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Negative psychological states impact immunity by altering the gut microbiome. However, the relationship between brain states and microbiome composition remains unclear. We show that Brunner's glands in the duodenum couple stress-sensitive brain circuits to bacterial homeostasis. Brunner's glands mediated the enrichment of gut Lactobacillus species in response to vagus nerve stimulation. Cell-specific ablation of the glands markedly suppressed Lactobacilli counts and heightened vulnerability to infection. In the forebrain, we mapped a vagally mediated, polysynaptic circuit connecting the central nucleus of the amygdala to Brunner's glands. Chronic stress suppressed central amygdala activity and phenocopied the effects of gland lesions. Conversely, excitation of either the central amygdala or parasympathetic vagal neurons activated Brunner's glands and reversed the effects of stress on the gut microbiome and immunity. The findings revealed a tractable brain-body mechanism linking psychological states to host defense.
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Glucagon-like peptide-1 (GLP-1) is a signal peptide released from enteroendocrine cells of the lower intestine. GLP-1 exerts anorectic and antimotility actions that protect the body against nutrient malabsorption. However, little is known about how intestinal GLP-1 affects distant organs despite rapid enzymatic inactivation. We show that intestinal GLP-1 inhibits gastric emptying and eating via intestinofugal neurons, a subclass of myenteric neurons that project to abdominal sympathetic ganglia. Remarkably, cell-specific ablation of intestinofugal neurons eliminated intestinal GLP-1 effects, and their chemical activation functioned as a GLP-1 mimetic. GLP-1 sensing by intestinofugal neurons then engaged a sympatho-gastro-spinal-reticular-hypothalamic pathway that links abnormal stomach distension to craniofacial programs for food rejection. Within this pathway, cell-specific activation of discrete neuronal populations caused systemic GLP-1-like effects. These molecularly identified, delimited enteric circuits may be targeted to ameliorate the abdominal bloating and loss of appetite typical of gastric motility disorders.
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Apetito , Péptido 1 Similar al Glucagón/metabolismo , Íleon , Neuronas , Estómago , Abdomen , Animales , Comunicación Celular , Receptor del Péptido 1 Similar al Glucagón/metabolismo , Íleon/inervación , Íleon/metabolismo , Masculino , Ratones , Neuronas/metabolismo , Óxido Nítrico/metabolismo , Transducción de Señal , Estómago/inervación , Estómago/metabolismoRESUMEN
The gut is now recognized as a major regulator of motivational and emotional states. However, the relevant gut-brain neuronal circuitry remains unknown. We show that optical activation of gut-innervating vagal sensory neurons recapitulates the hallmark effects of stimulating brain reward neurons. Specifically, right, but not left, vagal sensory ganglion activation sustained self-stimulation behavior, conditioned both flavor and place preferences, and induced dopamine release from Substantia nigra. Cell-specific transneuronal tracing revealed asymmetric ascending pathways of vagal origin throughout the CNS. In particular, transneuronal labeling identified the glutamatergic neurons of the dorsolateral parabrachial region as the obligatory relay linking the right vagal sensory ganglion to dopamine cells in Substantia nigra. Consistently, optical activation of parabrachio-nigral projections replicated the rewarding effects of right vagus excitation. Our findings establish the vagal gut-to-brain axis as an integral component of the neuronal reward pathway. They also suggest novel vagal stimulation approaches to affective disorders.
