The Mammalian Degenerin MDEG, an Amiloride-sensitive Cation Channel Activated by Mutations Causing Neurodegeneration in Caenorhabditis elegans(∗)

Mutations of the degenerins (deg-1, mec-4, mec-10) are the major known causes of hereditary neurodegeneration in the nematode Caenorhabditis elegans. We cloned a neuronal degenerin (MDEG) from human and rat brain. MDEG is an amiloride-sensitive cation channel permeable for Na⁺, K⁺, and Li⁺. This channel is activated by the same mutations which cause neurodegeneration in C. elegans. Like the hyperactive C. elegans degenerin mutants, constitutively active mutants of MDEG cause cell death, suggesting that gain of function of this novel neuronal ion channel might be involved in human forms of neurodegeneration.