Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 52
Filtrar
1.
Cell ; 184(16): 4329-4347.e23, 2021 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-34237253

RESUMO

We have produced gene expression profiles of all 302 neurons of the C. elegans nervous system that match the single-cell resolution of its anatomy and wiring diagram. Our results suggest that individual neuron classes can be solely identified by combinatorial expression of specific gene families. For example, each neuron class expresses distinct codes of ∼23 neuropeptide genes and ∼36 neuropeptide receptors, delineating a complex and expansive "wireless" signaling network. To demonstrate the utility of this comprehensive gene expression catalog, we used computational approaches to (1) identify cis-regulatory elements for neuron-specific gene expression and (2) reveal adhesion proteins with potential roles in process placement and synaptic specificity. Our expression data are available at https://cengen.org and can be interrogated at the web application CengenApp. We expect that this neuron-specific directory of gene expression will spur investigations of underlying mechanisms that define anatomy, connectivity, and function throughout the C. elegans nervous system.


Assuntos
Caenorhabditis elegans/metabolismo , Sistema Nervoso/metabolismo , Animais , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Corantes Fluorescentes/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Genes Reporter , Larva/metabolismo , Neurônios/metabolismo , Neuropeptídeos/genética , Neuropeptídeos/metabolismo , Motivos de Nucleotídeos/genética , RNA-Seq , Sequências Reguladoras de Ácido Nucleico/genética , Transdução de Sinais/genética , Fatores de Transcrição/metabolismo , Transcrição Gênica
2.
Proc Natl Acad Sci U S A ; 121(3): e2314699121, 2024 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-38198527

RESUMO

Energy metabolism supports neuronal function. While it is well established that changes in energy metabolism underpin brain plasticity and function, less is known about how individual neurons modulate their metabolic states to meet varying energy demands. This is because most approaches used to examine metabolism in living organisms lack the resolution to visualize energy metabolism within individual circuits, cells, or subcellular regions. Here, we adapted a biosensor for glycolysis, HYlight, for use in Caenorhabditis elegans to image dynamic changes in glycolysis within individual neurons and in vivo. We determined that neurons cell-autonomously perform glycolysis and modulate glycolytic states upon energy stress. By examining glycolysis in specific neurons, we documented a neuronal energy landscape comprising three general observations: 1) glycolytic states in neurons are diverse across individual cell types; 2) for a given condition, glycolytic states within individual neurons are reproducible across animals; and 3) for varying conditions of energy stress, glycolytic states are plastic and adapt to energy demands. Through genetic analyses, we uncovered roles for regulatory enzymes and mitochondrial localization in the cellular and subcellular dynamic regulation of glycolysis. Our study demonstrates the use of a single-cell glycolytic biosensor to examine how energy metabolism is distributed across cells and coupled to dynamic states of neuronal function and uncovers unique relationships between neuronal identities and metabolic landscapes in vivo.


Assuntos
Glicólise , Neurônios , Animais , Metabolismo Energético , Caenorhabditis elegans , Plasticidade Neuronal
3.
PLoS Genet ; 17(11): e1009877, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34818334

RESUMO

Injured axons must regenerate to restore nervous system function, and regeneration is regulated in part by external factors from non-neuronal tissues. Many of these extrinsic factors act in the immediate cellular environment of the axon to promote or restrict regeneration, but the existence of long-distance signals regulating axon regeneration has not been clear. Here we show that the Rab GTPase rab-27 inhibits regeneration of GABAergic motor neurons in C. elegans through activity in the intestine. Re-expression of RAB-27, but not the closely related RAB-3, in the intestine of rab-27 mutant animals is sufficient to rescue normal regeneration. Several additional components of an intestinal neuropeptide secretion pathway also inhibit axon regeneration, including NPDC1/cab-1, SNAP25/aex-4, KPC3/aex-5, and the neuropeptide NLP-40, and re-expression of these genes in the intestine of mutant animals is sufficient to restore normal regeneration success. Additionally, NPDC1/cab-1 and SNAP25/aex-4 genetically interact with rab-27 in the context of axon regeneration inhibition. Together these data indicate that RAB-27-dependent neuropeptide secretion from the intestine inhibits axon regeneration, and point to distal tissues as potent extrinsic regulators of regeneration.


