Peptidyl prolyl cis-trans isomerase activity of cyclophilin A in functional homo-oligomeric receptor expression.
The functional expression of homo-oligomeric alpha7 neuronal nicotinic and type 3 serotonin receptors is dependent on the activity of a cyclophilin. In this paper we demonstrate that the mechanism of cyclophilin action during functional homo-oligomeric receptor expression in Xenopus oocytes is distinct from the calcineurin-dependent immunosuppressive mechanism by showing that a nonimmunosuppressive analog of cyclosporin A (CsA), SDZ 211-811, reduces functional receptor expression to the same extent as CsA. The cytoplasmic subtype of cyclophilin, cyclophilin A (CyPA), appears to be required for functional receptor expression. This is because overexpression of CyPA and a CyPA mutant that is deficient in CsA binding activity reverses CsA-induced reduction in functional receptor expression. The mechanism of action of CyPA is likely to involve its prolyl isomerase activity because a mutant CyPA with a single amino acid substitution (arginine 55 to alanine) that is predicted to produce a 1000-fold attenuation in isomerase activity fails to reverse the cyclosporin A effect. Our data also suggest that CyPA does not form a stable complex with receptor subunits.
Helekar
S A
SA
Division of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA. shelekar@bcm.tmc.edu
Patrick
J
J
D000591:Amino Acid Isomerases / Q000096:biosynthesis / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology; D002352:Carrier Proteins / Q000096:biosynthesis / Q000378:metabolism*; D003001:Cloning, Molecular; D016572:Cyclosporine / Q000494:pharmacology*; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D066298:In Vitro Techniques; D007668:Kidney / Q000201:enzymology; D008564:Membrane Potentials / Q000187:drug effects; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000502:physiology; D016716:PC12 Cells; D019696:Peptidylprolyl Isomerase; D016133:Polymerase Chain Reaction; D051381:Rats; D011978:Receptors, Nicotinic / Q000096:biosynthesis / Q000502:physiology*; D011985:Receptors, Serotonin / Q000096:biosynthesis / Q000502:physiology*; D044406:Receptors, Serotonin, 5-HT3; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D014982:Xenopus laevis
D002352:Carrier Proteins; D011978:Receptors, Nicotinic; D011985:Receptors, Serotonin; D044406:Receptors, Serotonin, 5-HT3; D011993:Recombinant Fusion Proteins; C105951:SDZ 211-811; D016572:Cyclosporine; D000591:Amino Acid Isomerases; D019696:Peptidylprolyl Isomerase