Identification and functional analysis of seminal proteins governing male fertility of the silkworm, Bombyx mori.

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K06072
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 39050:Insect science-related
• Research Institution: Kyoto Institute of Technology
• Principal Investigator: Nagaoka Sumiharu 京都工芸繊維大学, 応用生物学系, 准教授 (00303933)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 蚕糸昆虫利用学 / 昆虫生理生化学 / 精子成熟 / 精漿タンパク質 / オス妊性 / 次世代シークエンス / ノックアウト系統 / カイコガ

Outline of Final Research Achievements

A database of expressed genes in the male reproductive organs of the silkworm, Bombyx mori, was constructed by long-read RNA-seq analysis. Many unidentified genes, genes with unknown functions, and splicing variants were found. Among them, long noncoding RNAs, novel serine proteases and inhibitors, and novel substrate proteins for trypsin-like proteases known to induce sperm maturation were identified. The proteins that change with sperm maturation were identified by separation and analysis using two-dimensional electrophoresis. The complete amino acid sequences were clarified using the constructed database, and the possibility that these proteins are substrates for trypsin-like protease, initiatorin was suggested. Next, knockout lines of the genes corresponding to these sperm proteins were generated by genome editing (TALEN). One of these lines resulted in complete male infertility caused by inadequate sperm movement in the female during sperm maturation.

Free Research Field

昆虫科学関連

Academic Significance and Societal Importance of the Research Achievements

カイコガ精漿を構成するタンパク質を網羅的に解析することが可能なデータベースが構築された。精子成熟時に変化するタンパク質を調査して，これらも構築したデータベースを利用して解析することで，有用性を確認すると共に，実際にカイコガ精子成熟誘発因子であるイニシャトリンの基質を見出して，これらはメス体内での精子移動に関与していて，これらのタンパク質の不全はオスに起因する不妊をもたらすものが存在することを明らかとした。総じて，体内受精型動物の精液タンパク質機能解析を進める研究基盤が構築でき，同時にその生理的機能の一端が明らかとなり，生殖補助やペストコントロールへの新規応用技術開発へと繋がるものと期待される。