RESUMO
Neurodevelopment and efferocytosis have fascinated scientists for decades. How an organism builds a nervous system that is precisely tuned for efficient behaviors and survival and how it simultaneously manages constant somatic cell turnover are complex questions that have resulted in distinct fields of study. Although neurodevelopment requires the overproduction of cells that are subsequently pruned back, very few studies marry these fields to elucidate the cellular and molecular mechanisms that drive nervous system development through the lens of cell clearance. In this review, we discuss these fields to highlight exciting areas of future synergy. We first review neurodevelopment from the perspective of overproduction and subsequent refinement and then discuss who clears this developmental debris and the mechanisms that control these events. We then end with how a more deliberate merger ofneurodevelopment and efferocytosis could reframe our understanding of homeostasis and disease and discuss areas of future study.
Assuntos
Apoptose , Fagócitos , Apoptose/fisiologia , Morte Celular , Homeostase , Fagócitos/metabolismo , Fagocitose/fisiologiaRESUMO
During development, inflammation or tissue injury, macrophages may successively engulf and process multiple apoptotic corpses via efferocytosis to achieve tissue homeostasis1. How macrophages may rapidly adapt their transcription to achieve continuous corpse uptake is incompletely understood. Transcriptional pause/release is an evolutionarily conserved mechanism, in which RNA polymerase (Pol) II initiates transcription for 20-60 nucleotides, is paused for minutes to hours and is then released to make full-length mRNA2. Here we show that macrophages, within minutes of corpse encounter, use transcriptional pause/release to unleash a rapid transcriptional response. For human and mouse macrophages, the Pol II pause/release was required for continuous efferocytosis in vitro and in vivo. Interestingly, blocking Pol II pause/release did not impede Fc receptor-mediated phagocytosis, yeast uptake or bacterial phagocytosis. Integration of data from three genomic approaches-precision nuclear run-on sequencing, RNA sequencing, and assay for transposase-accessible chromatin using sequencing (ATAC-seq)-on efferocytic macrophages at different time points revealed that Pol II pause/release controls expression of select transcription factors and downstream target genes. Mechanistic studies on transcription factor EGR3, prominently regulated by pause/release, uncovered EGR3-related reprogramming of other macrophage genes involved in cytoskeleton and corpse processing. Using lysosomal probes and a new genetic fluorescent reporter, we identify a role for pause/release in phagosome acidification during efferocytosis. Furthermore, microglia from egr3-deficient zebrafish embryos displayed reduced phagocytosis of apoptotic neurons and fewer maturing phagosomes, supporting defective corpse processing. Collectively, these data indicate that macrophages use Pol II pause/release as a mechanism to rapidly alter their transcriptional programs for efficient processing of the ingested apoptotic corpses and for successive efferocytosis.
Assuntos
Eferocitose , Macrófagos , RNA Polimerase II , Elongação da Transcrição Genética , Animais , Humanos , Masculino , Camundongos , Apoptose , Citoesqueleto/metabolismo , Proteína 3 de Resposta de Crescimento Precoce/deficiência , Proteína 3 de Resposta de Crescimento Precoce/genética , Eferocitose/genética , Concentração de Íons de Hidrogênio , Macrófagos/imunologia , Macrófagos/metabolismo , Neurônios/metabolismo , Fagossomos/metabolismo , RNA Polimerase II/metabolismo , Fatores de Transcrição/genética , Peixe-Zebra/embriologia , Peixe-Zebra/genética , Fatores de TempoRESUMO
Cellular reprogramming is characterized by the induced dedifferentiation of mature cells into a more plastic and potent state. This process can occur through artificial reprogramming manipulations in the laboratory such as nuclear reprogramming and induced pluripotent stem cell (iPSC) generation, and endogenously in vivo during amphibian limb regeneration. In amphibians such as the Mexican axolotl, a regeneration permissive environment is formed by nerve-dependent signaling in the wounded limb tissue. When exposed to these signals, limb connective tissue cells dedifferentiate into a limb progenitor-like state. This state allows the cells to acquire new pattern information, a property called positional plasticity. Here, we review our current understanding of endogenous reprogramming and why it is important for successful regeneration. We will also explore how naturally induced dedifferentiation and plasticity were leveraged to study how the missing pattern is established in the regenerating limb tissue.
