title: Mitochondrial biogenesis and fission in axons in cell culture and animal models of diabetic neuropathy.
abstract: Mitochondrial-mediated oxidative stress in response to high glucose is proposed as a primary cause of dorsal root ganglia (DRG) neuron injury in the pathogenesis of diabetic neuropathy. In the present study, we report a greater number of mitochondria in both myelinated and unmyelinated dorsal root axons in a well-established model of murine diabetic neuropathy. No similar changes were seen in younger diabetic animals without neuropathy or in the ventral motor roots of any diabetic animals. These findings led us to examine mitochondrial biogenesis and fission in response to hyperglycemia in the neurites of cultured DRG neurons. We demonstrate overall mitochondrial biogenesis via increases in mitochondrial transcription factors and increases in mitochondrial DNA in both DRG neurons and axons. However, this process occurs over a longer time period than a rapidly observed increase in the number of mitochondria in DRG neurites that appears to result, at least in part, from mitochondrial fission. We conclude that during acute hyperglycemia, mitochondrial fission is a prominent response, and excessive mitochondrial fission may result in dysregulation of energy production, activation of caspase 3, and subsequent DRG neuron injury. During more prolonged hyperglycemia, there is evidence of compensatory mitochondrial biogenesis in axons. Our data suggest that an imbalance between mitochondrial biogenesis and fission may play a role in the pathogenesis of diabetic neuropathy.
authors.affiliation: Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA. andreav@umich.edu
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Vincent
authors.forename: James L
authors.initials: JL
authors.lastname: Edwards
authors.forename: Lisa L
authors.initials: LL
authors.lastname: McLean
authors.forename: Yu
authors.initials: Y
authors.lastname: Hong
authors.forename: Federica
authors.initials: F
authors.lastname: Cerri
authors.forename: Ignazio
authors.initials: I
authors.lastname: Lopez
authors.forename: Angelo
authors.initials: A
authors.lastname: Quattrini
authors.forename: Eva L
authors.initials: EL
authors.lastname: Feldman
mesh_terms: D000367:Age Factors; D000818:Animals; D001369:Axons / Q000473:pathology / Q000648:ultrastructure*; D001786:Blood Glucose / Q000502:physiology; D002478:Cells, Cultured; D003929:Diabetic Neuropathies / Q000235:genetics / Q000473:pathology*; D004195:Disease Models, Animal; D005727:Ganglia, Spinal / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D005947:Glucose / Q000494:pharmacology; D006943:Hyperglycemia / Q000378:metabolism / Q000503:physiopathology; D051379:Mice; D008810:Mice, Inbred C57BL; D046529:Microscopy, Electron, Transmission / Q000379:methods; D008928:Mitochondria / Q000502:physiology*; D024101:Mitochondrial Proteins / Q000378:metabolism; D016501:Neurites / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009474:Neurons / Q000378:metabolism / Q000473:pathology*; D001678:Organelle Biogenesis; D018384:Oxidative Stress / Q000502:physiology; D010617:Phenanthridines; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D050994:Voltage-Dependent Anion Channels / Q000378:metabolism
chemical_list: C521281:5-(6'-triphenylphosphoniumhexyl)-5,6-dihydro-6-phenyl-3,8-phenanthridinediammine; D001786:Blood Glucose; D024101:Mitochondrial Proteins; D010617:Phenanthridines; D014157:Transcription Factors; D050994:Voltage-Dependent Anion Channels; D005947:Glucose
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