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1.
Nature ; 628(8006): 47-56, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38570716

RESUMO

Most life scientists would agree that understanding how cellular processes work requires structural knowledge about the macromolecules involved. For example, deciphering the double-helical nature of DNA revealed essential aspects of how genetic information is stored, copied and repaired. Yet, being reductionist in nature, structural biology requires the purification of large amounts of macromolecules, often trimmed off larger functional units. The advent of cryogenic electron microscopy (cryo-EM) greatly facilitated the study of large, functional complexes and generally of samples that are hard to express, purify and/or crystallize. Nevertheless, cryo-EM still requires purification and thus visualization outside of the natural context in which macromolecules operate and coexist. Conversely, cell biologists have been imaging cells using a number of fast-evolving techniques that keep expanding their spatial and temporal reach, but always far from the resolution at which chemistry can be understood. Thus, structural and cell biology provide complementary, yet unconnected visions of the inner workings of cells. Here we discuss how the interplay between cryo-EM and cryo-electron tomography, as a connecting bridge to visualize macromolecules in situ, holds great promise to create comprehensive structural depictions of macromolecules as they interact in complex mixtures or, ultimately, inside the cell itself.


Assuntos
Biologia Celular , Células , Microscopia Crioeletrônica , Tomografia com Microscopia Eletrônica , Microscopia Crioeletrônica/métodos , Microscopia Crioeletrônica/tendências , Tomografia com Microscopia Eletrônica/métodos , Tomografia com Microscopia Eletrônica/tendências , Substâncias Macromoleculares/análise , Substâncias Macromoleculares/química , Substâncias Macromoleculares/metabolismo , Substâncias Macromoleculares/ultraestrutura , Biologia Celular/instrumentação , Células/química , Células/citologia , Células/metabolismo , Células/ultraestrutura , Humanos
2.
J Cell Biol ; 223(7)2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38573225

RESUMO

Autophagy serves as a stress response pathway by mediating the degradation of cellular material within lysosomes. In autophagy, this material is encapsulated in double-membrane vesicles termed autophagosomes, which form from precursors referred to as phagophores. Phagophores grow by lipid influx from the endoplasmic reticulum into Atg9-positive compartments and local lipid synthesis provides lipids for their expansion. How phagophore nucleation and expansion are coordinated with lipid synthesis is unclear. Here, we show that Faa1, an enzyme activating fatty acids, is recruited to Atg9 vesicles by directly binding to negatively charged membranes with a preference for phosphoinositides such as PI3P and PI4P. We define the membrane-binding surface of Faa1 and show that its direct interaction with the membrane is required for its recruitment to phagophores. Furthermore, the physiological localization of Faa1 is key for its efficient catalysis and promotes phagophore expansion. Our results suggest a positive feedback loop coupling phagophore nucleation and expansion to lipid synthesis.


Assuntos
Autofagossomos , Ácidos Graxos , Macroautofagia , Autofagia , Ácidos Graxos/metabolismo , Retroalimentação , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/metabolismo
3.
J Cell Biol ; 223(5)2024 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-38558237

RESUMO

The p24 family of proteins have been regarded as cargo receptors for endoplasmic reticulum (ER) to Golgi transport; however, their precise functions have yet to be revealed. In this issue, Pastor-Pareja and colleagues (https://doi.org/10.1083/jcb.202309045) show that the interaction of these proteins with Tango1 is critical for their localization at the ER exit site (ERES) and efficient transport of secretory proteins in Drosophila.