Assuntos
Axônios/fisiologia , Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/fisiologia , Neurônios GABAérgicos/fisiologia , Intestinos/metabolismo , Regeneração , Proteínas rab de Ligação ao GTP/metabolismo , Proteínas rab27 de Ligação ao GTP/metabolismo , Animais , Proteínas de Caenorhabditis elegans/genética , Transdução de Sinais , Vesículas Sinápticas/metabolismo , Proteínas rab de Ligação ao GTP/genética , Proteínas rab27 de Ligação ao GTP/genética
4.
Annu Rev Genet ; 46: 499-513, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22974301

RESUMO

Axon regeneration is a medically relevant process that can repair damaged neurons. This review describes current progress in understanding axon regeneration in the model organism Caenorhabditis elegans. Factors that regulate axon regeneration in C. elegans have broadly similar roles in vertebrate neurons. This means that using C. elegans as a tool to leverage discovery is a legitimate strategy for identifying conserved mechanisms of axon regeneration.


Assuntos
Axônios/fisiologia , Caenorhabditis elegans/fisiologia , Regeneração Nervosa , Animais , Axônios/metabolismo , Axotomia/métodos , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Canais de Cálcio/metabolismo , AMP Cíclico/metabolismo , MAP Quinase Quinase Quinases/genética , MAP Quinase Quinase Quinases/metabolismo , Sistema de Sinalização das MAP Quinases , MicroRNAs/genética , MicroRNAs/metabolismo , Microtúbulos/metabolismo , Modelos Animais , Neurônios/metabolismo , Neurônios/fisiologia , Traumatismos do Sistema Nervoso/metabolismo , Traumatismos do Sistema Nervoso/fisiopatologia
5.
Proc Natl Acad Sci U S A ; 112(27): 8451-6, 2015 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-26100902

RESUMO

Activity of the RNA ligase RtcB has only two known functions: tRNA ligation after intron removal and XBP1 mRNA ligation during activation of the unfolded protein response. Here, we show that RtcB acts in neurons to inhibit axon regeneration after nerve injury. This function of RtcB is independent of its basal activities in tRNA ligation and the unfolded protein response. Furthermore, inhibition of axon regeneration is independent of the RtcB cofactor archease. Finally, RtcB is enriched at axon termini after nerve injury. Our data indicate that neurons have co-opted an ancient RNA modification mechanism to regulate specific and dynamic functions and identify neuronal RtcB activity as a critical regulator of neuronal growth potential.


Assuntos
Aminoacil-tRNA Sintetases/metabolismo , Axônios/fisiologia , Proteínas de Caenorhabditis elegans/metabolismo , Regeneração Nervosa , RNA Ligase (ATP)/metabolismo , RNA de Helmintos/metabolismo , Aminoacil-tRNA Sintetases/genética , Animais , Animais Geneticamente Modificados , Axônios/metabolismo , Axotomia/métodos , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/fisiologia , Proteínas de Caenorhabditis elegans/genética , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Microscopia de Fluorescência , Mutação , Neurônios/metabolismo , Neurônios/fisiologia , RNA Ligase (ATP)/genética , RNA de Helmintos/genética , RNA de Transferência/genética , RNA de Transferência/metabolismo
6.
Proc Natl Acad Sci U S A ; 111(7): 2776-81, 2014 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-24550307

RESUMO

The nematode Caenorhabditis elegans navigates toward a preferred temperature setpoint (Ts) determined by long-term temperature exposure. During thermotaxis, the worm migrates down temperature gradients at temperatures above Ts (negative thermotaxis) and performs isothermal tracking near Ts. Under some conditions, the worm migrates up temperature gradients below Ts (positive thermotaxis). Here, we analyze positive and negative thermotaxis toward Ts to study the role of specific neurons that have been proposed to be involved in thermotaxis using genetic ablation, behavioral tracking, and calcium imaging. We find differences in the strategies for positive and negative thermotaxis. Negative thermotaxis is achieved through biasing the frequency of reorientation maneuvers (turns and reversal turns) and biasing the direction of reorientation maneuvers toward colder temperatures. Positive thermotaxis, in contrast, biases only the direction of reorientation maneuvers toward warmer temperatures. We find that the AFD thermosensory neuron drives both positive and negative thermotaxis. The AIY interneuron, which is postsynaptic to AFD, may mediate the switch from negative to positive thermotaxis below Ts. We propose that multiple thermotactic behaviors, each defined by a distinct set of sensorimotor transformations, emanate from the AFD thermosensory neurons. AFD learns and stores the memory of preferred temperatures, detects temperature gradients, and drives the appropriate thermotactic behavior in each temperature regime by the flexible use of downstream circuits.


Assuntos
Caenorhabditis elegans/fisiologia , Memória de Longo Prazo/fisiologia , Modelos Neurológicos , Movimento/fisiologia , Neurônios/fisiologia , Sensação Térmica/fisiologia , Animais , Temperatura
7.
EMBO Rep ; 15(12): 1278-85, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25366321

RESUMO

RNA ligation can regulate RNA function by altering RNA sequence, structure and coding potential. For example, the function of XBP1 in mediating the unfolded protein response requires RNA ligation, as does the maturation of some tRNAs. Here, we describe a novel in vivo model in Caenorhabditis elegans for the conserved RNA ligase RtcB and show that RtcB ligates the xbp-1 mRNA during the IRE-1 branch of the unfolded protein response. Without RtcB, protein stress results in the accumulation of unligated xbp-1 mRNA fragments, defects in the unfolded protein response, and decreased lifespan. RtcB also ligates endogenous pre-tRNA halves, and RtcB mutants have defects in growth and lifespan that can be bypassed by expression of pre-spliced tRNAs. In addition, animals that lack RtcB have defects that are independent of tRNA maturation and the unfolded protein response. Thus, RNA ligation by RtcB is required for the function of multiple endogenous target RNAs including both xbp-1 and tRNAs. RtcB is uniquely capable of performing these ligation functions, and RNA ligation by RtcB mediates multiple essential processes in vivo.


Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , RNA Ligase (ATP)/metabolismo , Animais , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas de Transporte/genética , RNA Ligase (ATP)/genética , Resposta a Proteínas não Dobradas/genética , Resposta a Proteínas não Dobradas/fisiologia
8.
PLoS Genet ; 9(11): e1003921, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24244189

RESUMO

Forward genetic screens are important tools for exploring the genetic requirements for neuronal function. However, conventional forward screens often have difficulty identifying genes whose relevant functions are masked by pleiotropy. In particular, if loss of gene function results in sterility, lethality, or other severe pleiotropy, neuronal-specific functions cannot be readily analyzed. Here we describe a method in C. elegans for generating cell-specific knockdown in neurons using feeding RNAi and its application in a screen for the role of essential genes in GABAergic neurons. We combine manipulations that increase the sensitivity of select neurons to RNAi with manipulations that block RNAi in other cells. We produce animal strains in which feeding RNAi results in restricted gene knockdown in either GABA-, acetylcholine-, dopamine-, or glutamate-releasing neurons. In these strains, we observe neuron cell-type specific behavioral changes when we knock down genes required for these neurons to function, including genes encoding the basal neurotransmission machinery. These reagents enable high-throughput, cell-specific knockdown in the nervous system, facilitating rapid dissection of the site of gene action and screening for neuronal functions of essential genes. Using the GABA-specific RNAi strain, we screened 1,320 RNAi clones targeting essential genes on chromosomes I, II, and III for their effect on GABA neuron function. We identified 48 genes whose GABA cell-specific knockdown resulted in reduced GABA motor output. This screen extends our understanding of the genetic requirements for continued neuronal function in a mature organism.


