Potent activation of SARM1 by NMN analogue VMN underlies vacor neurotoxicity

Loreto, Andrea; Angeletti, Carlo Alberto; Gilley, Jonathan; Arthur‐Farraj, Peter; Merlini, Elisa; Amici, Adolfo; Desrochers, Laura M.; Wang, Qi; Orsomando, Giuseppe; Coleman, Michael P.

doi:10.1101/2020.09.18.304261

Cited by 13 publications

(38 citation statements)

References 59 publications

(94 reference statements)

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“…S3, Table S1). All of these activities increased further still in the presence of either NMN or VMN [20] and leveled off at a plateau of ~8-10 fold (Fig. 4B middle, right panels).…”

Section: Dominant and Unique Base Exchange Capability Of Hsarm1 Nad(p)asementioning

confidence: 92%

“…Reagents. Vacor (Pyrinuron N-13738) was purchased from Greyhound Chromatography (UK) and used to generate VMN and VAD enzymatically in vitro as reported [20,67]. The ribosides VR and NaR were also obtained enzymatically from digestion of VMN and NaAD, respectively (see Supplemental Methods).…”

Section: Methodsmentioning

confidence: 99%

“…• CIAP (Calf Intestine Alkaline Phosphatase) Applichem A3810 (~20U/mg at 25 °C) resuspended in 100 mM Tris/HCl, pH 9, 100 mM NaCl to final ~50mg/ml and stored at -20 °C until use • PDE-I (Phosphodiesterase I from Crotalus adamanteus) Merck P3134 (~0.02U/mg at 37 °C) resuspended in 100 mM Tris/HCl, pH 9, 100 mM NaCl to final ~10 mg/ml and stored at -20 °C until use • VMN purified as described [20] resuspended in H2O to final ~10 mM (ɛ340nm of 17.8 mM -1 cm -1 ) and stored at -20 °C until use • NaAD Merck N4256 resuspended in H20 to final ~5 mM and stored at -20 °C until use Mixtures (A) and (B) after incubation were boiled, centrifuged, and loaded on C18 reverse phase HPLC (Varian, 90 Å, 5 μm). Preparative runs were performed at two distinct temperatures under elution gradients in volatile buffers (see graphs).…”

Section: Reagents and Reaction Mixturesmentioning

confidence: 99%

“…NMN is now known to do this by binding an allosteric site on the SARM1 inhibitory ARM domain, and high levels of NAD compete to bind the same site, thereby opposing activation by NMN [17][18][19]. VMN, a metabolite of the neurotoxin and disused rodenticide vacor, binds the same site and activates SARM1 even more potently [20]. The current working model of the programmed axon death signalling pathway is shown in Figure 1A.…”

Section: Introductionmentioning

confidence: 99%

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Programmed axon death executor SARM1 is a multi-functional NAD(P)ase with prominent base exchange activity, all regulated by physiological levels of NMN, NAD, NADP and other metabolites

Angeletti

Amici

Gilley

et al. 2021

Preprint

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SARM1 is an NAD glycohydrolase and TLR adapter with an essential, prodegenerative role in programmed axon death (Wallerian degeneration). It has low basal NADase activity that becomes strongly activated by NAD precursor NMN. Very high levels of NAD oppose this activation, competing for the same allosteric site on SARM1′s regulatory ARM domain. Injury or diseases that deplete axons of NMNAT2, an essential enzyme converting NMN to NAD, cause SARM1 activation. The resulting NAD degradation by SARM1, combined with loss of NAD synthesis by NMNAT2, causes rapid depletion of axonal NAD. This NAD loss is widely assumed to mediate axon death and is consequently a key focus for therapeutic strategies for axonopathies. However, like other NAD(P) glycohydrolases, SARM1 has additional enzyme activities whose contributions, consequences and regulation need to be fully understood. Here, we compare the multiple actions and regulation of recombinant human SARM1 with those of two other NAD(P) glycohydrolases, human CD38 and Aplysia californica ADP ribosyl cyclase. We find that SARM1 has the highest transglycosidation (base exchange) activity of these enzymes at neutral pH and with some bases this dominates NAD(P) hydrolysis and cyclisation. Moreover, like its NADase and NADPase reactions, SARM1-mediated base exchange at neutral pH is activated by increases in the NMN:NAD ratio, which we show for the first time can act in the presence of physiological levels of both metabolites. We establish that SARM1 base exchange is the most likely physiological source of calcium mobilizing agent NaADP, and potentially of other NAD(P) analogues, which could contribute to axon and cell death. We also identify regulatory effects of free pyridine bases, of NADP and of nicotinic acid riboside (NaR) on SARM1 that represent further therapeutic opportunities. These data will help to pinpoint which of the multiple functions of SARM1 is responsible for axon degeneration and how it can be optimally targeted to block axon degeneration in disease.

