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1.
Immunity ; 56(3): 500-515.e6, 2023 03 14.
Artigo em Inglês | MEDLINE | ID: mdl-36921576

RESUMO

The cGAS-STING pathway mediates cytoplasmic DNA-triggered innate immunity. STING activation is initiated by cyclic-GMP-AMP (cGAMP)-induced translocation from the endoplasmic reticulum and sulfated glycosaminoglycans-induced polymerization at the Golgi. Here, we examine the mechanisms underlying STING transport and activation beyond the Golgi. A genome-wide CRISPR-Cas9 screen identified Armadillo-like helical domain-containing protein 3 (ARMH3) as critical for STING activation. Upon cGAMP-triggered translocation, ARMH3 interacted with STING at the Golgi and recruited phosphatidylinositol 4-kinase beta (PI4KB) to synthesize PI4P, which directed STING Golgi-to-endosome trafficking via PI4P-binding proteins AP-1 and GGA2. Disrupting PI4P-dependent lipid transport through RNAi of other PI4P-binding proteins impaired STING activation. Consistently, disturbed lipid composition inhibited STING activation, whereas aberrantly elevated cellular PI4P led to cGAS-independent STING activation. Armh3fl/fllLyzCre/Cre mice were susceptible to DNA virus challenge in vivo. Thus, ARMH3 bridges STING and PIK4B to generate PI4P for STING transportation and activation, an interaction conserved in all eukaryotes.


Assuntos
Fatores de Restrição Antivirais , Proteínas do Domínio Armadillo , Proteínas de Membrana , Animais , Camundongos , 1-Fosfatidilinositol 4-Quinase/metabolismo , Proteínas de Transporte , Endossomos/metabolismo , Imunidade Inata , Lipídeos , Proteínas de Membrana/metabolismo , Nucleotidiltransferases/metabolismo , Proteínas do Domínio Armadillo/metabolismo
2.
Cell ; 160(1-2): 161-76, 2015 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-25594179

RESUMO

Axonal death disrupts functional connectivity of neural circuits and is a critical feature of many neurodegenerative disorders. Pathological axon degeneration often occurs independently of known programmed death pathways, but the underlying molecular mechanisms remain largely unknown. Using traumatic injury as a model, we systematically investigate mitogen-activated protein kinase (MAPK) families and delineate a MAPK cascade that represents the early degenerative response to axonal injury. The adaptor protein Sarm1 is required for activation of this MAPK cascade, and this Sarm1-MAPK pathway disrupts axonal energy homeostasis, leading to ATP depletion before physical breakdown of damaged axons. The protective cytoNmnat1/Wld(s) protein inhibits activation of this MAPK cascade. Further, MKK4, a key component in the Sarm1-MAPK pathway, is antagonized by AKT signaling, which modulates the degenerative response by limiting activation of downstream JNK signaling. Our results reveal a regulatory mechanism that integrates distinct signals to instruct pathological axon degeneration.


Assuntos
Axônios/patologia , Sistema de Sinalização das MAP Quinases , Trifosfato de Adenosina/metabolismo , Animais , Proteínas do Domínio Armadillo/genética , Proteínas do Domínio Armadillo/metabolismo , Morte Celular , Proteínas do Citoesqueleto/genética , Proteínas do Citoesqueleto/metabolismo , MAP Quinase Quinase 4/metabolismo , Camundongos , Doenças Neurodegenerativas/metabolismo , Doenças Neurodegenerativas/patologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Células Ganglionares da Retina/metabolismo , Células Ganglionares da Retina/patologia
3.
Mol Cell ; 82(9): 1643-1659.e10, 2022 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-35334231

RESUMO

The NADase SARM1 (sterile alpha and TIR motif containing 1) is a key executioner of axon degeneration and a therapeutic target for several neurodegenerative conditions. We show that a potent SARM1 inhibitor undergoes base exchange with the nicotinamide moiety of nicotinamide adenine dinucleotide (NAD+) to produce the bona fide inhibitor 1AD. We report structures of SARM1 in complex with 1AD, NAD+ mimetics and the allosteric activator nicotinamide mononucleotide (NMN). NMN binding triggers reorientation of the armadillo repeat (ARM) domains, which disrupts ARM:TIR interactions and leads to formation of a two-stranded TIR domain assembly. The active site spans two molecules in these assemblies, explaining the requirement of TIR domain self-association for NADase activity and axon degeneration. Our results reveal the mechanisms of SARM1 activation and substrate binding, providing rational avenues for the design of new therapeutics targeting SARM1.


