Kinetochore proteins suppress neuronal microtubule dynamics and promote dendrite regeneration

Abstract

Kinetochores connect centromeric chromatin to spindle microtubules during mitosis. Neurons are post-mitotic, so it was surprising to identify transcripts of structural kinetochore (KT) proteins and regulatory chromosome passenger complex (CPC) and spindle assembly checkpoint (SAC) proteins in Drosophila neurons after dendrite injury. To test whether these proteins function during dendrite regeneration, post-mitotic RNAi was performed and dendrites or axons were removed using laser microsurgery. Reduction of KT, CPC and SAC proteins decreased dendrite regeneration without affecting axon regeneration. To understand whether neuronal functions of these proteins rely on microtubules, we analyzed microtubule behavior in uninjured neurons. The number of growing plus, but not minus, ends increased in dendrites with reduced KT, CPC and SAC proteins, while axonal microtubules were unaffected. Increased dendritic microtubule dynamics was independent of DLK-mediated stress, but was rescued by concurrent reduction of γTubulin, the core microtubule nucleation protein. Reduction of γTubulin also rescued dendrite regeneration in backgrounds containing kinetochore RNAi transgenes. We conclude that kinetochore proteins function post-mitotically in neurons to suppress dendritic microtubule dynamics by inhibiting nucleation. [Media: see text] [Media: see text]

Neuron tracing and quantitative analyses of dendritic architecture reveal symmetrical three-way-junctions and phenotypes of git-1 in C. elegans

“…This result is in agreement with earlier works that have shown that 3-way junctions represent the minimal energy shape for connecting tubular membrane surfaces [64]. Yet, the observed junction geometry may also be influenced by a local effect of cytoskeletal proteins or membrane coating proteins [65][66][67][68][69][70]. Our findings can therefore serve as a basis for further study of the physical mechanism for stabilization of PVD junctions.…”

Ataxin-2 is essential for cytoskeletal dynamics and neurodevelopment in Drosophila

“…For example, Atx2 has been previously indicated in actin regulation in the germline ( Satterfield et al., 2002 ) and microtubule organization in mitosis ( Gnazzo et al., 2016 ; Stubenvoll et al., 2016 ). Collectively, these observations are of note because there are strong parallels between the organization of the cytoskeleton in mitosis and in neurons ( Del Castillo et al., 2020 ; Cheerambathur et al., 2019 ; Hertzler et al., 2020 ; Lin et al., 2012 ; Norkett et al., 2020 ; Zhao et al., 2019 ). In mitosis, the cytoskeleton must be reorganized to facilitate chromosome separation and actin ring contraction ( Basant and Glotzer, 2018 ; Mishima et al., 2002 ).…”

Ataxin-2 is essential for cytoskeletal dynamics and neurodevelopment in Drosophila

“…For example, Atx2 has been previously indicated in actin regulation in the germline (Satterfield et al, 2002) and microtubule organization in mitosis (Gnazzo et al, 2016;Stubenvoll et al, 2016). Collectively, these observations are of note because there are strong parallels between organization of the cytoskeleton in mitosis and in neurons (Del Castillo et al, 2020;Cheerambathur et al, 2019;Hertzler et al, 2020;Lin et al, 2012;Norkett et al, 2020;Zhao et al, 2019). In mitosis, the cytoskeleton must be reorganized to facilitate chromosome separation and actin ring contraction (Basant and Glotzer, 2018;Mishima et al, 2002).…”