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Intestinos/fisiología , Recompensa , Sustancia Negra/fisiología , Nervio Vago/fisiología , Vías Aferentes/metabolismo , Vías Aferentes/fisiología , Animales , Dopamina/metabolismo , Neuronas Dopaminérgicas/fisiología , Ácido Glutámico/metabolismo , Intestinos/inervación , Masculino , Ratones , Ratones Endogámicos C57BL , OptogenéticaRESUMEN
Superior predatory skills led to the evolutionary triumph of jawed vertebrates. However, the mechanisms by which the vertebrate brain controls predation remain largely unknown. Here, we reveal a critical role for the central nucleus of the amygdala in predatory hunting. Both optogenetic and chemogenetic stimulation of central amygdala of mice elicited predatory-like attacks upon both insect and artificial prey. Coordinated control of cervical and mandibular musculatures, which is necessary for accurately positioning lethal bites on prey, was mediated by a central amygdala projection to the reticular formation in the brainstem. In contrast, prey pursuit was mediated by projections to the midbrain periaqueductal gray matter. Targeted lesions to these two pathways separately disrupted biting attacks upon prey versus the initiation of prey pursuit. Our findings delineate a neural network that integrates distinct behavioral modules and suggest that central amygdala neurons instruct predatory hunting across jawed vertebrates.
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Núcleo Amigdalino Central/fisiología , Conducta Predatoria , Animales , Ansiedad/metabolismo , Núcleo Amigdalino Central/anatomía & histología , Electromiografía , Interneuronas/metabolismo , Mandíbula/anatomía & histología , Mandíbula/inervación , Mandíbula/fisiología , Ratones , Cuello/anatomía & histología , Cuello/inervación , Cuello/fisiología , Neuronas/citología , Neuronas/fisiología , Sustancia Gris Periacueductal/fisiologíaRESUMEN
The dry mass and the orientation of biomolecules can be imaged without a label by measuring their permittivity tensor (PT), which describes how biomolecules affect the phase and polarization of light. Three-dimensional (3D) imaging of PT has been challenging. We present a label-free computational microscopy technique, PT imaging (PTI), for the 3D measurement of PT. PTI encodes the invisible PT into images using oblique illumination, polarization-sensitive detection and volumetric sampling. PT is decoded from the data with a vectorial imaging model and a multi-channel inverse algorithm, assuming uniaxial symmetry in each voxel. We demonstrate high-resolution imaging of PT of isotropic beads, anisotropic glass targets, mouse brain tissue, infected cells and histology slides. PTI outperforms previous label-free imaging techniques such as vector tomography, ptychography and light-field imaging in resolving the 3D orientation and symmetry of organelles, cells and tissue. We provide open-source software and modular hardware to enable the adoption of the method.
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Algoritmos , Imagenología Tridimensional , Imagenología Tridimensional/métodos , Animales , Ratones , Encéfalo/diagnóstico por imagen , Microscopía/métodos , Programas Informáticos , Humanos , Procesamiento de Imagen Asistido por Computador/métodosRESUMEN
The transcription factor WUSCHEL-RELATED HOMEOBOX 11 (WOX11) in Arabidopsis (Arabidopsis thaliana) initiates the formation of adventitious lateral roots upon mechanical injury in primary roots. Root-invading nematodes also induce de novo root organogenesis leading to excessive root branching, but it is not known if this symptom of disease involves mediation by WOX11 and if it benefits the plant. Here, we show with targeted transcriptional repression and reporter gene analyses in Arabidopsis that the beet cyst nematode Heterodera schachtii activates WOX11-mediated adventitious lateral rooting from primary roots close to infection sites. The activation of WOX11 in nematode-infected roots occurs downstream of jasmonic acid-dependent damage signaling via ETHYLENE RESPONSE FACTOR109, linking adventitious lateral root formation to nematode damage to host tissues. By measuring different root system components, we found that WOX11-mediated formation of adventitious lateral roots compensates for nematode-induced inhibition of primary root growth. Our observations further demonstrate that WOX11-mediated rooting reduces the impact of nematode infections on aboveground plant development and growth. Altogether, we conclude that the transcriptional regulation by WOX11 modulates root system plasticity under biotic stress, which is one of the key mechanisms underlying the tolerance of Arabidopsis to cyst nematode infections.
