?1A-adrenergic receptor induces activation of extracellular signal-regulated kinase 1/2 through endocytic pathway.

ABSTRACT: G protein-coupled receptors (GPCRs) activate mitogen-activated protein kinases through a number of distinct pathways in cells. Increasing evidence has suggested that endosomal signaling has an important role in receptor signal transduction. Here we investigated the involvement of endocytosis in ?(1A)-adrenergic receptor (?(1A)-AR)-induced activation of extracellular signal-regulated kinase 1/2 (ERK1/2). Agonist-mediated endocytic traffic of ?(1A)-AR was assessed by real-time imaging of living, stably transfected human embryonic kidney 293A cells (HEK-293A). ?(1A)-AR was internalized dynamically in cells with agonist stimulation, and actin filaments regulated the initial trafficking of ?(1A)-AR. ?(1A)-AR-induced activation of ERK1/2 but not p38 MAPK was sensitive to disruption of endocytosis, as demonstrated by 4°C chilling, dynamin mutation and treatment with cytochalasin D (actin depolymerizing agent). Activation of protein kinase C (PKC) and C-Raf by ?(1A)-AR was not affected by 4°C chilling or cytochalasin D treatment. U73122 (a phospholipase C [PLC] inhibitor) and Ro 31-8220 (a PKC inhibitor) inhibited ?(1B)-AR- but not ?(1A)-AR-induced ERK1/2 activation. These data suggest that the endocytic pathway is involved in ?(1A)-AR-induced ERK1/2 activation, which is independent of G(q)/PLC/PKC signaling.

SUBMITTER: Liu F 

PROVIDER: S-EPMC3125289 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature