Three-dimensional analysis of somatic mitochondrial dynamics in fission-deficient injured motor neurons using FIB/SEM

Hiromi Tamada, Sumiko Kiryu-Seo, Hiroki Hosokawa, Keisuke Ohta, Naotada Ishihara, Masatoshi Nomura, Katsuyoshi Mihara, Kei Ichiro Nakamura, Hiroshi Kiyama

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Mitochondria undergo morphological changes through fusion and fission for their quality control, which are vital for neuronal function. In this study, we examined three-dimensional morphologies of mitochondria in motor neurons under normal, nerve injured, and nerve injured plus fission-impaired conditions using the focused ion beam/scanning electron microscopy (FIB/SEM), because the FIB/SEM technology is a powerful tool to demonstrate both 3D images of whole organelle and the intra-organellar structure simultaneously. Crossing of dynamin-related protein 1 (Drp1) gene-floxed mice with neuronal injury-specific Cre driver mice, Atf3:BAC Tg mice, allowed for Drp1 ablation specifically in injured neurons. FIB/SEM analysis demonstrated that somatic mitochondrial morphologies in motor neurons were not altered before or after nerve injury. However, the fission impairment resulted in prominent somatic mitochondrial enlargement, which initially induced complex morphologies with round regions and long tubular processes, subsequently causing a decrease in the number of processes and further enlargement of the round regions, which eventually resulted in big spheroidal mitochondria without processes. The abnormal mitochondria exhibited several degradative morphologies: local or total cristae collapse, vacuolization, and mitophagy. These suggest that mitochondrial fission is crucial for maintaining mitochondrial integrity in injured motor neurons, and multiple forms of mitochondria degradation may accelerate neuronal degradation.

Original languageEnglish
Pages (from-to)2535-2548
Number of pages14
JournalJournal of Comparative Neurology
Volume525
Issue number11
DOIs
Publication statusPublished - Aug 1 2017

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

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