Transcription profiling of Drosophila imaginal disc cell line Cl.8+ stimulated with imaginal disc growth factor 2 (IDGF2)

Drosophila imaginal disc growth factors (IDGFs) comprise a small protein family of six members belonging to chitinase-like proteins (CLPs), which bind to, but do not cleave chitin or similar carbohydrates. IDGF2 is the prototypical member with known structure and reported to induce the proliferation of imaginal disc cells Cl.8+ in vitro. We characterized the effects of recombinant IDGF2 on tissue culture cells in vitro. We show that it is involved in cell protection from serum deprivation, as well as from the toxic effects of some xenobiotics and metabolites, when the cells are cultivated in serum-free medium conditions. Our results revealed that IDGF2 does not activate insulin pathway. Microarray-based gene expression analysis identified several IDGF2-dependent genes, including genes implicated in innate immune response, Wnt signaling and genes involved in the response to xenobiotics. Consistently, we observed that IDGF2 can be induced in vivo by aseptic or septic injury and high concentration of IDGF2 was detected in garland and pericardial nephrocytes. Our results suggest that IDGF2 is an important and abundant component of Drosophila hemolymph, which shows cytoprotective effects on insect cells in vitro and works as a modulator of multiple signaling pathways involved in morphogenesis, homeostasis and activation of innate immune response.

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