A Stochastic Model of Cortical Microtubule Anchoring and Mechanics Provides Regulatory Control of Microtubule Shape

• Published in: Bulletin of mathematical biology Vol. 85; no. 11; p. 103
• Main Authors: Tian, Tim Y. Y., Macdonald, Colin B., Cytrynbaum, Eric N.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-11-2023; Springer Nature B.V
• Subjects: Arrays; Buckling; Cell Biology; Circular cylinders; Deflection; Geodesy; Life Sciences; Mathematical and Computational Biology; Mathematical models; Mathematics; Mathematics and Statistics; Original Article; Plant cells; Segments; Stochastic models; Stochastic processes; Stochasticity; Elastic rods; Microtubule organization; Stochastic buckling; Microtubule mechanics
• ISSN: 0092-8240; 1522-9602
• DOI: 10.1007/s11538-023-01211-x

The organization of cortical microtubule arrays play an important role in the development of plant cells. Until recently, the direct mechanical influence of cell geometry on the constrained microtubule (MT) trajectories have been largely ignored in computational models. Modelling MTs as thin elastic rods constrained on a surface, a previous study examined the deflection of MTs using a fixed number of segments and uniform segment lengths between MT anchors. It is known that the resulting MT curves converge to geodesics as the anchor spacing approaches zero. In the case of long MTs on a cylinder, buckling has been found for transverse trajectories. There is a clear interplay between two factors in the problem of deflection: curvature of the membrane and the lengths of MT segments. Here, we examine the latter in detail, in the backdrop of a circular cylinder. In reality, the number of segments are not predetermined and their lengths are not uniform. We present a minimal, realistic model treating the anchor spacing as a stochastic process and examine the net effect on deflection. We find that, by tuning the ratio of growth speed to anchoring rate, it is possible to mitigate MT deflection and even prevent buckling for lengths significantly larger than the previously-derived critical buckling length. We suggest that this mediation of deflection by anchoring might provide cells with a means of preventing arrays from deflecting away from the transverse orientation.