Bombyx Adipokinetic Hormone Receptor Activates Extracellular Signal-Regulated Kinase 1 and 2 via G Protein-Dependent PKA and PKC but β-Arrestin-Independent Pathways

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• 作者：Haishan Huang ; Xiaobai He ; Xiaoyan Deng ; Guo Li ; Guoyuan Ying ; Yi Sun ; Liangen Shi ; Jeffrey L. Benovic ; Naiming Zhou
• 刊名：Biochemistry
• 出版年：2010
• 出版时间：December 28, 2010
• 年：2010
• 卷：49
• 期：51
• 页码：10862-10872
• 全文大小：1212K
• 年卷期：v.49,no.51(December 28, 2010)
• ISSN：1520-4995

文摘

Neuropeptides of the adipokinetic hormone (AKH) family are among the best studied hormone peptides. They play important roles in insect hemolymph sugar homeostasis, larval lipolysis, and storage-fat mobilization. Mechanistic investigations have shown that, upon AKH stimulation, adipokinetic hormone receptor (AKHR) couples to a Gs protein and enhances adenylate cyclase activity, leading to intracellular cAMP accumulation. However, the underlying molecular mechanism by which this signaling pathway connects to extracellular signal-regulated kinase 1/2 (ERK1/2) remains to be elucidated. Using HEK293 cells stably or transiently expressing AKHR, we demonstrated that activation of AKHR elicited transient phosphorylation of ERK1/2. Our investigation indicated that AKHR-mediated activation of ERK1/2 was significantly inhibited by H-89 (protein kinase A inhibitor), Go6983, and GF109203X (protein kinase C inhibitors) but not by U73122 (PLC inhibitor) or FIPI (PLD inhibitor). Moreover, AKHR-induced ERK1/2 phosphorylation was blocked by the calcium chelators EGTA and BAPTA-AM. Furthermore, ERK1/2 activation in both transiently and stably AKHR-expressing HEK293 cells was found to be sensitive to pretreatment of pertussis toxin, whereas AKHR-mediated ERK1/2 activation was insensitive to siRNA-induced knockdown of β-arrestins and to pretreatment of inhibitors of EGFR, Src, and PI3K. On the basis of our data, we propose that activated AKHR signals to ERK1/2 primarily via PKA- and calcium-involved PKC-dependent pathways. Our current study provides the first in-depth study defining the mechanisms of AKH-mediated ERK activation through the Bombyx AKHR.