Molecular and cellular basis of childhood-onset neurodegenerative disorders

Alzahrani, Ahmad (2025). Molecular and cellular basis of childhood-onset neurodegenerative disorders. University of Birmingham. Ph.D.

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Abstract

The neuronal ceroid lipofuscinoses (NCL) are a group of inherited progressive neurodegenerative diseases with variable ages of onset and a group of inherited lysosomal storage disorders that affect the brain and retina. One of the NCL disease genes is CLN7, which encodes a lysosomal membrane protein. The function of the CLN7 protein requires further study to discover how it functions in the lysosomal membrane and at synapses. Mutations in Drosophila CLN7 leads to developmental abnormalities in synapses but it is not clear how CLN7 operates at the synapse. One method of investigating CLN7 function is to identify its partner proteins in membrane complexes. Proximity labelling using BioID was used Drosophila cells in vitro to proteins neighbouring CLN7. CLN7 was seen to interact with multiple proteins, in particular with many related to cytoskeleton function, with proteins present at the Drosophila neuromuscular junction where CLN7 is also resident, and with glial proteins. However, the BioID technique proved impossible to apply in vivo in Drosophila. Therefore, I used a second-generation proximity labelling variant technique, TurboID, in both Drosophila S2 cells and in vivo in both Drosophila larval and adult stages. TurboID proximity labelling identified numerous CLN7-interacting proteins related to the cytoskeleton, synapse and plasma membrane. Several of these overlapped with the previous experiments. My experiments have identified key protein partners for CLN7 that will help discover how CLN7 functions at the synapse to regulate neural development.
For the role of CLN7 in Drosophila growth and development, I have shown that CLN7 mutant flies are larger than controls with potential dysregulation of mTORC signalling underpinning the dysregulation of growth and neurodevelopment.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):