Mutations in subunits of mitochondrial m-AAA proteases in the inner membrane cause neurodegeneration in spinocerebellar ataxia (SCA28) and hereditary spastic paraplegia (HSP7). m-AAA proteases preserve mitochondrial proteostasis, mitochondrial morphology, and efficient OXPHOS activity, but the cause for neuronal loss in disease is unknown. We have determined the neuronal interactome of m-AAA proteases in mice and identified a complex with C2ORF47 (termed MAIP1), which counteracts cell death by regulating the assembly of the mitochondrial Ca(2+) uniporter MCU. While MAIP1 assists biogenesis of the MCU subunit EMRE, the m-AAA protease degrades non-assembled EMRE and ensures efficient assembly of gatekeeper subunits with MCU. Loss of the m-AAA protease results in accumulation of constitutively active MCU-EMRE channels lacking gatekeeper subunits in neuronal mitochondria and facilitates mitochondrial Ca(2+) overload, mitochondrial permeability transition pore opening, and neuronal death. Together, our results explain neuronal loss in m-AAA protease deficiency by deregulated mitochondrial Ca(2+) homeostasis.

The m-AAA Protease Associated with Neurodegeneration Limits MCU Activity in Mitochondria

PATRON, MARIA;PAGGIO, ANGELA;RIZZUTO, ROSARIO;DE STEFANI, DIEGO;
2016

Abstract

Mutations in subunits of mitochondrial m-AAA proteases in the inner membrane cause neurodegeneration in spinocerebellar ataxia (SCA28) and hereditary spastic paraplegia (HSP7). m-AAA proteases preserve mitochondrial proteostasis, mitochondrial morphology, and efficient OXPHOS activity, but the cause for neuronal loss in disease is unknown. We have determined the neuronal interactome of m-AAA proteases in mice and identified a complex with C2ORF47 (termed MAIP1), which counteracts cell death by regulating the assembly of the mitochondrial Ca(2+) uniporter MCU. While MAIP1 assists biogenesis of the MCU subunit EMRE, the m-AAA protease degrades non-assembled EMRE and ensures efficient assembly of gatekeeper subunits with MCU. Loss of the m-AAA protease results in accumulation of constitutively active MCU-EMRE channels lacking gatekeeper subunits in neuronal mitochondria and facilitates mitochondrial Ca(2+) overload, mitochondrial permeability transition pore opening, and neuronal death. Together, our results explain neuronal loss in m-AAA protease deficiency by deregulated mitochondrial Ca(2+) homeostasis.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11577/3206185
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