A murine model of Menkes disease reveals a physiological function of metallothionein

Abstract
Human Menkes disease and the murine Mottled phenotype are X-linked diseases that result from copper deficiency due to mutations in a copper-effluxing ATPase, designated ATP7A1–5. Male mice with the Mottled-Brindled allele (Mo-brJ) accumulate copper in the intestine, fail to export copper to peripheral organs and die a few weeks after birth. Much of the intestinal copper is bound by metallothionein (MT)6. To determine the function of MT in the presence of Atp7a deficiency, we crossed Mo-brJ females with males that bear a targeted disruption of the Mt1 and Mt2 genes (Mt −/−)7. On an Mt −/− background, most Mo-brJ males as well as heterozygous Mo-brJ females die before embryonic day 11. The lethality in Mo-brJ females can be explained by preferential inactivation of the paternal X chromosome in extraembryonic tissues8 and resultant copper toxicity in the absence of MT. In support of this hypothesis, cell lines derived from Mt−/−, Mo-brJ embryos are very sensitive to copper toxicity.