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“…S3, Table S1). All of these activities increased further still in the presence of either NMN or VMN [20] and leveled off at a plateau of ~8-10 fold (Fig. 4B middle, right panels).…”

Section: Dominant and Unique Base Exchange Capability Of Hsarm1 Nad(p)asementioning

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Section: Reagents and Reaction Mixturesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Programmed axon death executor SARM1 is a multi-functional NAD(P)ase with prominent base exchange activity, all regulated by physiological levels of NMN, NAD, NADP and other metabolites

Angeletti

Amici

Gilley

et al. 2021

Preprint

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show abstract

“…Consistently, fluorescence-based NADase assays in vitro illustrated that NMN was indeed an activator of SARM1 ( Zhao et al, 2019 ; Bratkowski et al, 2020 ; Figley et al, 2021 ). Moreover, NMN analogues including CZ48, a synthetic cell-permeable molecule ( Zhao et al, 2019 ), and vacor mononucleotide (VMN), a metabolite of neurotoxin vacor ( Loreto et al, 2020a ), could also activate SARM1 NADase activity, the latter also inducing axon degeneration. However, this hypothesis could also not explain the experimental data that raising the level of both NMN and NAD together protects axons from degeneration ( Wang et al, 2015 ; Sasaki et al, 2016 ).…”

Section: Regulation Of Axon Degeneration By Nicotinamide Adenine Dinucleotide-mediated Signalingmentioning

confidence: 99%

A Novel NAD Signaling Mechanism in Axon Degeneration and its Relationship to Innate Immunity

Hopkins

Kobe

et al. 2021

Front. Mol. Biosci.

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Axon degeneration represents a pathological feature of many neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease where axons die before the neuronal soma, and axonopathies, such as Charcot-Marie-Tooth disease and hereditary spastic paraplegia. Over the last two decades, it has slowly emerged that a central signaling pathway forms the basis of this process in many circumstances. This is an axonal NAD-related signaling mechanism mainly regulated by the two key proteins with opposing roles: the NAD-synthesizing enzyme NMNAT2, and SARM1, a protein with NADase and related activities. The crosstalk between the axon survival factor NMNAT2 and pro-degenerative factor SARM1 has been extensively characterized and plays an essential role in maintaining the axon integrity. This pathway can be activated in necroptosis and in genetic, toxic or metabolic disorders, physical injury and neuroinflammation, all leading to axon pathology. SARM1 is also known to be involved in regulating innate immunity, potentially linking axon degeneration to the response to pathogens and intercellular signaling. Understanding this NAD-related signaling mechanism enhances our understanding of the process of axon degeneration and enables a path to the development of drugs for a wide range of neurodegenerative diseases.

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Lessons from Injury: How Nerve Injury Studies Reveal Basic Biological Mechanisms and Therapeutic Opportunities for Peripheral Nerve Diseases

Arthur‐Farraj

Coleman

2021

Neurotherapeutics

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Since Waller and Cajal in the nineteenth and early twentieth centuries, laboratory traumatic peripheral nerve injury studies have provided great insight into cellular and molecular mechanisms governing axon degeneration and the responses of Schwann cells, the major glial cell type of peripheral nerves. It is now evident that pathways underlying injury-induced axon degeneration and the Schwann cell injury-specific state, the repair Schwann cell, are relevant to many inherited and acquired disorders of peripheral nerves. This review provides a timely update on the molecular understanding of axon degeneration and formation of the repair Schwann cell. We discuss how nicotinamide mononucleotide adenylyltransferase 2 (NMNAT2) and sterile alpha TIR motif containing protein 1 (SARM1) are required for axon survival and degeneration, respectively, how transcription factor c-JUN is essential for the Schwann cell response to nerve injury and what each tells us about disease mechanisms and potential therapies. Human genetic association with NMNAT2 and SARM1 strongly suggests aberrant activation of programmed axon death in polyneuropathies and motor neuron disorders, respectively, and animal studies suggest wider involvement including in chemotherapy-induced and diabetic neuropathies. In repair Schwann cells, cJUN is aberrantly expressed in a wide variety of human acquired and inherited neuropathies. Animal models suggest it limits axon loss in both genetic and traumatic neuropathies, whereas in contrast, Schwann cell secreted Neuregulin-1 type 1 drives onion bulb pathology in CMT1A. Finally, we discuss opportunities for drug-based and gene therapies to prevent axon loss or manipulate the repair Schwann cell state to treat acquired and inherited neuropathies and neuronopathies.

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Potent activation of SARM1 by NMN analogue VMN underlies vacor neurotoxicity

Cited by 13 publications

References 59 publications

Programmed axon death executor SARM1 is a multi-functional NAD(P)ase with prominent base exchange activity, all regulated by physiological levels of NMN, NAD, NADP and other metabolites

Programmed axon death executor SARM1 is a multi-functional NAD(P)ase with prominent base exchange activity, all regulated by physiological levels of NMN, NAD, NADP and other metabolites

A Novel NAD Signaling Mechanism in Axon Degeneration and its Relationship to Innate Immunity

Lessons from Injury: How Nerve Injury Studies Reveal Basic Biological Mechanisms and Therapeutic Opportunities for Peripheral Nerve Diseases

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