RESUMO
Ultraviolet (UV) light and incompletely understood genetic and epigenetic variations determine skin color. Here we describe an UV- and microphthalmia-associated transcription factor (MITF)-independent mechanism of skin pigmentation. Targeting the mitochondrial redox-regulating enzyme nicotinamide nucleotide transhydrogenase (NNT) resulted in cellular redox changes that affect tyrosinase degradation. These changes regulate melanosome maturation and, consequently, eumelanin levels and pigmentation. Topical application of small-molecule inhibitors yielded skin darkening in human skin, and mice with decreased NNT function displayed increased pigmentation. Additionally, genetic modification of NNT in zebrafish alters melanocytic pigmentation. Analysis of four diverse human cohorts revealed significant associations of skin color, tanning, and sun protection use with various single-nucleotide polymorphisms within NNT. NNT levels were independent of UVB irradiation and redox modulation. Individuals with postinflammatory hyperpigmentation or lentigines displayed decreased skin NNT levels, suggesting an NNT-driven, redox-dependent pigmentation mechanism that can be targeted with NNT-modifying topical drugs for medical and cosmetic purposes.
Assuntos
Fator de Transcrição Associado à Microftalmia/metabolismo , NADP Trans-Hidrogenases/metabolismo , Pigmentação da Pele/efeitos da radiação , Raios Ultravioleta , Animais , Linhagem Celular , Estudos de Coortes , AMP Cíclico/metabolismo , Dano ao DNA , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Predisposição Genética para Doença , Humanos , Melanócitos/efeitos dos fármacos , Melanócitos/metabolismo , Melanossomas/efeitos dos fármacos , Melanossomas/metabolismo , Melanossomas/efeitos da radiação , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Monofenol Mono-Oxigenase/genética , Monofenol Mono-Oxigenase/metabolismo , NADP Trans-Hidrogenases/antagonistas & inibidores , Oxirredução/efeitos dos fármacos , Oxirredução/efeitos da radiação , Polimorfismo de Nucleotídeo Único/genética , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteólise/efeitos dos fármacos , Proteólise/efeitos da radiação , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Pigmentação da Pele/efeitos dos fármacos , Pigmentação da Pele/genética , Ubiquitina/metabolismo , Peixe-ZebraRESUMO
The rise of antibiotic resistance and declining discovery of new antibiotics has created a global health crisis. Of particular concern, no new antibiotic classes have been approved for treating Gram-negative pathogens in decades. Here, we characterize a compound, SCH-79797, that kills both Gram-negative and Gram-positive bacteria through a unique dual-targeting mechanism of action (MoA) with undetectably low resistance frequencies. To characterize its MoA, we combined quantitative imaging, proteomic, genetic, metabolomic, and cell-based assays. This pipeline demonstrates that SCH-79797 has two independent cellular targets, folate metabolism and bacterial membrane integrity, and outperforms combination treatments in killing methicillin-resistant Staphylococcus aureus (MRSA) persisters. Building on the molecular core of SCH-79797, we developed a derivative, Irresistin-16, with increased potency and showed its efficacy against Neisseria gonorrhoeae in a mouse vaginal infection model. This promising antibiotic lead suggests that combining multiple MoAs onto a single chemical scaffold may be an underappreciated approach to targeting challenging bacterial pathogens.
Assuntos
Bactérias Gram-Negativas/efeitos dos fármacos , Pirróis/metabolismo , Pirróis/farmacologia , Quinazolinas/metabolismo , Quinazolinas/farmacologia , Animais , Antibacterianos/farmacologia , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Farmacorresistência Bacteriana/efeitos dos fármacos , Farmacorresistência Bacteriana/genética , Feminino , Ácido Fólico/metabolismo , Bactérias Gram-Positivas/efeitos dos fármacos , Células HEK293 , Humanos , Masculino , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Ovariectomia , Proteômica , Pseudomonas aeruginosa/efeitos dos fármacosRESUMO
We show that SARS-CoV-2 spike protein interacts with both cellular heparan sulfate and angiotensin-converting enzyme 2 (ACE2) through its receptor-binding domain (RBD). Docking studies suggest a heparin/heparan sulfate-binding site adjacent to the ACE2-binding site. Both ACE2 and heparin can bind independently to spike protein in vitro, and a ternary complex can be generated using heparin as a scaffold. Electron micrographs of spike protein suggests that heparin enhances the open conformation of the RBD that binds ACE2. On cells, spike protein binding depends on both heparan sulfate and ACE2. Unfractionated heparin, non-anticoagulant heparin, heparin lyases, and lung heparan sulfate potently block spike protein binding and/or infection by pseudotyped virus and authentic SARS-CoV-2 virus. We suggest a model in which viral attachment and infection involves heparan sulfate-dependent enhancement of binding to ACE2. Manipulation of heparan sulfate or inhibition of viral adhesion by exogenous heparin presents new therapeutic opportunities.
