Biology subjects

Rosas Salvans, M.

Publications and source records attributed to Rosas Salvans, M..

3 recordsLinked to original sources

bioRxiv2025

Mammalian metaphase kinetochores are elastic and require condensin for robust structure and function

SummaryTran et al. show that mammalian metaphase kinetochores undergo large-scale, complex, and elastic deformations under forces of different timescales, magnitudes and directions. They demonstrate that condensin is required for kinetochore local structural organization and microtubule attachment under force. AbstractThe mammalian kinetochore connects chromosomes to dynamic spindle microtubules. To remain attached, it must maintain its structural integrity under force, but to what extent and how it does so remain unclear. Under spindle forces, we find using super resolution microscopy that inner (CENP-A) and outer (Hec1) metaphase kinetochores undergo correlated, large-scale (1 {micro}m) deformations along the force axis, suggesting dynamic, relative sliding of parallel protein linkages. Kinetochore shape changes can be asymmetric, with centromere-facing "tails" correlating with erroneous attachment geometries. Applying microneedle pulling forces, we demonstrate that kinetochores are elastic, stretching under force and relaxing in seconds afterwards. Finally, we show that SMC2 depletion results in more variable kinetochore deformations, despite maintained elasticity, and in reduced microtubule attachment stability. Thus, the kinetochore is structurally highly dynamic and requires a stable centromere base to maintain its structure and function under force. We propose a model whereby individual protein linkages are stiff yet global kinetochore structure flexible to accommodate different attachment geometries and forces while maintaining function.

cell biology↗

bioRxiv2024

SKAP binding to microtubules reduces friction at the kinetochore-microtubule interface and increases attachment stability under force

The kinetochore links chromosomes to spindle microtubules to drive chromosome segregation at cell division. We recently uncovered that the kinetochore complex Astrin-SKAP, which binds microtubules, reduces rather than increases friction at the mammalian kinetochore-microtubule interface. How it does so is not known. Astrin-SKAP could affect how other kinetochore complexes bind microtubules, reducing their friction along microtubules, or it could itself bind microtubules with similar affinity but lower friction than other attachment factors. Using SKAP mutants unable to bind microtubules, live imaging and laser ablation, we show that SKAPs microtubule binding is essential for sister kinetochore coordination, force dissipation at the interface and attachment responsiveness to force changes. Further, we show that SKAPs microtubule binding is essential to prevent chromosome detachment under both spindle forces and microneedle-generated forces. Together, our findings indicate that SKAPs microtubule binding reduces kinetochore friction and increases attachment responsiveness and stability under force. We propose that having complexes with both high and low sliding friction on microtubules, making a mechanically heterogeneous interface, is key to maintaining robust attachments under force and thus accurate segregation.

cell biology↗

bioRxiv2021

The Astrin/SKAP Complex Reduces Friction at the Kinetochore-Microtubule Interface

The kinetochore links chromosomes to spindle microtubules to drive chromosome segregation at cell division. While we know nearly all mammalian kinetochore proteins, how these give rise to the strong yet dynamic microtubule attachments required for function remains poorly understood. Here, we focus on the Astrin-SKAP complex, which localizes to bioriented kinetochores and is essential for chromosome segregation, but whose mechanical role is unclear. Live imaging reveals that SKAP depletion dampens movement and decreases coordination of metaphase sister kinetochores, and increases tension between them. Using laser ablation to isolate kinetochores bound to polymerizing vs depolymerizing microtubules, we show that without SKAP kinetochores move slower on both polymerizing and depolymerizing microtubules, and that more force is needed to rescue microtubules to polymerize. Thus, in contrast to previously described kinetochore proteins that increase grip on microtubules under force, Astrin-SKAP reduces grip, increasing attachment dynamics and force responsiveness and reducing friction. Together, our findings suggest a model where the Astrin-SKAP complex effectively "lubricates" correct, bioriented attachments to help preserve them.

cell biology↗