BGPT: Paper Review: Dissociation of the nuclear basket triggers chromosome loss in aging yeast

Fuel Your Discoveries

Quick Explanation Copied

Core claim (with critical framing)

The paper argues that in replicatively aging budding yeast, accumulation of extrachromosomal DNA circles (ERCs) remodels the nuclear pore complex (NPC) nuclear basket, which then causes age-associated chromosome loss via intron-dependent leakage of intron-containing pre-mRNAs to the cytoplasm and consequent failure to correct syntelic (co-oriented) kinetochore attachments in the Ipl1/Aurora B pathway.

Skeptical headline:

The mechanism is tightly argued with multiple genetic causality tests, but several steps remain mechanistically under-specified (how cytoplasmic intron-containing RNAs impair Ipl1/Aurora B syntelic error correction) and some perturbations (e.g., sir2∆, fob1∆) have plausible pleiotropic effects.

Long Explanation

Paper Review

“Dissociation of the nuclear basket triggers chromosome loss in aging yeast”

eLife, published 30 Oct 2025; DOI: 10.7554/eLife.104530

Model: Saccharomyces cerevisiae (replicative aging) Phenotype: chromosome loss & asymmetric sister chromatid partitioning

What the paper says (causal chain, as presented)

Old mother cells exhibit reporter chromosome loss (TetO-anchored Chr II/IV; also minichromosome reporter) at ~10–15% around 18–22 completed budding events (CBE), with chromosome dots lost primarily after anaphase and with high lethality of TetO-array loss events.

Mechanistic attribution: the paper argues that this chromosome loss is explained by increased sister chromatid non-disjunction with a strong asymmetric partition bias toward the bud, and that the bias is linked to attachment-error correction failure associated with Aurora B/Ipl1 pathways.

Upstream driver: the paper proposes ERC accumulation and SAGA-dependent attachment promote NPC basket displacement, which then triggers chromosome loss.

Downstream specificity: the paper argues that basket displacement acts largely through intron-dependent leakage of pre-mRNAs from exactly three intron-containing error-correction genes: NBL1, MCM21, and GLC7.

Proposed mechanism: basket loss increases cytoplasmic intron-containing RNA foci (smRNA FISH with long intron probes) and increases translation of an unspliced pre-mRNA reporter in the cytoplasm in old cells; the authors then connect this to failure of syntelic attachment correction in the Ipl1/Aurora B pathway.

Visual: age-dependent chromosome loss (from reported summary values)

Note: the figure below uses only the numeric summary points explicitly stated in the provided full-text excerpt (e.g., ~10–15% at 18–22 CBE, ~5% co-loss). The paper itself contains richer source data.

Evidence source: the excerpt reports ~10–15% chromosome loss at 18–22 CBE, ~5% co-loss, and “all young” cells retain reporter dots at 0–3 CBE.

Visual: dependence logic tested by the authors (timeline-less causal map)

Key perturbation axes (as reported):

ERC biology ↔ basket displacement ↔ chromosome loss (e.g., fob1∆, sir2∆, sgf73∆, artificial DNA circle YRp17).
Basket protein disruption ↔ early missegregation (mlp1∆ causes young + age phenotypes).
Intron removal (NBL1/MCM21/GLC7) ↔ suppression of missegregation and partial lifespan rescue.
Pre-mRNA leakage readouts ↔ intron specificity (smRNA FISH foci distribution and unspliced reporter).

This diagram is a conceptual reconstruction of the paper’s causal proposal and perturbation logic, not a quantified model.

Critical evaluation (skeptical, evidence-weighted)

Strengths

Multi-layer causality: the paper does not stop at correlation; it uses several genetic levers upstream (ERC formation/anchorage and basket perturbation) and downstream (intron deletions) that reportedly suppress the same core phenotype (chromosome loss/missegregation).

Reporter strategy triangulation: chromosome loss is scored by fluorescent chromosome foci with cross-validation using a second reporter array and a distinct short-lived GFP minichromosome marker (as described in the excerpt).

Specific intron dependency: the paper claims that removing only the introns from three error-correction genes nearly eliminates the age-associated chromosome loss and also rescues aspects of lifespan, suggesting proximity to cause.

Limitations / blind spots (what could change the interpretation)

Pleiotropy in upstream mutants: sir2∆ and fob1∆ are described as affecting more than ERC formation (e.g., rDNA instability / heterochromatin-related effects), so any shared overlap with basket displacement may still mask additional routes to chromosome instability.

Mechanistic gap: the paper asserts intron-dependent leakage impairs Ipl1/Aurora B syntelic error correction, but the molecular step(s) connecting cytoplasmic unspliced/intron-containing RNAs to kinetochore correction are not specified in the excerpt. Without identifying the direct molecular target, alternative intermediates (e.g., altered protein abundance, translation effects, or stress pathways) could remain plausible.

One-organism generality: the causal chain is shown in budding yeast; generality to metazoans is hypothesized (e.g., nuclear basket dynamics and intron retention with age) but remains speculative without direct homologous causality tests.

Fast falsification checklist (hypothesis-level)

A reader could try to disprove the core mechanism by showing that disrupting each proposed link fails to change the next phenotype (or changes it in the opposite direction):

ERC/basket link: preventing basket displacement should prevent age-associated chromosome loss as reported (basket disruption in young cells also increases missegregation).

Intron-specificity link: intron removal from NBL1/MCM21/GLC7 should suppress missegregation, whereas generic splicing disruption should not reproduce the same SPB-bias phenotype.

Leakage sufficiency: inducing pre-mRNA leakage should be sufficient to trigger intron-dependent asymmetric chromatid partitioning in young cells.

BGPT “go deeper” links (bespoke)

Author reviews (click to read)

Feedback:

Updated: May 02, 2026