the drugs on the binding of [(3)H]AMPA or [(3)H]fluorowillardiine to membranes from HEK293 cells that stably express the AMPA receptor subunits. Cyclothiazide had four to nine times lower EC(50) values at flip than at flop receptors, as previously reported. In contrast, the two analogs showed little discrimination for GluR3 or GluR4 splice variants and a clear preference for the flop variant in the case of GluR2. These results indicate that it is the norbornenyl component of cyclothiazide which confers the selectivity vis-a-vis flip-flop variants.
Kessler
M
M
Department of Pharmacology, Southern Illinois University School of Medicine, Springfield 62702, USA. mkessler@siumed.edu
Rogers
G
G
Arai
A
A
D000409:Alanine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D017398:Alternative Splicing / Q000502:physiology*; D000818:Animals; D000959:Antihypertensive Agents / Q000737:chemistry* / Q000378:metabolism; D001581:Benzothiadiazines / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics*; D001667:Binding, Competitive / Q000235:genetics; D002478:Cells, Cultured; D018690:Excitatory Amino Acid Agonists / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D007668:Kidney / Q000166:cytology; D011743:Pyrimidines / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D018091:Receptors, AMPA / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014316:Tritium; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000378:metabolism / Q000494:pharmacology
D000959:Antihypertensive Agents; D001581:Benzothiadiazines; D018690:Excitatory Amino Acid Agonists; D011743:Pyrimidines; D018091:Receptors, AMPA; C104723:glutamate receptor ionotropic, AMPA 3; C104724:glutamate receptor ionotropic, AMPA 4; D014316:Tritium; C095178:5-fluorowillardiine; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D000409:Alanine; C104722:glutamate receptor ionotropic, AMPA 2; C004639:cyclothiazide