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BP: Fachverband Biologische Physik
BP 2: Computational Biophysics I
BP 2.3: Vortrag
Montag, 9. März 2026, 10:00–10:15, BAR/0106
Synchronization of both microtubule ends facilitates robust spindle length control — •Shane Fiorenza1, Sheba Cheeran2, Elena Doria2, Iva Tolić3, Patrick Meraldi2, and Nenad Pavin1 — 1Faculty of Science, University of Zagreb — 2Faculty of Medicine, University of Geneva — 3Rudjer Bošković Institute, Zagreb
The mitotic spindle is a biomechanical structure that relies on a well-controlled geometry to accurately segregate genetic material, and so the mechanisms responsible for setting spindle length have been extensively studied both in vivo and in vitro. One of these myriad mechanisms, microtubule poleward flux, has proven difficult to characterize, with experiments showing that decreasing poleward flux can lead to spindle length increasing, decreasing, or remaining constant. How the spindle regulates its length and the role of poleward flux in this process remains unclear. Here we show that length-dependent regulation at both microtubule ends constitutes a fundamental mechanism of spindle length control through poleward flux. Our model demonstrates that length-dependent mechanisms at both microtubule ends allow plus- and minus-end dynamics to synchronize with one another, resulting in perturbations at either end having opposite effects on poleward flux for increasing spindle size. We predict that spindle length and poleward flux can be uncoupled via simultaneous perturbations, which we confirm with in vivo depletion experiments of KIF18A, KIF2A, and KATNB1 proteins. Our results provide a new way of understanding spindle length control and resolve a long-standing paradox of how poleward flux relates to spindle length.
Keywords: mitotic spindle; microtubules; minus-ends; poleward flux; analytic theory