FBS Colloquia No.343Germline Biology Group
| Seminar or Lecture |
A Pathway to Produce Non-coding piRNAs from Endogenous Protein-coding Regions Ensures Drosophila Spermatogenesis Taichiro Iki [Associate Prof., Germline Biology Group] In silico screening of protein-protein interactions using AlphaFold2 Shinichi Kawaguchi [Assistant Prof., Germline Biology Group] |
|---|---|
| Date and Time | 21 Nov. 2023 (Tue), 12:15～13:00 |
| Place | 2F Seminar Room, BioSystems Building |
| Language | English |
| Contact |
Shinichi Kawaguchi (Assistant Professor) |
A Pathway to Produce Non-coding piRNAs from Endogenous Protein-coding Regions Ensures Drosophila Spermatogenesis
PIWI-interacting (pi)RNA pathways play important roles in animal gamete formation. However, the underlying piRNA biogenesis mechanisms remain elusive. Here, we show endogenous protein-coding sequences (CDSs), that are normally used for translation, serve as origins of non-coding piRNA biogenesis in Drosophila melanogaster testes. The product, namely CDS-piRNAs, formed silencing complexes with Aubergine (Aub) in germ cells. We provide evidence that short interfering (si)RNAs and micro(mi)RNAs specify precursors to be processed into CDS-piRNAs. We further demonstrate that Aub is crucial in spermatid differentiation, regulating chromatins through mRNA cleavage. Collectively, our data illustrate a unique strategy employed by male germline, expanding piRNA repertoire for silencing of endogenous genes during spermatogenesis.
In silico screening of protein-protein interactions using AlphaFold2
With the advent of the AlphaFold2 program, it is now possible to predict the three-dimensional structure of a protein from its amino acid sequence with considerable accuracy. Furthermore, it has been suggested that AlphaFold2 can be applied to the prediction of protein-protein complexes. With the improvement of protein detection technology, protein-protein interactions have been analyzed on a large scale, and "big data" containing many candidate binding proteins have been accumulated. However, experimental verification of individual interactions requires a great deal of effort and has become a bottleneck in the advancement of research. Therefore, in silico screening is expected to predict protein complexes using the AlphaFold2 program. I applied complex prediction by AlphaFold2 to "Nuage," a non-membrane organelle in germ cells, to search for novel protein-binding pairs. The nuage is a site for the production of piRNAs, a type of small RNA. piRNAs repress transposon expression and contribute to genome stabilization. Many proteins have been reported to localize to the nuage and participate in the production of piRNAs, but it is still unclear how they work together. To elucidate the molecular mechanisms of nuage, I used the AlphaFold2 program to predict binding between 20 different piRNA-related proteins. In addition to protein pairs with reported binding, some protein pairs with no known direct interaction were found to have high prediction scores. Candidate protein pairs were expressed in cultured cells to find novel binding pairs. It is expected that computational screening can be used to rapidly identify novel binding candidates.