Assuntos
Proteínas do Domínio Armadillo , NAD , Proteínas do Domínio Armadillo/genética , Proteínas do Citoesqueleto/química , Proteínas do Citoesqueleto/genética , NAD/metabolismo , NAD+ Nucleosidase/metabolismo , Domínios Proteicos
4.
Immunity ; 50(6): 1412-1424.e6, 2019 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-31076360

RESUMO

Assembly of inflammasomes after infection or injury leads to the release of interleukin-1ß (IL-1ß) and to pyroptosis. After inflammasome activation, cells either pyroptose or enter a hyperactivated state defined by IL-1ß secretion without cell death, but what controls these different outcomes is unknown. Here, we show that removal of the Toll-IL-1R protein SARM from macrophages uncouples inflammasome-dependent cytokine release and pyroptosis, whereby cells displayed increased IL-1ß production but reduced pyroptosis. Correspondingly, increasing SARM in cells caused less IL-1ß release and more pyroptosis. SARM suppressed IL-1ß by directly restraining the NLRP3 inflammasome and, hence, caspase-1 activation. Consistent with a role for SARM in pyroptosis, Sarm1-/- mice were protected from lipopolysaccharide (LPS)-stimulated sepsis. Pyroptosis-inducing, but not hyperactivating, NLRP3 stimulants caused SARM-dependent mitochondrial depolarization. Thus, SARM-dependent mitochondrial depolarization distinguishes NLRP3 activators that cause pyroptosis from those that do not, and SARM modulation represents a cell-intrinsic mechanism to regulate cell fate after inflammasome activation.


Assuntos
Proteínas do Domínio Armadillo/metabolismo , Citocinas/metabolismo , Proteínas do Citoesqueleto/metabolismo , Inflamassomos/metabolismo , Animais , Proteínas do Domínio Armadillo/genética , Biomarcadores , Sobrevivência Celular , Proteínas do Citoesqueleto/genética , Macrófagos/imunologia , Macrófagos/metabolismo , Camundongos , Camundongos Knockout , Mitocôndrias/genética , Mitocôndrias/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Ligação Proteica , Piroptose , Transdução de Sinais
5.
Nat Rev Mol Cell Biol ; 17(1): 55-64, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26580716

RESUMO

ß-catenin is widely regarded as the primary transducer of canonical WNT signals to the nucleus. In most vertebrates, there are eight additional catenins that are structurally related to ß-catenin, and three α-catenin genes encoding actin-binding proteins that are structurally related to vinculin. Although these catenins were initially identified in association with cadherins at cell-cell junctions, more recent evidence suggests that the majority of catenins also localize to the nucleus and regulate gene expression. Moreover, the number of catenins reported to be responsive to canonical WNT signals is increasing. Here, we posit that multiple catenins form a functional network in the nucleus, possibly engaging in conserved protein-protein interactions that are currently better characterized in the context of actin-based cell junctions.


Assuntos
Núcleo Celular/metabolismo , beta Catenina/metabolismo , Animais , Proteínas do Domínio Armadillo/química , Proteínas do Domínio Armadillo/metabolismo , Humanos , Modelos Biológicos , Transdução de Sinais , Proteínas Wnt/metabolismo , beta Catenina/química
6.
Proc Natl Acad Sci U S A ; 121(27): e2318198121, 2024 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-38917007

RESUMO

Establishing modular binders as diagnostic detection agents represents a cost- and time-efficient alternative to the commonly used binders that are generated one molecule at a time. In contrast to these conventional approaches, a modular binder can be designed in silico from individual modules to, in principle, recognize any desired linear epitope without going through a selection and hit-validation process, given a set of preexisting, amino acid-specific modules. Designed armadillo repeat proteins (dArmRP) have been developed as modular binder scaffolds, and we report here the generation of highly specific dArmRP modules by yeast surface display selection, performed on a rationally designed dArmRP library. A selection strategy was developed to distinguish the binding difference resulting from a single amino acid mutation in the target peptide. Our reverse-competitor strategy introduced here employs the designated target as a competitor to increase the sensitivity when separating specific from cross-reactive binders that show similar affinities for the target peptide. With this switch in selection focus from affinity to specificity, we found that the enrichment during this specificity sort is indicative of the desired phenotype, regardless of the binder abundance. Hence, deep sequencing of the selection pools allows retrieval of phenotypic hits with only 0.1% abundance in the selectivity sort pool from the next-generation sequencing data alone. In a proof-of-principle study, a binder was created by replacing all corresponding wild-type modules with a newly selected module, yielding a binder with very high affinity for the designated target that has been successfully validated as a detection agent in western blot analysis.


