Stimulation by ghrelin of p42/p44 mitogen‐activated protein kinase through the GHS‐R1a receptor: Role of G‐proteins and β‐arrestins

This is the authors' abstract. We don't add key points for this paper.

Results presented in this study indicate that in human embryonic kidney 293 cells (HEK 293), the ghrelin receptor growth hormone secretagogue receptor type 1a (GHS-R1a) activates the extracellular signal-related kinases 1 and 2 (ERK 1/2) via three pathways. One pathway is mediated by the beta-arrestins 1 and 2, and requires entry of the receptor into a multiprotein complex with the beta-arrestins, Src, Raf-1, and ERK 1/2. A second pathway is G(q/11)-dependent and involves a Ca(2+)-dependent PKC (PKCalpha/beta) and Src. A third pathway is G(i)-dependent and involves phosphoinositide 3-kinase (PI3K), PKCepsilon, and Src. Our current study reveals that G(i/o)- and G(q/11)-proteins are crucially involved in the beta-arrestin-mediated ERK 1/2 activation. These results thus support the view that the beta-arrestins act as both scaffolding proteins and signal transducers in ERK 1/2 activation, as reported for other receptors. The different pathways of ERK 1/2 activation suggest that binding to GHS-R1a activates ERK 1/2 pools at different locations within the cell, and thus probably with different physiological consequences.