Tissue expression and subcellular localization of CLN3, the Batten diseaseprotein

Juvenile neuronal ceroid lipofuscinosis (Batten disease) is a progressive n eurologic disorder which results from mutations in the CLN3 gene, which nor mally produces a 48-kDa polypeptide of unknown function. To help characteri ze the CLN3 protein, we have studied its tissue distribution and subcellula r localization in human tissues using three epitope-specific polyclonal ant ibodies to human CLN3 by immunoblot, immunocytochemical, and immunoelectron microscopic analysis. The most abundant CLN3 protein expression was in the gray matter of the brain, where it was localized to astrocytes, capillary endothelium, and neurons. CLN3 was also evident in peripheral nerve, in pan creatic islet cells, and within the seminiferous tubules in the testis. Sta ining was generally diffuse within the cytoplasm with some nuclear reactivi ty. Subcellular localization identified the CLN3 protein within the nucleus and along cell membranes. These results were contrasted with the cellular distribution of palmitoyl-protein thioesterase (PPT), the enzyme whose defi ciency is responsible for infantile neuronal ceroid lipofuscinosis (CLN1). PPT was most abundant in brain and visceral macrophages where it displayed a coarse granular staining pattern typical of lysosomal distribution. Immun oelectron microscopy confirmed that PPT immunoreactivity was limited to lys osomes. (C) 1999 Academic Press.