Assuntos
Translocador Nuclear Receptor Aril Hidrocarboneto , Drosophila , Retículo Endoplasmático , Animais , Translocador Nuclear Receptor Aril Hidrocarboneto/metabolismo , Vesículas Revestidas pelo Complexo de Proteína do Envoltório/metabolismo , Drosophila/citologia , Drosophila/metabolismo , Retículo Endoplasmático/metabolismo , Complexo de Golgi/metabolismo , Transporte Proteico/fisiologia , Proteínas de Transporte Vesicular/genética , Proteínas de Transporte Vesicular/metabolismo
4.
J Cell Biol ; 223(7)2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38587472

RESUMO

The wound-healing process is a paradigm of the directed migration of various pools of stem cells from their niche to the site of injury where they replenish damaged cells. Two decades have elapsed since the observation that wounding activates multipotent hair follicle stem cells to infiltrate the epidermis, but the cues that coax these cells out of their niche remain unknown. Here, we report that Caspase-1, a protein classically known as an integral component of the cytosolic inflammasome, is secreted upon wounding and has a non-canonical role in the extracellular milieu. Through its caspase activation recruitment domain (CARD), Caspase-1 is sufficient to initiate the migration of hair follicle stem cells into the epidermis. Uncovering this novel function of Caspase-1 also facilitates a deeper understanding of the mechanistic basis of the epithelial hyperplasia found to accompany numerous inflammatory skin diseases.


Assuntos
Caspase 1 , Dermatite , Folículo Piloso , Células-Tronco , Cicatrização , Animais , Camundongos , Caspase 1/metabolismo , Movimento Celular , Dermatite/metabolismo , Dermatite/patologia , Cabelo , Folículo Piloso/citologia , Folículo Piloso/metabolismo , Inflamação/metabolismo
5.
Nature ; 628(8006): 180-185, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38480886

RESUMO

The gut microbiome has major roles in modulating host physiology. One such function is colonization resistance, or the ability of the microbial collective to protect the host against enteric pathogens1-3, including enterohaemorrhagic Escherichia coli (EHEC) serotype O157:H7, an attaching and effacing (AE) food-borne pathogen that causes severe gastroenteritis, enterocolitis, bloody diarrhea and acute renal failure4,5 (haemolytic uremic syndrome). Although gut microorganisms can provide colonization resistance by outcompeting some pathogens or modulating host defence provided by the gut barrier and intestinal immune cells6,7, this phenomenon remains poorly understood. Here, we show that activation of the neurotransmitter receptor dopamine receptor D2 (DRD2) in the intestinal epithelium by gut microbial metabolites produced upon dietary supplementation with the essential amino acid L-tryptophan protects the host against Citrobacter rodentium, a mouse AE pathogen that is widely used as a model for EHEC infection8,9. We further find that DRD2 activation by these tryptophan-derived metabolites decreases expression of a host actin regulatory protein involved in C. rodentium and EHEC attachment to the gut epithelium via formation of actin pedestals. Our results reveal a noncanonical colonization resistance pathway against AE pathogens that features an unconventional role for DRD2 outside the nervous system in controlling actin cytoskeletal organization in the gut epithelium. Our findings may inspire prophylactic and therapeutic approaches targeting DRD2 with dietary or pharmacological interventions to improve gut health and treat gastrointestinal infections, which afflict millions globally.


Assuntos
Citrobacter rodentium , Mucosa Intestinal , Receptores de Dopamina D2 , Triptofano , Animais , Feminino , Humanos , Masculino , Camundongos , Citoesqueleto de Actina/efeitos dos fármacos , Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Carga Bacteriana/efeitos dos fármacos , Citrobacter rodentium/crescimento & desenvolvimento , Citrobacter rodentium/metabolismo , Citrobacter rodentium/patogenicidade , Suplementos Nutricionais , Modelos Animais de Doenças , Infecções por Enterobacteriaceae/microbiologia , Infecções por Enterobacteriaceae/prevenção & controle , Infecções por Escherichia coli/microbiologia , Infecções por Escherichia coli/prevenção & controle , Escherichia coli O157/patogenicidade , Escherichia coli O157/fisiologia , Mucosa Intestinal/citologia , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/metabolismo , Mucosa Intestinal/microbiologia , Receptores de Dopamina D2/metabolismo , Triptofano/administração & dosagem , Triptofano/metabolismo , Triptofano/farmacologia
6.
Nature ; 628(8006): 154-161, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38480892

