Proceedings of The Physiological Society
King's College London (2011) Proc Physiol Soc 22, PC32
Characterisation of Late Infantile Neuronal Ceroid Lipofuscinosis gene CLN7 using Drosophila as a model organism
M. O'Hare1, R. I. Tuxworth1, G. Tear1
1. MRC Centre for Dev Neurobio, King's College London, London, United Kingdom.
Neuronal ceroid lipofuscionsis (NCL) disorders are a collection of childhood neurodegenerative diseases that fall into the larger category of lysosomal storage disorders. The different variants of the disease are defined by their age of onset with the most aggressive affecting children in their first year of life. The genes affected in ten of these disorders have been identified, the most recent of which is CLN7. Mutations in CLN7 cause late infantile NCL which follows the classical pathology of the other NCLs and exhibits the hallmark accumulation of autofluorescent pigment in all tissues, although as is seen in all the variant forms, only neuronal loss is observed. Very little is understood of the normal function of CLN7 nor how its mutation leads to disease. Drosophila has an orthologue of CLN7 and we hope to gain clues to the human disease by utilising the advantages of Drosophila to study the gene’s function. CLN7 is a 12 pass transmembrane protein. We have shown both human and fly CLN7 resides within the membrane of acidic vesicles when expressed in Drosophila derived BG3 cell lines, we also show that when Drosophila CLN7 is driven in primary cultured neuronal cells it co-localises with lysotracker in acidic vesicles. We have conducted a large-scale p-element excision screen to create a gene deficiency. From 750 excision lines we have 3 imprecise excision lines which carry varying sizes of deletion in the CLN7 locus but retain the surrounding genetic material. All 3 lines are homozygous viable. Our examination of the cln7-MB3 allele shows significantly decreased number of boutons at the neuromuscular junction (n=16, mean 14) compared with wild type (n=13, mean 19) using Mann-Whitney test. Combined with the localisation data, the results at the neuromuscular junction appear to suggest CLN7 plays a role in synaptic trafficking controlling bouton growth regulation.
Where applicable, experiments conform with Society ethical requirements