Assuntos
Ambystoma mexicanum , Transdução de Sinais , Animais , Reprogramação CelularRESUMO
Development and routine tissue homeostasis require a high turnover of apoptotic cells. These cells are removed by professional and non-professional phagocytes via efferocytosis1. How a phagocyte maintains its homeostasis while coordinating corpse uptake, processing ingested materials and secreting anti-inflammatory mediators is incompletely understood1,2. Here, using RNA sequencing to characterize the transcriptional program of phagocytes actively engulfing apoptotic cells, we identify a genetic signature involving 33 members of the solute carrier (SLC) family of membrane transport proteins, in which expression is specifically modulated during efferocytosis, but not during antibody-mediated phagocytosis. We assessed the functional relevance of these SLCs in efferocytic phagocytes and observed a robust induction of an aerobic glycolysis program, initiated by SLC2A1-mediated glucose uptake, with concurrent suppression of the oxidative phosphorylation program. The different steps of phagocytosis2-that is, 'smell' ('find-me' signals or sensing factors released by apoptotic cells), 'taste' (phagocyte-apoptotic cell contact) and 'ingestion' (corpse internalization)-activated distinct and overlapping sets of genes, including several SLC genes, to promote glycolysis. SLC16A1 was upregulated after corpse uptake, increasing the release of lactate, a natural by-product of aerobic glycolysis3. Whereas glycolysis within phagocytes contributed to actin polymerization and the continued uptake of corpses, lactate released via SLC16A1 promoted the establishment of an anti-inflammatory tissue environment. Collectively, these data reveal a SLC program that is activated during efferocytosis, identify a previously unknown reliance on aerobic glycolysis during apoptotic cell uptake and show that glycolytic by-products of efferocytosis can influence surrounding cells.
Assuntos
Transportador de Glucose Tipo 1/genética , Transportador de Glucose Tipo 1/metabolismo , Glucose/metabolismo , Ácido Láctico/metabolismo , Fagócitos/metabolismo , Fagocitose/genética , Transcriptoma/genética , Aerobiose , Animais , Apoptose , Linhagem Celular , Glicólise , Humanos , Inflamação/genética , Inflamação/prevenção & controle , Células Jurkat , Fagócitos/citologia , Análise de Sequência de RNA , Transcrição Gênica , Peixe-ZebraRESUMO
Some organisms, such as the Mexican axolotl, have the capacity to regenerate complicated biological structures throughout their lives. Which molecular pathways are sufficient to induce a complete endogenous regenerative response in injured tissue is an important question that remains unanswered. Using a gain-of-function regeneration assay, known as the Accessory Limb Model (ALM), we and others have begun to identify the molecular underpinnings of the three essential requirements for limb regeneration; wounding, neurotrophic signaling, and the induction of pattern from cells that retain positional memory. We have previously shown that treatment of Mexican axolotls with exogenous retinoic acid (RA) is sufficient to induce the formation of complete limb structures from blastemas that were generated by deviating a nerve bundle into an anterior-located wound site on the limb. Here we show that these ectopic structures are capable of regenerating and inducing new pattern to form when grafted into new anterior-located wounds. We additionally found that the expression of Alx4 decreases, and Shh expression increases in these anterior located blastemas, but not in the mature anterior tissues, supporting the hypothesis that RA treatment posteriorizes blastema tissue. Based on these and previous observations, we used the ALM assay to test the hypothesis that a complete regenerative response can be generated by treating anterior-located superficial limb wounds with a specific combination of growth factors at defined developmental stages. Our data shows that limb wounds that are first treated with a combination of FGF-2, FGF-8, and BMP-2, followed by RA treatment of the resultant mid-bud stage blastema, will result in the generation of limbs with complete proximal/distal and anterior/posterior limb axes. Thus, the minimal signaling requirements from the nerve and a positional disparity are achieved with the application of this specific combination of signaling molecules.
Assuntos
Ambystoma mexicanum/fisiologia , Transdução de Sinais , Animais , Proteínas Morfogenéticas Ósseas/metabolismo , Extremidades/fisiologia , Fatores de Crescimento de Fibroblastos/metabolismo , Regeneração , Tretinoína/metabolismoRESUMO
Aminimides are key intermediates in the thermal cycloadditions of suitable alkenyl-hydrazine derivatives. Substrate modifications (ß-N,N-dialkyl) allowed the isolation of these reactive intermediates, and the analysis of their stereochemistry provided support for concerted (Cope-type) hydroamination and concerted [3 + 2] aminocarbonylation reaction pathways. This work also establishes the applicability of these approaches to form complex aminimides in moderate to excellent yields.