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Proteínas de Arabidopsis , Arabidopsis , Regulación de la Expresión Génica de las Plantas , Raíces de Plantas , Factores de Transcripción , Tylenchoidea , Animales , Raíces de Plantas/parasitología , Raíces de Plantas/genética , Raíces de Plantas/crecimiento & desarrollo , Arabidopsis/parasitología , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Tylenchoidea/fisiología , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Enfermedades de las Plantas/parasitología , Enfermedades de las Plantas/genética , Oxilipinas/metabolismo , Ciclopentanos/metabolismo , Plantas Modificadas GenéticamenteRESUMEN
DNA gyrase is an essential nucleoprotein motor present in all bacteria and is a major target for antibiotic treatment of Mycobacterium tuberculosis (MTB) infection. Gyrase hydrolyzes ATP to add negative supercoils to DNA using a strand passage mechanism that has been investigated using biophysical and biochemical approaches. To analyze the dynamics of substeps leading to strand passage, single-molecule rotor bead tracking (RBT) has been used previously to follow real-time supercoiling and conformational transitions in Escherichia coli (EC) gyrase. However, RBT has not yet been applied to gyrase from other pathogenically relevant bacteria, and it is not known whether substeps are conserved across evolutionarily distant species. Here, we compare gyrase supercoiling dynamics between two evolutionarily distant bacterial species, MTB and EC. We used RBT to measure supercoiling rates, processivities, and the geometries and transition kinetics of conformational states of purified gyrase proteins in complex with DNA. Our results show that E. coli and MTB gyrases are both processive, with the MTB enzyme displaying velocities â¼5.5× slower than the EC enzyme. Compared with EC gyrase, MTB gyrase also more readily populates an intermediate state with DNA chirally wrapped around the enzyme, in both the presence and absence of ATP. Our substep measurements reveal common features in conformational states of EC and MTB gyrases interacting with DNA but also suggest differences in populations and transition rates that may reflect distinct cellular needs between these two species.
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Girasa de ADN , Escherichia coli , Mycobacterium tuberculosis , Adenosina Trifosfato/metabolismo , ADN , Girasa de ADN/química , Girasa de ADN/metabolismo , ADN Superhelicoidal , Escherichia coli/enzimología , Escherichia coli/metabolismo , Mycobacterium tuberculosis/enzimología , Mycobacterium tuberculosis/metabolismo , Simulación de Dinámica MolecularRESUMEN
Carbazole is a heterocyclic motif that can be found in a diverse array of natural and unnatural products displaying a wide range of biological and physiological properties. Furthermore, this heterocycle is part of electronic materials like photoconducting polymers and organic optoelectronic materials owing to its excellent photophysical characteristics. Consequently, the development of synthetic strategies for carbazole scaffolds holds potential significance in biological and material fields. In this regard, a variety of preparation methods has been developed to exploit their efficient and distinct formation of new C-C and C-heteroatom bonds under mild conditions and enabling broad substrate diversity and functional group tolerance. Therefore, this review focuses on the synthesis of a set of carbazole derivatives describing a variety of methodologies that involve direct irradiation, photosensitization, photoredox, electrochemical and thermal cyclization reactions.
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Blue LEDs-irradiation of a mixture of N,N,N',N'-tetramethylethylenediamine (TMEDA) and perfluoroalkyl iodides (RF-I) - Electron Donor Acceptor (EDA)-complex - in the presence of triphenylamines (TPAs) in an aqueous solvent mixture afforded mono-perfluoroalkylated triphenylamines (RF-TPA) in good yields. These RF-TPA were further subjected to acetone-sensitized [6π]-electrocyclization at 315â nm-irradiation affording exclusively perfluoroalkylated endo-carbazole derivatives (RF-CBz) in quantitative yields. Mechanistic studies and photophysical properties of products are studied.
