Photoswitchable Epothilone‐Based Microtubule Stabilisers Allow GFP‐Imaging‐Compatible, Optical Control over the Microtubule Cytoskeleton**

Abstract

Optical methods to modulate microtubule dynamics show promise for reaching the micron‐ and millisecond‐scale resolution needed to decrypt the roles of the cytoskeleton in biology. However, optical microtubule stabilisers are under‐developed. We introduce “STEpos” as GFP‐orthogonal, light‐responsive epothilone‐based microtubule stabilisers. They use a novel styrylthiazole photoswitch in a design to modulate hydrogen‐bonding and steric effects that control epothilone potency. STEpos photocontrol microtubule dynamics and cell division with micron‐ and second‐scale spatiotemporal precision. They substantially improve potency, solubility, and ease‐of‐use compared to previous optical microtubule stabilisers, and the structure‐photoswitching‐activity relationship insights in this work will guide future optimisations. The STEpo reagents can contribute greatly to high‐precision research in cytoskeleton biophysics, cargo transport, cell motility, cell division, development, and neuroscience.

Microtubule‐targeting agents for cancer treatment: Seven binding sites and three strategies

“…155 Among these efforts, analogs based on combretastatin A-4, paclitaxel, epothilone, and colchicinoid have garnered attention. [156][157][158][159][160] These photoswitchable MTAs have demonstrated potential for elucidating the intricate mechanisms underlying microtubule-related processes and have proven to be useful tools in the study of various fields such as embryology, neuroscience, and cytoskeleton research. 161 Importantly, these photopharmaceuticals also show potential for targeted therapeutic interventions by precisely modulating microtubule dynamics in cancer cells or disease-specific microtubule networks.…”

“…Hence, extensive efforts have been dedicated to the development of light‐triggered MTAs, aiming to achieve precise modulation of microtubule dynamics 155 . Among these efforts, analogs based on combretastatin A‐4, paclitaxel, epothilone, and colchicinoid have garnered attention 156–160 . These photoswitchable MTAs have demonstrated potential for elucidating the intricate mechanisms underlying microtubule‐related processes and have proven to be useful tools in the study of various fields such as embryology, neuroscience, and cytoskeleton research 161 .…”

Photocontrolling Microtubule Dynamics with Photoswitchable Chemical Reagents

“…STEpos have only been demonstrated in cell-free and 2D cell culture studies so far. They appear to have rather slow diffusional reversibility (halftime >5 min), which may be related to their binding potency and their mechanism of action, and this may be beneficial for long-term localised inhibition [13]. Azobenzene-based taxol derivatives, AzTax (best compound AzTax3MP), are moderate-potency MT stabiliser photopharmaceuticals which have moderate diffusional reversibility (halftime ca.…”

“…Note 2. Drug Scaffolds: Pharmaceuticals that have already been used as part of MT-inhibiting photopharmaceuticals include taxol [14] and epothilone [13] for MT-stabilising photopharmaceuticals AzTax and STEpo; and colchicinoids (analogues of colchicine-binding-site drugs like colchicine, colcemid, nocodazole or combretastatin) have been used in MT-destabilising photopharmaceuticals e.g. PST, SBTub and PHTub (Fig 5) [2,7,9,15,23,24].…”