Heffner, Catherine;
(2023)
ESCRT-Mediated Membrane Repair in Neurodegenerative Disease.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
C-terminal truncating mutations in the ESCRT-III protein, CHMP2B have been associated with frontotemporal dementia (FTD). While research has identified autophagic, endolysosomal, and synaptic defects as key underlying neuropathologies, the causative mechanisms linking CHMP2B mutations to FTD are thus far unknown. ESCRTs are known to mediate the repair of damaged endolysosomal and plasma membranes. However, the impact of CHMP2B C-truncating mutations on ESCRT-mediated membrane repair kinetics is yet to be investigated. I hypothesized that CHMP2B C-truncating mutations lead to FTD via defects in ESCRT-mediated membrane repair. I generated cell lines stably expressing GFP-tagged versions of CHMP2B and used them to study recruitment kinetics to damaged plasma membrane via laser wounding, and to damaged lysosomal membranes via treatment with LLOMe. These data suggest that mutant versions of CHMP2B have a delayed and prolonged recruitment to damaged membrane. I provide rationale for these defects via investigations of CHMP2B’s C-terminus which suggest that loss of nuclear export signals alters CHMP2B’s subcellular localization, and that loss of a MIM, which mediates interaction with VPS4, prevents CHMP2B’s dissociation from the membrane. I predicted that these defects in mutant CHMP2B recruitment to damaged membrane would affect membrane sealing. However, further analysis demonstrated that CHMP2B recruitment to damaged membrane is temporally and functionally distinct from membrane sealing. Following this observation, I investigated upstream effectors of ESCRT mediated repair and found that the ALS-associated protein, ANXA A11, recruits prior to ESCRTs and may facilitate ESCRT recruitment via interaction with the ESCRT-associated protein, ALG-2. I argue that together these data support a role for CHMP2B in long-term remodelling of the membrane after wounding, which is lost in CHMP2B-FTD and may contribute to underlying disease pathologies.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | ESCRT-Mediated Membrane Repair in Neurodegenerative Disease |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | © The Author(s). This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10173406 |
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