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Persistent acute kidney injury (pAKI), compared with acute kidney injury (AKI) that resolves in <72 h, is associated with worse prognosis in critically ill patients. Definitions and prognosis of pAKI are not well characterized in solid organ transplant patients. Our aims were to investigate (a) definitions and incidence of pAKI; (b) association with clinical outcomes; and (c) risk factors for pAKI among heart, lung, and liver transplant recipients. We systematically reviewed the literature including PubMed, Embase, Web of Science, and Cochrane from inception to 8/1/2023 for human prospective and retrospective studies reporting on the development of pAKI in heart, lung, or liver transplant recipients. We assessed heterogeneity using Cochran's Q and I2. We identified 25 studies including 6330 patients. AKI (8%-71.6%) and pAKI (2.7%-55.1%) varied widely. Definitions of pAKI included 48-72 h (six studies), 7 days (three studies), 14 days (four studies), or more (12 studies). Risk factors included age, body mass index (BMI), diabetes, preoperative chronic kidney disease (CKD), intraoperative vasopressor use, and intraoperative circulatory support. pAKI was associated with new onset of CKD (odds ratio [OR] 1.41-11.2), graft dysfunction (OR 1.81-8.51), and long-term mortality (OR 3.01-13.96), although significant heterogeneity limited certainty of CKD and graft dysfunction outcome analyses. pAKI is common and is associated with worse mortality among liver and lung transplant recipients. Standardization of the nomenclature of AKI will be important in future studies (PROSPERO CRD42022371952).
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Lesión Renal Aguda , Trasplante de Órganos , Receptores de Trasplantes , Humanos , Factores de Riesgo , Lesión Renal Aguda/etiología , Pronóstico , Trasplante de Órganos/efectos adversos , Receptores de Trasplantes/estadística & datos numéricos , Complicaciones PosoperatoriasRESUMEN
Experiencing adverse childhood experiences (ACEs) may impact personal opinions, attitudes, and judgments, which can further result in HIV-related stigma. HIV-related stigma consequentially may impact HIV preventive measures such as HIV testing, pre-exposure prophylaxis uptake, and condom use. The extent to which ACEs influence HIV-related stigma perception has not been well studied. Therefore, the study aimed to examine the association between ACEs and perceived and interpersonal HIV-related stigma among Tanzanian HIV-negative men. Quantitative survey data were obtained from the Tanzania STEP (Self-Testing Education and Promotion) project established in four wards: Mabibo, Manzese, Tandale, and Mwanyanamala. A total of 507 men responded to the ACEs and HIV-related stigma questionnaires. ACEs were operationalized as types of ACEs (environmental, physical/psychological, sexual abuse) and ACE score (0 (reference) vs. 1, 2, 3, ≥ 4). Perceived HIV-related stigma was analyzed both as a binary (HIV stigma vs. no HIV stigma) and a continuous variable. Unadjusted and adjusted multinomial logistic and linear regression models were used to assess the associations between ACEs and HIV-related stigma. ACE types were associated with HIV stigma (b = 0.237, 95% CI [0.122-0.352], p = < .0001). Findings of the adjusted multinomial logistic regression model show that experiencing one ACE (aOR = 1.9; p-value = 0.023), two ACEs (aOR = 1.8; p-value = 0.044), four or more ACEs (aOR = 4.1; p-value = < 0.0001) were associated with greater perceived HIV-related stigma. Moreover, experiencing environmental (aOR = 8.6; p-value = 0.005), physical/psychological (aOR = 2.5; p-value = 0.004), and sexual abuse (aOR = 3.4; p-value = < 0.0001) were associated with higher odds of HIV-related stigma. Our study findings suggest that those who experience childhood trauma are more likely to have a higher perception of HIV-related stigma. Intervention programs targeting HIV stigma should consider addressing ACEs entailing the behavioral and psychological impact of childhood trauma.
