Fig. 1: Vimentin IFs stabilize dynamic microtubules.

a Illustration of the experimental setup. We attached microtubule seeds (green) to a biotin-polyethylene glycol-silane (biotin-SiPEG) coated cover glass. Dynamic microtubules (cyan) grew from the seeds. Vimentin IFs (red) formed an entangled, fluctuating network. We imaged microtubules by TIRF microscopy. b Fluorescence micrograph of microtubules (cyan) embedded in a vimentin IF network (red). The inset shows the enlarged detail. Scale bar: 10 μm. c Example kymographs of microtubules growing at 20 or 25  μM tubulin in the presence (+vim; 2.3 μM) or absence of vimentin. Scale bars: 3 μm and 5 min. d, e Vimentin does not affect the microtubule growth and depolymerization rates, irrespective of the tubulin concentration. Cyan boxplots represent experiments with tubulin only; cyan- and red-striped boxplots illustrate experiments with tubulin and vimentin. Boxplots include the median as the center line, the 25th and 75th percentiles as box limits, and the entire data range as whiskers. In (d), for 20 μM tubulin and in the absence of vimentin, the boxplot represents the data from N = 6 samples and n = 106 growth events (we define a growth event as the new outgrowth of a microtubule from the seed or after a rescue event). For the other boxplots, from left to right, N = 5, 7, 4, 5, and 7, respectively, and n = 163, 282, 113, 160, and 218, respectively. In (e), from left to right, the boxplots represent the data from n = 58, 140, 228, 112, 133, and 165 depolymerization events, respectively. f The catastrophe frequency of the microtubules decreases in the presence of vimentin. Each circle represents an experiment including multiple microtubules. The area of the circle scales with the total summed microtubule growth time of the respective experiment. Black bars indicate the weighted mean. From left to right, the plot represents the data from a total of 805, 1469, 2692, 1142, 2203, and 2232 min of growth time, respectively. g Vimentin enhances the microtubule rescue frequency. Each circle represents an experiment including multiple microtubules. The area of the circle scales with the total microtubule depolymerization time. From left to right, the plot represents the data from a total of 51, 71, and 52 min depolymerization time, respectively. All tubulin and vimentin concentrations are input concentrations. Source data are provided as a Source Data file.