RESUMO

Several genetic risk factors for Alzheimer's disease implicate genes involved in lipid metabolism and many of these lipid genes are highly expressed in glial cells1. However, the relationship between lipid metabolism in glia and Alzheimer's disease pathology remains poorly understood. Through single-nucleus RNA sequencing of brain tissue in Alzheimer's disease, we have identified a microglial state defined by the expression of the lipid droplet-associated enzyme ACSL1 with ACSL1-positive microglia being most abundant in patients with Alzheimer's disease having the APOE4/4 genotype. In human induced pluripotent stem cell-derived microglia, fibrillar Aß induces ACSL1 expression, triglyceride synthesis and lipid droplet accumulation in an APOE-dependent manner. Additionally, conditioned media from lipid droplet-containing microglia lead to Tau phosphorylation and neurotoxicity in an APOE-dependent manner. Our findings suggest a link between genetic risk factors for Alzheimer's disease with microglial lipid droplet accumulation and neurotoxic microglia-derived factors, potentially providing therapeutic strategies for Alzheimer's disease.


Assuntos
Doença de Alzheimer , Apolipoproteína E4 , Gotículas Lipídicas , Microglia , Animais , Feminino , Humanos , Masculino , Camundongos , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Apolipoproteína E4/genética , Apolipoproteína E4/metabolismo , Células-Tronco Pluripotentes Induzidas/citologia , Gotículas Lipídicas/metabolismo , Gotículas Lipídicas/patologia , Microglia/citologia , Microglia/metabolismo , Microglia/patologia , Triglicerídeos , Proteínas tau , Meios de Cultivo Condicionados , Fosforilação , Predisposição Genética para Doença
7.
Nature ; 628(8006): 162-170, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38538791

RESUMO

Ageing of the immune system is characterized by decreased lymphopoiesis and adaptive immunity, and increased inflammation and myeloid pathologies1,2. Age-related changes in populations of self-renewing haematopoietic stem cells (HSCs) are thought to underlie these phenomena3. During youth, HSCs with balanced output of lymphoid and myeloid cells (bal-HSCs) predominate over HSCs with myeloid-biased output (my-HSCs), thereby promoting the lymphopoiesis required for initiating adaptive immune responses, while limiting the production of myeloid cells, which can be pro-inflammatory4. Ageing is associated with increased proportions of my-HSCs, resulting in decreased lymphopoiesis and increased myelopoiesis3,5,6. Transfer of bal-HSCs results in abundant lymphoid and myeloid cells, a stable phenotype that is retained after secondary transfer; my-HSCs also retain their patterns of production after secondary transfer5. The origin and potential interconversion of these two subsets is still unclear. If they are separate subsets postnatally, it might be possible to reverse the ageing phenotype by eliminating my-HSCs in aged mice. Here we demonstrate that antibody-mediated depletion of my-HSCs in aged mice restores characteristic features of a more youthful immune system, including increasing common lymphocyte progenitors, naive T cells and B cells, while decreasing age-related markers of immune decline. Depletion of my-HSCs in aged mice improves primary and secondary adaptive immune responses to viral infection. These findings may have relevance to the understanding and intervention of diseases exacerbated or caused by dominance of the haematopoietic system by my-HSCs.


Assuntos
Imunidade Adaptativa , Envelhecimento , Linhagem da Célula , Células-Tronco Hematopoéticas , Linfócitos , Células Mieloides , Rejuvenescimento , Animais , Feminino , Masculino , Camundongos , Imunidade Adaptativa/imunologia , Envelhecimento/imunologia , Linfócitos B/citologia , Linfócitos B/imunologia , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/imunologia , Inflamação/imunologia , Inflamação/patologia , Linfócitos/citologia , Linfócitos/imunologia , Linfopoese , Células Mieloides/citologia , Células Mieloides/imunologia , Mielopoese , Fenótipo , Linfócitos T/citologia , Linfócitos T/imunologia , Vírus/imunologia
8.
Immunohorizons ; 8(3): 281-294, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38551395

