Effects of dynein inhibitor on the number of motor proteins transporting synaptic cargos

Abstract

Synaptic cargo transport by kinesin and dynein in hippocampal neurons was investigated by noninvasively measuring the transport force based on nonequilibrium statistical mechanics. Although direct physical measurements such as force measurement using optical tweezers are difficult in an intracellular environment, the noninvasive estimations enabled enumerating force-producing units (FPUs) carrying a cargo comprising the motor proteins generating force. The number of FPUs served as a barometer for stable and long-distance transport by multiple motors, which was then used to quantify the extent of damage to axonal transport by dynarrestin, a dynein inhibitor. We found that dynarrestin decreased the FPU for retrograde transport more than for anterograde transport. This result indicates the applicability of the noninvasive force measurements. In the future, these measurements may be used to quantify damage to axonal transport resulting from neuronal diseases, including Alzheimer's, Parkinson's, and Huntington's diseases.

Intracellular force comparison of pathogenic KIF1A, KIF5, and dynein by fluctuation analysis

“…The software used to calculate χ is available from a website(38). The behavior of as a function of D , shown in Fig.1D, converging to a constant value as D → ∞, was explained in detail in our previous papers(15)(16)(17)(18)(19)(20).…”

“…1C). Note that CVSs were chosen so that Δ calculated from them belonged to the same statistical population (see Supplemental Information in (18)).…”

“…CC-BY-NC-ND 4.0 International license perpetuity. It is made available under a preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in The copyright holder for this this version posted September 12, 2021. ; https://doi.org/10.1101/2021.09.12.459977 doi: bioRxiv preprint This may be because the sizes of SVP cargos are smaller in the axons of C. elegans (18), resulting in no significant effect of force impairment under such a low load condition.…”

“…Chiba et al (23) reported that the mean velocity values of moving SVPs in C. elegans axons were similar for UNC104-WT and UNC104-V6M where UNC-104 is a homolog of KIF1A. This may be because the SVPs in C. elegans axons are substantially smaller than those in mouse neuronal axons (18), and the effect of force impairment was not significant under the low-load condition realized in C. elegans axons. Lastly, we investigated the effect of the presence of KIF1A originally derived from mice on EVA (Fig.…”

“…However, unlike in in-vitro singlemolecule experiments, it is difficult to extract physical information on motors from in-vivo time-course data because of the different cargo shapes and complex non-equilibrium environment. In recent years, to overcome these problems in time-course analysis under non-equilibrium conditions, we have developed a method for noninvasive force measurement of intracellular cargo transport based on time-course analysis using the statistical property of cargo fluctuation, obtaining idea from the non-equilibrium statistical mechanics (15)(16)(17)(18)(19)(20).…”