Biology subjects

Trier, I.

Publications and source records attributed to Trier, I..

4 recordsLinked to original sources

bioRxiv2025

ATR promotes genome instability via CENP-A eviction from centromeres under replication stress

Replication stress leads to genome instability in part by promoting missegregation of chromosomes lacking centromeres. Yet the molecular mechanism linking replication stress to centromere dysfunction has remained elusive. Here, we show that sustained replication stress induces eviction of the histone H3 variant CENP-A. Displaced CENP-A relocalizes to nucleoli. This process is dependent on the DNA damage response kinase, ATR, and occurs in both human and mouse cells. We show that ATR promotes CENP-A eviction by recruiting the AAA+ ATPase VCP to centromeres, destabilizing CENP-A-containing nucleosomes. The canonical CENP-A chaperone, HJURP, but not H3 histone chaperones DAXX or ATRX, is necessary for nucleolar CENP-A localization. Importantly, ATR-dependent CENP-A eviction endures after cell-cycle re-entry and correlates with the emergence of acentric chromosomes, linking replication stress directly to segregation defects. Our findings reveal an undiscovered role for ATR in regulating centromere identity under stress and uncover a mechanistic pathway that drives genome instability.

cell biology↗

bioRxiv2024

Chk2 sustains PLK1 activity in mitosis to ensure proper chromosome segregation

Polo-like kinase 1 (PLK1) protects against genome instability by ensuring timely and accurate mitotic cell division. PLK1 activity is tightly regulated throughout the cell cycle. Although the pathways that initially activate PLK1 in G2 are well-characterized, the factors that directly regulate PLK1 in mitosis remain poorly understood. Here, we identify that human PLK1 activity is sustained by the DNA damage response kinase Checkpoint kinase 2 (Chk2) in mitosis. Chk2 directly phosphorylates PLK1 T210, a residue on its T-loop whose phosphorylation is essential for full PLK1 kinase activity. Loss of Chk2-dependent PLK1 activity causes increased mitotic errors, including chromosome misalignment, chromosome missegregation, and cytokinetic defects. Moreover, Chk2 deficiency increases sensitivity to PLK1 inhibitors, suggesting that Chk2 status may be an informative biomarker for PLK1 inhibitor efficacy. This work demonstrates that Chk2 sustains mitotic PLK1 activity and protects genome stability through discrete functions in interphase DNA damage repair and mitotic chromosome segregation.

cell biology↗

bioRxiv2022

ATR protects centromere identity by promoting DAXX association with PML nuclear bodies

Centromere protein A (CENP-A) defines centromere identity and nucleates kinetochore formation for mitotic chromosome segregation. Here, we show that Ataxia telangiectasia and Rad3-related (ATR) kinase, a master regulator of the DNA damage response, protects CENP-A occupancy at interphase centromeres in a DNA damage-independent manner. As ATR localizes to promyelocytic leukemia nuclear bodies (PML NBs) in unperturbed cells, we hypothesized that ATR protects CENP-A occupancy by regulating the localization of the histone H3.3 chaperone and PML NB component, DAXX. Indeed, we found that ATR inhibition reduces DAXX association with PML NBs, resulting in the DAXX-dependent loss of CENP-A from interphase centromeres. Lastly, we demonstrate that CENP-A occupancy is not restored until G1 of the following cell cycle, leading to increased mitotic chromosome segregation defects. These findings demonstrate a novel mechanism by which ATR protects centromere identity and genome stability.

cell biology↗

bioRxiv2022

Molecular Mechanism of Hyperactivation Conferred by a Truncated TRPA1 Disease Mutant Suggests New Gating Insights

The wasabi receptor, TRPA1, is a non-selective homotetrameric cation channel expressed in primary sensory neurons of the pain pathway, where it is activated by diverse chemical irritants. A direct role for TRPA1 in human health has been highlighted by the discovery of genetic variants associated with severe pain disorders. One such TRPA1 mutant was identified in a father-son pair with cramp fasciculation syndrome (CFS) and neuronal hyperexcitability-hypersensitivity symptoms that may be caused by aberrant channel activity, though the mechanism of action for this mutant is unknown. Here, we show the CFS-associated R919* TRPA1 mutant is functionally inactive when expressed alone in heterologous cells, which is not surprising since it lacks the 201 C-terminal amino acids that house critical channel gating machinery including the pore-lining transmembrane helix. Interestingly, the R919* mutant confers enhanced agonist sensitivity when co-expressed with wild type (WT) TRPA1. This channel hyperactivation mechanism is conserved in distant TRPA1 species orthologues and can be recapitulated in the capsaicin receptor, TRPV1. Using a combination of ratiometric calcium imaging, immunostaining, surface biotinylation, pulldown assays, fluorescence size exclusion chromatography, and proximity biotinylation assays, we show that the R919* mutant co-assembles with WT subunits into heteromeric channels. Within these heteromers, we postulate that R919* TRPA1 subunits contribute to hyperactivation by lowering energetic barriers to channel activation contributed by the missing regions. Additionally, we show heteromer activation can originate from the R919* TRPA1 subunits, which suggests an unexpected role for the ankyrin repeat and coiled coil domains in concerted channel gating. Our results demonstrate the R919* TRPA1 mutant confers gain-of-function thereby expanding the physiological impact of nonsense mutations, reveals a novel and genetically tractable mechanism for selective channel sensitization that may be broadly applicable to other receptors, and uncovers new gating insights that may explain the molecular mechanism of temperature sensing by some TRPA1 orthologues.

biochemistry↗