The Expression Profiles And Immune Functional Analysis Of QM Gene In Silkworm,Bombyx Mori

QM is a tumor suppressor,widely existed in a variety of organisms,and a multifunctional protein,which is involved in basic life activities such as cell growth,differentiation,development and apoptosis,but its immunomodulation in insects is very little known.Bombyx mori is a kind of economic insect,which depends entirely on artificial breeding.The study of the innate immune defense mechanism of BmQM in silkworm is of great significance to enhance the resistance of silkworm.In this study,the expression profiles of BmQM in silkworm and its biological function were studied.The main results are as follows:1.The recombinant BmQM protein was successfully expressed in Escherichia coli,and the rabbit polyclonal antibody was prepared.2.The transcription and protein expression levels of BmQM in the midgut,fat body,silk gland,epidermis,Malpighian tube and hemocytes were examined.The results showed that BmQM was expressed in the five tissues,and the expression levels in silk gland and fat body were higher.In the spatiotemporal expression analysis,it was found that the expression of BmQM in the larval stage was significantly higher than that in the adult stage and the egg stage.3.The expression patterns of BmQM in fat bodies and hemocytes were detected by immunostimulation of fifth instar larvae of four different kinds of pathogenic microorganisms.The results showed that BmQM was up-regulated at both mRNA and protein levels after immunostimulation and the degree of up-regulation varied according to the species of different pathogenic microorganisms,indicating that BmQM plays an important role in the immune response of silkworm.4.After RNA interference of BmQM,the expression of other immune genes Moricin,PGRPS6,GloverinO was significantly decreased,and the expression of proPO1 and proP02 was significantly increased.However,the transcription level of Lysozyme did not change significantly.This indicates that the BmQM gene was interfered with and has a certain influence on the expression of other immune genes.5.After RNA interference,E.coli was injected to detect the activity of PO in the hemolymph of B.mori.The results showed that the activity of PO in the hemolymph of B.mori was decreased after BmQM was interfered.6.Purified recombinant BmQM protein was used to detect the hemolymph proPO act-ivation and PO activity in B.mori.The results indicate that BmQM protein can inhibit the activation of hemolymph proPO,but no effect on PO activity.7.The recombinant BmQM protein was injected into the B.mori in 30 min before the injection of M.luteus.The results showed that the recombinant BmQM protein could significantly inhibit the systemic melanization caused by Micrococcus luteus.8.Far-western Blot was carried out to investigate the interaction between BmQM and BmJun.The results indicate that the BmQM protein associates with BmJun directly.In conclusion,BmQM protein plays an important role in innate immunity of silkworm,which deepened our understanding of the mechanism of tumor suppressor QM in insect immunity.