Biology subjects

Poulin, G. B.

Publications and source records attributed to Poulin, G. B..

3 recordsLinked to original sources

bioRxiv2025

Eukaryotic translation initiation factor 3d regulates stress granule assembly via its RNA binding domain

Stress granules are cytoplasmic mRNA-protein complexes that form by liquid-liquid phase separation in response to a variety of stresses. Their assembly is contingent upon the inhibition of mRNA translation. Depending on the type of stress and severity, they can promote stress resistance or act to reduce cellular fitness. As such, stress granules are implicated in ageing and a range of related pathologies. Many translation factors are components of stress granules, but it is unclear how they contribute to granule assembly. Here we show that the eIF3d component of the eIF3 translation initiation complex is recruited to stress granules in human cells and is required for stress granule assembly in response to specific stresses. The RNA-binding domain of eIF3d mediates its recruitment to stress granules and deletion of this domain blocks granule formation and decreases cell viability. Furthermore, the exogenous expression of just the eIF3d RNA-binding domain can rescue stress granule assembly in eIF3d-depleted cells. We confirmed the importance of eIF3d for robust stress granule assembly in vivo using the nematode worm C. elegans. This study demonstrates that eIF3d is a critical evolutionary conserved stress granule assembly factor, rather than simply coalescing passively into stress granules following the inhibition of translation initiation.

cell biology↗

bioRxiv2025

Auxin-inducible degradation of UNC-116 in C. elegans inhibits bidirectional dense core vesicle transport and worm locomotion on different timescales

The microtubule motor kinesin-1 is vital in neurons, with mutations being associated with neurological diseases. Deletion of the Caenorhabditis elegans kinesin-1 gene unc-116 is lethal, and viable mutants are uncoordinated. Here, we use auxin-mediated degradation to deplete UNC-116 protein at different developmental stages and monitor the effects on cargo transport and locomotion. UNC-116 is substantially degraded within 1 hour of auxin treatment, by which time bidirectional dense core vesicle (DCV) motility is affected. After 4 hours, dynein-driven DCV movement is lost and only limited plus-end-directed DCV motility remains, likely driven by kinesin-3 (UNC-104). DCV movement recovers substantially after rescue from auxin for 24 hours. There is a time-lag between loss of protein and effects on locomotion, as crawling and swimming/thrashing is unaffected until 6-14 hours on auxin. By 18-24 hours, animals are as uncoordinated as the unc-116(rh24sb79) mutant. Notably, degradation of UNC-116 in neurons alone inhibits crawling and swimming, revealing the importance of neuronal kinesin-1 for locomotion. Overall, by bypassing early developmental UNC-116 functions, we reveal that UNC-116 is essential for bidirectional DCV transport and crucial for locomotion.

cell biology↗

bioRxiv2024

The role of Kinesin-1 in neuronal dense core vesicle transport and lifespan regulation in C. elegans

Fast axonal transport is crucial for neuronal function and is driven by kinesins and cytoplasmic dynein. We investigated the role of the kinesin-1 motor complex in dense core vesicle (DCV) transport in C. elegans, using mutants in kinesin light chains (klc-1 and klc-2) and the kinesin motor subunit (unc-116) expressing an ida-1::gfp transgene that labels DCVs in the ALA neuron. A reduced-function unc-116(rf) mutation greatly impaired DCV transport in both directions. A klc-2(rf) reduced-function mutation decreased DCV velocity in both directions and reduced the frequency of body bends during swimming. In contrast, the klc-1(-) null mutation had no effect on anterograde transport or swimming ability, but surprisingly it increased the speed of retrograde DCV transport. We also determined lifespan, finding that klc-1(-) or klc-2(rf) single mutants were wild-type whereas the unc-116(rf), ida-1::gfp and unc-116(rf); ida-1::gfp strains were short-lived. Strikingly, the ida-1::gfp transgenic synergistically interact with either klc mutant to extend lifespan compared to wild-type and parental strains. Our findings suggest that kinesin-1 not only influences anterograde and retrograde DCV transport but also plays a role in regulating lifespan.

cell biology↗