Power Grid Protection of the Muscle Mitochondrial Reticulum

Publication date: 18 April 2017
Source:Cell Reports, Volume 19, Issue 3
Author(s): Brian Glancy, Lisa M. Hartnell, Christian A. Combs, Armel Fenmou, Junhui Sun, Elizabeth Murphy, Sriram Subramaniam, Robert S. Balaban
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.

Graphical abstract

Teaser

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.


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