Microtubule assembly dynamics: new insights at the nanoscale

Abstract

Although the dynamic self-assembly behavior of microtubule ends has been well characterized at the spatial resolution of light microscopy (∼200 nm), the single-molecule events that lead to these dynamics are less clear. Recently, a number of in vitro studies used novel approaches combining laser tweezers, microfabricated chambers, and high-resolution tracking of microtubule-bound beads to characterize mechanochemical aspects of MT dynamics at nanometer scale resolution. In addition, computational modeling is providing a framework for integrating these experimental results into physically plausible models of molecular scale microtubule dynamics. These nanoscale studies are providing new fundamental insights about microtubule assembly, and will be important for advancing our understanding of how microtubule dynamic instability is regulated in vivo via microtubuleassociated proteins, therapeutic agents, and mechanical forces.

Discovery of Dual VEGFR-2 and Tubulin Inhibitors with in Vivo Efficacy

“…8 This work demonstrated that a trifluoromethyl group in the meta position in compound 1 or benzo [1,3]dioxol-5-yl functionality in triazole 4 results in an inhibitory activity in the VEGFR-2 enzymatic assay (Table 1). Moreover, triazole 1 along with several other analogues (not shown) exhibited VEGFR-2 activity around 1 μM in the cellular phosphorylation assay.…”

“…It is well documented that microtubules are crucial for the maintenance of cell shape, vesicle and protein trafficking, for cell signaling, and in forming the mitotic spindle used in cell division. 1 The predominant mode of action of microtubule inhibitors is disruption of mitotic spindle formation during cell division in rapidly dividing tumor cells, leading to mitotic arrest and subsequent apoptosis. 2 An alternative treatment in cancer is the use of antiangiogenic drugs such as bevacizumab.…”

“…The trifluoromethyl group on the phenyl moiety that had previously provided us with VEGFR-2 activity ( Table 1) resulted in a loss of tubulin potency in both tubulin polymerization and G 2 M block assays. Therefore, we focused on the benzo [1,3]dioxol-5-yl (piperonyl) group of analogue 4 since we had described the tubulin activity of piperonylcontaining compounds in our earlier work on tubulin active scaffolds. 6,7 We reasoned that the addition of a 4-pyridyl group, a common element of multiple VEGFR-2 active classes, [8][9][10] would lend VEGFR-2 activity to our compounds.…”

“…A breakthrough in our effort to introduce both VEGFR-2 kinase and tubulin activities simultaneously came from a substitution of the benzo [1,3]dioxol-5-yl functionality with the closely related 2,3-dihydro-benzo [1,4]dioxin-6-yl group ( Table 2). This group was shown to improve tubulin properties.…”

“…This group was shown to improve tubulin properties. 6,7 We incorporated a VEGFR-2-specific 4-pyridyl functionality into this new oxadiazole 2,3-dihydro-benzo [1,4]dioxin-6-yl scaffold by preparing analogues 14 and 17. Analogue 14 was the first compound that combined appreciable tubulin and kinase cellular activities.…”