Tracking of plus-ends reveals microtubule functional diversity in different cell types

TL;DR

This study investigates how microtubule dynamics differ across cell types by tracking plus-ends with EB1, revealing distinct behaviors in neurons versus fibroblasts that reflect their functional roles.

Contribution

It demonstrates that microtubule plus-end dynamics vary significantly between neurons and fibroblasts, linking these differences to their cellular functions.

Findings

Microtubule dynamics differ markedly between neurons and fibroblasts.

Plus-end density and catastrophe frequencies are higher near fibroblast margins.

MT length distributions follow exponential tails consistent with a two-state model.

Abstract

Many cellular processes are tightly connected to the dynamics of microtubules (MTs). While in neuronal axons MTs mainly regulate intracellular trafficking, they participate in cytoskeleton reorganization in many other eukaryotic cells, enabling the cell to efficiently adapt to changes in the environment. We show that the functional differences of MTs in different cell types and regions is reflected in the dynamic properties of MT tips. Using plus-end tracking proteins EB1 to monitor growing MT plus-ends, we show that MT dynamics and life cycle in axons of human neurons significantly differ from that of fibroblast cells. The density of plus-ends, as well as the rescue and catastrophe frequencies increase while the growth rate decreases toward the fibroblast cell margin. This results in a rather stable filamentous network structure and maintains the connection between nucleus and membrane. In contrast, plus-ends are uniformly distributed along the axons and exhibit diverse polymerization run times and spatially homogeneous rescue and catastrophe frequencies, leading to MT segments of various lengths. The probability distributions of the excursion length of polymerization and the MT length both follow nearly exponential tails, in agreement with the analytical predictions of a two-state model of MT dynamics.