Regulation of polarised trafficking by Klp98A
type: CreativeWork
description: Directional trafficking of cargo, a hallmark of living cells, relies on a polarised landscape of microtubule tracks. Here, I studied how the regulation of an endosomal motor affects polarised trafficking, using the asymmetric division of *Drosophila* Sensory Organ Precursor (SOP) cells as a model system. In this pathway, the PI(3)P-binding kinesin-3, Klp98A biases the motility of signalling endosomes towards the posterior daughter cell. Since these endosomes contain the cell fate determinants Notch and Delta, this contributes to an asymmetric cell fate. Mechanistically, Klp98A-mediated transport is achieved along the microtubule-based anaphase-specific spindle midzone, termed the central spindle. During SOP division, the central spindle becomes asymmetric, with a higher density of microtubules on the anterior side. Since Klp98A is a plus-end directed motor, this biases the motility of early endosomes into the posterior daughter cell, towards which more microtubule plus-ends point. In this work, I focused on how the modulation of Klp98A activity can control polarised trafficking on three levels: i) via post-translational modifications, ii) through changes in microtubule binding, and iii) by polarising the microtubules Klp98A walks on. By first using an *in vitro* reconstitution with purified motors on micropatterned supported lipid bilayers containing PI(3)P, I investigated how Klp98A is activated. Lipid-binding was sufficient to induce activation of Klp98A, so I proceeded to use both enzymatic-induced proximity labelling and a candidate-based approach to identify possible regulators of Klp98A activity. *In vivo*, modulation of two enzymes, p-21 activated kinase 1 (Pak1) and Sirtuin 2 (Sirt2), resulted in symmetric endosome segregation despite an asymmetric landscape of microtubule tracks. In the case of Pak1, this endosomal phenotype appeared to arise due to a delay in the targeting of endosomes to the central spindle, either directly due to modulation of post-trans…
abstract: Directional trafficking of cargo, a hallmark of living cells, relies on a polarised landscape of microtubule tracks. Here, I studied how the regulation of an endosomal motor affects polarised trafficking, using the asymmetric division of *Drosophila* Sensory Organ Precursor (SOP) cells as a model system. In this pathway, the PI(3)P-binding kinesin-3, Klp98A biases the motility of signalling endosomes towards the posterior daughter cell. Since these endosomes contain the cell fate determinants Notch and Delta, this contributes to an asymmetric cell fate. Mechanistically, Klp98A-mediated transport is achieved along the microtubule-based anaphase-specific spindle midzone, termed the central spindle. During SOP division, the central spindle becomes asymmetric, with a higher density of microtubules on the anterior side. Since Klp98A is a plus-end directed motor, this biases the motility of early endosomes into the posterior daughter cell, towards which more microtubule plus-ends point. In this work, I focused on how the modulation of Klp98A activity can control polarised trafficking on three levels: i) via post-translational modifications, ii) through changes in microtubule binding, and iii) by polarising the microtubules Klp98A walks on. By first using an *in vitro* reconstitution with purified motors on micropatterned supported lipid bilayers containing PI(3)P, I investigated how Klp98A is activated. Lipid-binding was sufficient to induce activation of Klp98A, so I proceeded to use both enzymatic-induced proximity labelling and a candidate-based approach to identify possible regulators of Klp98A activity. *In vivo*, modulation of two enzymes, p-21 activated kinase 1 (Pak1) and Sirtuin 2 (Sirt2), resulted in symmetric endosome segregation despite an asymmetric landscape of microtubule tracks. In the case of Pak1, this endosomal phenotype appeared to arise due to a delay in the targeting of endosomes to the central spindle, either directly due to modulation of post-trans…
author: Bittleston, Alice
language: eng
keywords: Asymmetric Cell Division, Kinesin, Klp98A, Microtubule, Mitosis, Polarised Trafficking
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/84906cc4-1d30-4545-a51d-a93feeebf29a/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2023-08-31
date modified: 2026-07-22T22:24:18Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.108143