Assuntos
Betacoronavirus/fisiologia , Heparitina Sulfato/metabolismo , Peptidil Dipeptidase A/metabolismo , Glicoproteína da Espícula de Coronavírus/metabolismo , Sequência de Aminoácidos , Enzima de Conversão de Angiotensina 2 , Betacoronavirus/isolamento & purificação , Sítios de Ligação , COVID-19 , Linhagem Celular , Infecções por Coronavirus/patologia , Infecções por Coronavirus/virologia , Heparina/química , Heparina/metabolismo , Heparitina Sulfato/química , Humanos , Rim/metabolismo , Pulmão/metabolismo , Simulação de Dinâmica Molecular , Pandemias , Peptidil Dipeptidase A/química , Pneumonia Viral/patologia , Pneumonia Viral/virologia , Ligação Proteica , Domínios Proteicos , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/genética , Internalização do VírusRESUMO
Yeast ataxin-2, also known as Pbp1, senses the activity state of mitochondria in order to regulate TORC1. A domain of Pbp1 required to adapt cells to mitochondrial activity is of low sequence complexity. The low-complexity (LC) domain of Pbp1 forms labile, cross-ß polymers that facilitate phase transition of the protein into liquid-like or gel-like states. Phase transition for other LC domains is reliant upon widely distributed aromatic amino acids. In place of tyrosine or phenylalanine residues prototypically used for phase separation, Pbp1 contains 24 similarly disposed methionine residues. Here, we show that the Pbp1 methionine residues are sensitive to hydrogen peroxide (H2O2)-mediated oxidation in vitro and in living cells. Methionine oxidation melts Pbp1 liquid-like droplets in a manner reversed by methionine sulfoxide reductase enzymes. These observations explain how reversible formation of labile polymers by the Pbp1 LC domain enables the protein to function as a sensor of cellular redox state.
Assuntos
Proteínas de Transporte/metabolismo , Metionina/química , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Sequência de Aminoácidos , Proteínas de Transporte/química , Proteínas de Transporte/genética , Peróxido de Hidrogênio/farmacologia , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Metionina/metabolismo , Metionina Sulfóxido Redutases/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mutagênese Sítio-Dirigida , Oxirredução , Estresse Oxidativo/efeitos dos fármacos , Transição de Fase , Domínios Proteicos , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genéticaRESUMO
Yeast ataxin-2, also known as Pbp1 (polyA binding protein-binding protein 1), is an intrinsically disordered protein implicated in stress granule formation, RNA biology, and neurodegenerative disease. To understand the endogenous function of this protein, we identify Pbp1 as a dedicated regulator of TORC1 signaling and autophagy under conditions that require mitochondrial respiration. Pbp1 binds to TORC1 specifically during respiratory growth, but utilizes an additional methionine-rich, low complexity (LC) region to inhibit TORC1. This LC region causes phase separation, forms reversible fibrils, and enables self-association into assemblies required for TORC1 inhibition. Mutants that weaken phase separation in vitro exhibit reduced capacity to inhibit TORC1 and induce autophagy. Loss of Pbp1 leads to mitochondrial dysfunction and reduced fitness during nutritional stress. Thus, Pbp1 forms a condensate in response to respiratory status to regulate TORC1 signaling.
Assuntos
Proteínas de Transporte/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Transdução de Sinais , Sequência de Aminoácidos , Autofagia/efeitos dos fármacos , Proteínas de Transporte/química , Proteínas de Transporte/genética , Alvo Mecanístico do Complexo 1 de Rapamicina/antagonistas & inibidores , Metionina/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mutagênese Sítio-Dirigida , Fosforilação , Ligação Proteica , Domínios Proteicos , Saccharomyces cerevisiae/crescimento & desenvolvimento , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Transdução de Sinais/efeitos dos fármacos , Sirolimo/farmacologiaRESUMO
Cell shape matters across the kingdoms of life, and cells have the remarkable capacity to define and maintain specific shapes and sizes. But how are the shapes of micron-sized cells determined from the coordinated activities of nanometer-sized proteins? Here, we review general principles that have surfaced through the study of rod-shaped bacterial growth. Imaging approaches have revealed that polymers of the actin homolog MreB play a central role. MreB both senses and changes cell shape, thereby generating a self-organizing feedback system for shape maintenance. At the molecular level, structural and computational studies indicate that MreB filaments exhibit tunable mechanical properties that explain their preference for certain geometries and orientations along the cylindrical cell body. We illustrate the regulatory landscape of rod-shape formation and the connectivity between cell shape, cell growth, and other aspects of cell physiology. These discoveries provide a framework for future investigations into the architecture and construction of microbes.
Assuntos
Membrana Celular/genética , Parede Celular/genética , Proteínas de Escherichia coli/genética , Escherichia coli/genética , Membrana Celular/metabolismo , Parede Celular/metabolismo , Escherichia coli/citologia , Escherichia coli/crescimento & desenvolvimento , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Modelos Moleculares , Mutação , Conformação ProteicaRESUMO
Glial cells and central nervous system (CNS)-infiltrating leukocytes contribute to multiple sclerosis (MS). However, the networks that govern crosstalk among these ontologically distinct populations remain unclear. Here, we show that, in mice and humans, CNS-resident astrocytes and infiltrating CD44hiCD4+ T cells generated interleukin-3 (IL-3), while microglia and recruited myeloid cells expressed interleukin-3 receptor-É (IL-3RÉ). Astrocytic and T cell IL-3 elicited an immune migratory and chemotactic program by IL-3RÉ+ myeloid cells that enhanced CNS immune cell infiltration, exacerbating MS and its preclinical model. Multiregional snRNA-seq of human CNS tissue revealed the appearance of IL3RA-expressing myeloid cells with chemotactic programming in MS plaques. IL3RA expression by plaque myeloid cells and IL-3 amount in the cerebrospinal fluid predicted myeloid and T cell abundance in the CNS and correlated with MS severity. Our findings establish IL-3:IL-3RA as a glial-peripheral immune network that prompts immune cell recruitment to the CNS and worsens MS.
Assuntos
Esclerose Múltipla , Animais , Humanos , Camundongos , Sistema Nervoso Central , Interleucina-3 , Microglia , Neuroglia/metabolismoRESUMO
Maintenance of proper levels of the methyl donor S-adenosylmethionine (SAM) is critical for a wide variety of biological processes. We demonstrate that the N6-adenosine methyltransferase METTL16 regulates expression of human MAT2A, which encodes the SAM synthetase expressed in most cells. Upon SAM depletion by methionine starvation, cells induce MAT2A expression by enhanced splicing of a retained intron. Induction requires METTL16 and its methylation substrate, a vertebrate conserved hairpin (hp1) in the MAT2A 3' UTR. Increasing METTL16 occupancy on the MAT2A 3' UTR is sufficient to induce efficient splicing. We propose that, under SAM-limiting conditions, METTL16 occupancy on hp1 increases due to inefficient enzymatic turnover, which promotes MAT2A splicing. We further show that METTL16 is the long-unknown methyltransferase for the U6 spliceosomal small nuclear RNA (snRNA). These observations suggest that the conserved U6 snRNA methyltransferase evolved an additional function in vertebrates to regulate SAM homeostasis.