Assuntos
Proteínas do Domínio Armadillo , Saccharomyces cerevisiae , Proteínas do Domínio Armadillo/genética , Proteínas do Domínio Armadillo/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Ligação Proteica , Peptídeos/metabolismo , Peptídeos/genética , Peptídeos/química , Epitopos/genética , Biblioteca de Peptídeos
7.
Nature ; 588(7839): 658-663, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33053563

RESUMO

Pathological degeneration of axons disrupts neural circuits and represents one of the hallmarks of neurodegeneration1-4. Sterile alpha and Toll/interleukin-1 receptor motif-containing protein 1 (SARM1) is a central regulator of this neurodegenerative process5-8, and its Toll/interleukin-1 receptor (TIR) domain exerts its pro-neurodegenerative action through NADase activity9,10. However, the mechanisms by which the activation of SARM1 is stringently controlled are unclear. Here we report the cryo-electron microscopy structures of full-length SARM1 proteins. We show that NAD+ is an unexpected ligand of the armadillo/heat repeat motifs (ARM) domain of SARM1. This binding of NAD+ to the ARM domain facilitated the inhibition of the TIR-domain NADase through the domain interface. Disruption of the NAD+-binding site or the ARM-TIR interaction caused constitutive activation of SARM1 and thereby led to axonal degeneration. These findings suggest that NAD+ mediates self-inhibition of this central pro-neurodegenerative protein.


Assuntos
Proteínas do Domínio Armadillo/antagonistas & inibidores , Proteínas do Domínio Armadillo/metabolismo , Proteínas do Citoesqueleto/antagonistas & inibidores , Proteínas do Citoesqueleto/metabolismo , NAD/metabolismo , Doenças Neurodegenerativas/metabolismo , Neurônios/metabolismo , Animais , Proteínas do Domínio Armadillo/química , Proteínas do Domínio Armadillo/genética , Sítios de Ligação , Microscopia Crioeletrônica , Proteínas do Citoesqueleto/química , Proteínas do Citoesqueleto/genética , Feminino , Células HEK293 , Humanos , Ligantes , Camundongos , Modelos Moleculares , NAD+ Nucleosidase/metabolismo , Ligação Proteica , Domínios Proteicos , Células Sf9
8.
J Neurosci ; 44(24)2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38692735

RESUMO

Sterile alpha and TIR motif containing 1 (SARM1) is an inducible NADase that localizes to mitochondria throughout neurons and senses metabolic changes that occur after injury. Minimal proteomic changes are observed upon either SARM1 depletion or activation, suggesting that SARM1 does not exert broad effects on neuronal protein homeostasis. However, whether SARM1 activation occurs throughout the neuron in response to injury and cell stress remains largely unknown. Using a semiautomated imaging pipeline and a custom-built deep learning scoring algorithm, we studied degeneration in both mixed-sex mouse primary cortical neurons and male human-induced pluripotent stem cell-derived cortical neurons in response to a number of different stressors. We show that SARM1 activation is differentially restricted to specific neuronal compartments depending on the stressor. Cortical neurons undergo SARM1-dependent axon degeneration after mechanical transection, and SARM1 activation is limited to the axonal compartment distal to the injury site. However, global SARM1 activation following vacor treatment causes both cell body and axon degeneration. Context-specific stressors, such as microtubule dysfunction and mitochondrial stress, induce axonal SARM1 activation leading to SARM1-dependent axon degeneration and SARM1-independent cell body death. Our data reveal that compartment-specific SARM1-mediated death signaling is dependent on the type of injury and cellular stressor.


Assuntos
Proteínas do Domínio Armadillo , Córtex Cerebral , Proteínas do Citoesqueleto , Células-Tronco Pluripotentes Induzidas , Neurônios , Proteínas do Domínio Armadillo/metabolismo , Proteínas do Domínio Armadillo/genética , Animais , Proteínas do Citoesqueleto/metabolismo , Proteínas do Citoesqueleto/genética , Camundongos , Neurônios/metabolismo , Neurônios/patologia , Masculino , Córtex Cerebral/metabolismo , Córtex Cerebral/patologia , Humanos , Feminino , Células-Tronco Pluripotentes Induzidas/metabolismo , Degeneração Neural/patologia , Degeneração Neural/metabolismo , Degeneração Neural/genética , Células Cultivadas , Camundongos Endogâmicos C57BL , Estresse Fisiológico/fisiologia , Axônios/metabolismo , Axônios/patologia , Mitocôndrias/metabolismo
9.
J Biol Chem ; 300(2): 105620, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38176648

