MUTATION ANALYSIS AND EXPRESSION OF THE MOTTLED GENE IN THE MACULAR MOUSE MODEL OF MENKES DISEASE

The gene for Menkes disease, an X-linked disorder of copper transport, has recently been identified and shown to encode a copper-transportin g P-type ATPase. The macular mutant mouse has; been proposed as an ani mal model for Menkes disease. In the present study, we report the find ing of a missense mutation in the mottled gene of the macular mouse. A single base change, T to C, at nucleotide position 4223, is predicted to result in an amino acid change from serine to proline at residue 1 382 in the eighth transmembrane domain, This mutation differs from the 6-bp deletion we find in brindled cDNA. With validation of macular as an animal model of Menkes disease, we compared mottled gene expressio n in the intestine, kidney, and brain of macular and normal mice. La N orthern analyses an 8.3-kb transcript was detected in the intestine, k idney, and brain of both normal and macular mice, with the level of tr anscript in macular approximately 80% that of normal, In situ hybridiz ation studies revealed that the mottled gene was clearly expressed in intestinal epithelial cells, Paneth cells, and renal proximal tubular cells of both normal and macular mice. In normal brain, mottled gene e xpression was most intensely observed in the choroid plexus, in Ammon' s horn and the dentate: gyrus in the hippocampus. in Purkinje cells, a nd the granular layer of the cerebellum. The intensity and localizatio n of the signals in the brain of macular mice were similar to those of the controls. The distribution of expression of mottled is correlated with cells and tissues showing histopathology or abnormal copper sequ estration in macular and other mutants.