Assuntos
Caenorhabditis elegans/genética , Neurônios GABAérgicos/metabolismo , Genes Essenciais , Interferência de RNA , Ácido gama-Aminobutírico/genética , Animais , Caenorhabditis elegans/crescimento & desenvolvimento , Cromossomos/genética , Dopamina/genética , Dopamina/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Técnicas de Silenciamento de Genes , Sistema Nervoso/crescimento & desenvolvimento , Sistema Nervoso/metabolismo
9.
J Neurosci ; 34(2): 629-45, 2014 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-24403161

RESUMO

Axons of the mammalian CNS lose the ability to regenerate soon after development due to both an inhibitory CNS environment and the loss of cell-intrinsic factors necessary for regeneration. The complex molecular events required for robust regeneration of mature neurons are not fully understood, particularly in vivo. To identify genes affecting axon regeneration in Caenorhabditis elegans, we performed both an RNAi-based screen for defective motor axon regeneration in unc-70/ß-spectrin mutants and a candidate gene screen. From these screens, we identified at least 50 conserved genes with growth-promoting or growth-inhibiting functions. Through our analysis of mutants, we shed new light on certain aspects of regeneration, including the role of ß-spectrin and membrane dynamics, the antagonistic activity of MAP kinase signaling pathways, and the role of stress in promoting axon regeneration. Many gene candidates had not previously been associated with axon regeneration and implicate new pathways of interest for therapeutic intervention.


Assuntos
Axônios/fisiologia , Caenorhabditis elegans/genética , Regeneração Nervosa/genética , Transdução de Sinais/fisiologia , Animais , RNA Interferente Pequeno
10.
EMBO Rep ; 13(4): 286-8, 2012 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-22402665

RESUMO

The Cold Spring Harbour Asia conference on 'Assembly, Plasticity, Dysfunction and Repair of Neural Circuits' took place in Suzhou, China, in October 2011. Developmental, cell, molecular and systems neuroscientists convened to discuss the establishment, function and plasticity of neural circuits in diverse organisms.


Assuntos
Rede Nervosa/fisiologia , Animais , Axônios/fisiologia , Caenorhabditis elegans/fisiologia , China , Drosophila melanogaster/fisiologia , Humanos , Camundongos , Plasticidade Neuronal/fisiologia , Sinapses/metabolismo
11.
bioRxiv ; 2024 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-39314452

RESUMO

Neurons rely on local protein synthesis to rapidly modify the proteome of neurites distant from the cell body. A prerequisite for local protein synthesis is the presence of ribosomes in the neurite, but the mechanisms of ribosome transport in neurons remain poorly defined. Here, we find that ribosomes hitchhike on mitochondria for their delivery to the dendrite of a sensory neuron in C. elegans. Ribosomes co-transport with dendritic mitochondria, and their association requires the atypical Rho GTPase MIRO-1. Disrupting mitochondrial transport prevents ribosomes from reaching the dendrite, whereas ectopic re-localization of mitochondria results in a concomitant re-localization of ribosomes, demonstrating that mitochondria are required and sufficient for instructing ribosome distribution in dendrites. Endolysosomal organelles that are involved in mRNA transport and translation can associate with mitochondria and ribosomes but do not play a significant role in ribosome transport. These results reveal a mechanism for dendritic ribosome delivery, which is a critical upstream requirement for local protein synthesis.

12.
J Cell Biol ; 223(5)2024 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-38470363

RESUMO

Mitochondria transport is crucial for axonal mitochondria distribution and is mediated by kinesin-1-based anterograde and dynein-based retrograde motor complexes. While Miro and Milton/TRAK were identified as key adaptors between mitochondria and kinesin-1, recent studies suggest the presence of additional mechanisms. In C. elegans, ric-7 is the only single gene described so far, other than kinesin-1, that is absolutely required for axonal mitochondria localization. Using CRISPR engineering in C. elegans, we find that Miro is important but is not essential for anterograde traffic, whereas it is required for retrograde traffic. Both the endogenous RIC-7 and kinesin-1 act at the leading end to transport mitochondria anterogradely. RIC-7 binding to mitochondria requires its N-terminal domain and partially relies on MIRO-1, whereas RIC-7 accumulation at the leading end depends on its disordered region, kinesin-1, and metaxin2. We conclude that transport complexes containing kinesin-1 and RIC-7 polarize at the leading edge of mitochondria and are required for anterograde axonal transport in C. elegans.