RESUMO

Sterile alpha and HEAT/armadillo motif-containing protein (SARM1) was recently described as a NAD+-consuming enzyme and has previously been shown to regulate immune responses in macrophages. Neuronal SARM1 is known to contribute to axon degeneration due to its NADase activity. However, how SARM1 affects macrophage metabolism has not been explored. Here, we show that macrophages from Sarm1-/- mice display elevated NAD+ concentrations and lower cyclic ADP-ribose, a known product of SARM1-dependent NAD+ catabolism. Further, SARM1-deficient macrophages showed an increase in the reserve capacity of oxidative phosphorylation and glycolysis compared to WT cells. Stimulation of macrophages to a proinflammatory state by lipopolysaccharide (LPS) revealed that SARM1 restricts the ability of macrophages to upregulate glycolysis and limits the expression of the proinflammatory gene interleukin (Il) 1b, but boosts expression of anti-inflammatory Il10. In contrast, we show macrophages lacking SARM1 induced to an anti-inflammatory state by IL-4 stimulation display increased oxidative phosphorylation and glycolysis, and reduced expression of the anti-inflammatory gene, Fizz1. Overall, these data show that SARM1 fine-tunes immune gene transcription in macrophages via consumption of NAD+ and altered macrophage metabolism.


Assuntos
Proteínas do Domínio Armadillo , Proteínas do Citoesqueleto , Neurônios , Animais , Camundongos , Proteínas do Domínio Armadillo/genética , Proteínas do Domínio Armadillo/metabolismo , Axônios/metabolismo , ADP-Ribose Cíclica/metabolismo , Proteínas do Citoesqueleto/genética , Proteínas do Citoesqueleto/metabolismo , NAD/metabolismo , Neurônios/metabolismo
10.
J Biol Chem ; 300(2): 105630, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38199568

RESUMO

Sterile alpha and toll/interleukin receptor motif-containing 1 (SARM1) is a critical regulator of axon degeneration that acts through hydrolysis of NAD+ following injury. Recent work has defined the mechanisms underlying SARM1's catalytic activity and advanced our understanding of SARM1 function in axons, yet the role of SARM1 signaling in other compartments of neurons is still not well understood. Here, we show in cultured hippocampal neurons that endogenous SARM1 is present in axons, dendrites, and cell bodies and that direct activation of SARM1 by the neurotoxin Vacor causes not just axon degeneration, but degeneration of all neuronal compartments. In contrast to the axon degeneration pathway defined in dorsal root ganglia, SARM1-dependent hippocampal axon degeneration in vitro is not sensitive to inhibition of calpain proteases. Dendrite degeneration downstream of SARM1 in hippocampal neurons is dependent on calpain 2, a calpain protease isotype enriched in dendrites in this cell type. In summary, these data indicate SARM1 plays a critical role in neurodegeneration outside of axons and elucidates divergent pathways leading to degeneration in hippocampal axons and dendrites.


Assuntos
Proteínas do Domínio Armadillo , Proteínas do Citoesqueleto , Neurônios , Animais , Camundongos , Proteínas do Domínio Armadillo/genética , Proteínas do Domínio Armadillo/metabolismo , Axônios/metabolismo , Calpaína/metabolismo , Proteínas do Citoesqueleto/metabolismo , Dendritos/metabolismo , Neurônios/metabolismo , Transdução de Sinais
11.
Nat Rev Neurosci ; 21(4): 183-196, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32152523

RESUMO

Wallerian degeneration is a widespread mechanism of programmed axon degeneration. In the three decades since the discovery of the Wallerian degeneration slow (WldS) mouse, research has generated extensive knowledge of the molecular mechanisms underlying Wallerian degeneration, demonstrated its involvement in non-injury disorders and found multiple ways to block it. Recent developments have included: the detection of NMNAT2 mutations that implicate Wallerian degeneration in rare human diseases; the capacity for lifelong rescue of a lethal condition related to Wallerian degeneration in mice; the discovery of 'druggable' enzymes, including SARM1 and MYCBP2 (also known as PHR1), in Wallerian pathways; and the elucidation of protein structures to drive further understanding of the underlying mechanisms and drug development. Additionally, new data have indicated the potential of these advances to alleviate a number of common disorders, including chemotherapy-induced and diabetic peripheral neuropathies, traumatic brain injury, and amyotrophic lateral sclerosis.


