Alpha 2 adrenergic receptor subtypes expressed in Chinese hamster ovary cells activate differentially mitogen-activated protein kinase by a p21ras independent pathway.

C. S. Flordellis , M. Berguerand , P. Gouache , V. Barbu , H. Gavras , D. E. Handy , G. Béréziat (1) , J. Masliah (1, 2)

1 CHU Saint-Antoine [AP-HP]
2 UPMC - Université Pierre et Marie Curie - Paris 6

Epinephrine stimulation of rat alpha 2D, alpha 2B, and alpha 2C adrenergic receptor subtypes, expressed stably in Chinese hamster ovary (CHO) cells, caused a rapid, transient activation of mitogen-activated protein kinase (MAPK), with subtype-specific different efficiencies. The order of activation was CHO-2B approximately CHO-2D much greater than CHO-2C. Pertussis toxin blocked the stimulation of MAPK enzymatic activity and the parallel MAPK phosphorylation, demonstrating that these responses are mediated by pertussis toxin-sensitive Gi proteins. Contrary to what has been reported for the alpha 2A subtype expressed in rat-1 fibroblasts, epinephrine did not cause any detectable activation of p21ras in the CHO transfectants. Furthermore, combined application of epinephrine and phorbol myristate acetate had a potent cooperative but not additive effect in clones CHO-2D and CHO-2B but not in CHO-2C, suggesting that protein kinase C is probably differently involved in the signaling by the three alpha 2 receptor subtypes. These results show that in CHO cells, the different alpha 2 adrenergic receptor subtypes utilize differential pathways to activate MAPK in a p21ras-independent way.

Domaines: Chimie organique

C. S. Flordellis, M. Berguerand, P. Gouache, V. Barbu, H. Gavras, et al.. Alpha 2 adrenergic receptor subtypes expressed in Chinese hamster ovary cells activate differentially mitogen-activated protein kinase by a p21ras independent pathway.. Journal of Biological Chemistry, 1995, 270 ((8)), pp.3491-4. ⟨hal-00815402⟩