Biology subjects

Kinugasa, Y.

Publications and source records attributed to Kinugasa, Y..

3 recordsLinked to original sources

bioRxiv2025

Ultra-parallel ribosome profiling platform with RNA-dependent RNA amplification

Translation regulation plays a pivotal role in the diversification of gene expression and the response to intra- and extracellular environmental cues. Ribosome profiling (or Ribo-Seq) serves as a sensitive, quantitative, comprehensive, and data-rich technique to survey ribosome traversal across the cellular transcriptome. However, due to the intricacy of library preparation, applications to low-input and a large number of samples have presented analytic challenges. Here, we developed the semi-automated platform of Ribo-Seq and Disome-Seq, which allowed us to assess the translation status from a vast collection of samples with reduced amounts in a plate format. Through an siRNA-mediated knockdown screen for ribosome-associated proteins, this technique identified factors that (i) mediate regulation via RNA elements such as the TOP motif, (ii) assist efficient ribosome recycling, (iii) support ribosome-associated quality control (RQC), (iv) enhance translation elongation across inhibitory G-quadruplex sequences, and (v) repress mitochondrial translation. The application to human-derived samples revealed that stop codon readthrough and mitochondrial translation deficiency are associated with severe symptoms in COVID-19. Our approach provides a versatile option to investigate the translatome in a highly parallel manner.

molecular biology↗

bioRxiv2021

Distinctive nuclear zone for RAD51-mediated homologous recombinational DNA repair

Genome-based functions are inseparable from the dynamic higher-order architecture of the cell nucleus. In this context, the repair of DNA damage is coordinated by precise spatiotemporal controls that target and regulate the repair machinery required to maintain genome integrity. However, the mechanisms that pair damaged DNA with intact template for repair by homologous recombination (HR) without illegitimate recombination remain unclear. This report highlights the intimate relationship between nuclear architecture and HR in mammalian cells. RAD51, the key recombinase of HR, forms spherical foci in S/G2 phases spontaneously. Using super-resolution microscopy, we show that following induction of DNA double-strand breaks RAD51 foci at damaged sites elongate to bridge between intact and damaged sister chromatids; this assembly occurs within bundle-shaped distinctive nuclear zones, requires interactions of RAD51 with various factors, and precedes ATP-dependent events involved the recombination of intact and damaged DNA. We observed a time-dependent transfer of single-stranded DNA overhangs, generated during HR, into such zones. Our observations suggest that RAD51-mediated homologous pairing during HR takes place within the distinctive nuclear zones to execute appropriate recombination.

cell biology↗

bioRxiv2021

The inner nuclear membrane protein Lem2 coordinates RNA degradation at the nuclear periphery

Transcriptionally silent chromatin often localizes to the nuclear periphery. However, whether the nuclear envelope (NE) is a site for post-transcriptional gene repression is unknown. Here we demonstrate that S. pombe Lem2, an NE protein, regulates nuclear exosome-mediated RNA degradation. Lem2 deletion causes accumulation of non-coding RNAs and meiotic transcripts. Indeed, an engineered exosome substrate RNA shows Lem2-dependent localization to the nuclear periphery. Lem2 does not directly bind RNA, but instead physically interacts with the exosome-targeting MTREC complex and promotes RNA recruitment. The Lem2-assisted pathway acts independently of nuclear bodies where exosome factors assemble, revealing that multiple spatially distinct degradation pathways exist. The Lem2 pathway is environmentally responsive: nutrient availability modulates Lem2 regulation of meiotic transcripts. Our data indicate that Lem2 recruits exosome co-factors to the nuclear periphery to coordinate RNA surveillance and regulates transcripts during the mitosis-to-meiosis switch.

molecular biology↗