Electron tomographic analysis reveals ultrastructural features of mitochondrial cristae architecture which reflect energetic state and aging

Abstract

Within mitochondria, the ability to produce energy relies upon the architectural hallmarks of double membranes and cristae invaginations. Herein, we describe novel features of mitochondrial cristae structure, which correspond to the energetic state of the organelle. In concordance with high-energy demand, mitochondria of Drosophila indirect flight muscle exhibited extensive intra-mitochondrial membrane switches between densely packed lamellar cristae that resulted in a spiral-like cristae network and allowed for bidirectional matrix confluency. This highly interconnected architecture is expected to allow rapid equilibration of membrane potential and biomolecules across integrated regions. In addition, mutant flies with mtDNA replication defect and an accelerated aging phenotype accumulated mitochondria that contained subsections of swirling membrane alongside normal cristae. The swirling membrane had impaired energy production capacity as measured by protein composition and function. Furthermore, mitochondrial fusion and fission dynamics were affected in the prematurely aged flies. Interestingly, the normal cristae that remained in the mitochondria with swirling membranes maintained acceptable function that camouflaged them from quality control elimination. Overall, structural features of mitochondrial cristae were described in three-dimension from serial section electron tomographic analysis which reflect energetic state and mtDNA-mediated aging.

Mitochondrial cristae biogenesis coordinates with ETC complex IV assembly during Drosophila maturation

“…to be what was observed in the matured flies ( Fig 1b) (Jiang et al, 2017b). The 77 mitochondrial protein abundance during maturation was analyzed.…”

“…contain only scarce lamellar cristae in the indirect flight muscle (IFM). Upon eclosion, 62 mitochondria undergo development and establish densely arranged lamellar cristae 63 that form connective membrane networks (Jiang, Lin et al, 2017b). It provides a 64…”

Connecting mitochondrial dynamics and life-or-death events via Bcl-2 family proteins

“…Complete fusions are believed to result from the merge of two mitochondria moving towards each other along the same microtubule, and transient fusion events occur between mitochondria traveling along separate microtubules (Liu et al, 2009). In this latter case, merging mitochondria first appear to quickly engage oblique interactions before undergoing Drp1-induced fission due to the pulling forces exerted by the microtubule motor proteins, in a transient or kiss-and-run manner, and the mechanisms are currently under investigation (Jiang et al, 2017; Lavorato et al, 2017; Picard et al, 2015). …”

3D Mitochondrial Ultrastructure of <em>Drosophila</em> Indirect Flight Muscle Revealed by Serial-section Electron Tomography

“…We applied serial-section electron tomography to analyze structural features of mitochondrial cristae that reflects its energetic state and aging. We showed that mitochondria of Drosophila IFM form an integrated cristae and matrix network in 3D ( Figure 4 ) 7 . In addition, mutant flies with mitochondrial DNA replication defect and an accelerated aging phenotype accumulated mitochondria that contained subsections of onion-like swirling core ( Figure 5 ) 7 .…”

“…Here, we describe the application of serial-section electron tomography to study mitochondrial ultrastructure of Drosophila indirect flight muscle (IFM) 6 7 8 9 . In order to obtain 3D reconstructions covering entire mitochondria (approximately 2.5 µm-thick), serial sections were obtained from Drosophila IFM tissue blocks.…”