Ceruloplasmin gene expression in the murine central nervous system

Aceruloplasminemia is an autosomal recessive disorder resulting in neurodegeneration of the retina and basal ganglia in association with iron accumulation in these tissues. To begin to define the mechanisms of central nervous system iron accumulation and neuronal loss in this disease, cDNA clones encoding murine ceruloplasmin were isolated and characterized. RNA blot analysis using these clones detected a 3.7-kb ceruloplasmin-specific transcript in multiple murine tissues including the eye and several regions of the brain. In situ hybridization of systemic tissues revealed cell-specific ceruloplasmin gene expression in hepatocytes, the splenic reticuloendothelial system and the bronchiolar epithelium of the lung. In the central nervous system, abundant ceruloplasmin gene expression was detected in specific populations of astrocytes within the retina and the brain as well as the epithelium of the choroid plexus. Analysis of primary cell cultures confirmed that astrocytes expressed ceruloplasmin mRNA and biosynthetic studies revealed synthesis and secretion of ceruloplasmin by these cells. Taken together these results demonstrate abundant cell-specific ceruloplasmin expression within the central nervous system which may account for the unique clinical and pathologic findings observed in patients with aceruloplasminemia.