Assuntos
Íntrons , Metionina Adenosiltransferase/genética , Metiltransferases/metabolismo , Splicing de RNA , S-Adenosilmetionina/metabolismo , Animais , Sequência de Bases , Regulação Enzimológica da Expressão Gênica , Células HEK293 , Humanos , Sequências Repetidas Invertidas , Metionina Adenosiltransferase/química , Metilação , Metiltransferases/química , Schizosaccharomyces/metabolismoRESUMO
Pathogenic Vibrio cholerae remains a major human health concern. V. cholerae has a characteristic curved rod morphology, with a longer outer face and a shorter inner face. The mechanism and function of this curvature were previously unknown. Here, we identify and characterize CrvA, the first curvature determinant in V. cholerae. CrvA self-assembles into filaments at the inner face of cell curvature. Unlike traditional cytoskeletons, CrvA localizes to the periplasm and thus can be considered a periskeletal element. To quantify how curvature forms, we developed QuASAR (quantitative analysis of sacculus architecture remodeling), which measures subcellular peptidoglycan dynamics. QuASAR reveals that CrvA asymmetrically patterns peptidoglycan insertion rather than removal, causing more material insertions into the outer face than the inner face. Furthermore, crvA is quorum regulated, and CrvA-dependent curvature increases at high cell density. Finally, we demonstrate that CrvA promotes motility in hydrogels and confers an advantage in host colonization and pathogenesis.
Assuntos
Vibrio cholerae/citologia , Vibrio cholerae/patogenicidade , Sequência de Aminoácidos , Animais , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Locomoção , Camundongos , Peptidoglicano/metabolismo , Periplasma/metabolismo , Alinhamento de Sequência , Vibrio cholerae/genética , Vibrio cholerae/metabolismo , VirulênciaRESUMO
Antimicrobial resistance (AMR) - the ability of microorganisms to adapt and survive under diverse chemical selection pressures - is influenced by complex interactions between humans, companion and food-producing animals, wildlife, insects and the environment. To understand and manage the threat posed to health (human, animal, plant and environmental) and security (food and water security and biosecurity), a multifaceted 'One Health' approach to AMR surveillance is required. Genomic technologies have enabled monitoring of the mobilization, persistence and abundance of AMR genes and mutations within and between microbial populations. Their adoption has also allowed source-tracing of AMR pathogens and modelling of AMR evolution and transmission. Here, we highlight recent advances in genomic AMR surveillance and the relative strengths of different technologies for AMR surveillance and research. We showcase recent insights derived from One Health genomic surveillance and consider the challenges to broader adoption both in developed and in lower- and middle-income countries.
Assuntos
Farmacorresistência Bacteriana , Saúde Única , Animais , Humanos , Farmacorresistência Bacteriana/genética , Antibacterianos/farmacologia , Genômica , Animais SelvagensRESUMO
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating region of sunspot emergence appears around 30° latitude and vanishes near the equator every 11 years (ref. 1). Moreover, longitudinal flows called torsional oscillations closely shadow sunspot migration, undoubtedly sharing a common cause2. Contrary to theories suggesting deep origins of these phenomena, helioseismology pinpoints low-latitude torsional oscillations to the outer 5-10% of the Sun, the near-surface shear layer3,4. Within this zone, inwardly increasing differential rotation coupled with a poloidal magnetic field strongly implicates the magneto-rotational instability5,6, prominent in accretion-disk theory and observed in laboratory experiments7. Together, these two facts prompt the general question: whether the solar dynamo is possibly a near-surface instability. Here we report strong affirmative evidence in stark contrast to traditional models8 focusing on the deeper tachocline. Simple analytic estimates show that the near-surface magneto-rotational instability better explains the spatiotemporal scales of the torsional oscillations and inferred subsurface magnetic field amplitudes9. State-of-the-art numerical simulations corroborate these estimates and reproduce hemispherical magnetic current helicity laws10. The dynamo resulting from a well-understood near-surface phenomenon improves prospects for accurate predictions of full magnetic cycles and space weather, affecting the electromagnetic infrastructure of Earth.
RESUMO
A single dose of psilocybin, a psychedelic that acutely causes distortions of space-time perception and ego dissolution, produces rapid and persistent therapeutic effects in human clinical trials1-4. In animal models, psilocybin induces neuroplasticity in cortex and hippocampus5-8. It remains unclear how human brain network changes relate to subjective and lasting effects of psychedelics. Here we tracked individual-specific brain changes with longitudinal precision functional mapping (roughly 18 magnetic resonance imaging visits per participant). Healthy adults were tracked before, during and for 3 weeks after high-dose psilocybin (25 mg) and methylphenidate (40 mg), and brought back for an additional psilocybin dose 6-12 months later. Psilocybin massively disrupted functional connectivity (FC) in cortex and subcortex, acutely causing more than threefold greater change than methylphenidate. These FC changes were driven by brain desynchronization across spatial scales (areal, global), which dissolved network distinctions by reducing correlations within and anticorrelations between networks. Psilocybin-driven FC changes were strongest in the default mode network, which is connected to the anterior hippocampus and is thought to create our sense of space, time and self. Individual differences in FC changes were strongly linked to the subjective psychedelic experience. Performing a perceptual task reduced psilocybin-driven FC changes. Psilocybin caused persistent decrease in FC between the anterior hippocampus and default mode network, lasting for weeks. Persistent reduction of hippocampal-default mode network connectivity may represent a neuroanatomical and mechanistic correlate of the proplasticity and therapeutic effects of psychedelics.
