SPG7 targets the m-AAA protease complex to process MCU for uniporter assembly, Ca2+ influx, and regulation of mitochondrial permeability transition pore opening.

Abstract

The mitochondrial matrix ATPase associated with diverse cellular activities (m-AAA) protease spastic paraplegia 7 (SPG7) has been recently implicated as either a negative or positive regulatory component of the mitochondrial permeability transition pore (mPTP) by two research groups. To address this controversy, we investigated possible mechanisms that explain the discrepancies between these two studies. We found that loss of the SPG7 gene increased resistance to Ca2+-induced mPTP opening. However, this occurs independently of cyclophilin D (cyclosporine A insensitive) rather it is through decreased mitochondrial Ca2+ concentrations and subsequent adaptations mediated by impaired formation of functional mitochondrial Ca2+ uniporter complexes. We found that SPG7 directs the m-AAA complex to favor association with the mitochondrial Ca2+ uniporter (MCU) and MCU processing regulates higher order MCU-complex formation. The results suggest that SPG7 does not constitute a core component of the mPTP but can modulate mPTP through regulation of the basal mitochondrial Ca2+ concentration.

• Authors: Stephen Hurst, Ariele Baggett, Gyorgy Csordas, Shey-Shing Sheu
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 294 Issue 28 Pg. 10807-10818 (07 12 2019) ISSN: 1083-351X [Electronic] United States
• PMID: 31097542 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)
• Copyright: © 2019 Hurst et al.

Chemical References

• Calcium Channels
• Mitochondrial Membrane Transport Proteins
• Mitochondrial Permeability Transition Pore
• mitochondrial calcium uniporter
• Metalloendopeptidases
• SPG7 protein, human
• m-AAA proteases
• Proton-Translocating ATPases
• ATPases Associated with Diverse Cellular Activities
• Calcium

Topics

• ATPases Associated with Diverse Cellular Activities (metabolism, physiology)
• Calcium (metabolism)
• Calcium Channels (metabolism)
• Cell Membrane Permeability (physiology)
• HEK293 Cells
• Humans
• Metalloendopeptidases (metabolism, physiology)
• Mitochondria (metabolism)
• Mitochondrial Membrane Transport Proteins (metabolism, physiology)
• Mitochondrial Membranes (metabolism)
• Mitochondrial Permeability Transition Pore
• Mitochondrial Transmembrane Permeability-Driven Necrosis (physiology)
• Paraplegia (metabolism)
• Proton-Translocating ATPases (metabolism)
• Spastic Paraplegia, Hereditary (metabolism)