Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2022.05.22.492960

A bifunctional kinase-phosphatase module integrates mitotic checkpoint and error-correction signalling to ensure mitotic fidelity

Corno, A.·Cordeiro, M. H.·Allan, L. A.·Lim, Q. W.·Harrington, E.·Smith, R. J.·Saurin, A. T.
View original source ↗Export metadata ↓

Abstract

Two major mechanisms have evolved to safeguard genome stability during mitosis: the mitotic checkpoint delays mitosis until all chromosomes have attached to microtubules, and the kinetochore-microtubule error-correction pathway keeps this attachment process free from errors. We demonstrate here that the optimal strength and dynamics of both processes is set by a kinase-phosphatase pair (PLK1-PP2A) that engage in negative feedback on the BUB complex. Uncoupling this homeostatic feedback to skew the balance towards PLK1 produces a strong checkpoint, weak microtubule attachments, and mitotic delays. Conversely, skewing the balance towards PP2A causes a weak checkpoint, strong microtubule attachments, and chromosome segregation errors. The number of MELT motifs on the KNL1 signalling scaffold sets the optimal levels of each enzyme, because engineering KNL1 to recruit too many BUB complexes increases KNL1-PLK1/PP2A levels, and enhances checkpoint/microtubule attachment strength. In contrast, recruiting too few BUB complexes lowers KNL1-PLK1/PP2A, and decreases checkpoint/microtubule attachment strength. Both of these situations are associated with chromosome segregation errors. Together, these data demonstrate how a single bifunctional kinase-phosphatase module integrates two major mitotic processes to help preserve genome stability.

Source connections

Explore related subjects

cell biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Corno, A., Cordeiro, M. H., Allan, L. A., Lim, Q. W., Harrington, E., Smith, R. J., Saurin, A. T.. 2022-05-22. A bifunctional kinase-phosphatase module integrates mitotic checkpoint and error-correction signalling to ensure mitotic fidelity. https://doi.org/10.1101/2022.05.22.492960

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

OPN3 mediates retinal-dependent lipofuscin accumulation and its loss sensitizes keratinocytes to blue-light-induced proteomic remodeling

Lipofuscin is a blue-light-absorbing pigment that contributes to oxidative damage. Whether all-trans retinal (atRAL) contributes to its formation in response to light remains unclear. We asked whether blue-light photosensitization of atRAL promotes lipofuscin accumulation in human keratinocytes and whether this depends on Opsin 3 (OPN3). Blue-light excitation of atRAL reduced mitochondrial and lysosomal viability, impaired autophagic flux, and increased lipofuscin. OPN3 knockdown significantly reduced this accumulation. Label-free data-independent acquisition (DIA) proteomics showed that OPN3 acts at three levels. In the dark, OPN3 loss altered proteome networks associated with autophagy, apoptosis, and interferon-related responses. Under blue light, control cells activated a stress-adaptive program spanning inflammatory regulation, lipid metabolism, and mitochondrial function, which atRAL strongly amplified. This molecular signature, including induction of cellular respiration and ATP-production proteins, was largely absent when OPN3 was silenced. Respirometry showed that blue light suppressed oxygen consumption in both lines over the first 24 h, but a faster recovery in OPN3 knockdown cells at 48 and 72 h was observed. Together, these data define three functions of OPN3: maintaining the basal proteome in a blue-light-independent manner, enabling the adaptive blue-light response, and enabling retinal-dependent lipofuscin formation in keratinocytes.

cell biology↗
bioRxiv2026

Uncoupling microtubule lifetime, stability and post-translational modifications.

Microtubules (MTs) undergo continuous cycles of growth and disassembly. Because the transitions between these states are stochastic, MT age varies widely within a population. As MTs age, they are thought to accumulate post-translational modifications (PTMs) that, directly or indirectly, enhance their stability and thereby extend their lifetime. The rare MTs that withstand prolonged exposure to destabilizing drugs such as nocodazole (NZ) are indeed enriched in PTMs; yet the relationships between MT age, PTMs and stability remain unclear. Using microinjection of labelled tubulin, we measured microtubule network turnover in immortalized mouse embryonic fibroblasts. Half of the network was renewed within 3 minutes and 80% within 10 minutes, while approximately 5% of microtubules persisted for more than 20 minutes. These dynamics were comparable in quiescent and senescent cells, although the fraction of slowly renewing or non-renewing microtubules rose to 20% in senescent cells. Unexpectedly, neither the amount of PTMs (acetylation and detyrosination) nor resistance to NZ increased with MT age, and resistance to NZ was independent of these PTMs. Degrees of acetylation and detyrosination should therefore not be taken as readouts of MT age or stability. Because these PTMs do not accumulate on MTs over time, the chemical modification of polymerized tubulin is likely more reversible and dynamic than previously assumed.

cell biology↗
bioRxiv2026

Evidence of complete myofibril remodeling after severe damage in adult Drosophila.

Muscle function depends on the ability of myofibrils to withstand and repair mechanical damage, yet how adult muscles remodel damaged myofibrils remains poorly understood. Here, we establish a Drosophila model that allows the induction and longitudinal visualization of extensive myofibril damage and recovery in intact adult femur muscles. Sustained muscle depolarization caused extensive disruption of myofibrillar organization, with severe damage characterized by near-complete loss of Z-disc structures. Remarkably, myofibril architecture and muscle function were largely restored within days, revealing a substantial capacity for myofibril reconstruction in adult femur muscles. We identified two distinct states of myofibril damage, mild and severe, with mild damage appearing before severe damage during aging, suggesting a progressive process of myofibril deterioration and repair failure. We further show that filamins mechanosignaling is required for efficient myofibril remodeling. Following damage, wild-type filamin redistributes from the Z-disc and accumulates outside the myofibrils, whereas constitutively open filamin remains Z-disc-associated and constitutively closed filamin redistributes but results in increased damage and impaired recovery. These findings suggest that effective repair requires dynamic transitions between filamin conformational states and that filamin redistribution is an active component of the damage response rather than simply a consequence of muscle injury. During aging, filamin progressively redistributes from the Z-disc and muscle damage accumulates, with severe damage increasing after the appearance of mild damage. Together, our findings reveal a previously unappreciated capacity of adult muscle to reassemble damaged myofibrils and identify filamin mechanosignaling as a key component of this repair process, providing a framework for understanding how defective mechanosensing may contribute to age-related muscle decline and muscle disease.

cell biology↗