Assuntos
Encéfalo , Alucinógenos , Rede Nervosa , Psilocibina , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem , Encéfalo/citologia , Encéfalo/diagnóstico por imagem , Encéfalo/efeitos dos fármacos , Encéfalo/fisiologia , Mapeamento Encefálico , Rede de Modo Padrão/citologia , Rede de Modo Padrão/diagnóstico por imagem , Rede de Modo Padrão/efeitos dos fármacos , Rede de Modo Padrão/fisiologia , Alucinógenos/farmacologia , Alucinógenos/administração & dosagem , Voluntários Saudáveis , Hipocampo/citologia , Hipocampo/diagnóstico por imagem , Hipocampo/efeitos dos fármacos , Hipocampo/fisiologia , Imageamento por Ressonância Magnética , Metilfenidato/farmacologia , Metilfenidato/administração & dosagem , Rede Nervosa/citologia , Rede Nervosa/diagnóstico por imagem , Rede Nervosa/efeitos dos fármacos , Rede Nervosa/fisiologia , Psilocibina/farmacologia , Psilocibina/administração & dosagem , Percepção Espacial/efeitos dos fármacos , Percepção do Tempo/efeitos dos fármacos , EgoRESUMO
The mergers of binary compact objects such as neutron stars and black holes are of central interest to several areas of astrophysics, including as the progenitors of gamma-ray bursts (GRBs)1, sources of high-frequency gravitational waves (GWs)2 and likely production sites for heavy-element nucleosynthesis by means of rapid neutron capture (the r-process)3. Here we present observations of the exceptionally bright GRB 230307A. We show that GRB 230307A belongs to the class of long-duration GRBs associated with compact object mergers4-6 and contains a kilonova similar to AT2017gfo, associated with the GW merger GW170817 (refs. 7-12). We obtained James Webb Space Telescope (JWST) mid-infrared imaging and spectroscopy 29 and 61 days after the burst. The spectroscopy shows an emission line at 2.15 microns, which we interpret as tellurium (atomic mass A = 130) and a very red source, emitting most of its light in the mid-infrared owing to the production of lanthanides. These observations demonstrate that nucleosynthesis in GRBs can create r-process elements across a broad atomic mass range and play a central role in heavy-element nucleosynthesis across the Universe.
RESUMO
Acetyl-CoA is a key intermediate situated at the intersection of many metabolic pathways. The reliance of histone acetylation on acetyl-CoA enables the coordination of gene expression with metabolic state. Abundant acetyl-CoA has been linked to the activation of genes involved in cell growth or tumorigenesis through histone acetylation. However, the role of histone acetylation in transcription under low levels of acetyl-CoA remains poorly understood. Here, we use a yeast starvation model to observe the dramatic alteration in the global occupancy of histone acetylation following carbon starvation; the location of histone acetylation marks shifts from growth-promoting genes to gluconeogenic and fat metabolism genes. This reallocation is mediated by both the histone deacetylase Rpd3p and the acetyltransferase Gcn5p, a component of the SAGA transcriptional coactivator. Our findings reveal an unexpected switch in the specificity of histone acetylation to promote pathways that generate acetyl-CoA for oxidation when acetyl-CoA is limiting.
