Sustained norepinephrine stimulation induces different regulation of expression in three alpha1-adrenoceptor subtypes.
The norepinephrine (NE)-induced regulation of alpha1-adrenoceptors (ARs) expression in human embryonic kidney (HEK) 293 cells stably expressing cloned alpha1-AR subtypes with similar receptor densities was investigated. In the presence of 10 microM propranolol, the treatment of cells with 10 microM NE for 4-72 h down-regulated alpha1A- and alpha1D-AR. but increased alpha1B-AR expression in a time-dependent manner. The down-regulation of alpha1A-AR reached maximum of 40.3 +/- 14.7 % at 48h. The down-regulation of alpha1D-AR reached maximum of 51.3 +/- 3.7% at 24h. With the stimulation of NE, alpha1B-AR density was increased maximally by 112.4 +/- 43.4% at 48h. The protein kinase C (PKC) inhibitor calphostin C or R0-31-8220 abolished the NE-induced down-regulation of alpha1A- and alpha1D-AR, but showed no effect on the up-regulation of alpha1B-AR. The PKC agonist PMA not only mimicked the NE-induced down-regulation of alpha1A- and alpha1D-AR, but also induced a down-regulation of alpha1B-AR. The endoplasmic reticulum Ca2+-ATPase inhibitor cyclopiazonic acid (CPA) or thapsigargin, or the calcium chelator BAPTA/AM did not affect the down-regulation of alpha1A-AR, but inhibited the up-regulation of alpha1B-AR induced by NE. Calmodulin antagonist W-7. tyrosine kinase inhibitor genistein or tyrphostin A25 had no effect on NE-induced up-regulation of alpha1B-AR. The results suggest that three alpha1-AR subtypes are differently regulated by sustained NE stimulation with different signal transduction pathways.
Lei
B
B
Institute of Vascular Medicine, The Third Hospital, Beijing Medical University, PR of China.
Zhang
Y
Y
Han
C
C
D002460:Cell Line; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000196:embryology; D009638:Norepinephrine / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D018340:Receptors, Adrenergic, alpha-1 / Q000096:biosynthesis* / Q000145:classification / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013449:Sulfonamides / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D014162:Transfection; D020032:Tyrphostins / Q000494:pharmacology
D007211:Indoles; D012333:RNA, Messenger; D018340:Receptors, Adrenergic, alpha-1; D013449:Sulfonamides; D020032:Tyrphostins; C079836:tyrphostin 25; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; C017967:W 7; D019284:Thapsigargin; D019833:Genistein; D013755:Tetradecanoylphorbol Acetate; C064758:Ro 31-8220; D009638:Norepinephrine; C000543:cyclopiazonic acid