Biology subjects

Tate, S.-i.

Publications and source records attributed to Tate, S.-i..

4 recordsLinked to original sources

bioRxiv2026

hnRNPA2B1 Modulates Early TIA1 Recruitment into Stress Granules through an RNA-Dependent Assembly Mechanism

Stress granules (SGs) are dynamic, membrane-less assemblies that form in the cytoplasm in response to cellular stress. The ordered recruitment of proteins into SGs is fundamental to condensate composition and function, yet the molecular determinants of this ordered client recruitment remain incompletely understood. Using proximity photo-crosslinking proteomics, we identified heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1) as a TIA1-proximal protein preferentially enriched in SGs under arsenite stress. Knockdown of hnRNPA2B1 preferentially delayed TIA1 enrichment in G3BP1-marked SGs at 20 min without affecting G3BP1 or the overall SG-positive cell fraction, and this phenotype showed directional rescue upon re-expression. In vitro droplet reconstitution assays with purified proteins revealed that hnRNPA2B1 and RNA cooperatively increased TIA1 incorporation capacity into G3BP1 condensates, an effect not attributable to changes in droplet size. Kinetic fitting identified hnRNPA2B1 + RNA as uniquely increasing the plateau amplitude of TIA1 recruitment (Cohens d = 1.62 versus RNA-alone condition). Coarse-grained simulations support an inside-out assembly model in which hnRNPA2B1 stabilizes the condensate core through homotypic interactions while RNA-bound TIA1 accumulates at the periphery. Together, these findings identify hnRNPA2B1 as a capacity-determining modulator of early TIA1 recruitment and provide a framework for understanding ordered protein assembly within stress granules.

cell biology↗

bioRxiv2025

ISRIB promotes aggregation of TIA-1 by modulating its phase separation in vitro

Stress granules (SGs) are non-membranous biomolecular condensates formed through liquid-liquid phase separation (LLPS) of RNA-binding proteins (RBPs) and RNA under stress conditions. T-cell intracellular antigen-1 (TIA-1), a major RBP of SGs, can undergo LLPS via its low-complexity domain, contributing to SG nucleation. Integrated stress response inhibitor (ISRIB), a small molecule that enhances eIF2B activity and inhibits the integrated stress response, has been widely studied for its therapeutic potential in neurodegenerative diseases. However, little is known about how ISRIB directly affects the behavior of SG proteins. Here, we show that ISRIB enhances TIA-1 phase separation and promotes its aggregation in vitro. Interestingly, this effect was mitigated in the presence of RNA or cell lysates, suggesting that RNA-binding plays a protective role against ISRIB-induced aggregation. These findings imply that ISRIB alters the physical properties of SG in an RNA-dependent manner, raising important considerations for their therapeutic application. Graphic abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=56 SRC="FIGDIR/small/663586v1_ufig1.gif" ALT="Figure 1"> View larger version (14K): org.highwire.dtl.DTLVardef@7e281org.highwire.dtl.DTLVardef@1a7863eorg.highwire.dtl.DTLVardef@15e89b6org.highwire.dtl.DTLVardef@1a33ca4_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2021

Valosin-containing protein regulates the stability of amyotrophic lateral sclerosis-causing fused in sarcoma granules in cells by changing ATP concentrations inside the granules

Fused in sarcoma (FUS) undergoes liquid-liquid phase separation (LLPS) to form granules in cells, leading to pathogenic aggregations that cause neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). Proteomics analysis revealed that FUS granules contain valosin-containing protein (VCP), a member of the AAA family ATPase. Confocal microscopy images showed that VCP co-localized in the FUS granules in cells. This study demonstrates that VCP in granules has a two-faced role in FUS granulation: VCP stabilizes de novo FUS granules, while VCP present in the granules for extended periods dissolves them. This VCP function relies on its ATPase activity to consume ATP in granules. VCP stabilizes de novo FUS by reducing intragranular ATP concentrations to a range below the cytosolic concentration. VCP continually consumes ATP during its stay in the granules, which eventually lowers ATP concentrations to a range that destabilizes the granules. VCP, therefore, acts as a timer to limit the residence of FUS granules in cells and thereby prohibits the FUS fibrillization that occurs in persistent granules. VCP ATPase activity plays a role in FUS granule turnover. Summary statementVCP recruited to FUS granules regulates the stability of the granules in a time-dependent manner by consuming intragranular ATP with its ATPase activity.

cell 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↗