Receptor tyrosine kinases regulate alpha1D-adrenoceptor signaling properties: phosphorylation and desensitization.
Human alpha(1D)-adrenoceptors (truncated at the amino terminus (Delta1-79) to increase their membrane expression) were stably expressed in Rat-1 fibroblasts (1-1.5 pmol/mg protein). The receptors were functional as evidenced by a robust increase in intracellular calcium in response to noradrenaline. Using this cell line, the possibility that activation of receptor tyrosine kinases could modulate this adrenoceptor subtype was studied. It was observed that cell preincubation with insulin, IGF-I, EGF or PDGF markedly reduced the intracellular calcium increase observed in response to noradrenaline. Inhibitors of PI3K and PKC essentially blocked insulin-, IGF-I- and EGF-induced desensitizations. Interestingly, PDGF-induced alpha(1D)-adrenergic desensitization was only partially ameliorated by PI3K inhibitors and was not affected by those of PKC. Insulin, IGF-I, EGF and PDGF induced concentration-dependent increases in the phosphorylation state of alpha(1D)-adrenoceptors; phosphorylation took place on serine residues. Inhibitors of PI3K and PKC markedly reduced the effects of insulin, IGF-I and EGF on this parameter. These inhibitors only marginally reduced PDGF-induced alpha(1D)-adrenoceptors phosphorylation. The ability of IGF-I to induce alpha(1D)-adrenergic desensitization and phosphorylation was confirmed in cells expressing non-truncated rat alpha(1D)-adrenoceptors. Our data indicate that the function and phosphorylation state of alpha(1D)-adrenoceptors is modulated by activation of receptor tyrosine kinases. Insulin, IGF-I and EGF actions take place through the action of PI3K and PKC; additional pathway(s) seem to participate in PDGF-induced alpha(1D)-adrenoceptor desensitization and phosphorylation.
Rodríguez-Pérez
C Ekaterina
CE
Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-248, México, DF 04510, Mexico.
Calvo-Ochoa
Erika
E
Kalashnikova
Ekaterina V
EV
Reyes-Cruz
Guadalupe
G
Romero-Avila
M Teresa
MT
García-Sáinz
J Adolfo
JA
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D020794:Receptor Protein-Tyrosine Kinases / Q000819:agonists / Q000378:metabolism*; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism*; D015398:Signal Transduction; D019311:Staurosporine / Q000494:pharmacology
D002118:Calcium; D004815:Epidermal Growth Factor; D007328:Insulin; D007334:Insulin-Like Growth Factor I; D009638:Norepinephrine; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010982:Platelet-Derived Growth Factor; D011493:Protein Kinase C; D020794:Receptor Protein-Tyrosine Kinases; D018340:Receptors, Adrenergic, alpha-1; D019311:Staurosporine; C547719:ADRA1D protein, human; C547721:Adra1d protein, rat