Functional analysis of sex-determination genes by gene silencing with LNA–DNA gapmers in the silkworm, Bombyx mori. (August 2015)

• Record Type: Journal Article
• Authors: Sakai, Hiroki; Sakaguchi, Honami; Aoki, Fugaku; Suzuki, Masataka G.
• Is Part Of: Mechanisms of development. Volume 137(2015)
• Page Start: 45
• Page End: 52
• Publication Date: 2015-08
• Subjects: Sex determination -- Fem -- Masc -- Imp -- Bmdsx -- Bombyx mori; Developmental biology -- Periodicals; Molecular biology -- Periodicals; Developmental Biology -- Periodicals; Molecular Biology -- Periodicals; Biologie du développement -- Périodiques; Biologie moléculaire -- Périodiques; Developmental biology; Molecular biology; Periodicals; Electronic journals; 571.8
• DOI: 10.1016/j.mod.2015.03.002
• Languages: English
• ISSNs: 0925-4773

Abstract

Highlights: The anti-sense LNA–DNA gapmers efficiently knockdown Fem and Imp M expressions. Masc knockdown dramatically reduces Imp M expression in male embryos. We herein propose a possible genetic cascade regulating sex determination in B . mori. Graphical Abstract: Abstract: The sexual fate of B. mori is determined genetically; ZW, female and ZZ, male. Recently, we successfully identified a strong candidate gene at the top of the sex determination cascade in B. mori . This gene was termed Feminizer ( Fem ) and revealed to be a source of Fem -piRNA. Further, we found that B. mori doublesex ( Bmdsx ) splicing was markedly altered to produce the male-type isoform when a Fem -piRNA inhibitor was injected into ZW embryos. Moreover, knockdown of Masculinizer ( Masc ), a Fem -piRNA target gene, altered to produce the female-type isoform of Bmdsx in male embryos. However, it remains unclear as to whether Masc directly regulates the sex-specific expression of Bmdsx . In previous studies, we determined that the male-specific isoform of the Bombyx homolog of IGF-II mRNA-binding protein ( Imp M ) was involved in the male-specific splicing of Bmdsx . In an attempt to clarify the genetic relationship between Fem, Masc, Imp M, and Bmdsx, knockdown experiments were performed. Knockdown of Fem shifted into male-type Bmdsx, Imp M and Masc in female embryos. Knockdown of Masc led to the production of the female-type Bmdsx and a dramatic reduction in Imp M expression in male embryos. Knockdown of Imp M shifted Bmdsx splice mode from the male-type into the female-type. Our results suggest that: (1) Fem reduces Masc expression, (2) Masc dramatically induces Imp M expression, and (3) Imp M shifting Bmdsx splice mode from the female-type into the male-type. Based on these findings, we propose a possible genetic cascade regulating sex determination in B. mori.