Functional analysis of sex differentiation by Piwi-piRNA system expressed in germ cells

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K15152
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Morphology/Structure
• Research Institution: Osaka Medical College
• Principal Investigator: Yamamoto Yasuhiro 大阪医科大学, 医学部, 講師 (20613558)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 性分化 / PIWI-piRNA

Outline of Final Research Achievements

To understand the role of PIWI-piRNA system in medaka sex differentiation, we analyzed the PIWI mutant medaka and whole genome analysis of small RNAs. Some Piwil1 mutants showed no secondary sex characteristics and predominantly low sex hormone levels. The number of ftz-f1 positive cells was decreased in the gonads of Piwil1 mutants, and expression of sexual differentiation-related genes was not confirmed in the gonads of Piwil1 mutants. In NGS analysis of small RNAs in gametes, we identified a candidate genes of Piwil1 target whose expression was elevated only in germ cells of the Piwil1 mutant. From these results, it was expected that the Piwil1 mutant could not suppress the expression of the target genes, leading to the failure of sexual differentiation in the gonad.

Free Research Field

性分化

Academic Significance and Societal Importance of the Research Achievements

カイコや柿ではPiwi-piRNAによる性分化制御機構が明らかになっている。魚類やほ乳類においてもPIWIの変異体の表現型解析から、性分化におけるPiwi-piRNAの役割が示唆されてきた。本研究により、生殖細胞で特異的に発現するpiRNAが生殖腺体細胞のステロイド産生を制御しており、個体の二次性徴に関わることを示した。本研究は「piRNAが標的遺伝子の発現制御を介して、性ホルモンを調節する」全く新しい知見と考えられる。