带有丝素重链信号肽序列的家蚕丝胶蛋白启动子驱动DsRed的瞬时分泌表达

为了探讨家蚕Bombyx mori丝素蛋白重链信号肽序列在中部丝腺组织中是否具有功能活性，根据家蚕丝蛋白基因的启动子活性高、丝蛋白具有高效分泌的特性，构建了带有丝素重链基因fib-H信号肽的家蚕丝胶-1(ser-1)启动子(ser-HS)，用ser-HS驱动DsRed基因构建了分泌型瞬时表达载体pSK-SerHS-DsRed-polyA。转染细胞实验显示，该载体能在家蚕BmN细胞中瞬时表达DsRed。家蚕注射载体后，可在中部丝腺腔中检测到红色荧光，表明瞬时表达的DsRed已分泌到丝腺腔内。据此提出克隆的fib-H信号肽序列在家蚕中部丝腺组织中具有信号肽的功能。

Transiently secretory expression of DsRed driven by sericin promoter with the signal peptide sequence of fibroin H chain of Bombyx mori

To verify whether the signal peptide sequence of fibroin H chain (fib-H) functionally possesses the activity in the middle silk gland, based on the characteristics of the strong promoter of the silk protein gene and the high level secretion of silk protein of the silkworm, Bombyx mori, we constructed the promoter ser-HS of sericin-1 gene (ser-1) with the signal peptide sequence of fib-H. Then, we constructed the transitorily secretory expression vector pSK-serHS-DsRed-polyA via driving the DsRed gene with the promoter ser-HS. We transfected pSK-serHS-DsRed-polyA into BmN cells by liposome. From the cells transfected with the vector, the red fluorescence could be detected, which verified that the expression vector could express DsRed in BmN cells transiently. Furthermore, when silkworm had been injected with the expression vector pSK-serHS-DsRed-polyA, red fluorescence could be observed in the lumen of the middle silk gland of silkworm. The results indicated that DsRed was expressed transiently and was secreted into the lumen of the middle silk gland. We concluded that the cloned signal peptide sequence of fib-H possesses the biological functions of the signal peptide in the middle silk gland.