RESUMO

Inhibitory proteins, such as programmed cell death protein 1 (PD-1), have been studied extensively in peripheral T cell responses to foreign Ags, self-Ags, and neoantigens. Notably, these proteins are first expressed during T cell development in the thymus. Reports suggest that PD-1 limits regulatory T cell (Treg) development, but the mechanism by which PD-1 exerts this function remains unknown. The present study expands the evaluation of murine PD-1 and its ligands in the thymus, demonstrating that some of the highest expressers of PD-1 and programmed death-ligand 1 are agonist selected cells. Surprisingly, we reveal a selective role for PD-1 in regulating the developmental niche only for Tregs because other agonist selected cell populations, such as NK T cells, remain unchanged. We also ruled out PD-1 as a regulator of proliferation or cell death of agonist selected Tregs and further demonstrated that PD-1-deficient Tregs have reduced TCR signaling. Unexpectedly, the data suggest that PD-1-deficient thymocytes produce elevated levels of IL-2, a Treg niche-limiting cytokine. Collectively, these data suggest a novel role for PD-1 in regulating IL-2 production and the concurrent agonist selection of murine thymic Tregs. This observation has implications for the use of checkpoint blockade in the context of cancer and infection.


Assuntos
Interleucina-2 , Receptor de Morte Celular Programada 1 , Linfócitos T Reguladores , Timo , Animais , Camundongos , Citocinas/metabolismo , Interleucina-2/metabolismo , Receptor de Morte Celular Programada 1/metabolismo , Linfócitos T Reguladores/imunologia , Timo/citologia , Timo/imunologia
9.
Science ; 383(6690): 1478-1483, 2024 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-38547293

RESUMO

Experiences need to be tagged during learning for further consolidation. However, neurophysiological mechanisms that select experiences for lasting memory are not known. By combining large-scale neural recordings in mice with dimensionality reduction techniques, we observed that successive maze traversals were tracked by continuously drifting populations of neurons, providing neuronal signatures of both places visited and events encountered. When the brain state changed during reward consumption, sharp wave ripples (SPW-Rs) occurred on some trials, and their specific spike content decoded the trial blocks that surrounded them. During postexperience sleep, SPW-Rs continued to replay those trial blocks that were reactivated most frequently during waking SPW-Rs. Replay content of awake SPW-Rs may thus provide a neurophysiological tagging mechanism to select aspects of experience that are preserved and consolidated for future use.


Assuntos
Ondas Encefálicas , Região CA1 Hipocampal , Consolidação da Memória , Neurônios , Animais , Camundongos , Neurônios/fisiologia , Consolidação da Memória/fisiologia , Aprendizagem em Labirinto , Região CA1 Hipocampal/citologia , Região CA1 Hipocampal/fisiologia
10.
Nature ; 627(8003): 399-406, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38448581

RESUMO

Immune cells rely on transient physical interactions with other immune and non-immune populations to regulate their function1. To study these 'kiss-and-run' interactions directly in vivo, we previously developed LIPSTIC (labelling immune partnerships by SorTagging intercellular contacts)2, an approach that uses enzymatic transfer of a labelled substrate between the molecular partners CD40L and CD40 to label interacting cells. Reliance on this pathway limited the use of LIPSTIC to measuring interactions between CD4+ T helper cells and antigen-presenting cells, however. Here we report the development of a universal version of LIPSTIC (uLIPSTIC), which can record physical interactions both among immune cells and between immune and non-immune populations irrespective of the receptors and ligands involved. We show that uLIPSTIC can be used, among other things, to monitor the priming of CD8+ T cells by dendritic cells, reveal the steady-state cellular partners of regulatory T cells and identify germinal centre-resident T follicular helper cells on the basis of their ability to interact cognately with germinal centre B cells. By coupling uLIPSTIC with single-cell transcriptomics, we build a catalogue of the immune populations that physically interact with intestinal epithelial cells at the steady state and profile the evolution of the interactome of lymphocytic choriomeningitis virus-specific CD8+ T cells in multiple organs following systemic infection. Thus, uLIPSTIC provides a broadly useful technology for measuring and understanding cell-cell interactions across multiple biological systems.


