Enhancer activity of Helitron in sericin‐1 gene promoter from Bombyx mori

• Published in: Insect science Vol. 23; no. 3; pp. 396 - 405
• Main Authors: Huang, Ke, Li, Chun-Feng, Wu, Jie, Wei, Jun-Hong, Zou, Yong, Han, Min-Jin, Zhou, Ze-Yang
• Format: Journal Article
• Language: English
• Published: Australia John Wiley & Sons, Ltd 01.06.2016; Blackwell Publishing Ltd; Wiley Subscription Services, Inc
• Subjects: Animals; Animals, Genetically Modified; Bmhel-8; Bombyx - genetics; Bombyx mandarina; Bombyx mori; Cell Line; DNA Transposable Elements; enhancer; Gene expression; Insect Proteins - genetics; Polymorphism, Genetic; promoter; Promoter Regions, Genetic; regulation; sericin-1; Sericins - genetics; enhancer; promoter; Bmhel-8; regulation; sericin-1
• ISSN: 1672-9609; 1744-7917
• DOI: 10.1111/1744-7917.12347

Sericin is a kind of water‐soluble protein expressed specifically in the middle silk gland of Bombyx mori. When the sericin‐1 gene promoter was cloned and a transgenic vector was constructed to express a foreign protein, a specific Helitron, Bmhel‐8, was identified in the sericin‐1 gene promoter sequence in some genotypes of Bombyx mori and Bombyx mandarina. Given that the Bmhel‐8 Helitron transposon was present only in some genotypes, it could be the source of allelic variation in the sericin‐1 promoter. The length of the sericin‐1 promoter sequence is approximately 1063 or 643 bp. The larger size of the sequence or allele is ascribed to the presence of Bmhel‐8. Silkworm genotypes can be homozygous for either the shorter or larger promoter sequence or heterozygous, containing both alleles. Bmhel‐8 in the sericin‐1 promoter exhibits enhancer activity, as demonstrated by a dual‐luciferase reporter system in BmE cell lines. Furthermore, Bmhel‐8 displays enhancer activity in a sericin‐1 promoter‐driven gene expression system but does not regulate the tissue‐specific expression of sericin‐1.