Mutations in SOD1 cause amyotrophic lateral sclerosis (ALS), an incurable motor neuron disease. The pathogenesis of the disease is poorly understood, but intracellular copper dyshomeostasis has been implicated as a key process in the disease. We recently observed that metallothioneins (MTs) are an excellent target for the modification of copper dyshomeostasis in a mouse model of ALS (SOD1G93A). Here, we offer a therapeutic strategy designed to increase the level of endogenous MTs. The upregulation of endogenous MTs by dexamethasone, a synthetic glucocorticoid, significantly improved the disease course and rescued motor neurons in SOD1G93A mice, even if the induction was initiated when peak body weight had decreased by 10 %. Neuroprotection was associated with the normalization of copper dyshomeostasis, as well as with decreased levels of SOD1G93A aggregates. Importantly, these benefits were clearly mediated in a MT-dependent manner, as dexamethasone did not provide any protection when endogenous MTs were abolished from SOD1G93A mice. In conclusion, the upregulation of endogenous MTs represents a promising strategy for the treatment of ALS linked to mutant SOD1.
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