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Anthropogenic noise imposes novel selection pressures, especially on species that communicate acoustically. Many animals-including insects, frogs, whales and birds-produce sounds at higher frequencies in areas with low-frequency noise pollution. Although there is support for animals changing their vocalizations in real time in response to noise (i.e. immediate flexibility), other evolutionary mechanisms for animals that learn their vocalizations remain largely unexplored. We hypothesize that cultural selection for signal structures less masked by noise is a mechanism of acoustic adaptation to anthropogenic noise. We test this hypothesis by presenting nestling white-crowned sparrows (Zonotrichia leucophyrs) with less-masked (higher-frequency) and more-masked (lower-frequency) tutor songs either during playback of anthropogenic noise (noise-tutored treatment) or at a different time from noise playback (control treatment). As predicted, we find that noise-tutored males learn less-masked songs significantly more often, whereas control males show no copying preference, providing strong experimental support for cultural selection in response to anthropogenic noise. Further, noise-tutored males reproduce songs at higher frequencies than their tutor, indicating a distinct mechanism to increase signal transmission in a noisy environment. Notably, noise-tutored males achieve lower performance songs than their tutors, suggesting potential costs in a sexual selection framework.
Assuntos
Ruído , Aves Canoras/fisiologia , Vocalização Animal , Acústica , Adaptação Fisiológica , Animais , Cidades , Masculino , São Francisco , Pardais/fisiologiaRESUMO
A phase separation/continuous flow strategy employing an oxidative Glaser-Hay coupling of alkynes has been applied toward the synthesis of the macrocyclic core of complex pharmaceutical vaniprevir. The phase separation/continuous flow strategy afforded similar yields at 100-500 times the concentration and at shorter reaction times than common slow addition/high dilution techniques. In addition, dendritic PEG cosolvents were employed in the phase separation strategy for the first time and shown to allow productive macrocyclization at concentrations up to 200 mM.
Assuntos
Indóis/síntese química , Alcinos/química , Ciclização , Ciclopropanos , Indóis/química , Isoindóis , Lactamas Macrocíclicas , Leucina/análogos & derivados , Substâncias Macromoleculares/síntese química , Substâncias Macromoleculares/química , Micro-Ondas , Estrutura Molecular , Prolina/análogos & derivados , SulfonamidasRESUMO
BACKGROUND: To our knowledge, there are no studies of patients with idiopathic intracranial hypertension (IIH) that address the relationship between level of intracranial pressure (ICP) and likelihood of progressive visual loss despite uncomplicated optic nerve sheath decompression (ONSD). This study investigated whether patients with IIH undergoing ONSD had a higher risk of surgical failure if opening pressure (OP) on lumbar puncture was ≥50 cm H2O compared to those with OP <50 cm H2O. METHODS: We conducted a retrospective chart review of consecutive patients with IIH who failed maximal medical therapy and underwent ONSD between January, 1992 and November, 2014, and were followed at least 3 months postoperatively. The main outcome measure was the relationship between OP on lumbar puncture and ONSD failure. We also investigated the relationship of OP with visual acuity, visual fields, age, and gender. RESULTS: During this period, 174 patients met inclusion criteria. Of the 40 patients who had an OP ≥50 cm H2O, 6 (15%) had progressive visual loss after uncomplicated ONSD, vs 6 (4.5%) of 134 patients with an OP <50 cm H2O (P = 0.032, Fisher exact test). Patients with worse visual acuity at presentation also had a higher risk of progressive visual loss after ONSD (P < 0.001, Cochran-Armitage trend test), as did men (P = 0.048, Fisher exact test). CONCLUSIONS: Patients with IIH and an OP ≥50 cm H2O had a 3-fold increased risk of failure of ONSD to prevent progressive visual loss, requiring a shunting procedure when compared to those with OP <50 cm H2O. Visual acuity at presentation and male sex also were associated with progressive visual decline after ONSD. These risk factors merit closer follow-up in the postoperative period when signs of further visual deterioration would indicate an urgent need for neurosurgical shunting.
