Skip to Main content Skip to Navigation
Journal articles

Gbeta gamma-independent coupling of alpha2-adrenergic receptor to p21(rhoA) in preadipocytes.

Abstract : In preadipocytes, alpha2-adrenergic receptor (alpha2-AR) stimulation leads to a Gi/Go-dependent rearrangement of actin cytoskeleton. This is characterized by a rapid cell spreading, the formation of actin stress fibers, and the increase in tyrosyl phosphorylation of the focal adhesion kinase (pp125(FAK)). These cellular events being tightly controlled by the small GTPase p21(rhoA), the existence of a Gi/Go-dependent coupling of alpha2-AR to p21(rhoA) in preadipocytes was proposed. In alpha2AF2 preadipocytes (a cell clone derived from the 3T3F442A preadipose cell line and which stably expresses the human alpha2C10-adrenergic receptor) alpha2-adrenergic-dependent induction of cell spreading, formation of actin stress fibers, and increase in tyrosyl phosphorylation of pp125(FAK) were abolished by pretreatment of the preadipocytes with the C3 exoenzyme, a toxin which impairs p21(rhoA) activity by ADP-ribosylation. Conversely, C3 exoenzyme had no effect on the alpha2-adrenergic-dependent increase in tyrosyl phosphorylation and shift of ERK2 mitogen-activated protein kinase. alpha2-Adrenergic stimulation also led to an increase in GDP/GTP exchange on p21(rhoA), as well as to an increase in the amount of p21(rhoA) in the particulate fraction of alpha2AF2 preadipocytes. Stable transfection of alpha2AF2 preadipocytes with the COOH-terminal domain of betaARK1 (betaARK-CT) (a blocker of Gbeta gamma-action), strongly inhibited the alpha2-adrenergic-dependent increase in tyrosyl phos- phorylation and shift of ERK2, without modification of the tyrosyl phosphorylation of pp125(FAK) and spreading of preadipocytes. These results show that alpha2-adrenergic-dependent reorganization of actin cytoskeleton requires the activation of p21(rhoA) in preadipocytes. Conversely to the activation of the p21(ras)/mitogen-activated protein kinase pathway, the alpha2-adrenergic activation of p21(rhoA)-dependent pathways are independent of the beta gamma-subunits of heterotrimeric G proteins.
Document type :
Journal articles
Complete list of metadata
Contributor : Jean Sébastien Saulnier-Blache Connect in order to contact the contributor
Submitted on : Monday, January 8, 2007 - 2:58:27 PM
Last modification on : Monday, July 4, 2022 - 9:29:16 AM
Long-term archiving on: : Tuesday, April 6, 2010 - 9:06:51 PM


  • HAL Id : inserm-00110175, version 1
  • PUBMED : 9624180


Sandrine Bétuing, Danièle Daviaud, Céline Pagès, Elisabeth Bonnard, Philippe Valet, et al.. Gbeta gamma-independent coupling of alpha2-adrenergic receptor to p21(rhoA) in preadipocytes.. Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology, 1998, 273 (25), pp.15804-10. ⟨inserm-00110175⟩



Record views


Files downloads