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Herein, we have showed the photophysical properties of favipiravir and its 6-substituted analogues. Also, we interpreted the origin of fluorescence of favipiravir and its 6-substituted analogues as a function of tautomerism modulation in ground and excited states. Favipiravir, the 6-fluorine derivative, showed the best photophysical profile, exhibiting a dominant emission wavelength of 430 nm, a high quantum yield (Q.Y.) of 1.0 and a long-lived state (10 ns). Its analogues also showed a maximum emission at 430 nm, but their Q.Y. values were 5-fold lower than that found for favipiravir, decreasing as a function of 6-substitution as follows: F > Cl > Br > I > H. Pyrazines bearing the least electronegative 6-substituent (X = Br, I, H) showed an extra lifetime, which was shorter (0.2-0.3 ns) and less abundant (>15%) than the main lifetime (10 ns, 85%). Further 2D excitation-emission matrix and solvent studies supported that these 3-hydroxy-2-pyrazinecarboxamides present two emissive states. The first of them (λem = 430 nm), which was the most abundant, most fluorescent and long-lived state, was characterized as "locally excited" (LE). Its fluorescence was favored with an increase of the hydrogen-donor nature of the solvent and for pyrazines having a high enolic characteristic. Thus, the high LE-fluorescence of these types of pyrazines depends on the keto-tautomerization of the ground state using a protic solvent and its feasible enol-tautomerization upon excitation. Finally, the second excited state (λem = 536 nm) was suggested as an excited-state intramolecular proton-transfer (ESIPT), and it was observed only, although discretely, for pyrazines bearing the least electronegative 6-substituent.
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Although there are several pathways to ensure that proteins are folded properly in the cell, little is known about the molecular mechanisms regulating histone folding and proteostasis. In this work, we identified that chaperone-mediated autophagy (CMA) is the main pathway involved in the degradation of newly synthesized histones H3 and H4. This degradation is finely regulated by the interplay between HSC70 and tNASP, two histone interacting proteins. tNASP stabilizes histone H3 levels by blocking the direct transport of histone H3 into lysosomes. We further demonstrate that CMA degrades unfolded histone H3. Thus, we reveal that CMA is the main degradation pathway involved in the quality control of histone biogenesis, evidencing an additional mechanism in the intricate network of histone cellular proteostasis.
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Autofagia Mediada por Chaperones , Histonas , Autofagia , Histonas/metabolismo , Lisosomas/metabolismo , Biosíntesis de ProteínasRESUMEN
The plant pathogen Pseudomonas syringae secretes multiple effectors that modulate plant defenses. Some effectors trigger defenses due to specific recognition by plant immune complexes, whereas others can suppress the resulting immune responses. The HopZ3 effector of P. syringae pv. syringae B728a (PsyB728a) is an acetyltransferase that modifies not only components of plant immune complexes, but also the Psy effectors that activate these complexes. In Arabidopsis, HopZ3 acetylates the host RPM1 complex and the Psy effectors AvrRpm1 and AvrB3. This study focuses on the role of HopZ3 during tomato infection. In Psy-resistant tomato, the main immune complex includes PRF and PTO, a RIPK-family kinase that recognizes the AvrPto effector. HopZ3 acts as a virulence factor on tomato by suppressing AvrPto1Psy-triggered immunity. HopZ3 acetylates AvrPto1Psy and the host proteins PTO, SlRIPK and SlRIN4s. Biochemical reconstruction and site-directed mutagenesis experiments suggest that acetylation acts in multiple ways to suppress immune signaling in tomato. First, acetylation disrupts the critical AvrPto1Psy-PTO interaction needed to initiate the immune response. Unmodified residues at the binding interface of both proteins and at other residues needed for binding are acetylated. Second, acetylation occurs at residues important for AvrPto1Psy function but not for binding to PTO. Finally, acetylation reduces specific phosphorylations needed for promoting the immune-inducing activity of HopZ3's targets such as AvrPto1Psy and PTO. In some cases, acetylation competes with phosphorylation. HopZ3-mediated acetylation suppresses the kinase activity of SlRIPK and the phosphorylation of its SlRIN4 substrate previously implicated in PTO-signaling. Thus, HopZ3 disrupts the functions of multiple immune components and the effectors that trigger them, leading to increased susceptibility to infection. Finally, mass spectrometry used to map specific acetylated residues confirmed HopZ3's unusual capacity to modify histidine in addition to serine, threonine and lysine residues.
