Graduate School of Frontier Biosciences, Osaka University

Japanese

Colloquium 225

Speaker Lin Yuxuan (Doctoral student D4/D5 / Germline Biology Group (Kai Lab.))
Title Function of Tejas & Spindle-E in piRNA biogenesis pathway of Drosophila
Speaker Taichiro Iki (Assistant Prof. / Laboratory of Germline Biology, FBS)
Title Gene Silencing Regulator Cyclophilin 40 Plays Essential Roles during Sperm Maturation in Drosophila
Date Thu., Oct. 10, 2019, 12:15~13:00
Place 2F Seminar room, BioSystems Building
Host Name:Shinichi Kawaguchi        
Tel :7974
E-mail:shinkawa@fbs.osaka-u.ac.jp
Language English










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Title/Abstract

Function of Tejas & Spindle-E in piRNA biogenesis pathway of Drosophila

Unique small RNA piRNAs safeguard the germline genome, ensuring fitness of the offspring by repressing the transposons. In somatic gonadal cells and germline cells, the piRNA precursor transcripts produced from piRNA clusters are processed into primary piRNA in the cytoplasm. In addition to this linear pathway operating both in somatic and germline cells, an additional feed-forward piRNA amplification loop called ping-pong cycle takes place on perinuclear foci of germline celles, called nuage, where the key components involved in this secondary processing are localized. Aub and Ago3, two PIWI-family proteins, collaborate with a set of protein components including RNA helicase Vasa and Spindle-E (Tdrd9) and Tudor domain proteins, such as Tudor, Qin/Kumo, Tejas (Tdrd5), Tapas (Tdrd7), Krimp to establish a multistep piRNA biogenesis mechanism. I will talk about the research that focuses on how we try to reveal the unknown function of Tudor domain protein Tejas (Tdrd5) and the Tudor domain-containing Helicase Spindle-E (Tdrd9), which both are set on the upstream of secondary piRNA biogenesis pathway.

Gene Silencing Regulator Cyclophilin 40 Plays Essential Roles during Sperm Maturation in Drosophila

Small non-coding (s)RNAs induce gene silencing by forming effector RNA-induced silencing complexes (RISC) with Argonaute (Ago) family proteins. At the most downstream of sRNA biogenesis, RISC formation is the key step regulating the repertoire of expressing sRNA and determining the silencing poteintial of cells. Past studies proposed the concept shared by eukaryotes that RISC formation relies on the functions of molecular chaperone machineries. However, our understanding is still far from answering how RISC formation is regulated by chaperones in cells and how important the regulation is biologically. The core chaperones including Hsp70 and Hsp90 involved in general protein foldings can be specified in gene silencing pathways by associating unique co-chaperones. To identify and characterize such “silencing cochaperones”, we are performing systemic knockout approarches on different Hsp90 cochaperones. I want to share and discuss our preliminary data suggesting the essential roles of Cyclophilin 40 as regulator of RISC formation during sperm maturation in testes.


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