Assuntos
Linfócitos B , Linfócitos T CD8-Positivos , Comunicação Celular , Células Dendríticas , Células Epiteliais , Células T Auxiliares Foliculares , Linfócitos T Reguladores , Linfócitos T CD8-Positivos/citologia , Linfócitos T CD8-Positivos/imunologia , Comunicação Celular/imunologia , Células Dendríticas/citologia , Células Dendríticas/imunologia , Ligantes , Linfócitos T Reguladores/citologia , Linfócitos T Reguladores/imunologia , Células T Auxiliares Foliculares/citologia , Células T Auxiliares Foliculares/imunologia , Linfócitos B/citologia , Linfócitos B/imunologia , Centro Germinativo/citologia , Análise da Expressão Gênica de Célula Única , Células Epiteliais/citologia , Células Epiteliais/imunologia , Mucosa Intestinal/citologia , Mucosa Intestinal/imunologia , Vírus da Coriomeningite Linfocítica/imunologia , Coriomeningite Linfocítica/imunologia , Coriomeningite Linfocítica/virologia , Especificidade de Órgãos
11.
Cell ; 187(5): 1314-1314.e1, 2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-38428399

RESUMO

Ribosome production is essential for cell growth. Approximately 200 assembly factors drive this complicated pathway that starts in the nucleolus and ends in the cytoplasm. A large number of structural snapshots of the pre-60S pathway have revealed the principles behind large subunit synthesis. To view this SnapShot, open or download the PDF.


Assuntos
Nucléolo Celular , Células Eucarióticas , Ribossomos , Nucléolo Celular/metabolismo , Proteínas Ribossômicas/genética , Proteínas Ribossômicas/química , Subunidades Ribossômicas Maiores de Eucariotos/metabolismo , Ribossomos/metabolismo , Células Eucarióticas/química , Células Eucarióticas/citologia , Células Eucarióticas/metabolismo
12.
Cell ; 187(7): 1733-1744.e12, 2024 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-38552612

RESUMO

Mastigonemes, the hair-like lateral appendages lining cilia or flagella, participate in mechanosensation and cellular motion, but their constituents and structure have remained unclear. Here, we report the cryo-EM structure of native mastigonemes isolated from Chlamydomonas at 3.0 Å resolution. The long stem assembles as a super spiral, with each helical turn comprising four pairs of anti-parallel mastigoneme-like protein 1 (Mst1). A large array of arabinoglycans, which represents a common class of glycosylation in plants and algae, is resolved surrounding the type II poly-hydroxyproline (Hyp) helix in Mst1. The EM map unveils a mastigoneme axial protein (Mstax) that is rich in heavily glycosylated Hyp and contains a PKD2-like transmembrane domain (TMD). Mstax, with nearly 8,000 residues spanning from the intracellular region to the distal end of the mastigoneme, provides the framework for Mst1 assembly. Our study provides insights into the complexity of protein and glycan interactions in native bio-architectures.


Assuntos
Chlamydomonas , Cílios , Chlamydomonas/citologia , Cílios/química , Cílios/ultraestrutura , Flagelos , Polissacarídeos , Proteínas
13.
Nature ; 627(8004): 604-611, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38448582