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Acetiltransferasas/metabolismo , Complejo Antígeno-Anticuerpo/inmunología , Proteínas Bacterianas/antagonistas & inhibidores , Enfermedades de las Plantas/inmunología , Proteínas de Plantas/metabolismo , Pseudomonas syringae/patogenicidad , Solanum lycopersicum/inmunología , Acetilación , Acetiltransferasas/genética , Acetiltransferasas/inmunología , Proteínas Bacterianas/genética , Proteínas Bacterianas/inmunología , Proteínas Bacterianas/metabolismo , Solanum lycopersicum/microbiología , Enfermedades de las Plantas/microbiología , Proteínas de Plantas/genética , Proteínas de Plantas/inmunología , Virulencia , Factores de Virulencia/genética , Factores de Virulencia/inmunología , Factores de Virulencia/metabolismoRESUMEN
Chemical exchange saturation transfer (CEST) MRI has gained recognition as a valuable addition to the molecular imaging and quantitative biomarker arsenal, especially for characterization of brain tumors. There is also increasing interest in the use of CEST-MRI for applications beyond the brain. However, its translation to body oncology applications lags behind those in neuro-oncology. The slower migration of CEST-MRI to non-neurologic applications reflects the technical challenges inherent to imaging of the torso. In this review, we discuss the application of CEST-MRI to oncologic conditions of the breast and torso (i.e., body imaging), emphasizing the challenges and potential solutions to address them. While data are still limited, reported studies suggest that CEST signal is associated with important histology markers such as tumor grade, receptor status, and proliferation index, some of which are often associated with prognosis and response to therapy. However, further technical development is still needed to make CEST a reliable clinical application for body imaging and establish its role as a predictive and prognostic biomarker.
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Neoplasias Encefálicas , Imagen por Resonancia Magnética , Humanos , Imagen por Resonancia Magnética/métodos , Neoplasias Encefálicas/patología , Encéfalo/patología , Pronóstico , Imagen MolecularRESUMEN
The substituent and solvent effects on the spectroscopic behavior and on the photoinduced [6π]-electrocyclization reaction of substituted triphenylamine derivatives have been investigated. Direct irradiation of triphenylamines bearing electron-donor substituents in different solvents has provided for the first time the substituted exo/endo carbazole derivatives from modest to good yields, whereas triphenylamines bearing electron-withdrawing substituents did not provide the carbazoles due to the formation of charge transfer complexes (CTCs). A corollary of the experiments purports that the photoreaction is favored with weak electron-acceptor groups in polar solvents. The lowest-frequency absorption bands of the triarylamines (π,π* electronic transitions) displayed bathochromic shifts as the solvent polarity is increased. The fluorescence emission spectra of triarylamines bearing electron-donor substituents behave as mirror images of the lowest absorption bands, showing dependence on the solvent polarity. Conversely, triarylamines bearing formyl, acetyl, and nitro groups formed CTCs behaving as good fluorescence chromophores in polar solvents. Hammett correlations on the ΔE(0,0) energies of monosubstituted amines showed a bell-shape behavior where the ρ values depended on the solvent polarity. The physical quenching of the photoreaction of triarylamines has demonstrated for the first time that the triplet excited state is univocally the photoreactive state leading to exo/endo carbazole derivatives.
