Biology subjects

Ferreira, J. G.

Publications and source records attributed to Ferreira, J. G..

5 recordsLinked to original sources

bioRxiv2025

Chromosome condensation mechanically primes the nucleus for mitosis

Accurate transition into mitosis driven by cyclin B1-CDK1 activity is essential to avoid chromosome segregation errors and preserve genome integrity. How this activity is spatially controlled to trigger mitotic onset remains unclear. Here, we show that chromosome condensation triggers an increase in nuclear envelope (NE) tension. This increased tension is required for nuclear translocation of cyclin B1 and dynein loading on nuclear pore complexes (NPCs), ensuring timely mitotic entry. Micromanipulation experiments further indicate this tension-dependent mechanism requires SUN proteins on the NE. Disruption of chromosome condensation leads to an accumulation of the G2 checkpoint kinase Wee1 and inhibition of CDK1 activity, which result in a temporary delay in mitotic entry. This delay can be overridden by increasing tension on the NE, which accelerates the nuclear translocation of cyclin B1 and dynein loading. We propose that mitotic onset is controlled by a chromosome-dependent NE tension mechanism that enables robust spatiotemporal coupling between chromosome condensation and the structural changes required for an efficient mitosis.

cell biology↗

bioRxiv2023

A nuclear signal in prophase determines centrosome positioning and ensures efficient mitotic spindle assembly

Accurate centrosome separation and positioning during early mitosis relies on force- generating mechanisms regulated by a combination of extracellular, cytoplasmic, and nuclear cues. The identity of the nuclear cues involved in this process remains largely unknown. Here, we investigate how the prophase nucleus contributes to centrosome positioning during the initial stages of mitosis, by using a combination of cell micropatterning, high-resolution live-cell imaging and quantitative 3D cellular reconstruction. We show that in untransformed RPE-1 cells, centrosome positioning is regulated by a nuclear signal, independently of external cues. This nuclear mechanism relies on the linker of nucleoskeleton and cytoskeleton (LINC) complex that controls the timely loading of dynein on the nuclear envelope (NE), providing spatial cues for robust centrosome positioning on the shortest nuclear axis, prior to nuclear envelope permeabilization (NEP). Our results demonstrate how nuclear-cytoskeletal coupling maintains a robust centrosome positioning mechanism to ensure efficient mitotic spindle assembly. Summary blurbCentrosome positioning in prophase is essential for efficient spindle assembly. Here, we show that centrosome positioning requires LINC complex-mediated loading of dynein on the nuclear envelope.

cell biology↗

bioRxiv2021

Mechanosensitive control of mitotic entry

As cells prepare to divide, they must ensure that enough space is available to assemble the mitotic machinery without perturbing tissue homeostasis1. To do so, cells undergo a series of biochemical reactions regulated by cyclin B1-CDK1 that trigger the reorganization of the actomyosin cytoskeleton2 and ensure the coordination of cytoplasmic and nuclear events3. Along with the biochemical events that control mitotic entry, mechanical forces have recently emerged as important players in the regulation of cell cycle events4-6. However, the exact link between mechanical forces and the biochemical pathways that control mitotic progression remains to be established. Here, we identify a mechanical signal on the nucleus that helps set the time for nuclear envelope permeabilization (NEP) and mitotic entry. This signal relies on actomyosin contractility, which leads to nuclear unfolding during the G2-M transition, activating the stretch-sensitive cPLA2 on the nuclear envelope. This contributes to the spatiotemporal translocation of cyclin B1 to the nucleus. Our data demonstrate how nuclear mechanics during the G2-M transition contribute to timely and efficient mitotic spindle assembly and prevents chromosomal instability.

cell biology↗

bioRxiv2019

Microtubule tyrosination/detyrosination specifies a mitotic error code

Incorrect kinetochore-microtubule attachments during mitosis can lead to chromosomal instability, a hallmark of human cancers. Mitotic error correction relies on the kinesin-13 MCAK, a microtubule depolymerase whose activity in vitro is suppressed by -tubulin detyrosination - a post-translational modification enriched on long-lived microtubules. However, whether and how MCAK activity required for mitotic error correction is regulated by microtubule tyrosination/detyrosination remains unknown. Here we found that microtubule detyrosination accumulates on correct, more stable, kinetochore-microtubule attachments, whereas constitutively high microtubule detyrosination near kinetochores compromised efficient error correction. Rescue experiments suggest that mitotic errors due to excessive microtubule detyrosination result from suppression of MCAK activity, without globally affecting kinetochore microtubule half-life. Importantly, MCAK centromeric activity was required and sufficient to rescue mitotic errors due to excessive microtubule detyrosination. Thus, microtubules are not just passive elements during mitotic error correction, and their tyrosination/detyrosination works as a mitotic error code that allows centromeric MCAK to discriminate correct and incorrect kinetochore-microtubule attachments, thereby promoting mitotic fidelity.

cell biology↗

bioRxiv2019

Spatial Asymmetries of the Prophase Nucleus Regulate Dynein Recruitment to Ensure Mitotic Fidelity

During prophase, centrosomes need to separate and position to correctly assemble the mitotic spindle. This process occurs through the action of molecular motors, cytoskeletal networks and the nucleus. How the combined activity of these different components is spatiotemporally regulated to ensure efficient spindle assembly remains unclear. Here we show that during prophase the centrosomes-nucleus axis reorients, so that centrosomes are positioned on the shortest nuclear axis at nuclear envelope (NE) breakdown. This centrosomes-nucleus configuration depends on mechanical cues generated by mitotic chromosome condensation on the prophase nucleus. We further show these mechanosensitive cues act through SUN1/2 and NudE+NudEL to enable the polarized loading of Dynein on the NE. Finally, we observe this centrosome configuration favors the establishment of an initial bipolar spindle scaffold, facilitating chromosome capture and accurate segregation, without compromising division plane orientation. We propose that chromosome segregation fidelity depends on the mechanical properties of the prophase nucleus that facilitate spindle assembly by regulating NE-Dynein localization.

cell biology↗