RESUMO

Human brains vary across people and over time; such variation is not yet understood in cellular terms. Here we describe a relationship between people's cortical neurons and cortical astrocytes. We used single-nucleus RNA sequencing to analyse the prefrontal cortex of 191 human donors aged 22-97 years, including healthy individuals and people with schizophrenia. Latent-factor analysis of these data revealed that, in people whose cortical neurons more strongly expressed genes encoding synaptic components, cortical astrocytes more strongly expressed distinct genes with synaptic functions and genes for synthesizing cholesterol, an astrocyte-supplied component of synaptic membranes. We call this relationship the synaptic neuron and astrocyte program (SNAP). In schizophrenia and ageing-two conditions that involve declines in cognitive flexibility and plasticity1,2-cells divested from SNAP: astrocytes, glutamatergic (excitatory) neurons and GABAergic (inhibitory) neurons all showed reduced SNAP expression to corresponding degrees. The distinct astrocytic and neuronal components of SNAP both involved genes in which genetic risk factors for schizophrenia were strongly concentrated. SNAP, which varies quantitatively even among healthy people of similar age, may underlie many aspects of normal human interindividual differences and may be an important point of convergence for multiple kinds of pathophysiology.


Assuntos
Envelhecimento , Astrócitos , Neurônios , Córtex Pré-Frontal , Esquizofrenia , Adulto , Idoso , Idoso de 80 Anos ou mais , Humanos , Pessoa de Meia-Idade , Adulto Jovem , Envelhecimento/metabolismo , Envelhecimento/patologia , Astrócitos/citologia , Astrócitos/metabolismo , Astrócitos/patologia , Colesterol/metabolismo , Cognição , Neurônios GABAérgicos/metabolismo , Predisposição Genética para Doença , Glutamina/metabolismo , Saúde , Individualidade , Inibição Neural , Plasticidade Neuronal , Neurônios/citologia , Neurônios/metabolismo , Neurônios/patologia , Córtex Pré-Frontal/citologia , Córtex Pré-Frontal/metabolismo , Córtex Pré-Frontal/patologia , Esquizofrenia/genética , Esquizofrenia/metabolismo , Esquizofrenia/patologia , Análise da Expressão Gênica de Célula Única , Sinapses/genética , Sinapses/metabolismo , Sinapses/patologia , Membranas Sinápticas/química , Membranas Sinápticas/metabolismo
14.
Nature ; 627(8004): 553-558, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38480895

RESUMO

Ranging from subcellular organelle biogenesis to embryo development, the formation of self-organized structures is a hallmark of living systems. Whereas the emergence of ordered spatial patterns in biology is often driven by intricate chemical signalling that coordinates cellular behaviour and differentiation1-4, purely physical interactions can drive the formation of regular biological patterns such as crystalline vortex arrays in suspensions of spermatozoa5 and bacteria6. Here we discovered a new route to self-organized pattern formation driven by physical interactions, which creates large-scale regular spatial structures with multiscale ordering. Specifically we found that dense bacterial living matter spontaneously developed a lattice of mesoscale, fast-spinning vortices; these vortices each consisted of around 104-105 motile bacterial cells and were arranged in space at greater than centimetre scale and with apparent hexagonal order, whereas individual cells in the vortices moved in coordinated directions with strong polar and vortical order. Single-cell tracking and numerical simulations suggest that the phenomenon is enabled by self-enhanced mobility in the system-that is, the speed of individual cells increasing with cell-generated collective stresses at a given cell density. Stress-induced mobility enhancement and fluidization is prevalent in dense living matter at various scales of length7-9. Our findings demonstrate that self-enhanced mobility offers a simple physical mechanism for pattern formation in living systems and, more generally, in other active matter systems10 near the boundary of fluid- and solid-like behaviours11-17.


Assuntos
Bactérias , Movimento , Bactérias/citologia , Rastreamento de Células , Modelos Biológicos , Suspensões
15.
Front Biosci (Landmark Ed) ; 29(3): 96, 2024 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-38538257

RESUMO

BACKGROUND: Type 1 diabetes mellitus (T1D) represents a severe threat to human health. Persistent hyperglycemia and dyslipidemia can lead to damaged liver function, while effective interventions for these complications are currently lacking. Deer antler stem cells (AnSCs), a novel type of adult stem cells, significantly reduced liver injury, which was speculated to be achieved through the paracrine pathway. METHODS: In this study, AnSC-conditioned medium (AnSC-CM) was used to treat C57BL/6 mice with T1D symptoms induced by streptozotocin (STZ). The therapeutic effects of AnSC-CM on T1D were evaluated, and the underlying mechanism was investigated. RESULTS: It was shown that AnSC-CM alleviated the T1D symptom: decreased body weight, increased blood glucose levels and islet lesions, and reduced insulin secretion. Moreover, AnSC-CM treatment improved liver function and mitigated liver injury in T1D mice. Impressively, the therapeutic effects of AnSC-CM on T1D were better than those of bone marrow mesenchymal stem cell-CM (BMSC-CM). The mechanistic study revealed that AnSC-CM significantly downregulated the NF-κB signaling pathway in both pancreatic and liver tissues. CONCLUSIONS: Therapeutic effects of AnSC-CM on STZ-induced T1D and liver injury may be achieved through targeting the NF-κB signaling pathway.


Assuntos
Chifres de Veado , Cervos , Diabetes Mellitus Tipo 1 , Adulto , Animais , Humanos , Camundongos , Chifres de Veado/citologia , Chifres de Veado/metabolismo , Meios de Cultivo Condicionados/farmacologia , Diabetes Mellitus Tipo 1/terapia , Camundongos Endogâmicos C57BL , NF-kappa B/metabolismo , Transdução de Sinais , Células-Tronco/metabolismo
16.
Cell ; 187(7): 1762-1768.e9, 2024 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-38471501

RESUMO

Biological dinitrogen (N2) fixation is a key metabolic process exclusively performed by prokaryotes, some of which are symbiotic with eukaryotes. Species of the marine haptophyte algae Braarudosphaera bigelowii harbor the N2-fixing endosymbiotic cyanobacteria UCYN-A, which might be evolving organelle-like characteristics. We found that the size ratio between UCYN-A and their hosts is strikingly conserved across sublineages/species, which is consistent with the size relationships of organelles in this symbiosis and other species. Metabolic modeling showed that this size relationship maximizes the coordinated growth rate based on trade-offs between resource acquisition and exchange. Our findings show that the size relationships of N2-fixing endosymbionts and organelles in unicellular eukaryotes are constrained by predictable metabolic underpinnings and that UCYN-A is, in many regards, functioning like a hypothetical N2-fixing organelle (or nitroplast).


Assuntos
Cianobactérias , Haptófitas , Fixação de Nitrogênio , Cianobactérias/metabolismo , Haptófitas/citologia , Haptófitas/metabolismo , Haptófitas/microbiologia , Nitrogênio/metabolismo , Simbiose
17.
J Cell Biol ; 223(5)2024 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-38470363

RESUMO

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


Assuntos
Transporte Axonal , Cinesinas , Animais , Axônios , Caenorhabditis elegans/citologia , Caenorhabditis elegans/metabolismo , Cinesinas/metabolismo , Mitocôndrias/metabolismo
18.
J Cell Biol ; 223(6)2024 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-38478017

RESUMO

SM proteins including Sly1 are essential cofactors of SNARE-mediated membrane fusion. Using SNARE and Sly1 mutants and chemically defined in vitro assays, we separate and assess proposed mechanisms through which Sly1 augments fusion: (i) opening the closed conformation of the Qa-SNARE Sed5; (ii) close-range tethering of vesicles to target organelles, mediated by the Sly1-specific regulatory loop; and (iii) nucleation of productive trans-SNARE complexes. We show that all three mechanisms are important and operate in parallel, and that close-range tethering promotes trans-complex assembly when cis-SNARE assembly is a competing process. Further, we demonstrate that the autoinhibitory N-terminal Habc domain of Sed5 has at least two positive activities: it is needed for correct Sed5 localization, and it directly promotes Sly1-dependent fusion. "Split Sed5," with Habc presented solely as a soluble fragment, can function both in vitro and in vivo. Habc appears to facilitate events leading to lipid mixing rather than promoting opening or stability of the fusion pore.


Assuntos
Fusão de Membrana , Proteínas Munc18 , Proteínas SNARE , Proteínas de Saccharomyces cerevisiae , Proteínas Munc18/metabolismo , Ligação Proteica , Proteínas Qa-SNARE/metabolismo , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas SNARE/genética , Proteínas SNARE/metabolismo , Proteínas de Transporte Vesicular/metabolismo
19.
J Cell Biol ; 223(6)2024 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-38478018

RESUMO

The essential Golgi protein Sly1 is a member of the Sec1/mammalian Unc-18 (SM) family of SNARE chaperones. Sly1 was originally identified through remarkable gain-of-function alleles that bypass requirements for diverse vesicle tethering factors. Employing genetic analyses and chemically defined reconstitutions of ER-Golgi fusion, we discovered that a loop conserved among Sly1 family members is not only autoinhibitory but also acts as a positive effector. An amphipathic lipid packing sensor (ALPS)-like helix within the loop directly binds high-curvature membranes. Membrane binding is required for relief of Sly1 autoinhibition and also allows Sly1 to directly tether incoming vesicles to the Qa-SNARE on the target organelle. The SLY1-20 mutation bypasses requirements for diverse tethering factors but loses this ability if the tethering activity is impaired. We propose that long-range tethers, including Golgins and multisubunit tethering complexes, hand off vesicles to Sly1, which then tethers at close range to initiate trans-SNARE complex assembly and fusion in the early secretory pathway.


Assuntos
Vesículas Citoplasmáticas , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Animais , Complexo de Golgi/genética , Complexo de Golgi/metabolismo , Mamíferos/metabolismo , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Proteínas Munc18/análise , Proteínas Munc18/genética , Proteínas Munc18/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas SNARE/genética , Proteínas SNARE/metabolismo , Proteínas de Transporte Vesicular/metabolismo , Vesículas Citoplasmáticas/metabolismo , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/metabolismo
20.
Nature ; 627(8005): 854-864, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38480880

RESUMO

The heart, which is the first organ to develop, is highly dependent on its form to function1,2. However, how diverse cardiac cell types spatially coordinate to create the complex morphological structures that are crucial for heart function remains unclear. Here we integrated single-cell RNA-sequencing with high-resolution multiplexed error-robust fluorescence in situ hybridization to resolve the identity of the cardiac cell types that develop the human heart. This approach also provided a spatial mapping of individual cells that enables illumination of their organization into cellular communities that form distinct cardiac structures. We discovered that many of these cardiac cell types further specified into subpopulations exclusive to specific communities, which support their specialization according to the cellular ecosystem and anatomical region. In particular, ventricular cardiomyocyte subpopulations displayed an unexpected complex laminar organization across the ventricular wall and formed, with other cell subpopulations, several cellular communities. Interrogating cell-cell interactions within these communities using in vivo conditional genetic mouse models and in vitro human pluripotent stem cell systems revealed multicellular signalling pathways that orchestrate the spatial organization of cardiac cell subpopulations during ventricular wall morphogenesis. These detailed findings into the cellular social interactions and specialization of cardiac cell types constructing and remodelling the human heart offer new insights into structural heart diseases and the engineering of complex multicellular tissues for human heart repair.


Assuntos
Padronização Corporal , Coração , Miocárdio , Animais , Humanos , Camundongos , Coração/anatomia & histologia , Coração/embriologia , Cardiopatias/metabolismo , Cardiopatias/patologia , Ventrículos do Coração/anatomia & histologia , Ventrículos do Coração/citologia , Ventrículos do Coração/embriologia , Hibridização in Situ Fluorescente , Modelos Animais , Miocárdio/citologia , Miócitos Cardíacos/citologia , Miócitos Cardíacos/metabolismo , Análise da Expressão Gênica de Célula Única
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