CDNA Cloning And Gene Expression Of Integrin β Subunits From Bombyx Mori

The integrin is a superfamily of transmembrane protein which were composed ofαandβsubunits.In mammalian,integrins triggers a large variety of signal transduction events such as adhesion,proliferation,survival or apoptosis,shape,polarity,motility, haptotaxis,gene expression,and differentiation.The integrin also play a very important role in the insects encapsulation-one kind of cell-mediated immunity.The integrin is a huge gene family in mammalian.At least 18αand 8βsubunits were known in human.But the study of insect integrin is relatively less.In the Hymenoptera insects Drosophilia melanogaster and Anopheles gambiae they only found two differentβsubunits,Integrinαandβsubunits gene family were so huge,but theβsubunits of the Lepidoptera were simply researched.We use silkworm as a material,identify theβsubunits from its genome and carried out our research in the following areas1.Identification of integrinβsubunits:Using bioinformatics methods,we identified two integrinβsubtmits in the silkworm genome.Complete integrinβsubunits cDNA sequence of Bombyx mori was obtained through RT-PCR,Theβ1 subunit cDNA was 2670bp in length and encoded 833 amino acid residues.Theβ2 subunit cDNA was 2314bp in length and encoded 747 amino acid residues.These cDNA shared the typical structural features of integrinβsubunits with other insects,such as I-like domain,the NPxY motifs and four cysteine-rich repeats.2.Construction of integrinβsubunit phylogenetic tree.The results showed that integrinβsubunit of insects is divided into two main clusters,the twoβsubunits of silkworm are also within the two cluster just as the Drosophila melanogaster and Anopheles gambiae.In addition,in view of there being only twoβsubunits in these three insects,we speculate that there is a relatively small number of integrinβsubunit in insects.3.Transcription of integrinβsubunits in Bombyx rnori:We investigatedβsubunits transcription proflie in seven tissues of 5th larva of Bombyx mori using RT-PCR.The results showed that Theβ1 mRNA was expressed in epidermis,fatbody,head,malpighian tube and hemolymph.It had a highest transcription level in the head and a lowest level in the epidermis.Theβ2 mRNA was expressed in epidermis,head and hemolymph.It had a lowest transcription level in the head.4.Effects of encapsulation of gel-beads on the transcription ofβsubunits:We studied imegrinβsubunits transcription of Bombyx mori injected with gel-beads using real-time fluorescent quantitative PCR.The results showed that the transcription of these two subunits showed increase in the 24 hour after injecton.There is no significant change in the 2,6,12 huors after injecton.In conclusion,we cloned the full-length cDNA sequence of integrinβsubunits of Bombyx mori and investigated there expression profile after the insects being injected with gel-beads.All these works enriched the study of the integrinβsubunits of Lepidoptera and provided the basis material for the relationship of integrin and insects cell-mediated immunity.