Identification and characterization of three novel hemocyte-specific promoters in silkworm Bombyx mori

Insect hemocytes play essential roles in the metabolism, metamorphosis and immunity, which are closely related events of growth and development. Here, four novel hemocyte-specific genes were obtained and conformed in our study, namely, Bmintβ2, Bmintβ3, BmCatO, and BmSw04862, respectively. Subsequently, their promoter sequences were cloned, and their activity in hemocytes, fat body, and silk gland were analyzed using recombinant AcNPV vector system in vivo. Our results showed that Bmintβ2, Bmintβ3, and BmCatO were hemocyte-specific promoters in the silkworm, Bombyx mori. Interestingly, Bmintβ2, and Bmintβ3 promoter regions were both located in their first intron. Further analysis of a series of BmCatO promoter truncations showed that a 254 bp region could function as a promoter element in the tissue-specificity expression. In summary, the results of this study revealed that we have identified three hemocyte-specific promoters in silkworm that will not only great significance for better understanding of hemocyte-specific gene, but also has potential applications in insect hematopoiesis and innate immunity research.