imaginal disc growth factor mediates melanin synthesis and energy metabolism in bombyx mori

Imaginal disc growth factor (IDGF) belongs to the glycoside hydrolase 18 family, is certified as structural protein to maintain the epithelial apical extracellular matrix scaffold, and plays an important role in various physiological processes such as eclosion, development regulation and sugar metabolism in insects. However, the combined molecular regulation mechanisms of IDGF are poorly understood from the transcriptome and metabolome. In this study, transcriptome analysis was performed using fatbody isolated from staged control and BmIDGF mutant silkworm larvae. Our knockout experiments showed that IDGF is suggested to impact the expression levels of melanin metabolism transcription factors TH and Y-FA to further control melanin synthesis and metabolism. Furthermore, transcriptional profiling revealed that BmIDGF significantly affected several DEGs involved in tyrosine metabolism, purine metabolism, and multiple energy metabolism pathways. More specifically, multiple energy metabolism including glycolysis, galactose metabolism, starch and sucrose metabolism were significantly induced in the BmIDGF mutants. To understand the molecular regulatory mechanisms of IDGF, we constructed a genome-scale metabolic network integrating metabolomic and transcriptomic datasets, revealing that 11 pathways in the fat body are significantly altered at the transcriptional and metabolic levels. Metabolomic and transcriptomic data suggest that the same metabolic pathways are altered, and multi-omics analysis suggests that IDGF is involved in gene-metabolism interactions, reveal the unique role in melanin synthesis and energy metabolism, provide new insights into the understanding of IDGF function, and further deepen our understanding of the molecular mechanisms of melanin synthesis and formation.