Assuntos
Gluconeogênese , Glucose/deficiência , Histonas/metabolismo , Metabolismo dos Lipídeos , Processamento de Proteína Pós-Traducional , Saccharomyces cerevisiae/metabolismo , Acetilcoenzima A/metabolismo , Acetilação , Regulação Fúngica da Expressão Gênica , Histona Acetiltransferases/genética , Histona Acetiltransferases/metabolismo , Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Metabolismo dos Lipídeos/genética , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Transativadores/genética , Transativadores/metabolismoRESUMO
CRISPR systems are prokaryotic adaptive immune systems that use RNA-guided Cas nucleases to recognize and destroy foreign genetic elements. To overcome CRISPR immunity, bacteriophages have evolved diverse families of anti-CRISPR proteins (Acrs). Recently, Lin et al. (2020) described the discovery and characterization of 7 Acr families (AcrVIA1-7) that inhibit type VI-A CRISPR systems. We detail several inconsistencies that question the results reported in the Lin et al. (2020) study. These include inaccurate bioinformatics analyses and bacterial strains that are impossible to construct. Published strains were provided by the authors, but MS2 bacteriophage plaque assays did not support the published results. We also independently tested the Acr sequences described in the original report, in E. coli and mammalian cells, but did not observe anti-Cas13a activity. Taken together, our data and analyses prompt us to question the claim that AcrVIA1-7 reported in Lin et al. are type VI anti-CRISPR proteins.
Assuntos
Bacteriófagos , Proteínas Associadas a CRISPR , Animais , Bacteriófagos/genética , Proteínas Associadas a CRISPR/genética , Proteínas Associadas a CRISPR/metabolismo , Sistemas CRISPR-Cas , Escherichia coli/genética , Escherichia coli/metabolismo , Leptotrichia/genética , Mamíferos/metabolismo , Prófagos/genética , Prófagos/metabolismo , Ribonucleases/metabolismoRESUMO
Acetyl-CoA represents a central node of carbon metabolism that plays a key role in bioenergetics, cell proliferation, and the regulation of gene expression. Highly glycolytic or hypoxic tumors must produce sufficient quantities of this metabolite to support cell growth and survival under nutrient-limiting conditions. Here, we show that the nucleocytosolic acetyl-CoA synthetase enzyme, ACSS2, supplies a key source of acetyl-CoA for tumors by capturing acetate as a carbon source. Despite exhibiting no gross deficits in growth or development, adult mice lacking ACSS2 exhibit a significant reduction in tumor burden in two different models of hepatocellular carcinoma. ACSS2 is expressed in a large proportion of human tumors, and its activity is responsible for the majority of cellular acetate uptake into both lipids and histones. These observations may qualify ACSS2 as a targetable metabolic vulnerability of a wide spectrum of tumors.
Assuntos
Acetato-CoA Ligase/metabolismo , Acetatos/metabolismo , Neoplasias/metabolismo , Acetato-CoA Ligase/análise , Acetato-CoA Ligase/genética , Acetilcoenzima A/metabolismo , Animais , Humanos , Imuno-Histoquímica , Neoplasias Hepáticas/metabolismo , Camundongos , Neoplasias/química , Neoplasias/patologia , Tomografia por Emissão de Pósitrons , Neoplasias de Mama Triplo Negativas/química , Neoplasias de Mama Triplo Negativas/patologiaRESUMO
Glioblastomas and brain metastases are highly proliferative brain tumors with short survival times. Previously, using (13)C-NMR analysis of brain tumors resected from patients during infusion of (13)C-glucose, we demonstrated that there is robust oxidation of glucose in the citric acid cycle, yet glucose contributes less than 50% of the carbons to the acetyl-CoA pool. Here, we show that primary and metastatic mouse orthotopic brain tumors have the capacity to oxidize [1,2-(13)C]acetate and can do so while simultaneously oxidizing [1,6-(13)C]glucose. The tumors do not oxidize [U-(13)C]glutamine. In vivo oxidation of [1,2-(13)C]acetate was validated in brain tumor patients and was correlated with expression of acetyl-CoA synthetase enzyme 2, ACSS2. Together, the data demonstrate a strikingly common metabolic phenotype in diverse brain tumors that includes the ability to oxidize acetate in the citric acid cycle. This adaptation may be important for meeting the high biosynthetic and bioenergetic demands of malignant growth.
