BATTEN DISEASE, MEMBRANE LIPIDS AND SIGNAL TRANSDUCTION

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The long-term objective of this research is to elucidate the primary biochemical and molecular defect that results in Juvenile Neuronal Ceroid-Lipofuscinosis (JNCL, Batten disease, Spielmeyer-Vogt-Sjogren disease). The NCL's are a group of severe untreatable inherited neurodegenerative diseases for which the basic defects remain unknown. Originally classified as a common group of disorders, recent molecular studies have demonstrated heterogeneity. This project will focus studies upon a homogeneous cohort of patients with JNCL, defined by linkage studies of the disease to chromosome 16, in whom we have documented a severe deficiency of circulating erythrocyte and platelet membrane phospholipids. We have developed a model, based upon cultured skin fibroblasts to study membrane phospholipids and phospholipid-dependant membrane functions. We will present preliminary data and outline further experiments to confirm that cultured cells express the disease process both in terms of abnormal accumulation of storage material and membrane phospholipid deficiency. We propose to use this model to study the effects of in vitro perturbations with polyunsaturated fatty acids (PUFA's) as there is growing in vivo evidence to suggest that PUFA supplementation is clinically beneficial in JNCL and its animal, model canine NCL. We will use our model to probe important phospholipid-dependant membrane functions with particular reference to signal transduction and the activities and genetic expression of the protein kinase C (PKC) gene families. The PKC's are an important enzymes in the regulation of signal transduction. These are highly dependant upon, and may regulate, normal membrane phospholipid remodeling processes. We will present preliminary evidence and a research strategy to demonstrate a failure of PKC membrane translocation in our JNCL fibroblast cell lines, and propose that a defect in PKC may be the primary defect in JNCL. We will also present a strategy to evaluate a PKC gene family residing on chromosome 16 (within the region linked to the JNCL gene) and to test the hypothesis that a mutation affecting a novel PKC isozyme is a candidate gene for JNCL. Knowledge of the biochemical and molecular cause of JNCL will allow us to develop new strategies for diagnosis and treatment. The studies will provide more fundamental information regarding the function and metabolism of PKC and membrane phospholipids.