Regulation of adenylate cyclase type VIII splice variants by acute and chronic Gi/o-coupled receptor activation.
We previously reported that acute agonist activation of G(i/o)-coupled receptors inhibits adenylate cyclase (AC) type VIII activity, whereas agonist withdrawal following chronic activation of these receptors induces AC-VIII superactivation. Three splice variants of AC-VIII have been identified, which are called AC-VIII-A, -B and -C (with AC-VIII-B missing the glycosylation domain and AC-VIII-C lacking most of the C1b area). We report here that AC-VIII-A and -B, but not -C, are inhibited by acute mu-opioid and dopaminergic type D2 receptor activation, indicating that the C1b area of AC-VIII has an important role in AC inhibition by G(i/o)-coupled receptor activation. On the other hand the glycosylation sites in AC-VIII did not play a role in AC-VIII regulation. Although AC-VIII-A and -C differed in their capacity to be inhibited by acute agonist exposure, agonist withdrawal after prolonged treatment led to a similar superactivation of all three splice variants, with no significant change in AC-VIII expression. AC-VIII superactivation was not affected by pre-incubation with a cell permeable cAMP analogue, indicating that the superactivation does not depend on the agonist-induced reduction in cAMP levels. The superactivated AC-VIII-A, -B and -C were similarly re-inhibited by re-application of agonist (morphine or quinpirole), returning the activity to control levels. These results demonstrate marked differences in the agonist inhibition of the AC-VIII splice variants before, but not after, superactivation.
Steiner
Debora
D
Department of Neurobiology, The Weizmann Institute of Science, 76100 Rehovot, Israel.
Avidor-Reiss
Tomer
T
Schallmach
Ester
E
Butovsky
Elena
E
Lev
Nirit
N
Vogel
Zvi
Z
D000262:Adenylyl Cyclases / Q000378:metabolism / Q000502:physiology*; D017398:Alternative Splicing / Q000502:physiology*; D000818:Animals; D019556:COS Cells / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D002522:Chlorocebus aethiops; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology; D014644:Genetic Variation / Q000502:physiology*; D005822:Genetic Vectors; D015759:Ionomycin / Q000494:pharmacology; D009020:Morphine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D037342:Pertussis Toxin / Q000494:pharmacology; D017448:Receptors, Dopamine D2; D043562:Receptors, G-Protein-Coupled / Q000502:physiology*; D013997:Time Factors
D017448:Receptors, Dopamine D2; D043562:Receptors, G-Protein-Coupled; D005576:Colforsin; D015759:Ionomycin; D009020:Morphine; D000242:Cyclic AMP; D037342:Pertussis Toxin; D000262:Adenylyl Cyclases; C118292:adenylyl cyclase 8