Assuntos
Transporte Axonal , Cinesinas , Animais , Axônios , Caenorhabditis elegans/citologia , Caenorhabditis elegans/metabolismo , Cinesinas/metabolismo , Mitocôndrias/metabolismo
13.
Nat Metab ; 6(9): 1712-1735, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39261628

RESUMO

Glucose, the primary cellular energy source, is metabolized through glycolysis initiated by the rate-limiting enzyme hexokinase (HK). In energy-demanding tissues like the brain, HK1 is the dominant isoform, primarily localized on mitochondria, and is crucial for efficient glycolysis-oxidative phosphorylation coupling and optimal energy generation. This study unveils a unique mechanism regulating HK1 activity, glycolysis and the dynamics of mitochondrial coupling, mediated by the metabolic sensor enzyme O-GlcNAc transferase (OGT). OGT catalyses reversible O-GlcNAcylation, a post-translational modification influenced by glucose flux. Elevated OGT activity induces dynamic O-GlcNAcylation of the regulatory domain of HK1, subsequently promoting the assembly of the glycolytic metabolon on the outer mitochondrial membrane. This modification enhances the mitochondrial association with HK1, orchestrating glycolytic and mitochondrial ATP production. Mutation in HK1's O-GlcNAcylation site reduces ATP generation in multiple cell types, specifically affecting metabolic efficiency in neurons. This study reveals a previously unappreciated pathway that links neuronal metabolism and mitochondrial function through OGT and the formation of the glycolytic metabolon, providing potential strategies for tackling metabolic and neurological disorders.


Assuntos
Glicólise , Hexoquinase , Mitocôndrias , N-Acetilglucosaminiltransferases , Mitocôndrias/metabolismo , Hexoquinase/metabolismo , Humanos , N-Acetilglucosaminiltransferases/metabolismo , N-Acetilglucosaminiltransferases/genética , Animais , Neurônios/metabolismo , Trifosfato de Adenosina/metabolismo , Glucose/metabolismo , Processamento de Proteína Pós-Traducional , Camundongos , Fosforilação Oxidativa
14.
Proc Natl Acad Sci U S A ; 107(52): 22399-406, 2010 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-21139055

RESUMO

Intracellular membrane fusion is mediated by the concerted action of N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) and Sec1/Munc18 (SM) proteins. During fusion, SM proteins bind the N-terminal peptide (N-peptide) motif of the SNARE subunit syntaxin, but the function of this interaction is unknown. Here, using FRET-based biochemical reconstitution and Caenorhabditis elegans genetics, we show that the N-peptide of syntaxin-1 recruits the SM protein Munc18-1/nSec1 to the SNARE bundle, facilitating their assembly into a fusion-competent complex. The recruitment is achieved through physical tethering rather than allosteric activation of Munc18-1. Consistent with the recruitment role, the N-peptide is not spatially constrained along syntaxin-1, and it is functional when translocated to another SNARE subunit SNAP-25 or even when simply anchored in the target membrane. The N-peptide function is restricted to an early initiation stage of the fusion reaction. After association, Munc18-1 and the SNARE bundle together drive membrane merging without further involving the N-peptide. Thus, the syntaxin N-peptide is an initiation factor for the assembly of the SNARE-SM membrane fusion complex.


Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Fusão de Membrana , Fosfoproteínas/metabolismo , Proteínas SNARE/metabolismo , Sintaxina 1/metabolismo , Proteínas de Transporte Vesicular/metabolismo , Motivos de Aminoácidos/genética , Sequência de Aminoácidos , Animais , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/química , Proteínas de Caenorhabditis elegans/genética , Feminino , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Masculino , Microscopia Confocal , Modelos Moleculares , Complexos Multiproteicos/química , Complexos Multiproteicos/metabolismo , Proteínas Munc18/química , Proteínas Munc18/genética , Proteínas Munc18/metabolismo , Mutação , Fosfoproteínas/química , Fosfoproteínas/genética , Ligação Proteica , Conformação Proteica , Estrutura Terciária de Proteína , Proteínas SNARE/química , Proteínas SNARE/genética , Sintaxina 1/química , Sintaxina 1/genética , Fatores de Tempo , Proteínas de Transporte Vesicular/química , Proteínas de Transporte Vesicular/genética
15.
bioRxiv ; 2023 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-37502914

RESUMO

Mitochondria transport is crucial for mitochondria distribution in axons and is mediated by kinesin-1-based anterograde and dynein-based retrograde motor complexes. While Miro and Milton/TRAK were identified as key adaptors between mitochondria and kinesin-1, recent studies suggest the presence of additional mechanisms. In C. elegans, ric-7 is the only single gene described so far, other than kinesin-1, that is absolutely required for axonal mitochondria localization. Using CRISPR engineering in C. elegans, we find that Miro is important but is not essential for anterograde traffic, whereas it is required for retrograde traffic. Both the endogenous RIC-7 and kinesin-1 act at the leading end to transport mitochondria anterogradely. RIC-7 recruitment to mitochondria requires its N-terminal domain and partially relies on MIRO-1, whereas RIC-7 accumulation at the leading end depends on its disordered region, kinesin-1 and metaxin2. We conclude that polarized transport complexes containing kinesin-1 and RIC-7 form at the leading edge of mitochondria, and that these complexes are required for anterograde axonal transport.

16.
bioRxiv ; 2023 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-37745399

RESUMO

Programmed cell death is a common feature of animal development. During development of the C. elegans hermaphrodite, programmed cell death (PCD) removes 131 cells from stereotyped positions in the cell lineage, mostly in neuronal lineages. Blocking cell death results in supernumerary "undead" neurons. We find that undead neurons can be wired into circuits, can display activity, and can modify specific behaviors. The two undead RIM-like neurons participate in the RIM-containing circuit that computes movement. The addition of these two extra neurons results in animals that initiate fewer reversals and lengthens the duration of those reversals that do occur. We describe additional behavioral alterations of cell-death mutants, including in turning angle and pharyngeal pumping. These findings reveal that, like too much PCD, too little PCD can modify nervous system function and animal behavior.

17.
Cell Rep ; 42(9): 113026, 2023 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-37635352

RESUMO

Wallerian axonal degeneration (WD) does not occur in the nematode C. elegans, in contrast to other model animals. However, WD depends on the NADase activity of SARM1, a protein that is also expressed in C. elegans (ceSARM/ceTIR-1). We hypothesized that differences in SARM between species might exist and account for the divergence in WD. We first show that expression of the human (h)SARM1, but not ceTIR-1, in C. elegans neurons is sufficient to confer axon degeneration after nerve injury. Next, we determined the cryoelectron microscopy structure of ceTIR-1 and found that, unlike hSARM1, which exists as an auto-inhibited ring octamer, ceTIR-1 forms a readily active 9-mer. Enzymatically, the NADase activity of ceTIR-1 is substantially weaker (10-fold higher Km) than that of hSARM1, and even when fully active, it falls short of consuming all cellular NAD+. Our experiments provide insight into the molecular mechanisms and evolution of SARM orthologs and WD across species.


