CLN3 AND SUBUNIT 9 GENES AND NEURONAL SURVIVAL

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Batten's disease comprises the late infantile and juvenile types of neuronal ceroid-lipofuscinosis(LINCL and JNCL). The underlying pathophysiology of this group of diseases remains poorly understood. The determination of the responsible genetic defects at a molecular level will 1) explain heterogeneity between and within clinical subtypes; 2) revolutionize diagnostic methods by providing subtype-specific carrier and prenatal detection; 3) provide valuable insight into mechanisms of rapid neuronal cell death and the role of defective gene products in the developing nervous system. Detailed clinical and linkage studies by the investigator have established LINCL and JNCL as two distinct entities. We have shown JNCL to be linked to the haptoglobin locus. LINCL has been and will remain a poor substrate for linkage studies as the number of multiaffected families are limited due to the early demise of these patients. Fortunately, recent biochemical evidence on accumulation in the lysosome of subunit-9 of ATP synthase and dolichyl-pyrophosphate oligosaccharides that have already undergone processing implicates at least one of four genes in the pathogenesis of Batten's disease: These are the two genes coding for the precursors of subunit-9 of mitochondrial ATP synthase and the genes for microsomal glucosidase and glucosidase II. This application proposes to 1) clone the normal cDNAs for subunit-9 and study regulation of subunit-9 expression in humans by "anchored PCR" and Northern blot analysis; 2) determine the type and level of expression of subunit-9 in LINCL using the normal cDNAs as probes, detect mutations in the cDNAs for subunit-9 in LINCL by cloning and sequencing., and to confirm the occurrence of these mutations in genomic DNA from LINCL patients in single or double dose by allele-specific hybridization; 3) determine activity levels of microsomal glucosidase I and II in LINCL and JNCL by developing assay methods in human fibroblasts and lymphoblasts using colorimetric and radioactive substrates; 4) determine the effects of microsomal glucosidase I and II activity on subunit-9 accumulation in normal and Batten cell lines by Western Blot and ELISA using an affinity purified subunit-9-specific antibody. It is hoped that these studies will provide important and novel information on the etiology and pathogenesis of Batten's disease.