Investigating the function and regulation of the neuronal ceroid lipofuscinosis protein Cln7 using Drosophila melanogaster

Connolly, Kyle John ORCID: 0000-0003-2425-3910 (2020). Investigating the function and regulation of the neuronal ceroid lipofuscinosis protein Cln7 using Drosophila melanogaster. University of Birmingham. Ph.D.

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Abstract

The neuronal ceroid lipofuscinoses (NCLs) are inherited lysosomal disorders that manifest in neurodegeneration, mainly affecting children. Such early pathology is suggestive of a role in neurodevelopment. However the roles of NCL genes within the nervous system are not well understood. Mutations to CLN7 were only discovered to cause NCL in 2007. Currently, few models exist to investigate the function of CLN7 at the molecular level. Here, I used a Drosophila model to accelerate our understanding of CLN7 function. Using an unbiased lipidomic analysis, I characterised a novel defect in sphingolipid metabolism resembling a block in sphingolipid degradation. Defects in sphingolipid degradation are characteristic of the sphingolipidoses, and pathological accumulations of sphingolipids are associated with age-related conditions, such as Alzheimer’s and Parkinson’s diseases. In addition, I established a proximity labelling tool for investigation of the CLN7 interactome in vitro and in vivo. Initial labelling in vitro identified several cytoskeletal proteins that function at the Drosophila neuromuscular junction (NMJ), where Cln7 is known to reside in vivo. Finally, I characterised a reduction in TORC1 activity in Cln7 mutant flies and cells. Interestingly, the Drosophila insulin receptor substrate, chico, was also identified by proximity labelling, suggesting a role for Cln7 in insulin signalling.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):