Thesis
Molecular analysis of zDHHC9 and its links to physiology and pathophysiology
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2025
- Thesis identifier
- T17446
- Person Identifier (Local)
- 202077153
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- S-Acylation is a reversible protein modification that is mediated by a family of 23 “zDHHC” enzymes. zDHHC9 is important for brain physiology, and mutations in the gene encoding this enzyme cause intellectual disability and epilepsy. This thesis aimed to shine new light on the interaction of zDHHC9 with its accessory protein, GCP16, to explore how mutations in ZDHHC9 that cause brain dysfunction affect the zDHHC9-GCP16 interaction, and to further investigate how ZDHHC9 loss-of-function might lead to clinical phenotypes. Cycloheximide chase experiments revealed that the zDHHC9-GCP16 interaction promotes stabilisation of each protein. The stabilisation of zDHHC9 was dependent on GCP16 being S-acylated. Click chemistry assays revealed that zDHHC9 catalysed the S-acylation of GCP16, and that GCP16 also stabilised the S-acylated state of zDHHC9. Thus, both the protein stability and S-acylation of zDHHC9 and GCP16 are modulated by the zDHHC9-GCP16 interaction. The R96W substitution in zDHHC9 causes intellectual disability, and work in this thesis showed that this change perturbed both the catalytic activity against GCP16 and the S-acylated state of zDHHC9. AlphaFold predictions suggested that R96W disrupts hydrogen bonding between this region of zDHHC9 and the active site of the enzyme, providing a potential molecular explanation for its loss of activity. Finally, providing Zdhhc9 knockout mice with a ketogenic diet to mimic GLUT1 deficiency treatment led to metabolic profiles that aligned with GLUT1 deficiency models. This suggests that Zdhhc9 loss may impair GLUT1 function, which could underlie some of the symptoms seen in patients with ZDHHC9 mutations, and that this might be possible to manage through dietary intervention. Overall, these findings establish GCP16 as a critical regulator of zDHHC9 stability and activity, provide new insight into molecular perturbations of disease-causing ZDHHC9 mutants, and uncover a novel phenotype following dietary intervention with Zdhhc9 knockout mice.
- Advisor / supervisor
- Chamberlain, Luke
- Resource Type
- DOI
Relazioni
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PDF of thesis T17446. | 2025-09-17 | Pubblico | Scaricare |