Assuntos
Axônios , Caenorhabditis elegans , Animais , Humanos , Axônios/metabolismo , Caenorhabditis elegans/metabolismo , Microscopia Crioeletrônica , Neurônios/metabolismo , Proteínas do Domínio Armadillo/metabolismo , NAD+ Nucleosidase/metabolismo , Degeneração Walleriana/metabolismo
18.
bioRxiv ; 2023 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-37662343

RESUMO

Glucose, the primary cellular energy source, is metabolized through glycolysis initiated by the rate-limiting enzyme Hexokinase (HK). In energy-demanding tissues like the brain, HK1 is the dominant isoform, primarily localized on mitochondria, crucial for efficient glycolysis-oxidative phosphorylation coupling and optimal energy generation. This study unveils a unique mechanism regulating HK1 activity, glycolysis, and the dynamics of mitochondrial coupling, mediated by the metabolic sensor enzyme O-GlcNAc transferase (OGT). OGT catalyzes reversible O-GlcNAcylation, a post-translational modification, influenced by glucose flux. Elevated OGT activity induces dynamic O-GlcNAcylation of HK1's regulatory domain, subsequently promoting the assembly of the glycolytic metabolon on the outer mitochondrial membrane. This modification enhances HK1's mitochondrial association, orchestrating glycolytic and mitochondrial ATP production. Mutations in HK1's O-GlcNAcylation site reduce ATP generation, affecting synaptic functions in neurons. The study uncovers a novel pathway that bridges neuronal metabolism and mitochondrial function via OGT and the formation of the glycolytic metabolon, offering new prospects for tackling metabolic and neurological disorders.

19.
bioRxiv ; 2023 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-37662365

RESUMO

Energy metabolism supports neuronal function. While it is well established that changes in energy metabolism underpin brain plasticity and function, less is known about how individual neurons modulate their metabolic states to meet varying energy demands. This is because most approaches used to examine metabolism in living organisms lack the resolution to visualize energy metabolism within individual circuits, cells, or subcellular regions. Here we adapted a biosensor for glycolysis, HYlight, for use in C. elegans to image dynamic changes in glycolysis within individual neurons and in vivo. We determined that neurons perform glycolysis cell-autonomously, and modulate glycolytic states upon energy stress. By examining glycolysis in specific neurons, we documented a neuronal energy landscape comprising three general observations: 1) glycolytic states in neurons are diverse across individual cell types; 2) for a given condition, glycolytic states within individual neurons are reproducible across animals; and 3) for varying conditions of energy stress, glycolytic states are plastic and adapt to energy demands. Through genetic analyses, we uncovered roles for regulatory enzymes and mitochondrial localization in the cellular and subcellular dynamic regulation of glycolysis. Our study demonstrates the use of a single-cell glycolytic biosensor to examine how energy metabolism is distributed across cells and coupled to dynamic states of neuronal function, and uncovers new relationships between neuronal identities and metabolic landscapes in vivo.

20.
Dev Cell ; 58(19): 1847-1863.e12, 2023 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-37751746

RESUMO

An actin-spectrin lattice, the membrane periodic skeleton (MPS), protects axons from breakage. MPS integrity relies on spectrin delivery via slow axonal transport, a process that remains poorly understood. We designed a probe to visualize endogenous spectrin dynamics at single-axon resolution in vivo. Surprisingly, spectrin transport is bimodal, comprising fast runs and movements that are 100-fold slower than previously reported. Modeling and genetic analysis suggest that the two rates are independent, yet both require kinesin-1 and the coiled-coil proteins UNC-76/FEZ1 and UNC-69/SCOC, which we identify as spectrin-kinesin adaptors. Knockdown of either protein led to disrupted spectrin motility and reduced distal MPS, and UNC-76 overexpression instructed excessive transport of spectrin. Artificially linking spectrin to kinesin-1 drove robust motility but inefficient MPS assembly, whereas impairing MPS assembly led to excessive spectrin transport, suggesting a balance between transport and assembly. These results provide insight into slow axonal transport and MPS integrity.


Assuntos
Proteínas de Caenorhabditis elegans , Caenorhabditis elegans , Espectrina , Animais , Transporte Axonal , Axônios/metabolismo , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Cinesinas/metabolismo , Espectrina/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA