Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 759.049
Filtrar
1.
Nat Commun ; 14(1): 180, 2023 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-36635295

RESUMO

The potential of pluripotent cells to respond to developmental cues and trigger cell differentiation is enhanced during the G1 phase of the cell cycle, but the molecular mechanisms involved are poorly understood. Variations in polycomb activity during interphase progression have been hypothesized to regulate the cell-cycle-phase-dependent transcriptional activation of differentiation genes during lineage transition in pluripotent cells. Here, we show that recruitment of Polycomb Repressive Complex 1 (PRC1) and associated molecular functions, ubiquitination of H2AK119 and three-dimensional chromatin interactions, are enhanced during S and G2 phases compared to the G1 phase. In agreement with the accumulation of PRC1 at target promoters upon G1 phase exit, cells in S and G2 phases show firmer transcriptional repression of developmental regulator genes that is drastically perturbed upon genetic ablation of the PRC1 catalytic subunit RING1B. Importantly, depletion of RING1B during retinoic acid stimulation interferes with the preference of mouse embryonic stem cells (mESCs) to induce the transcriptional activation of differentiation genes in G1 phase. We propose that incremental enrolment of polycomb repressive activity during interphase progression reduces the tendency of cells to respond to developmental cues during S and G2 phases, facilitating activation of cell differentiation in the G1 phase of the pluripotent cell cycle.


Assuntos
Histonas , Células-Tronco Pluripotentes , Complexo Repressor Polycomb 1 , Animais , Camundongos , Diferenciação Celular/genética , Cromatina/genética , Histonas/metabolismo , Interfase , Complexo Repressor Polycomb 1/genética , Complexo Repressor Polycomb 1/metabolismo , Proteínas do Grupo Polycomb/genética , Proteínas do Grupo Polycomb/metabolismo , Células-Tronco Pluripotentes/citologia
2.
Sci Adv ; 9(3): eade5348, 2023 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-36652509

RESUMO

A critical stage of T cell development is ß-selection; at this stage, the T cell receptor ß (TCRß) chain is generated, and the developing T cell starts to acquire antigenic specificity. Progression through ß-selection is assisted by low-affinity interactions between the nascent TCRß chain and peptide presented on stromal major histocompatibility complex and cues provided by the niche. In this study, we identify a cue within the developing T cell niche that is critical for T cell development. E-cadherin mediates cell-cell interactions and influences cell fate in many developmental systems. In developing T cells, E-cadherin contributed to the formation of an immunological synapse and the alignment of the mitotic spindle with the polarity axis during division, which facilitated subsequent T cell development. Collectively, these data suggest that E-cadherin facilitates interactions with the thymic niche to coordinate the ß-selection stage of T cell development.


Assuntos
Caderinas , Linfócitos T , Animais , Camundongos , Caderinas/metabolismo , Comunicação Celular , Receptores de Antígenos de Linfócitos T alfa-beta , Linfócitos T/citologia , Linfócitos T/metabolismo , Timo , Fuso Acromático/metabolismo
3.
Cell ; 186(1): 80-97.e26, 2023 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-36608661

RESUMO

Glucose is a universal bioenergy source; however, its role in controlling protein interactions is unappreciated, as are its actions during differentiation-associated intracellular glucose elevation. Azido-glucose click chemistry identified glucose binding to a variety of RNA binding proteins (RBPs), including the DDX21 RNA helicase, which was found to be essential for epidermal differentiation. Glucose bound the ATP-binding domain of DDX21, altering protein conformation, inhibiting helicase activity, and dissociating DDX21 dimers. Glucose elevation during differentiation was associated with DDX21 re-localization from the nucleolus to the nucleoplasm where DDX21 assembled into larger protein complexes containing RNA splicing factors. DDX21 localized to specific SCUGSDGC motif in mRNA introns in a glucose-dependent manner and promoted the splicing of key pro-differentiation genes, including GRHL3, KLF4, OVOL1, and RBPJ. These findings uncover a biochemical mechanism of action for glucose in modulating the dimerization and function of an RNA helicase essential for tissue differentiation.


Assuntos
RNA Helicases DEAD-box , Glucose , Queratinócitos , Nucléolo Celular/metabolismo , Núcleo Celular/metabolismo , RNA Helicases DEAD-box/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Glucose/metabolismo , Queratinócitos/citologia , Queratinócitos/metabolismo , Humanos
4.
Science ; 379(6627): 84-88, 2023 01 06.
Artigo em Inglês | MEDLINE | ID: mdl-36603070

RESUMO

The central nervous system is lined by meninges, classically known as dura, arachnoid, and pia mater. We show the existence of a fourth meningeal layer that compartmentalizes the subarachnoid space in the mouse and human brain, designated the subarachnoid lymphatic-like membrane (SLYM). SLYM is morpho- and immunophenotypically similar to the mesothelial membrane lining of peripheral organs and body cavities, and it encases blood vessels and harbors immune cells. Functionally, the close apposition of SLYM with the endothelial lining of the meningeal venous sinus permits direct exchange of small solutes between cerebrospinal fluid and venous blood, thus representing the mouse equivalent of the arachnoid granulations. The functional characterization of SLYM provides fundamental insights into brain immune barriers and fluid transport.


Assuntos
Encéfalo , Espaço Subaracnóideo , Animais , Humanos , Camundongos , Dura-Máter/citologia , Dura-Máter/fisiologia , Endotélio/citologia , Endotélio/fisiologia , Espaço Subaracnóideo/citologia , Espaço Subaracnóideo/fisiologia , Epitélio/fisiologia , Encéfalo/anatomia & histologia , Encéfalo/imunologia , Líquido Cefalorraquidiano/fisiologia
5.
Nature ; 613(7943): 345-354, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36599983

RESUMO

Understanding how a subset of expressed genes dictates cellular phenotype is a considerable challenge owing to the large numbers of molecules involved, their combinatorics and the plethora of cellular behaviours that they determine1,2. Here we reduced this complexity by focusing on cellular organization-a key readout and driver of cell behaviour3,4-at the level of major cellular structures that represent distinct organelles and functional machines, and generated the WTC-11 hiPSC Single-Cell Image Dataset v1, which contains more than 200,000 live cells in 3D, spanning 25 key cellular structures. The scale and quality of this dataset permitted the creation of a generalizable analysis framework to convert raw image data of cells and their structures into dimensionally reduced, quantitative measurements that can be interpreted by humans, and to facilitate data exploration. This framework embraces the vast cell-to-cell variability that is observed within a normal population, facilitates the integration of cell-by-cell structural data and allows quantitative analyses of distinct, separable aspects of organization within and across different cell populations. We found that the integrated intracellular organization of interphase cells was robust to the wide range of variation in cell shape in the population; that the average locations of some structures became polarized in cells at the edges of colonies while maintaining the 'wiring' of their interactions with other structures; and that, by contrast, changes in the location of structures during early mitotic reorganization were accompanied by changes in their wiring.


Assuntos
Células-Tronco Pluripotentes Induzidas , Espaço Intracelular , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Análise de Célula Única , Conjuntos de Dados como Assunto , Interfase , Forma Celular , Mitose , Polaridade Celular , Sobrevivência Celular
6.
J Neurosci ; 43(2): 211-220, 2023 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-36639906

RESUMO

In the developing cortex, excitatory neurons migrate along the radial fibers to their final destinations and build up synaptic connection with each other to form functional circuitry. The shaping of neuronal morphologies by actin cytoskeleton dynamics is crucial for neuronal migration. However, it is largely unknown how the distribution and assembly of the F-actin cytoskeleton are coordinated. In the present study, we found that an actin regulatory protein, coronin 2B, is indispensable for the transition from a multipolar to bipolar morphology during neuronal migration in ICR mice of either sex. Loss of coronin 2B led to heterotopic accumulation of migrating neurons in the intermediate zone along with reduced dendritic complexity and aberrant neuronal activity in the cortical plate. This was accompanied by increased seizure susceptibility, suggesting the malfunction of cortical development in coronin 2B-deficient brains. Coronin 2B knockdown disrupted the distribution of the F-actin cytoskeleton at the leading processes, while the migration defect in coronin 2B-deficient neurons was partially rescued by overexpression of Rac1 and its downstream actin-severing protein, cofilin. Our results collectively reveal the physiological function of coronin 2B during neuronal migration whereby it maintains the proper distribution of activated Rac1 and the F-actin cytoskeleton.SIGNIFICANCE STATEMENT Deficits in neuronal migration during cortical development result in various neurodevelopmental disorders (e.g., focal cortical dysplasia, periventricular heterotopia, epilepsy, etc.). Most signaling pathways that control neuronal migration process converge to regulate actin cytoskeleton dynamics. Therefore, it is important to understand how actin dynamics is coordinated in the critical processes of neuronal migration. Herein, we report that coronin 2B is a key protein that regulates neuronal migration through its ability to control the distribution of the actin cytoskeleton and its regulatory signaling protein Rac1 during the multipolar-bipolar transition in the intermediate zone, providing insights into the molecular machinery that drives the migration process of newborn neurons.


Assuntos
Actinas , Proteínas dos Microfilamentos , Neurônios , Proteínas rac1 de Ligação ao GTP , Animais , Camundongos , Actinas/fisiologia , Movimento Celular/fisiologia , Camundongos Endogâmicos ICR , Proteínas dos Microfilamentos/fisiologia , Proteínas rac1 de Ligação ao GTP/fisiologia , Neurônios/citologia
7.
Int J Mol Sci ; 24(2)2023 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-36675161

RESUMO

Lysosomes are acidic Ca2+ storage organelles that actively generate local Ca2+ signaling events to regulate a plethora of cell functions. Here, we characterized lysosomal Ca2+ signals in mouse renal collecting duct (CD) cells and we assessed their putative role in aquaporin 2 (AQP2)-dependent water reabsorption. Bafilomycin A1 and ML-SA1 triggered similar Ca2+ oscillations, in the absence of extracellular Ca2+, by alkalizing the acidic lysosomal pH or activating the lysosomal cation channel mucolipin 1 (TRPML1), respectively. TRPML1-dependent Ca2+ signals were blocked either pharmacologically or by lysosomes' osmotic permeabilization, thus indicating these organelles as primary sources of Ca2+ release. Lysosome-induced Ca2+ oscillations were sustained by endoplasmic reticulum (ER) Ca2+ content, while bafilomycin A1 and ML-SA1 did not directly interfere with ER Ca2+ homeostasis per se. TRPML1 activation strongly increased AQP2 apical expression and depolymerized the actin cytoskeleton, thereby boosting water flux in response to an hypoosmotic stimulus. These effects were strictly dependent on the activation of the Ca2+/calcineurin pathway. Conversely, bafilomycin A1 led to perinuclear accumulation of AQP2 vesicles without affecting water permeability. Overall, lysosomal Ca2+ signaling events can be differently decoded to modulate Ca2+-dependent cellular functions related to the dock/fusion of AQP2-transporting vesicles in principal cells of the CD.


Assuntos
Aquaporina 2 , Túbulos Renais Coletores , Lisossomos , Água , Animais , Camundongos , Aquaporina 2/genética , Aquaporina 2/metabolismo , Lisossomos/genética , Lisossomos/metabolismo , Macrolídeos/farmacologia , Macrolídeos/metabolismo , Água/metabolismo , Túbulos Renais Coletores/citologia , Túbulos Renais Coletores/metabolismo
8.
Int J Mol Sci ; 24(2)2023 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-36675167

RESUMO

Four Ras guanine nucleotide-releasing proteins (RasGRP1 through 4) belong to the family of guanine nucleotide exchange factors (GEFs). RasGRPs catalyze the release of GDP from small GTPases Ras and Rap and facilitate their transition from an inactive GDP-bound to an active GTP-bound state. Thus, they regulate critical cellular responses via many downstream GTPase effectors. Similar to other RasGRPs, the catalytic module of RasGRP1 is composed of the Ras exchange motif (REM) and Cdc25 domain, and the EF hands and C1 domain contribute to its cellular localization and regulation. RasGRP1 can be activated by a diacylglycerol (DAG)-mediated membrane recruitment and protein kinase C (PKC)-mediated phosphorylation. RasGRP1 acts downstream of the T cell receptor (TCR), B cell receptors (BCR), and pre-TCR, and plays an important role in the thymocyte maturation and function of peripheral T cells, B cells, NK cells, mast cells, and neutrophils. The dysregulation of RasGRP1 is known to contribute to numerous disorders that range from autoimmune and inflammatory diseases and schizophrenia to neoplasia. Given its position at the crossroad of cell development, inflammation, and cancer, RASGRP1 has garnered interest from numerous disciplines. In this review, we outline the structure, function, and regulation of RasGRP1 and focus on the existing knowledge of the role of RasGRP1 in leukemia and other cancers.


Assuntos
Fatores de Troca do Nucleotídeo Guanina , Sistema Imunitário , Neoplasias , Humanos , Fatores de Troca do Nucleotídeo Guanina/genética , Fatores de Troca do Nucleotídeo Guanina/imunologia , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Nucleotídeos de Guanina , Neoplasias/genética , Neoplasias/imunologia , Neoplasias/metabolismo , Receptores de Antígenos de Linfócitos T , Linfócitos T/imunologia , Sistema Imunitário/citologia , Sistema Imunitário/imunologia
10.
PLoS One ; 18(1): e0278607, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36696395

RESUMO

Here we report urine-derived cell (UDC) culture and subsequent use for cloning which resulted in the successful development of cloned canine pups, which have remained healthy into adulthood. Bovine UDCs were used in vitro to establish comparative differences between cell sources. UDCs were chosen as a readily available and noninvasive source for obtaining cells. We analyzed the viability of cells stored in urine over time and could consistently culture cells which had remained in urine for 48hrs. Cells were shown to be viable and capable of being transfected with plasmids. Although primarily of epithelial origin, cells were found from multiple lineages, indicating that they enter the urine from more than one source. Held in urine, at 4°C, the majority of cells maintained their membrane integrity for several days. When compared to in vitro fertilization (IVF) derived embryos or those from traditional SCNT, UDC derived embryos did not differ in total cell number or in the number of DNA breaks, measured by TUNEL stain. These results indicate that viable cells can be obtained from multiple species' urine, capable of being used to produce live offspring at a comparable rate to other cell sources, evidenced by a 25% pregnancy rate and 2 live births with no losses in the canine UDC cloning trial. This represents a noninvasive means to recover the breeding capacity of genetically important or infertile animals. Obtaining cells in this way may provide source material for human and animal studies where cells are utilized.


Assuntos
Clonagem de Organismos , Nascido Vivo , Animais , Cães , Feminino , Gravidez , Clonagem de Organismos/métodos , Clonagem de Organismos/veterinária , Nascido Vivo/veterinária , Taxa de Gravidez , Urina/citologia
11.
Nature ; 613(7942): 120-129, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36517604

RESUMO

Myelin is required for the function of neuronal axons in the central nervous system, but the mechanisms that support myelin health are unclear. Although macrophages in the central nervous system have been implicated in myelin health1, it is unknown which macrophage populations are involved and which aspects they influence. Here we show that resident microglia are crucial for the maintenance of myelin health in adulthood in both mice and humans. We demonstrate that microglia are dispensable for developmental myelin ensheathment. However, they are required for subsequent regulation of myelin growth and associated cognitive function, and for preservation of myelin integrity by preventing its degeneration. We show that loss of myelin health due to the absence of microglia is associated with the appearance of a myelinating oligodendrocyte state with altered lipid metabolism. Moreover, this mechanism is regulated through disruption of the TGFß1-TGFßR1 axis. Our findings highlight microglia as promising therapeutic targets for conditions in which myelin growth and integrity are dysregulated, such as in ageing and neurodegenerative disease2,3.


Assuntos
Sistema Nervoso Central , Microglia , Bainha de Mielina , Adulto , Animais , Humanos , Camundongos , Axônios/metabolismo , Sistema Nervoso Central/citologia , Sistema Nervoso Central/metabolismo , Sistema Nervoso Central/patologia , Microglia/citologia , Microglia/metabolismo , Microglia/patologia , Bainha de Mielina/metabolismo , Bainha de Mielina/patologia , Doenças Neurodegenerativas/metabolismo , Doenças Neurodegenerativas/patologia , Oligodendroglia/metabolismo , Oligodendroglia/patologia , Cognição , Fator de Crescimento Transformador beta1/metabolismo , Receptor do Fator de Crescimento Transformador beta Tipo I/metabolismo , Metabolismo dos Lipídeos , Envelhecimento/metabolismo , Envelhecimento/patologia
12.
Nature ; 613(7942): 160-168, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36477540

RESUMO

Multilocular adipocytes are a hallmark of thermogenic adipose tissue1,2, but the factors that enforce this cellular phenotype are largely unknown. Here, we show that an adipocyte-selective product of the Clstn3 locus (CLSTN3ß) present in only placental mammals facilitates the efficient use of stored triglyceride by limiting lipid droplet (LD) expansion. CLSTN3ß is an integral endoplasmic reticulum (ER) membrane protein that localizes to ER-LD contact sites through a conserved hairpin-like domain. Mice lacking CLSTN3ß have abnormal LD morphology and altered substrate use in brown adipose tissue, and are more susceptible to cold-induced hypothermia despite having no defect in adrenergic signalling. Conversely, forced expression of CLSTN3ß is sufficient to enforce a multilocular LD phenotype in cultured cells and adipose tissue. CLSTN3ß associates with cell death-inducing DFFA-like effector proteins and impairs their ability to transfer lipid between LDs, thereby restricting LD fusion and expansion. Functionally, increased LD surface area in CLSTN3ß-expressing adipocytes promotes engagement of the lipolytic machinery and facilitates fatty acid oxidation. In human fat, CLSTN3B is a selective marker of multilocular adipocytes. These findings define a molecular mechanism that regulates LD form and function to facilitate lipid utilization in thermogenic adipocytes.


Assuntos
Adipócitos , Proteínas de Ligação ao Cálcio , Metabolismo dos Lipídeos , Proteínas de Membrana , Animais , Feminino , Humanos , Camundongos , Adipócitos/citologia , Adipócitos/metabolismo , Tecido Adiposo Marrom/citologia , Tecido Adiposo Marrom/metabolismo , Proteínas de Ligação ao Cálcio/deficiência , Proteínas de Ligação ao Cálcio/metabolismo , Proteínas de Membrana/deficiência , Proteínas de Membrana/metabolismo , Placenta , Triglicerídeos/metabolismo , Retículo Endoplasmático/metabolismo , Gotículas Lipídicas/metabolismo , Ácidos Graxos/metabolismo , Hipotermia/metabolismo , Termogênese
13.
Appl Immunohistochem Mol Morphol ; 31(1): 57-63, 2023 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-36121292

RESUMO

Osteoarthritis (OA) is the main joint disease associated with aging. Previous studies have confirmed that both osteopontin (OPN) and αvß3 integrin are involved in the progression of knee OA. The purpose of this study was to determine the expression of OPN and αvß3 integrin and chondrocyte senescence levels in OA. Forty-six cartilage tissues from normal and knee OA patients were divided into 4 groups of normal, minor, moderate, and severe lesions based on the Mankin score. Immunohistochemistry and western blotting were used to determine the expression of αvß3, OPN, and senescent-associated-ß-galactosidase (SAß-gal) in articular cartilage. Then, Spearman's correlation was used to analyze the correlations between the Mankin scores and αvß3, OPN and SAß-gal. Pearson correlation analysis was used to analyze the correlations among αvß3, OPN, and SAß-gal. The expression of OPN, αvß3, and SAß-gal in articular cartilage was explored. αvß3, OPN, and SAß-gal proteins were all elevated in OA cartilage, and the correlation coefficient between the Mankin score and the average optical density value of αvß3, OPN, SAß-gal were r =0.60, r =0.75, and r =0.87, respectively, all P <0.001; the correlation between the average optical density value of αvß3 and OPN was r =0.3191, P <0.05; the correlation between αvß3 and SAß-gal was r =0.4955, P <0.001; and the correlation between OPN and SAß-gal was r =0.7821, P <0.001. The correlations among αvß3, OPN, and SAß-gal expression in articular cartilage might be important in OA progression and pathogenesis. Nonetheless, more research is needed to elucidate the exact contribution of αvß3, OPN, and SAß-gal to the degenerative process of OA.


Assuntos
Cartilagem , Condrócitos , Integrina alfaVbeta3 , Osteopontina , Humanos , Gravidade do Paciente , Integrina alfaVbeta3/metabolismo , Condrócitos/citologia , Senescência Celular
14.
Diabetologia ; 66(1): 223-240, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36260124

RESUMO

AIMS/HYPOTHESIS: Senescent renal tubular cells may be linked to diabetic kidney disease (DKD)-related tubulopathy. We studied mice with or without diabetes in which hedgehog interacting protein (HHIP) was present or specifically knocked out in renal tubules (HhipRT-KO), hypothesising that local deficiency of HHIP in the renal tubules would attenuate tubular cell senescence, thereby preventing DKD tubulopathy. METHODS: Low-dose streptozotocin was employed to induce diabetes in both HhipRT-KO and control (Hhipfl/fl) mice. Transgenic mice overexpressing Hhip in renal proximal tubular cells (RPTC) (HhipRPTC-Tg) were used for validation, and primary RPTCs and human RPTCs (HK2) were used for in vitro studies. Kidney morphology/function, tubular senescence and the relevant molecular measurements were assessed. RESULTS: Compared with Hhipfl/fl mice with diabetes, HhipRT-KO mice with diabetes displayed lower blood glucose levels, normalised GFR, ameliorated urinary albumin/creatinine ratio and less severe DKD, including tubulopathy. Sodium-glucose cotransporter 2 (SGLT2) expression was attenuated in RPTCs of HhipRT-KO mice with diabetes compared with Hhipfl/fl mice with diabetes. In parallel, an increased tubular senescence-associated secretory phenotype involving release of inflammatory cytokines (IL-1ß, IL-6 and monocyte chemoattractant protein-1) and activation of senescence markers (p16, p21, p53) in Hhipfl/fl mice with diabetes was attenuated in HhipRT-KO mice with diabetes. In contrast, HhipRPTC-Tg mice had increased tubular senescence, which was inhibited by canagliflozin in primary RPTCs. In HK2 cells, HHIP overexpression or recombinant HHIP increased SGLT2 protein expression and promoted cellular senescence by targeting both ataxia-telangiectasia mutated and ataxia-telangiectasia and Rad3-related-mediated cell arrest. CONCLUSIONS/INTERPRETATION: Tubular HHIP deficiency prevented DKD-related tubulopathy, possibly via the inhibition of SGLT2 expression and cellular senescence.


Assuntos
Proteínas de Transporte , Diabetes Mellitus Tipo 1 , Glicoproteínas de Membrana , Transportador 2 de Glucose-Sódio , Animais , Humanos , Camundongos , Diabetes Mellitus Tipo 1/genética , Células Epiteliais , Proteínas Hedgehog , Transportador 2 de Glucose-Sódio/genética , Proteínas de Transporte/genética , Glicoproteínas de Membrana/genética , Camundongos Transgênicos , Diabetes Mellitus Experimental/genética , Túbulos Renais/citologia , Senescência Celular
15.
Nature ; 613(7942): 111-119, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36544025

RESUMO

When faced with predatory threats, escape towards shelter is an adaptive action that offers long-term protection against the attacker. Animals rely on knowledge of safe locations in the environment to instinctively execute rapid shelter-directed escape actions1,2. Although previous work has identified neural mechanisms of escape initiation3,4, it is not known how the escape circuit incorporates spatial information to execute rapid flights along the most efficient route to shelter. Here we show that the mouse retrosplenial cortex (RSP) and superior colliculus (SC) form a circuit that encodes the shelter-direction vector and is specifically required for accurately orienting to shelter during escape. Shelter direction is encoded in RSP and SC neurons in egocentric coordinates and SC shelter-direction tuning depends on RSP activity. Inactivation of the RSP-SC pathway disrupts the orientation to shelter and causes escapes away from the optimal shelter-directed route, but does not lead to generic deficits in orientation or spatial navigation. We find that the RSP and SC are monosynaptically connected and form a feedforward lateral inhibition microcircuit that strongly drives the inhibitory collicular network because of higher RSP input convergence and synaptic integration efficiency in inhibitory SC neurons. This results in broad shelter-direction tuning in inhibitory SC neurons and sharply tuned excitatory SC neurons. These findings are recapitulated by a biologically constrained spiking network model in which RSP input to the local SC recurrent ring architecture generates a circular shelter-direction map. We propose that this RSP-SC circuit might be specialized for generating collicular representations of memorized spatial goals that are readily accessible to the motor system during escape, or more broadly, during navigation when the goal must be reached as fast as possible.


Assuntos
Reação de Fuga , Giro do Cíngulo , Vias Neurais , Neurônios , Navegação Espacial , Colículos Superiores , Animais , Camundongos , Reação de Fuga/fisiologia , Neurônios/fisiologia , Comportamento Predatório , Memória Espacial , Navegação Espacial/fisiologia , Colículos Superiores/citologia , Colículos Superiores/fisiologia , Giro do Cíngulo/citologia , Giro do Cíngulo/fisiologia , Fatores de Tempo , Objetivos
16.
Nature ; 613(7943): 332-339, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36544020

RESUMO

Asgard archaea are considered to be the closest known relatives of eukaryotes. Their genomes contain hundreds of eukaryotic signature proteins (ESPs), which inspired hypotheses on the evolution of the eukaryotic cell1-3. A role of ESPs in the formation of an elaborate cytoskeleton and complex cellular structures has been postulated4-6, but never visualized. Here we describe a highly enriched culture of 'Candidatus Lokiarchaeum ossiferum', a member of the Asgard phylum, which thrives anaerobically at 20 °C on organic carbon sources. It divides every 7-14 days, reaches cell densities of up to 5 × 107 cells per ml and has a significantly larger genome compared with the single previously cultivated Asgard strain7. ESPs represent 5% of its protein-coding genes, including four actin homologues. We imaged the enrichment culture using cryo-electron tomography, identifying 'Ca. L. ossiferum' cells on the basis of characteristic expansion segments of their ribosomes. Cells exhibited coccoid cell bodies and a network of branched protrusions with frequent constrictions. The cell envelope consists of a single membrane and complex surface structures. A long-range cytoskeleton extends throughout the cell bodies, protrusions and constrictions. The twisted double-stranded architecture of the filaments is consistent with F-actin. Immunostaining indicates that the filaments comprise Lokiactin-one of the most highly conserved ESPs in Asgard archaea. We propose that a complex actin-based cytoskeleton predated the emergence of the first eukaryotes and was a crucial feature in the evolution of the Asgard phylum by scaffolding elaborate cellular structures.


Assuntos
Citoesqueleto de Actina , Archaea , Eucariotos , Filogenia , Citoesqueleto de Actina/metabolismo , Actinas/classificação , Actinas/genética , Actinas/metabolismo , Archaea/classificação , Archaea/citologia , Archaea/genética , Archaea/crescimento & desenvolvimento , Eucariotos/classificação , Eucariotos/citologia , Eucariotos/metabolismo , Anaerobiose , Ribossomos/metabolismo , Estruturas da Membrana Celular/metabolismo , Proteínas Arqueais/classificação , Proteínas Arqueais/genética , Proteínas Arqueais/metabolismo , Evolução Molecular
17.
Nature ; 613(7943): 317-323, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36544024

RESUMO

Cochlear implants (CIs) are neuroprosthetic devices that can provide hearing to deaf people1. Despite the benefits offered by CIs, the time taken for hearing to be restored and perceptual accuracy after long-term CI use remain highly variable2,3. CI use is believed to require neuroplasticity in the central auditory system, and differential engagement of neuroplastic mechanisms might contribute to the variability in outcomes4-7. Despite extensive studies on how CIs activate the auditory system4,8-12, the understanding of CI-related neuroplasticity remains limited. One potent factor enabling plasticity is the neuromodulator noradrenaline from the brainstem locus coeruleus (LC). Here we examine behavioural responses and neural activity in LC and auditory cortex of deafened rats fitted with multi-channel CIs. The rats were trained on a reward-based auditory task, and showed considerable individual differences of learning rates and maximum performance. LC photometry predicted when CI subjects began responding to sounds and longer-term perceptual accuracy. Optogenetic LC stimulation produced faster learning and higher long-term accuracy. Auditory cortical responses to CI stimulation reflected behavioural performance, with enhanced responses to rewarded stimuli and decreased distinction between unrewarded stimuli. Adequate engagement of central neuromodulatory systems is thus a potential clinically relevant target for optimizing neuroprosthetic device use.


Assuntos
Implantes Cocleares , Surdez , Locus Cerúleo , Animais , Ratos , Implante Coclear , Surdez/fisiopatologia , Surdez/terapia , Audição/fisiologia , Aprendizagem/fisiologia , Locus Cerúleo/citologia , Locus Cerúleo/fisiologia , Plasticidade Neuronal , Norepinefrina/metabolismo , Córtex Auditivo/citologia , Córtex Auditivo/fisiologia , Córtex Auditivo/fisiopatologia , Neurônios/fisiologia , Recompensa , Optogenética , Fotometria
18.
Nature ; 613(7943): 308-316, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36544022

RESUMO

The testis produces gametes through spermatogenesis and evolves rapidly at both the morphological and molecular level in mammals1-6, probably owing to the evolutionary pressure on males to be reproductively successful7. However, the molecular evolution of individual spermatogenic cell types across mammals remains largely uncharacterized. Here we report evolutionary analyses of single-nucleus transcriptome data for testes from 11 species that cover the three main mammalian lineages (eutherians, marsupials and monotremes) and birds (the evolutionary outgroup), and include seven primates. We find that the rapid evolution of the testis was driven by accelerated fixation rates of gene expression changes, amino acid substitutions and new genes in late spermatogenic stages, probably facilitated by reduced pleiotropic constraints, haploid selection and transcriptionally permissive chromatin. We identify temporal expression changes of individual genes across species and conserved expression programs controlling ancestral spermatogenic processes. Genes predominantly expressed in spermatogonia (germ cells fuelling spermatogenesis) and Sertoli (somatic support) cells accumulated on X chromosomes during evolution, presumably owing to male-beneficial selective forces. Further work identified transcriptomal differences between X- and Y-bearing spermatids and uncovered that meiotic sex-chromosome inactivation (MSCI) also occurs in monotremes and hence is common to mammalian sex-chromosome systems. Thus, the mechanism of meiotic silencing of unsynapsed chromatin, which underlies MSCI, is an ancestral mammalian feature. Our study illuminates the molecular evolution of spermatogenesis and associated selective forces, and provides a resource for investigating the biology of the testis across mammals.


Assuntos
Evolução Molecular , Mamíferos , Espermatogênese , Testículo , Animais , Masculino , Cromatina/genética , Mamíferos/genética , Meiose/genética , Espermatogênese/genética , Testículo/citologia , Transcriptoma , Análise de Célula Única , Aves/genética , Primatas/genética , Regulação da Expressão Gênica , Espermatogônias/citologia , Células de Sertoli/citologia , Cromossomo X/genética , Cromossomo Y/genética , Compensação de Dosagem (Genética) , Inativação Gênica
19.
J Cell Physiol ; 238(1): 274-284, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36502471

RESUMO

Pleural epithelial adaptations to mechanical stress are relevant to both normal lung function and parenchymal lung diseases. Assessing regional differences in mechanical stress, however, has been complicated by the nonlinear stress-strain properties of the lung and the large displacements with ventilation. Moreover, there is no reliable method of isolating pleural epithelium for structural studies. To define the topographic variation in pleural structure, we developed a method of en face harvest of murine pleural epithelium. Silver-stain was used to highlight cell borders and facilitate imaging with light microscopy. Machine learning and watershed segmentation were used to define the cell area and cell perimeter of the isolated pleural epithelial cells. In the deflated lung at residual volume, the pleural epithelial cells were significantly larger in the apex (624 ± 247 µm2 ) than in basilar regions of the lung (471 ± 119 µm2 ) (p < 0.001). The distortion of apical epithelial cells was consistent with a vertical gradient of pleural pressures. To assess epithelial changes with inflation, the pleura was studied at total lung capacity. The average epithelial cell area increased 57% and the average perimeter increased 27% between residual volume and total lung capacity. The increase in lung volume was less than half the percent change predicted by uniform or isotropic expansion of the lung. We conclude that the structured analysis of pleural epithelial cells complements studies of pulmonary microstructure and provides useful insights into the regional distribution of mechanical stresses in the lung.


Assuntos
Células Epiteliais , Pulmão , Pleura , Animais , Camundongos , Pulmão/anatomia & histologia , Aprendizado de Máquina , Pleura/anatomia & histologia , Respiração , Tórax , Células Epiteliais/citologia
20.
J Cell Biol ; 222(1)2023 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-36399182

RESUMO

Maintaining long, energetically demanding axons throughout the life of an animal is a major challenge for the nervous system. Specialized glia ensheathe axons and support their function and integrity throughout life, but glial support mechanisms remain poorly defined. Here, we identified a collection of secreted and transmembrane molecules required in glia for long-term axon survival in vivo. We showed that the majority of components of the TGFß superfamily are required in glia for sensory neuron maintenance but not glial ensheathment of axons. In the absence of glial TGFß signaling, neurons undergo age-dependent degeneration that can be rescued either by genetic blockade of Wallerian degeneration or caspase-dependent death. Blockade of glial TGFß signaling results in increased ATP in glia that can be mimicked by enhancing glial mitochondrial biogenesis or suppressing glial monocarboxylate transporter function. We propose that glial TGFß signaling supports axon survival and suppresses neurodegeneration through promoting glial metabolic support of neurons.


Assuntos
Axônios , Neuroglia , Fator de Crescimento Transformador beta , Animais , Axônios/metabolismo , Neuroglia/metabolismo , Nervos Periféricos/citologia , Células Receptoras Sensoriais , Fator de Crescimento Transformador beta/metabolismo , Drosophila melanogaster , Biogênese de Organelas , Transportadores de Ácidos Monocarboxílicos/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...