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Why Move It When You Can Make It? Drosophila Neuronal Microtubule Polarity Requires Local Microtubule Nucleation
| Content Provider | Semantic Scholar |
|---|---|
| Author | Nguyen, Michelle M. |
| Copyright Year | 2013 |
| Abstract | The polarization of neurons into axons and dendrites is essential in building functional neuronal circuits. The arrangement of microtubules is an important factor in neuronal polarity, as microtubules are used for long-range trafficking of vesicles and other cargo, cytoskeletal structure, and synaptic growth. In vertebrate neurons, axonal microtubules are primarily plus-end-out, while dendritic microtubules have mixed polarity. In contrast, Drosophila melanogaster has a simpler arrangement of neuronal microtubules. In Drosophila neurons, microtubules have opposite orientation in axons and dendrites: axons have microtubules with plus ends distal to the soma, while dendrites have minus ends distal to the cell body. Due to this simplicity, Drosophila provides a good model for the study of neuronal microtubule polarity. The commonly accepted model for how neuronal microtubules are organized is that microtubules are nucleated from the centrosome in the cell body, severed into small pieces, and transported down axons and dendrites via microtubule sliding. Using Drosophila, this model was investigated in dendritic arborization neurons. First, the role of the centrosome, an organelle that is the primary microtubule nucleator and organizer in dividing cells, was tested, since it is a key component of the microtubule sliding mechanism. Immunostaining experiments showed that the centrosome was inactive in neurons compared to mitotic cells. Additionally, the increase in microtubule nucleation after axon severing did not originate from the centriole, a core centrosomal component, and neither disruption nor ablation of the centriole yielded any changes in microtubule dynamics in the neuron. Second, the existence of an axon initial segment in Drosophila was directly assayed. Previous studies have found that the axon initial segment serves as a cue for axon recognition and sorting by molecular motors, and thus the axon initial segment could play a role in microtubule sliding. However, although FRAP experiments confirm the presence of an ankyrinbased axon initial segment in Drosophila, disruption of this plasma membrane diffusion barrier did not change microtubule orientation in axons. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://etda.libraries.psu.edu/files/final_submissions/9204 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