Assuntos
Descompressão Cirúrgica/métodos , Pressão Intracraniana/fisiologia , Doenças do Nervo Óptico/cirurgia , Pseudotumor Cerebral/cirurgia , Punção Espinal , Baixa Visão/etiologia , Adulto , Feminino , Humanos , Masculino , Nervo Óptico/patologia , Doenças do Nervo Óptico/complicações , Doenças do Nervo Óptico/fisiopatologia , Pseudotumor Cerebral/complicações , Pseudotumor Cerebral/fisiopatologia , Estudos Retrospectivos , Falha de Tratamento , Baixa Visão/fisiopatologia , Acuidade Visual , Campos VisuaisRESUMO
Macrocyclic olefin metathesis has seen advances in the areas of stereochemistry, chemoselectivity, and catalyst stability, but strategies aimed at controlling dilution effects in macrocyclizations are rare. Herein, a protocol to promote macrocyclic olefin metathesis, one of the most common synthetic tools used to prepare macrocycles, at relatively high concentrations (up to 60â mM) is described by exploitation of a phase-separation strategy. A variety of macrocyclic skeletons could be prepared having either different alkyl, aryl, or amino acids spacers.
Assuntos
Alcenos/química , Compostos Macrocíclicos/química , Alcenos/síntese química , Catálise , Ciclização , Compostos Macrocíclicos/síntese química , Transição de Fase , Polietilenoglicóis/química , Rutênio/químicaRESUMO
Idiopathic intracranial hypertension is defined by headaches and a decline in visual acuity due to increased intracranial pressure. Treatment options historically included weight loss, acetazolamide, and/or cerebrospinal fluid diversion surgery. Recent understanding of the contributions of dural venous sinus hypertension and stenosis has led to venous sinus stenting as a treatment option.
Assuntos
Pseudotumor Cerebral , Humanos , Acetazolamida/uso terapêutico , Cavidades Cranianas/cirurgia , Hipertensão Intracraniana/terapia , Pseudotumor Cerebral/cirurgia , Pseudotumor Cerebral/terapia , StentsRESUMO
Prion disease is caused by misfolding of the prion protein (PrP) into pathogenic self-propagating conformations, leading to rapid-onset dementia and death. However, elimination of endogenous PrP halts prion disease progression. In this study, we describe Coupled Histone tail for Autoinhibition Release of Methyltransferase (CHARM), a compact, enzyme-free epigenetic editor capable of silencing transcription through programmable DNA methylation. Using a histone H3 tail-Dnmt3l fusion, CHARM recruits and activates endogenous DNA methyltransferases, thereby reducing transgene size and cytotoxicity. When delivered to the mouse brain by systemic injection of adeno-associated virus (AAV), Prnp-targeted CHARM ablates PrP expression across the brain. Furthermore, we have temporally limited editor expression by implementing a kinetically tuned self-silencing approach. CHARM potentially represents a broadly applicable strategy to suppress pathogenic proteins, including those implicated in other neurodegenerative diseases.
Assuntos
Encéfalo , Metilação de DNA , Dependovirus , Inativação Gênica , Histonas , Proteínas Priônicas , Animais , Humanos , Camundongos , Encéfalo/metabolismo , Dependovirus/genética , DNA (Citosina-5-)-Metiltransferases/metabolismo , DNA (Citosina-5-)-Metiltransferases/genética , Histonas/metabolismo , Doenças Priônicas/genética , Doenças Priônicas/metabolismo , Proteínas Priônicas/genética , Proteínas Priônicas/metabolismo , TransgenesRESUMO
In this research, we explored correlates of individuals' beliefs in altruism, free will, and nonreductionism, as opposed to contrasting beliefs in psychological egoism, determinism, and biological reductionism. Beliefs in altruism, free will, and nonreductionism were associated with heightened a) senses of meaning in life, b) levels of life satisfaction, c) beliefs in morality as a legitimate and important dimension of life, and d) standards of personal moral conduct; they were not associated with levels of social isolation. Implications of these findings are discussed.
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Atitude , Autonomia Pessoal , Comportamento Social , Adolescente , Adulto , Altruísmo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Princípios Morais , Satisfação Pessoal , Isolamento Social/psicologia , Inquéritos e Questionários , Adulto JovemRESUMO
When the Accessory Limb Model (ALM) regenerative assay was first published by Endo, Bryant, and Gardiner in 2004, it provided a robust system for testing the cellular and molecular contributions during each of the basic steps of regeneration: the formation of the wound epithelium, neural induction of the apical epithelial cap, and the formation of a positional disparity between blastema cells. The basic ALM procedure was developed in the axolotl and involves deviating a limb nerve into a lateral wound and grafting skin from the opposing side of the limb axis into the site of injury. In this chapter, we will review the studies that lead to the conception of the ALM, as well as the studies that have followed the development of this assay. We will additionally describe in detail the standard ALM surgery and how to perform this surgery on different limb positions.
