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Eid SA, Rumora AE, Beirowski B, Bennett DL, Hur J, Savelieff MG, Feldman EL. New perspectives in diabetic neuropathy. Neuron 2023; 111:2623-2641. [PMID: 37263266 PMCID: PMC10525009 DOI: 10.1016/j.neuron.2023.05.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 04/20/2023] [Accepted: 05/03/2023] [Indexed: 06/03/2023]
Abstract
Diabetes prevalence continues to climb with the aging population. Type 2 diabetes (T2D), which constitutes most cases, is metabolically acquired. Diabetic peripheral neuropathy (DPN), the most common microvascular complication, is length-dependent damage to peripheral nerves. DPN pathogenesis is complex, but, at its core, it can be viewed as a state of impaired metabolism and bioenergetics failure operating against the backdrop of long peripheral nerve axons supported by glia. This unique peripheral nerve anatomy and the injury consequent to T2D underpins the distal-to-proximal symptomatology of DPN. Earlier work focused on the impact of hyperglycemia on nerve damage and bioenergetics failure, but recent evidence additionally implicates contributions from obesity and dyslipidemia. This review will cover peripheral nerve anatomy, bioenergetics, and glia-axon interactions, building the framework for understanding how hyperglycemia and dyslipidemia induce bioenergetics failure in DPN. DPN and painful DPN still lack disease-modifying therapies, and research on novel mechanism-based approaches is also covered.
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Affiliation(s)
- Stephanie A Eid
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI 48109, USA
| | - Amy E Rumora
- Department of Neurology, Columbia University, New York, NY 10032, USA
| | - Bogdan Beirowski
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA; Neuroscience Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - David L Bennett
- Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford OX3 9DU, UK
| | - Junguk Hur
- Department of Biomedical Sciences, University of North Dakota, Grand Forks, ND 58202, USA
| | - Masha G Savelieff
- Department of Biomedical Sciences, University of North Dakota, Grand Forks, ND 58202, USA
| | - Eva L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; NeuroNetwork for Emerging Therapies, University of Michigan, Ann Arbor, MI 48109, USA.
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Dustin E, McQuiston AR, Honke K, Palavicini JP, Han X, Dupree JL. Adult-onset depletion of sulfatide leads to axonal degeneration with relative myelin sparing. Glia 2023; 71:2285-2303. [PMID: 37283058 PMCID: PMC11007682 DOI: 10.1002/glia.24423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 05/10/2023] [Accepted: 05/12/2023] [Indexed: 06/08/2023]
Abstract
3-O-sulfogalactosylceramide (sulfatide) constitutes a class of sphingolipids that comprise about 4% of myelin lipids in the central nervous system. Previously, our group characterized a mouse with sulfatide's synthesizing enzyme, cerebroside sulfotransferase (CST), constitutively disrupted. Using these mice, we demonstrated that sulfatide is required for establishment and maintenance of myelin, axoglial junctions, and axonal domains and that sulfatide depletion results in structural pathologies commonly observed in Multiple Sclerosis (MS). Interestingly, sulfatide is reduced in regions of normal appearing white matter (NAWM) of MS patients. Sulfatide reduction in NAWM suggests depletion occurs early in disease development and consistent with functioning as a driving force of disease progression. To closely model MS, an adult-onset disease, our lab generated a "floxed" CST mouse and mated it against the PLP-creERT mouse, resulting in a double transgenic mouse that provides temporal and cell-type specific ablation of the Cst gene (Gal3st1). Using this mouse, we demonstrate adult-onset sulfatide depletion has limited effects on myelin structure but results in the loss of axonal integrity including deterioration of domain organization accompanied by axonal degeneration. Moreover, structurally preserved myelinated axons progressively lose the ability to function as myelinated axons, indicated by the loss of the N1 peak. Together, our findings indicate that sulfatide depletion, which occurs in the early stages of MS progression, is sufficient to drive the loss of axonal function independent of demyelination and that axonal pathology, which is responsible for the irreversible loss of neuronal function that is prevalent in MS, may occur earlier than previously recognized.
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Affiliation(s)
- E Dustin
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, Virginia, USA
- Research Service, Central Virginia Veterans Affairs Health Care Systems, Richmond, Virginia, USA
| | - A R McQuiston
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - K Honke
- Department of Biochemistry, Kochi University Medical School, Kochi, Japan
| | - J P Palavicini
- Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
- Barshop Institute for Longevity and Aging Studies, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - X Han
- Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
- Barshop Institute for Longevity and Aging Studies, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - J L Dupree
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, Virginia, USA
- Research Service, Central Virginia Veterans Affairs Health Care Systems, Richmond, Virginia, USA
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Metabolic and Cellular Compartments of Acetyl-CoA in the Healthy and Diseased Brain. Int J Mol Sci 2022; 23:ijms231710073. [PMID: 36077475 PMCID: PMC9456256 DOI: 10.3390/ijms231710073] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 08/29/2022] [Accepted: 08/31/2022] [Indexed: 11/25/2022] Open
Abstract
The human brain is characterised by the most diverse morphological, metabolic and functional structure among all body tissues. This is due to the existence of diverse neurons secreting various neurotransmitters and mutually modulating their own activity through thousands of pre- and postsynaptic interconnections in each neuron. Astroglial, microglial and oligodendroglial cells and neurons reciprocally regulate the metabolism of key energy substrates, thereby exerting several neuroprotective, neurotoxic and regulatory effects on neuronal viability and neurotransmitter functions. Maintenance of the pool of mitochondrial acetyl-CoA derived from glycolytic glucose metabolism is a key factor for neuronal survival. Thus, acetyl-CoA is regarded as a direct energy precursor through the TCA cycle and respiratory chain, thereby affecting brain cell viability. It is also used for hundreds of acetylation reactions, including N-acetyl aspartate synthesis in neuronal mitochondria, acetylcholine synthesis in cholinergic neurons, as well as divergent acetylations of several proteins, peptides, histones and low-molecular-weight species in all cellular compartments. Therefore, acetyl-CoA should be considered as the central point of metabolism maintaining equilibrium between anabolic and catabolic pathways in the brain. This review presents data supporting this thesis.
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