Programmed neurite degeneration in human central nervous system neurons driven by changes in NAD+ metabolism

Abstract Neurite degeneration (ND) precedes cell death in many neurodegenerative diseases. However, it remains unclear how this compartmentalized cell death process is orchestrated in the central nervous system (CNS). The establishment of a CNS axotomy model (using modified 3D LUHMES cultures) allow...

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Main Authors: Markus Brüll, Selina Multrus, Michael Schäfer, Ivana Celardo, Christiaan Karreman, Marcel Leist
Format: Article
Language:English
Published: Nature Publishing Group 2025-01-01
Series:Cell Death and Disease
Online Access:https://doi.org/10.1038/s41419-024-07326-w
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author Markus Brüll
Selina Multrus
Michael Schäfer
Ivana Celardo
Christiaan Karreman
Marcel Leist
author_facet Markus Brüll
Selina Multrus
Michael Schäfer
Ivana Celardo
Christiaan Karreman
Marcel Leist
author_sort Markus Brüll
collection DOAJ
description Abstract Neurite degeneration (ND) precedes cell death in many neurodegenerative diseases. However, it remains unclear how this compartmentalized cell death process is orchestrated in the central nervous system (CNS). The establishment of a CNS axotomy model (using modified 3D LUHMES cultures) allowed us to study metabolic control of ND in human midbrain-derived neurons without the use of toxicants or other direct disturbance of cellular metabolism. Axotomy lead to a loss of the NAD+ synthesis enzyme NMNAT2 within 2 h and a depletion of NAD+ within 4-6 h. This process appeared specific, as isolated neurites maintained ATP levels and a coupled mitochondrial respiration for at least 6 h. In the peripheral nervous system (PNS) many studies observed that NAD+ metabolism, in particular by the NADase SARM1, plays a major role in the ND occurring after axotomy. Since neither ferroptosis nor necroptosis, nor caspase-dependent apoptosis seemed to be involved in neurite loss, we investigated SARM1 as potential executioner (or controller). Knock-down or expression of a dominant-negative isoform of SARM1 indeed drastically delayed ND. Various modifications of NAD+ metabolism known to modulate SARM1 activity showed the corresponding effects on ND. Moreover, supplementation with NAD+ attenuated ND. As a third approach to investigate the role of altered NAD+ metabolism, we made use of the WLD(s) protein, which has been found in a mutant mouse to inhibit Wallerian degeneration of axons. This protein, which has a stable NMNAT activity, and thus can buffer the loss of NMNAT2, protected the neurites by stabilizing neurite NAD+ levels. Thus CNS-type ND was tightly linked to neurite metabolism in multiple experimental setups. Based on this knowledge, several new strategies for treating neurodegenerative diseases can be envisaged.
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spelling doaj-art-026954625b4d40efa46dcdc96dccf0972025-01-19T12:40:42ZengNature Publishing GroupCell Death and Disease2041-48892025-01-0116111410.1038/s41419-024-07326-wProgrammed neurite degeneration in human central nervous system neurons driven by changes in NAD+ metabolismMarkus Brüll0Selina Multrus1Michael Schäfer2Ivana Celardo3Christiaan Karreman4Marcel Leist5In vitro Toxicology and Biomedicine, Dept. inaugurated by the Doerenkamp-Zbinden foundation, University of KonstanzIn vitro Toxicology and Biomedicine, Dept. inaugurated by the Doerenkamp-Zbinden foundation, University of KonstanzIn vitro Toxicology and Biomedicine, Dept. inaugurated by the Doerenkamp-Zbinden foundation, University of KonstanzIn vitro Toxicology and Biomedicine, Dept. inaugurated by the Doerenkamp-Zbinden foundation, University of KonstanzIn vitro Toxicology and Biomedicine, Dept. inaugurated by the Doerenkamp-Zbinden foundation, University of KonstanzIn vitro Toxicology and Biomedicine, Dept. inaugurated by the Doerenkamp-Zbinden foundation, University of KonstanzAbstract Neurite degeneration (ND) precedes cell death in many neurodegenerative diseases. However, it remains unclear how this compartmentalized cell death process is orchestrated in the central nervous system (CNS). The establishment of a CNS axotomy model (using modified 3D LUHMES cultures) allowed us to study metabolic control of ND in human midbrain-derived neurons without the use of toxicants or other direct disturbance of cellular metabolism. Axotomy lead to a loss of the NAD+ synthesis enzyme NMNAT2 within 2 h and a depletion of NAD+ within 4-6 h. This process appeared specific, as isolated neurites maintained ATP levels and a coupled mitochondrial respiration for at least 6 h. In the peripheral nervous system (PNS) many studies observed that NAD+ metabolism, in particular by the NADase SARM1, plays a major role in the ND occurring after axotomy. Since neither ferroptosis nor necroptosis, nor caspase-dependent apoptosis seemed to be involved in neurite loss, we investigated SARM1 as potential executioner (or controller). Knock-down or expression of a dominant-negative isoform of SARM1 indeed drastically delayed ND. Various modifications of NAD+ metabolism known to modulate SARM1 activity showed the corresponding effects on ND. Moreover, supplementation with NAD+ attenuated ND. As a third approach to investigate the role of altered NAD+ metabolism, we made use of the WLD(s) protein, which has been found in a mutant mouse to inhibit Wallerian degeneration of axons. This protein, which has a stable NMNAT activity, and thus can buffer the loss of NMNAT2, protected the neurites by stabilizing neurite NAD+ levels. Thus CNS-type ND was tightly linked to neurite metabolism in multiple experimental setups. Based on this knowledge, several new strategies for treating neurodegenerative diseases can be envisaged.https://doi.org/10.1038/s41419-024-07326-w
spellingShingle Markus Brüll
Selina Multrus
Michael Schäfer
Ivana Celardo
Christiaan Karreman
Marcel Leist
Programmed neurite degeneration in human central nervous system neurons driven by changes in NAD+ metabolism
Cell Death and Disease
title Programmed neurite degeneration in human central nervous system neurons driven by changes in NAD+ metabolism
title_full Programmed neurite degeneration in human central nervous system neurons driven by changes in NAD+ metabolism
title_fullStr Programmed neurite degeneration in human central nervous system neurons driven by changes in NAD+ metabolism
title_full_unstemmed Programmed neurite degeneration in human central nervous system neurons driven by changes in NAD+ metabolism
title_short Programmed neurite degeneration in human central nervous system neurons driven by changes in NAD+ metabolism
title_sort programmed neurite degeneration in human central nervous system neurons driven by changes in nad metabolism
url https://doi.org/10.1038/s41419-024-07326-w
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