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Spinal Muscular Atrophy (SMA) is a neurodegenerative, inherited disease caused by an insufficient amount of functional Survival of Motor Neurone protein (SMN), though the exact mechanism underlying this is not fully understood. The primary function of SMN is assembling a ring of Sm proteins around small nuclear RNA (snRNA) in an early, cytoplasmic stage of small nuclear ribonucleoprotein (snRNP) biogenesis, a process essential in eukaryotes. SMN, together with several mRNA binding proteins, has been linked to neural transport of mRNA towards areas of growth in Motor neurons for local translation of transcripts. Previous research in our group has found that this may involve Coatomer protein-containing vesicles transported by Dynein and requiring the Sm family protein, SmB, for maintenance. Little is known, however, about what other proteins are also present and required for correct transport and localisation of these vesicles. To further investigate this, we have produced plasmids expressing each Sm protein tagged to fluorescent proteins to help track their behaviour, in some cases for the first time, and developed a detergent-free fractionation protocol to enrich for SMN containing vesicles, providing tools that can be used to further probe behaviour and interactions in the future. Using these approaches, SmN, a neural specific Sm protein, was identified to also be present in SMN-containing vesicles similarly to SmB. Analysis of the interactomes of different Sm proteins identified a novel interactor of SMN, Neurochondrin (NCDN), that appears to be required for the correct localisation of SMN in neural cells. NCDN was found to not associate with snRNPs, indicating an snRNP-independent interaction with SMN. NCDN and SMN both independently associated and co-enriched with Rab5, indicating a potential endocytic and cell polarity role for the interaction. This interaction has the potential to be key in SMA pathology and may have therapeutic potential.

Lens growth and development is a life-long process in which epithelial cells from the perimeter of the lens migrate towards the centre of the lens and follow a dynamic programme of differentiation and structured DNA and organelle degradation resulting in the optical clarity of the lens. Myotonic dystrophy type 1 (DM1) is a genetic disease resulting in multiple symptoms including skeletal muscle wasting, cardiac conduction defects, myotonia and endocrine system malfunction. DM1 is caused by an expanded CTG repeat in the 3' untranslated region (UTR) of the myotonic dystrophy protein kinase (DMPK) gene. Mutant DMPK RNA has been demonstrated to form abnormal foci within the cell nucleus in muscle cells from DM1 patients. The link between these foci and the multiple symptoms of DM1 is not fully understood. The alternative pre-mRNA splicing factor muscle blind-like 1 (MBNL1) is found in the foci and sequestration of MBNL1 is a leading hypothesis for pathogenesis. Results shown in this thesis demonstrate that only a small percentage of nuclear MBNL1 is sequestrated into foci. Furthermore MBNL1 is shown to co-localise with splicing speckles in a transcriptionally dependent manner. Interestingly eye lens histological samples suggest a change in MBNL1 distribution during lens growth. The data presented in this thesis shows a strong relationship between MBNL1 and CUGexp pre-mRNA foci and presents data which highlights the sensitivity of lens epitheial cells to changes in MBNL1.