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Insect cytokine growth‐blocking peptide signaling cascades regulate two separate groups of target genes
Author(s) -
Ninomiya Yosuke,
Kurakake Maiko,
Oda Yasunori,
Tsuzuki Seiji,
Hayakawa Yoichi
Publication year - 2008
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2008.06252.x
Subject(s) - blocking (statistics) , peptide , gene , microbiology and biotechnology , cytokine , signal transduction , suppressor of cytokine signaling 1 , chemistry , biology , genetics , biochemistry , suppressor , computer science , computer network
Growth‐blocking peptide (GBP) is a 25 amino acid insect cytokine found in lepidopteran insects that has diverse biological activities, such as larval growth regulation, paralysis induction, cell proliferation, and stimulation of immune cells. GBP also enhances expression of the tyrosine hydroxylase (TH, EC 1.14.16.2) and 3,4‐dihydroxy‐ l ‐phenylalanine (Dopa) decarboxylase (DDC, EC 4.1.1.26) genes, which elevate dopamine levels in insect epidermal cells. We used insect epidermis and cultured cells to define the role of the GBP signaling pathway in the enhancement of TH and DDC gene expression. It has been recently reported that robust expression of the DDC gene requires activation of extracellular signal‐regulated kinase (ERK) in epidermal cells of wounded Drosophila embryos. This study confirmed that GBP activates ERK, but this activation is not directly linked to the enhancement of TH and DDC gene expression. One of the GBP pathway components is phospholipase C, whose activation is essential for the activation of ERK and elevation of expression of both enzyme genes. The downstream signaling pathways diverge to ERK activation through activated protein kinase C and expression of the enzyme genes through inositol triphosphate receptor‐mediated Ca 2+ influx from extracellular fluid. Our data indicate that the diverged GBP signaling pathways enable GBP to exert completely different biological functions, even in a single cell type.