Absence of physiological Ca2+ transients is an initial trigger for mitochondrial dysfunction in skeletal muscle following denervation
| Autor: | Kaitao Li, Chehade N. Karam, Lin Zhang, Jianjie Ma, Kamal Dhakal, Xuejun Li, Jingsong Zhou, Heping Cheng, Carlo Manno, Jiejia Xu, Jianxun Yi, Yajuan Xiao |
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| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
Mitochondrial ROS medicine.medical_specialty lcsh:Diseases of the musculoskeletal system Calcium imaging Calcium intracellular release Biology Mitochondrion E-C coupling 03 medical and health sciences Internal medicine medicine Myocyte Orthopedics and Sports Medicine Molecular Biology Calcium signaling Denervation Skeletal muscle Cell Biology Muscle atrophy Mitochondria 030104 developmental biology Endocrinology medicine.anatomical_structure Mitochondrial permeability transition pore lcsh:RC925-935 medicine.symptom |
| Zdroj: | Skeletal Muscle, Vol 7, Iss 1, Pp 1-18 (2017) |
| ISSN: | 2044-5040 |
| DOI: | 10.1186/s13395-017-0123-0 |
| Popis: | Background Motor neurons control muscle contraction by initiating action potentials in muscle. Denervation of muscle from motor neurons leads to muscle atrophy, which is linked to mitochondrial dysfunction. It is known that denervation promotes mitochondrial reactive oxygen species (ROS) production in muscle, whereas the initial cause of mitochondrial ROS production in denervated muscle remains elusive. Since denervation isolates muscle from motor neurons and deprives it from any electric stimulation, no action potentials are initiated, and therefore, no physiological Ca2+ transients are generated inside denervated muscle fibers. We tested whether loss of physiological Ca2+ transients is an initial cause leading to mitochondrial dysfunction in denervated skeletal muscle. Methods A transgenic mouse model expressing a mitochondrial targeted biosensor (mt-cpYFP) allowed a real-time measurement of the ROS-related mitochondrial metabolic function following denervation, termed “mitoflash.” Using live cell imaging, electrophysiological, pharmacological, and biochemical studies, we examined a potential molecular mechanism that initiates ROS-related mitochondrial dysfunction following denervation. Results We found that muscle fibers showed a fourfold increase in mitoflash activity 24 h after denervation. The denervation-induced mitoflash activity was likely associated with an increased activity of mitochondrial permeability transition pore (mPTP), as the mitoflash activity was attenuated by application of cyclosporine A. Electrical stimulation rapidly reduced mitoflash activity in both sham and denervated muscle fibers. We further demonstrated that the Ca2+ level inside mitochondria follows the time course of the cytosolic Ca2+ transient and that inhibition of mitochondrial Ca2+ uptake by Ru360 blocks the effect of electric stimulation on mitoflash activity. Conclusions The loss of cytosolic Ca2+ transients due to denervation results in the downstream absence of mitochondrial Ca2+ uptake. Our studies suggest that this could be an initial trigger for enhanced mPTP-related mitochondrial ROS generation in skeletal muscle. |
| Databáze: | OpenAIRE |
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