Agonist-mediated activation of Bombyx mori diapause hormone receptor signals to extracellular signal-regulated kinases 1 and 2 through Gq-PLC-PKC-dependent cascade.
Diapause is a developmental strategy adopted by insects to survive in challenging environments such as the low temperatures of a winter. This unique process is regulated by diapause hormone (DH), which is a neuropeptide hormone that induces egg diapause in Bombyx mori and is involved in terminating pupal diapause in heliothis moths. An G protein-coupled receptor from the silkworm, B. mori, has been identified as a specific cell surface receptor for DH. However, the detailed information on the DH-DHR system and its mechanism(s) involved in the induction of embryonic diapause remains unknown. Here, we combined functional assays with various specific inhibitors to elucidate the DHR-mediated signaling pathways. Upon activation by DH, B. mori DHR is coupled to the Gq protein, leading to a significant increase of intracellular Ca(2+) and cAMP response element-driven luciferase activity in an UBO-QIC, a specific Gq inhibitor, sensitive manner. B. mori DHR elicited ERK1/2 phosphorylation in a dose- and time-dependent manner in response to DH. This effect was almost completely inhibited by co-incubation with UBO-QIC and was also significantly suppressed by PLC inhibitor U73122, PKC inhibitors Gö6983 and the Ca(2+) chelator EGTA. Moreover, DHR-induced activation of ERK1/2 was significantly attenuated by treatment with the Gβγ specific inhibitors gallein and M119K and the PI3K specific inhibitor Wortmannin, but not by the Src specific inhibitor PP2. Our data also demonstrates that the EGFR-transactivation pathway is not involved in the DHR-mediated ERK1/2 phosphorylation. Future efforts are needed to clarify the role of the ERK1/2 signaling pathway in the DH-mediated induction of B. mori embryonic diapause.
Department of Economic Zoology, College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China.
Xue
X
Jiang
National Engineering Research Center of Marine Facilities Aquaculture, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, China.
Jingwen
J
Yang
Department of Economic Zoology, College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China.
Zhangfei
Z
Shen
Department of Economic Zoology, College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China.
Yajie
Y
Chen
Department of Economic Zoology, College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China.
Liangen
L
Shi
Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China. Electronic address: znm2000@yahoo.com.
Naiming
N
Zhou
D000818:Animals; D012831:Bombyx / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D007814:Larva / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D008675:Metamorphosis, Biological; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics* / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics* / Q000378:metabolism; D009479:Neuropeptides / Q000378:metabolism*; D011679:Pupa / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics* / Q000378:metabolism; D061987:Sf9 Cells; D015398:Signal Transduction; D018411:Spodoptera
D019476:Insect Proteins; D009479:Neuropeptides; D018160:Receptors, Cytoplasmic and Nuclear; C075027:diapause hormone; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3
Diapause; Extracellular signal-regulated kinase; G protein-coupled receptor; Neuropeptide; Phosphorylation; Protein kinase C; Signaling