Assuntos
Acetato-CoA Ligase/metabolismo , Acetatos/metabolismo , Neoplasias Encefálicas/metabolismo , Ciclo do Ácido Cítrico , Glioblastoma/metabolismo , Acetato-CoA Ligase/genética , Animais , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/secundário , Modelos Animais de Doenças , Glioblastoma/patologia , Ácido Glutâmico/metabolismo , Humanos , Camundongos , Metástase Neoplásica/patologiaRESUMO
Motor cortex (M1) has been thought to form a continuous somatotopic homunculus extending down the precentral gyrus from foot to face representations1,2, despite evidence for concentric functional zones3 and maps of complex actions4. Here, using precision functional magnetic resonance imaging (fMRI) methods, we find that the classic homunculus is interrupted by regions with distinct connectivity, structure and function, alternating with effector-specific (foot, hand and mouth) areas. These inter-effector regions exhibit decreased cortical thickness and strong functional connectivity to each other, as well as to the cingulo-opercular network (CON), critical for action5 and physiological control6, arousal7, errors8 and pain9. This interdigitation of action control-linked and motor effector regions was verified in the three largest fMRI datasets. Macaque and pediatric (newborn, infant and child) precision fMRI suggested cross-species homologues and developmental precursors of the inter-effector system. A battery of motor and action fMRI tasks documented concentric effector somatotopies, separated by the CON-linked inter-effector regions. The inter-effectors lacked movement specificity and co-activated during action planning (coordination of hands and feet) and axial body movement (such as of the abdomen or eyebrows). These results, together with previous studies demonstrating stimulation-evoked complex actions4 and connectivity to internal organs10 such as the adrenal medulla, suggest that M1 is punctuated by a system for whole-body action planning, the somato-cognitive action network (SCAN). In M1, two parallel systems intertwine, forming an integrate-isolate pattern: effector-specific regions (foot, hand and mouth) for isolating fine motor control and the SCAN for integrating goals, physiology and body movement.
Assuntos
Mapeamento Encefálico , Cognição , Córtex Motor , Mapeamento Encefálico/métodos , Mãos/fisiologia , Imageamento por Ressonância Magnética , Córtex Motor/anatomia & histologia , Córtex Motor/fisiologia , Humanos , Recém-Nascido , Lactente , Criança , Animais , Macaca/anatomia & histologia , Macaca/fisiologia , Pé/fisiologia , Boca/fisiologia , Conjuntos de Dados como AssuntoRESUMO
Cristae membrane state plays a central role in regulating mitochondrial function and cellular metabolism. The protein Optic atrophy 1 (Opa1) is an important crista remodeler that exists as two forms in the mitochondrion, a membrane-anchored long form (l-Opa1) and a processed short form (s-Opa1). The mechanisms for how Opa1 influences cristae shape have remained unclear due to lack of native three-dimensional views of cristae. We perform in situ cryo-electron tomography of cryo-focused ion beam milled mouse embryonic fibroblasts with defined Opa1 states to understand how each form of Opa1 influences cristae architecture. In our tomograms, we observe a variety of cristae shapes with distinct trends dependent on s-Opa1:l-Opa1 balance. Increased l-Opa1 levels promote cristae stacking and elongated mitochondria, while increased s-Opa1 levels correlated with irregular cristae packing and round mitochondria shape. Functional assays indicate a role for l-Opa1 in wild-type apoptotic and calcium handling responses, and show a compromised respiratory function under Opa1 imbalance. In summary, we provide three-dimensional visualization of cristae architecture to reveal relationships between mitochondrial ultrastructure and cellular function dependent on Opa1-mediated membrane remodeling.
Assuntos
Fibroblastos , Membranas Mitocondriais , Animais , Camundongos , Fibroblastos/metabolismo , Membranas Mitocondriais/metabolismo , Mitocôndrias/metabolismo , Proteínas Mitocondriais/metabolismoRESUMO
Autophagy is a process of cellular self-digestion induced by various forms of starvation. Although nitrogen deficit is a common trigger, some yeast cells induce autophagy upon switch from a rich to minimal media without nitrogen starvation. We show that the amino acid methionine is sufficient to inhibit such non-nitrogen-starvation (NNS)-induced autophagy. Methionine boosts synthesis of the methyl donor, S-adenosylmethionine (SAM). SAM inhibits autophagy and promotes growth through the action of the methyltransferase Ppm1p, which modifies the catalytic subunit of PP2A in tune with SAM levels. Methylated PP2A promotes dephosphorylation of Npr2p, a component of a conserved complex that regulates NNS autophagy and other growth-related processes. Thus, methionine and SAM levels represent a critical gauge of amino acid availability that is sensed via the methylation of PP2A to reciprocally regulate cell growth and autophagy.