Assuntos
Degeneração Walleriana/metabolismo , Animais , Proteínas do Domínio Armadillo/metabolismo , Proteínas do Citoesqueleto/metabolismo , Modelos Animais de Doenças , Drosophila melanogaster , Humanos , Camundongos , Camundongos Transgênicos , NAD/metabolismo , Nicotinamida-Nucleotídeo Adenililtransferase/metabolismo , Transdução de Sinais , Pesquisa Translacional Biomédica
12.
Mol Cell ; 67(2): 181-193.e5, 2017 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-28689657

RESUMO

Extracellular signals are transduced to the cell nucleus by effectors that bind to enhancer complexes to operate transcriptional switches. For example, the Wnt enhanceosome is a multiprotein complex associated with Wnt-responsive enhancers through T cell factors (TCF) and kept silent by Groucho/TLE co-repressors. Wnt-activated ß-catenin binds to TCF to overcome this repression, but how it achieves this is unknown. Here, we discover that this process depends on the HECT E3 ubiquitin ligase Hyd/UBR5, which is required for Wnt signal responses in Drosophila and human cell lines downstream of activated Armadillo/ß-catenin. We identify Groucho/TLE as a functionally relevant substrate, whose ubiquitylation by UBR5 is induced by Wnt signaling and conferred by ß-catenin. Inactivation of TLE by UBR5-dependent ubiquitylation also involves VCP/p97, an AAA ATPase regulating the folding of various cellular substrates including ubiquitylated chromatin proteins. Thus, Groucho/TLE ubiquitylation by Hyd/UBR5 is a key prerequisite that enables Armadillo/ß-catenin to activate transcription.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Proteínas Correpressoras/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/enzimologia , Proteínas Repressoras/metabolismo , Transcrição Gênica , Ubiquitina-Proteína Ligases/metabolismo , Via de Sinalização Wnt , Adenosina Trifosfatases/genética , Adenosina Trifosfatases/metabolismo , Animais , Animais Geneticamente Modificados , Proteínas do Domínio Armadillo/genética , Proteínas do Domínio Armadillo/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Sistemas CRISPR-Cas , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proteínas Correpressoras/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Técnicas de Silenciamento de Genes , Células HCT116 , Células HEK293 , Células HeLa , Humanos , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Estabilidade Proteica , Proteólise , Proteínas Repressoras/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Ativação Transcricional , Transfecção , Ubiquitina-Proteína Ligases/genética , Ubiquitinação , Proteína com Valosina , beta Catenina/genética , beta Catenina/metabolismo
13.
Proc Natl Acad Sci U S A ; 119(35): e2208457119, 2022 08 30.
Artigo em Inglês | MEDLINE | ID: mdl-35994671

RESUMO

The nicotinamide adenine dinucleotide hydrolase (NADase) sterile alpha toll/interleukin receptor motif containing-1 (SARM1) acts as a central executioner of programmed axon death and is a possible therapeutic target for neurodegenerative disorders. While orthosteric inhibitors of SARM1 have been described, this multidomain enzyme is also subject to intricate forms of autoregulation, suggesting the potential for allosteric modes of inhibition. Previous studies have identified multiple cysteine residues that support SARM1 activation and catalysis, but which of these cysteines, if any, might be selectively targetable by electrophilic small molecules remains unknown. Here, we describe the chemical proteomic discovery of a series of tryptoline acrylamides that site-specifically and stereoselectively modify cysteine-311 (C311) in the noncatalytic, autoregulatory armadillo repeat (ARM) domain of SARM1. These covalent compounds inhibit the NADase activity of WT-SARM1, but not C311A or C311S SARM1 mutants, show a high degree of proteome-wide selectivity for SARM1_C311 and stereoselectively block vincristine- and vacor-induced neurite degeneration in primary rodent dorsal root ganglion neurons. Our findings describe selective, covalent inhibitors of SARM1 targeting an allosteric cysteine, pointing to a potentially attractive therapeutic strategy for axon degeneration-dependent forms of neurological disease.


Assuntos
Proteínas do Domínio Armadillo , Cisteína , Proteínas do Citoesqueleto , Proteínas do Domínio Armadillo/antagonistas & inibidores , Proteínas do Domínio Armadillo/química , Proteínas do Domínio Armadillo/genética , Axônios , Proteínas do Citoesqueleto/antagonistas & inibidores , Proteínas do Citoesqueleto/química , Proteínas do Citoesqueleto/genética , Homeostase , NAD+ Nucleosidase , Proteômica
14.
PLoS Genet ; 18(6): e1010257, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35737721

RESUMO

Elucidating signal transduction mechanisms of innate immune pathways is essential to defining how they elicit distinct cellular responses. Toll-like receptors (TLR) signal through their cytoplasmic TIR domains which bind other TIR domain-containing adaptors. dSARM/SARM1 is one such TIR domain adaptor best known for its role as the central axon degeneration trigger after injury. In degeneration, SARM1's domains have been assigned unique functions: the ARM domain is auto-inhibitory, SAM-SAM domain interactions mediate multimerization, and the TIR domain has intrinsic NAD+ hydrolase activity that precipitates axonal demise. Whether and how these distinct functions contribute to TLR signaling is unknown. Here we show divergent signaling requirements for dSARM in injury-induced axon degeneration and TLR-mediated developmental glial phagocytosis through analysis of new knock-in domain and point mutations. We demonstrate intragenic complementation between reciprocal pairs of domain mutants during development, providing evidence for separability of dSARM functional domains in TLR signaling. Surprisingly, dSARM's NAD+ hydrolase activity is strictly required for both degenerative and developmental signaling, demonstrating that TLR signal transduction requires dSARM's enzymatic activity. In contrast, while SAM domain-mediated dSARM multimerization is important for axon degeneration, it is dispensable for TLR signaling. Finally, dSARM functions in a linear genetic pathway with the MAP3K Ask1 during development but not in degenerating axons. Thus, we propose that dSARM exists in distinct signaling states in developmental and pathological contexts.


Assuntos
Proteínas do Domínio Armadillo , NAD , Proteínas do Domínio Armadillo/genética , Proteínas do Domínio Armadillo/metabolismo , Proteínas do Citoesqueleto/genética , Hidrolases/metabolismo , Fagocitose/genética , Transdução de Sinais/genética
15.
PLoS Genet ; 18(6): e1010246, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35737728

RESUMO

SARM1 is the founding member of the TIR-domain family of NAD+ hydrolases and the central executioner of pathological axon degeneration. SARM1-dependent degeneration requires NAD+ hydrolysis. Prior to the discovery that SARM1 is an enzyme, SARM1 was studied as a TIR-domain adaptor protein with non-degenerative signaling roles in innate immunity and invertebrate neurodevelopment, including at the Drosophila neuromuscular junction (NMJ). Here we explore whether the NADase activity of SARM1 also contributes to developmental signaling. We developed transgenic Drosophila lines that express SARM1 variants with normal, deficient, and enhanced NADase activity and tested their function in NMJ development. We find that NMJ overgrowth scales with the amount of NADase activity, suggesting an instructive role for NAD+ hydrolysis in this developmental signaling pathway. While degenerative and developmental SARM1 signaling share a requirement for NAD+ hydrolysis, we demonstrate that these signals use distinct upstream and downstream mechanisms. These results identify SARM1-dependent NAD+ hydrolysis as a heretofore unappreciated component of developmental signaling. SARM1 now joins sirtuins and Parps as enzymes that regulate signal transduction pathways via mechanisms that involve NAD+ cleavage, greatly expanding the potential scope of SARM1 TIR NADase functions.


Assuntos
Proteínas do Domínio Armadillo , NAD , Animais , Proteínas do Domínio Armadillo/genética , Proteínas do Domínio Armadillo/metabolismo , Axônios/metabolismo , Proteínas do Citoesqueleto/genética , Proteínas do Citoesqueleto/metabolismo , Drosophila/genética , Drosophila/metabolismo , NAD/genética , NAD+ Nucleosidase/genética , NAD+ Nucleosidase/metabolismo
16.
Proc Natl Acad Sci U S A ; 119(47): e2203824119, 2022 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-36375051

RESUMO

Autophagy is a cellular catabolic pathway generally thought to be neuroprotective. However, autophagy and in particular its upstream regulator, the ULK1 kinase, can also promote axonal degeneration. We examined the role and the mechanisms of autophagy in axonal degeneration using a mouse model of contusive spinal cord injury (SCI). Consistent with activation of autophagy during axonal degeneration following SCI, autophagosome marker LC3, ULK1 kinase, and ULK1 target, phospho-ATG13, accumulated in the axonal bulbs and injured axons. SARM1, a TIR NADase with a pivotal role in axonal degeneration, colocalized with ULK1 within 1 h after SCI, suggesting possible interaction between autophagy and SARM1-mediated axonal degeneration. In our in vitro experiments, inhibition of autophagy, including Ulk1 knockdown and ULK1 inhibitor, attenuated neurite fragmentation and reduced accumulation of SARM1 puncta in neurites of primary cortical neurons subjected to glutamate excitotoxicity. Immunoprecipitation data demonstrated that ULK1 physically interacted with SARM1 in vitro and in vivo and that SAM domains of SARM1 were necessary for ULK1-SARM1 complex formation. Consistent with a role in regulation of axonal degeneration, in primary cortical neurons ULK1-SARM1 interaction increased upon neurite damage. Supporting a role for autophagy and ULK1 in regulation of SARM1 in axonal degeneration in vivo, axonal ULK1 activation and accumulation of SARM1 were both decreased after SCI in Becn1+/- autophagy hypomorph mice compared to wild-type (WT) controls. These findings suggest a regulatory crosstalk between autophagy and axonal degeneration pathways, which is mediated through ULK1-SARM1 interaction and contributes to the ability of SARM1 to accumulate in injured axons.


Assuntos
Proteínas do Domínio Armadillo , Proteína Homóloga à Proteína-1 Relacionada à Autofagia , Proteínas do Citoesqueleto , Traumatismos da Medula Espinal , Animais , Camundongos , Proteínas do Domínio Armadillo/genética , Proteínas do Domínio Armadillo/metabolismo , Autofagia , Axônios/metabolismo , Proteínas do Citoesqueleto/genética , Proteínas do Citoesqueleto/metabolismo , Camundongos Knockout , Traumatismos da Medula Espinal/metabolismo , Proteína Homóloga à Proteína-1 Relacionada à Autofagia/genética , Proteína Homóloga à Proteína-1 Relacionada à Autofagia/metabolismo
17.
J Cell Mol Med ; 28(12): e18449, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38924214

RESUMO

Mitochondrial dynamics has emerged as an important target for neuronal protection after cerebral ischaemia/reperfusion. Therefore, the aim of this study was to investigate the mechanism by which ARMC10 regulation of mitochondrial dynamics affects mitochondrial function involved in ischaemic stroke (IS). Mitochondrial morphology was detected by laser scanning confocal microscopy (LSCM), and mitochondrial ultrastructural alterations were detected by electron microscopy. The expression of mitochondrial dynamics-related genes Drp1, Mfn1, Mfn2, Fis1, OPA1 and ARMC10 and downstream target genes c-Myc, CyclinD1 and AXIN2 was detected by RT-qPCR. Western blot was used to detect the protein expression of ß-catenin, GSK-3ß, p-GSK-3ß, Bcl-2 and Bax. DCFH-DA fluorescent probe was to detect the effect of ARMC10 on mitochondrial ROS level, Annexin V-FITC fluorescent probe was to detect the effect of ARMC10 on apoptosis, and ATP assay kit was to detect the effect of ARMC10 on ATP production. Mitochondrial dynamics was dysregulated in clinical IS samples and in the OGD/R cell model, and the relative expression of ARMC10 gene was significantly decreased in IS group (p < 0.05). Knockdown and overexpression of ARMC10 could affect mitochondrial dynamics, mitochondrial function and neuronal apoptosis. Agonist and inhibitor affected mitochondrial function and neuronal apoptosis by targeting Wnt/ß-Catenin signal pathway. In the OGD/R model, ARMC10 affected mitochondrial function and neuronal apoptosis through the mechanism that regulates Wnt/ß-catenin signalling pathway. ARMC10 regulates mitochondrial dynamics and protects mitochondrial function by activating Wnt/ß-catenin signalling pathway, to exert neuroprotective effects.


Assuntos
Apoptose , Proteínas do Domínio Armadillo , AVC Isquêmico , Mitocôndrias , Dinâmica Mitocondrial , Via de Sinalização Wnt , Humanos , Proteínas do Domínio Armadillo/metabolismo , Proteínas do Domínio Armadillo/genética , beta Catenina/metabolismo , beta Catenina/genética , Isquemia Encefálica/metabolismo , Isquemia Encefálica/genética , Isquemia Encefálica/patologia , AVC Isquêmico/metabolismo , AVC Isquêmico/genética , AVC Isquêmico/patologia , Mitocôndrias/metabolismo , Espécies Reativas de Oxigênio/metabolismo
18.
J Biol Chem ; 299(11): 105284, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37742918

RESUMO

Axonal degeneration is a hallmark feature of neurodegenerative diseases. Activation of the NAD(P)ase sterile alpha and toll-interleukin receptor motif containing protein 1 (SARM1) is critical for this process. In resting neurons, SARM1 activity is inhibited, but upon damage, SARM1 is activated and catalyzes one of three NAD(P)+ dependent reactions: (1) NAD(P)+ hydrolysis to form ADP-ribose (ADPR[P]) and nicotinamide; (2) the formation of cyclic-ADPR (cADPR[P]); or (3) a base exchange reaction with nicotinic acid (NA) and NADP+ to form NA adenine dinucleotide phosphate. Production of these metabolites triggers axonal death. Two activation mechanisms have been proposed: (1) an increase in the nicotinamide mononucleotide (NMN) concentration, which leads to the allosteric activation of SARM1, and (2) a phase transition, which stabilizes the active conformation of the enzyme. However, neither of these mechanisms have been shown to occur at the same time. Using in vitro assay systems, we show that the liquid-to-solid phase transition lowers the NMN concentration required to activate the catalytic activity of SARM1 by up to 140-fold. These results unify the proposed activation mechanisms and show for the first time that a phase transition reduces the threshold for NMN-based SARM1 activation to physiologically relevant levels. These results further our understanding of SARM1 activation and will be important for the future development of therapeutics targeting SARM1.


Assuntos
NAD , Mononucleotídeo de Nicotinamida , Proteínas do Domínio Armadillo/genética , Proteínas do Domínio Armadillo/metabolismo , Axônios/metabolismo , Hidrolases/metabolismo , NAD/metabolismo , Neurônios/metabolismo , Mononucleotídeo de Nicotinamida/metabolismo , Humanos , Linhagem Celular
19.
J Neurosci Res ; 102(1): e25292, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-38284842

RESUMO

Autophagic dysfunction in neurodegenerative diseases is being extensively studied, yet the exact mechanism of macroautophagy/autophagy in axon degeneration is still elusive. A recent study by Kim et al. links autophagic stress to the sterile α and toll/interleukin 1 receptor motif containing protein 1 (SARM1)-dependent core axonal degeneration program, providing a new insight into the role of autophagy in axon degeneration. In the classical Wallerian axon degeneration model of axotomy, disruption of axonal transport destroys the coordinated activity of pro-survival and pro-degenerative factors in the axoplasm and activates the NADase activity of SARM1, thus triggering the axonal self-destruction program. However, the mechanism for SARM1 activation in the chronic neurodegenerative disorders is more complex. Mitochondrial defects and oxidative stress contribute to the activation of SARM1, while mitophagy can inhibit mitochondrial dysfunction and promote the clearance of SARM1 on mitochondria, thus protecting against neuronal degeneration. Therefore, in-depth elucidation of the underlying mechanisms of mitophagy during axonal degeneration can help develop promising strategies for the prevention and treatment of various neurodegenerative disorders.


Assuntos
Autofagia , Doenças Neurodegenerativas , Humanos , Axônios , Mitocôndrias , Proteínas do Citoesqueleto , Proteínas do Domínio Armadillo
20.
J Neurooncol ; 168(3): 405-413, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38630387

RESUMO

INTRODUCTION: Meningiomas are the most common primary brain and central nervous system tumors, accounting for approximately 40% of these tumors. The most important exams for the radiological study of meningiomas are computed tomography (CT) and magnetic resonance imaging (MRI). We aimed to analyze the radiological features of patients with meningioma related to the simultaneous presence of bilateral macronodular adrenocortical disease (BMAD), with or without pathogenic variants of ARMC5. METHODS: This study included 10 patients who were diagnosed with BMAD. All of them had a radiological diagnosis of expansive brain lesions suggestive of meningioma. All patients underwent brain MRI and a neuroradiolgist analyzed the following parameters: number, site and size of lesions; presence of calcification, edema and bone involvement. RESULTS AND DISCUSSION: Eight patients presented with germline variants of ARMC5; the other 2, did not. The most significant result was the incidence of multiple meningiomas, which was 50% in BMAD patients, whereas the average incidence described thus far is lower than 10%. Considering location, the 22 tumors in the BMAD patients were 5 convexity tumors (22.7%), and 17 skull base tumors (77.2%), the opposite proportion of patients without BMAD. A total of 40.9% of the tumors had calcification, 9% had cerebral edema and 40.9% had bone invasion due to hyperostosis. The literature describes meningioma calcification in 25% of patients, bone invasion by tumor hyperostosis in 20%, and cerebral edema in approximately 60%. CONCLUSION: Relevant results were found considering the rate of multiple meningiomas and tumor location. This finding reinforces the need for further research into the neurological effects caused by genetic variants of ARMC5 in patients with BMAD.


Assuntos
Imageamento por Ressonância Magnética , Neoplasias Meníngeas , Meningioma , Humanos , Meningioma/genética , Meningioma/diagnóstico por imagem , Meningioma/patologia , Feminino , Masculino , Neoplasias Meníngeas/genética , Neoplasias Meníngeas/diagnóstico por imagem , Neoplasias Meníngeas/patologia , Pessoa de Meia-Idade , Adulto , Idoso , Tomografia Computadorizada por Raios X , Proteínas do Domínio Armadillo
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