Desensitization of the histamine H1-receptor and transcriptional down-regulation of histamine H1-receptor gene expression in bovine tracheal smooth muscle.
We have investigated the role of protein kinase C (PKC) in the desensitization of histamine H1-receptors and in the expression of the histamine H1-receptor gene in airway smooth muscle. Prolonged 4beta-phorbol 12,13 dibutyrate (PDBu) pretreatment (4 h, 100 nM-1 microM) of bovine trachealis caused a concentration-dependent loss of contraction in response to histamine H1-receptor stimulation, which was associated with a concentration-dependent decrease in histamine-induced total [3H]-inositol phosphates accumulation. In contrast, the responses to sodium fluoride, a direct G-protein activator, were unalterd by PDBu (100-300 nM) pre-incubation and only slightly reduced following incubation with 1 microM PDBu. A selective PKC inhibitor, GF 109203X, partially blocked the PDBu (1 microM)-induced desensitization and completely blocked the effect of 100 nM PDBu, confirming the involvement of PKC. Binding experiments using [3H]-pyrilamine revealed a class of high-affinity binding sites within the range for the histamine H1 receptor in airway smooth muscle. PDBu (1 microM) pretreatment for 4 h did not change the number of histamine H1 receptors. PDBu (1 microM) exposure caused a time-dependent reduction in the steady-state levels of histamine H1-receptor mRNA, which was inhibited by pre-incubation with GF 109203X and by cycloheximide, a protein synthesis inhibitor. Nuclear run-on assays revealed a 50% reduction in the rate of histamine H1-receptor gene transcription after 17 h PDBu pretreatment, whereas mRNA stability was not affected by PDBu pretreatment (17 h). In conclusion, we have shown a PKC-mediated desensitization of the histamine H1-receptor in BTSM and a transcriptional down-regulation of the histamine H1-receptor gene expression, which requires new protein synthesis.
Pype
J L
JL
Katholieke Universiteit Leuven, Laboratory of Pneumology, O&N, Belgium.
Mak
J C
JC
Dupont
L J
LJ
Verleden
G M
GM
Barnes
P J
PJ
D000818:Animals; D015152:Blotting, Northern; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006632:Histamine; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D007295:Inositol Phosphates / Q000378:metabolism; D008301:Maleimides / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011969:Receptors, Histamine H1 / Q000235:genetics / Q000378:metabolism*; D012969:Sodium Fluoride / Q000494:pharmacology; D014132:Trachea / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014316:Tritium
D004791:Enzyme Inhibitors; D007211:Indoles; D007295:Inositol Phosphates; D008301:Maleimides; D011969:Receptors, Histamine H1; D014316:Tritium; D015240:Phorbol 12,13-Dibutyrate; D006632:Histamine; D012969:Sodium Fluoride; D011493:Protein Kinase C; C070515:bisindolylmaleimide I