Mechanism of isoproterenol-induced heterologous desensitization of mucin secretion from rat submandibular glands regulation of phosphorylation of Gi proteins controls the cell response to the subsequent stimulation
| Autor: | Hajime Ishida, Ichiro Amano, Takafumi Eguchi, Yasuko Ishikawa |
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| Rok vydání: | 1995 |
| Předmět: |
Male
medicine.medical_specialty G protein Submandibular Gland Rat submandibular gland Gi alpha subunit Adenylate kinase Desensitization In Vitro Techniques Biology Pertussis toxin Second Messenger Systems Radioligand Assay GTP-Binding Proteins Internal medicine medicine Animals Secretion Rats Wistar Phosphorylation Protein kinase A Molecular Biology Cyclic AMP-dependent protein kinase Isoproterenol Mucins Cell Biology Adrenergic beta-Agonists Molecular biology Rats Endocrinology GTP binding protein ADP-ribosylation Mucin secretion Cyclase activity Signal Transduction |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Molecular Cell Research. 1265:173-180 |
| ISSN: | 0167-4889 |
| DOI: | 10.1016/0167-4889(94)00216-2 |
| Popis: | Short-term treatment of rat submandibular tissues with 10 microM isoproterenol (IPR) resulted in reduction of mucin secretion in response to the agonist during further incubation, and in increases in EC50 values. This IPR-induced reduction of secretion was coupled with selective decreases in the number of beta-adrenoceptors in the tissues and in their affinity for agonists, as assessed by measurement of the specific binding of [3H]dihydroalprenolol. Treatment of the tissues with IPR caused a 30% decrease in IPR-stimulated adenylate cyclase activity and a 25% increase in the GTP binding capacity of inhibitory G proteins (Gi proteins). This IPR treatment triggered a 60% increase in the ability of pertussis toxin (IAP) to catalyze ADP-ribosylation of Gi proteins in the tissue membranes. Enhanced function of stimulatory G proteins (Gs proteins) was observed only during the first incubation of the tissues with IPR. The IAP-catalyzed ADP-ribosylation of Gi proteins in tissues treated with IPR was decreased by prior treatment with cyclic AMP dependent protein kinase, but was increased markedly by prior treatment with alkaline phosphatase. Neither IPR-induced desensitization of protein secretion nor increase in the IAP-catalyzed ADP-ribosylation of Gi proteins was observed in the tissues pretreated with 0.25 microM okadaic acid. These findings suggest that the regulation of Gi protein phosphorylation plays an important role in the IPR-induced heterologous desensitization of mucin secretion from rat submandibular glands. |
| Databáze: | OpenAIRE |
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