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In the present work, the study of the unusual interaction between copper hexafluoroacetylacetonate and the diacetyliminoxyl radical resulted in two discoveries from different fields: the determination of the oxime radical spatial structure and the introduction of an oxime radical into the field of molecular magnetic material design. Oxime radicals are key plausible intermediates in the processes of oxidative CH-functionalization and in the synthesis of functionalized isoxazolines from oximes. Due to the lack of X-ray diffraction data for oxime radicals, the knowledge about their structure is based mainly on indirect approaches, spectroscopic methods (electron paramagnetic resonance and IR), and quantum chemical calculations. The structure of the oxime radical was determined for the first time by stabilizing the diacetyliminoxyl radical in the form of its complex with copper (II) hexafluoroacetylacetonate (Cu(hfac)2), followed by single-crystal X-ray diffraction analysis. Although oxime radicals are known to undergo oxidative coupling with acetylacetonate ligands in transition-metal complexes, a complex is formed with intact hfac ligands. X-ray diffraction studies have shown that the oxime radical is coordinated with copper ions through the oxygen atoms of the carbonyl groups without the direct involvement of the CâN-O⢠radical moiety. The structure of the coordinated diacetyliminoxyl is in good agreement with the density functional theory (DFT) prediction for free diacetyliminoxyl due to the very weak interaction of the radical molecule with copper ions. Remarkably, both weak ferromagnetic and antiferromagnetic interactions between Cu (II) and oxime radicals have been revealed by modeling the temperature dependence of magnetic susceptibility and confirmed by DFT calculations, rendering diacetyliminoxyl a promising building block for the design of molecular magnets.
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The CRISPR-Cas9 nuclease has been widely repurposed as a molecular and cell biology tool for its ability to programmably target and cleave DNA. Cas9 recognizes its target site by unwinding the DNA double helix and hybridizing a 20-nucleotide section of its associated guide RNA to one DNA strand, forming an R-loop structure. A dynamic and mechanical description of R-loop formation is needed to understand the biophysics of target searching and develop rational approaches for mitigating off-target activity while accounting for the influence of torsional strain in the genome. Here we investigate the dynamics of Cas9 R-loop formation and collapse using rotor bead tracking (RBT), a single-molecule technique that can simultaneously monitor DNA unwinding with base-pair resolution and binding of fluorescently labeled macromolecules in real time. By measuring changes in torque upon unwinding of the double helix, we find that R-loop formation and collapse proceed via a transient discrete intermediate, consistent with DNA:RNA hybridization within an initial seed region. Using systematic measurements of target and off-target sequences under controlled mechanical perturbations, we characterize position-dependent effects of sequence mismatches and show how DNA supercoiling modulates the energy landscape of R-loop formation and dictates access to states competent for stable binding and cleavage. Consistent with this energy landscape model, in bulk experiments we observe promiscuous cleavage under physiological negative supercoiling. The detailed description of DNA interrogation presented here suggests strategies for improving the specificity and kinetics of Cas9 as a genome engineering tool and may inspire expanded applications that exploit sensitivity to DNA supercoiling.
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Proteínas Asociadas a CRISPR/química , Sistemas CRISPR-Cas , ADN/química , Emparejamiento Base , Proteínas Asociadas a CRISPR/metabolismo , División del ADN , Endonucleasas/metabolismo , Edición Génica , Genoma , Estructuras R-Loop , ARN/química , ARN Guía de Kinetoplastida/metabolismoRESUMEN
Chronic pain is a highly prevalent disease with poorly understood pathophysiology. In particular, the brain mechanisms mediating the transition from acute to chronic pain remain largely unknown. Here, we identify a subcortical signature of back pain. Specifically, subacute back pain patients who are at risk for developing chronic pain exhibit a smaller nucleus accumbens volume, which persists in the chronic phase, compared to healthy controls. The smaller accumbens volume was also observed in a separate cohort of chronic low-back pain patients and was associated with dynamic changes in functional connectivity. At baseline, subacute back pain patients showed altered local nucleus accumbens connectivity between putative shell and core, irrespective of the risk of transition to chronic pain. At follow-up, connectivity changes were observed between nucleus accumbens and rostral anterior cingulate cortex in the patients with persistent pain. Analysis of the power spectral density of nucleus accumbens resting-state activity in the subacute and chronic back pain patients revealed loss of power in the slow-5 frequency band (0.01 to 0.027 Hz) which developed only in the chronic phase of pain. This loss of power was reproducible across two cohorts of chronic low-back pain patients obtained from different sites and accurately classified chronic low-back pain patients in two additional independent datasets. Our results provide evidence that lower nucleus accumbens volume confers risk for developing chronic pain and altered nucleus accumbens activity is a signature of the state of chronic pain.