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Adaptor protein is essential for insect cytokine signaling in hemocytes

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Title: Adaptor protein is essential for insect cytokine signaling in hemocytes
Authors: Oda, Yasunori Browse this author
Matsumoto, Hitoshi Browse this author
Kurakake, Maiko Browse this author
Ochiai, Masanori Browse this author →KAKEN DB
Ohnishi, Atsushi Browse this author
Hayakawa, Yoichi Browse this author
Keywords: growth-blocking peptide
tyrosine phosphorylation
SH2/SH3 domain binding
Issue Date: 7-Sep-2010
Publisher: National Academy of Sciences
Journal Title: Proceedings of the National Academy of Sciences of the United States of America
Volume: 107
Issue: 36
Start Page: 15862
End Page: 15867
Publisher DOI: 10.1073/pnas.1003785107
Abstract: Growth-blocking peptide (GBP) is an insect cytokine that stimulates a class of immune cells called plasmatocytes to adhere to each other and foreign surfaces. Although structure-activity studies have been extensively performed on the GBP and its mutants in Lepidoptera Pseudaletia separata, the signaling pathway of GBP-dependent activation of plasmatocytes remains unknown. We identified a novel adaptor protein (P77) with a molecular mass of 77 kDa containing SH2/SH3 domain binding motifs and an immunoreceptor tyrosine-based activation motif (ITAM)-like domain in the cytoplasmic region of the C-terminus. Although P77 did not show the capacity for direct binding with GBP, its cytoplasmic tyrosine residues were specifically phosphorylated within seconds after addition of GBP to a plasmatocyte suspension. Tyrosine phosphorylation of P77 was also observed when hemocytes were incubated with Enterobactor cloacae or Micrococcus luteus, but this phosphorylation was found to be induced by GBP released from hemocytes stimulated by the pathogens. We further detected tyrosine phosphorylation of the integrin β subunit in plasmatocytes stimulated by GBP. Double-stranded RNAs targeting P77 not only decreased GBP-dependent tyrosine phosphorylation of the integrin β subunit, but also abolished GBP-induced spreading of plasmatocytes on foreign surfaces. P77 RNAi larvae also showed significantly higher mortality than control larvae following infection with Serratia marcescens, thus indicating that P77 is essential for GBP to mediate a normal innate cellular immunity in insects. These results demonstrated that GBP signaling in plasmatocytes requires the adaptor protein P77 and that active P77-assisted tyrosine phosphorylation of integrins is critical for the activation of plasmatocytes.
Type: article (author version)
Appears in Collections:低温科学研究所 (Institute of Low Temperature Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 落合 正則

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