Power Grid Protection of the Muscle Mitochondrial Reticulum

Mitochondrial network connectivity enables rapid communication and distribution of potential energy throughout the cell. However, this connectivity puts the energy conversion system at risk, because damaged elements could jeopardize the entire network. Here, we demonstrate the mechanisms for mitocho...

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Bibliographic Details
Published in:	Cell reports (Cambridge) 2017-04, Vol.19 (3), p.487-496
Main Authors:	Glancy, Brian, Hartnell, Lisa M., Combs, Christian A., Femnou, Armel, Sun, Junhui, Murphy, Elizabeth, Subramaniam, Sriram, Balaban, Robert S.
Format:	Article
Language:	eng
Subjects:	3D electron microscopy Animals energy distribution Energy Metabolism Male Membrane Potential, Mitochondrial Mice, Inbred C57BL Mitochondria, Heart - metabolism Mitochondria, Heart - ultrastructure Mitochondria, Muscle - metabolism Mitochondria, Muscle - ultrastructure mitochondrial dynamics mitochondrial retraction muscle energetics oxidative phosphorylation
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Summary:	Mitochondrial network connectivity enables rapid communication and distribution of potential energy throughout the cell. However, this connectivity puts the energy conversion system at risk, because damaged elements could jeopardize the entire network. Here, we demonstrate the mechanisms for mitochondrial network protection in heart and skeletal muscle (SKM). We find that the cardiac mitochondrial reticulum is segmented into subnetworks comprising many mitochondria linked through abundant contact sites at highly specific intermitochondrial junctions (IMJs). In both cardiac and SKM subnetworks, a rapid electrical and physical separation of malfunctioning mitochondria occurs, consistent with detachment of IMJs and retraction of elongated mitochondria into condensed structures. Regional mitochondrial subnetworks limit the cellular impact of local dysfunction while the dynamic disconnection of damaged mitochondria allows the remaining mitochondria to resume normal function within seconds. Thus, mitochondrial network security is comprised of both proactive and reactive mechanisms in striated muscle cells. [Display omitted] •Mitochondrial networks are functionally linked through intermitochondrial junctions•Regional mitochondrial subnetworks proactively limit spread of local dysfunction•Dysfunctional mitochondria are electrically separated from the network in seconds•Physical network separation involves mitochondrial retraction Network connectivity allows information sharing and distribution but also enables propagation of localized dysfunction. Glancy et al. demonstrate the existence of both proactive and reactive network protection mechanisms designed to minimize the spread of dysfunction throughout the coupled mitochondrial networks in heart and skeletal muscle cells.
ISSN:	2211-1247 2211-1247