Identification of Tyrosine Kinase Src Responsible for Antimicrobial Peptides Production in Bombyx mori

Src is a non-receptor protein tyrosine kinase ubiquitously expressed in animals. It is involved in various cellular processes, including the innate immune response in mammals. However, less is known about the function of insect Src. Here we presented a homologue of Src in silkworm (Bombyx mori), named as BmSrc by phylogenetic analysis, homologous comparison and domain prediction. BmSrc contains the conserved phosphorylation residues and possesses tyrosine kinase activity. The expression pattern of BmSrc mRNA was specific in developmental stages and tissues. The highest expression of BmSrc was detected in moth stage, and the gonads showed the highest expression during larval stage. We then found over-expression of BmSrc in BmE cell resulted in an increase of p38 mitogen-activated protein kinase (p38 MAPK) and Akt phosphorylation but a decrease in extracellular signal–regulated kinase (ERK) phosphorylation. Finally, we demonstrated that BmSrc promoted the production of antimicrobial peptides (AMPs). These results implied that BmSrc is involved in immune response of silkworm possibly through activating p38 MAPK and Akt signaling pathway. Our study may provide reference for further investigation of the biological function of BmSrc in Bombyx mori.