Assuntos
Ambystoma mexicanum , Tecido Nervoso , Animais , Ambystoma mexicanum/fisiologia , Extremidades/fisiologia , Pele/inervação , EpitélioRESUMO
Introduction: Little is known about how the newly regenerated limb tissues in the Mexican axolotl seamlessly integrate with the remaining stump tissues to form a functional structure, and why this doesn't occur in some regenerative scenarios. In this study, we evaluate the phenomenological and transcriptional characteristics associated with integration failure in ectopic limb structures generated by treating anterior-located ectopic blastemas with Retinoic Acid (RA) and focusing on the "bulbus mass" tissue that forms between the ectopic limb and the host site. We additionally test the hypothesis that the posterior portion of the limb base contains anterior positional identities. Methods: The positional identity of the bulbus mass was evaluated by assaying regenerative competency, the ability to induce new pattern in the Accessory Limb Model (ALM) assay, and by using qRTPCR to quantify the relative expression of patterning genes as the bulbus mass deintegrates from the host site. We additionally use the ALM and qRTPCR to analyze the distribution of anterior and posterior positional identities along the proximal/distal limb axis of uninjured and regenerating limbs. Results: The bulbus mass regenerates limb structures with decreased complexity when amputated and is able to induce complex ectopic limb structure only when grafted into posterior-located ALMs. Expressional analysis shows significant differences in FGF8, BMP2, TBX5, Chrdl1, HoxA9, and HoxA11 expression between the bulbus mass and the host site when deintegration is occuring. Grafts of posterior skin from the distal limb regions into posterior ALMs at the base of the limb induce ectopic limb structures. Proximally-located blastemas express significantly less HoxA13 and Ptch1, and significantly more Alx4 and Grem1 than distally located blastemas. Discussion: These findings show that the bulbus mass has an anterior-limb identity and that the expression of limb patterning genes is mismatched between the bulbus mass and the host limb. Our findings additionally show that anterior positional information is more abundant at the limb base, and that anterior patterning genes are more abundantly expressed in proximally located blastemas compared to blastemas in the more distal regions of the limb. These experiments provide valuable insight into the underlying causes of integration failure and further map the distribution of positional identities in the mature limb.
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The retina is highly metabolically active, relying on glucose uptake and aerobic glycolysis. Situated in close contact to photoreceptors, a key function of cells in the retinal pigment epithelium (RPE) is phagocytosis of damaged photoreceptor outer segments (POS). Here we identify RPE as a local source of insulin in the eye that is stimulated by POS phagocytosis. We show that Ins2 messenger RNA and insulin protein are produced by RPE cells and that this production correlates with RPE phagocytosis of POS. Genetic deletion of phagocytic receptors ('loss of function') reduces Ins2, whereas increasing the levels of the phagocytic receptor MerTK ('gain of function') increases Ins2 production in male mice. Contrary to pancreas-derived systemic insulin, RPE-derived local insulin is stimulated during starvation, which also increases RPE phagocytosis. Global or RPE-specific Ins2 gene deletion decreases retinal glucose uptake in starved male mice, dysregulates retinal physiology, causes defects in phototransduction and exacerbates photoreceptor loss in a mouse model of retinitis pigmentosa. Collectively, these data identify RPE cells as a phagocytosis-induced local source of insulin in the retina, with the potential to influence retinal physiology and disease.
Assuntos
Insulina , Receptores Proteína Tirosina Quinases , Masculino , Camundongos , Animais , Receptores Proteína Tirosina Quinases/genética , Receptores Proteína Tirosina Quinases/metabolismo , Insulina/metabolismo , Retina/metabolismo , Fagocitose/fisiologia , Glucose/metabolismoRESUMO
BACKGROUND: Voluntary shoulder instability is characterized by a patient's ability to sublux their shoulder using selective muscle contraction and relaxation. High failure rates exist with open shoulder stabilization in this group of patients. The purpose of this study was to report the outcomes for patients with voluntary instability treated arthroscopically. METHODS: All patients with voluntary instability from 2006 to 2008 treated with arthroscopic stabilization were included. All patients had documentation of preoperative and postoperative American Shoulder and Elbow Surgeons (ASES) questionnaire score, visual analogue scale of pain, simple shoulder test, and range of motion. Subjective satisfaction and return to sport was also determined. RESULTS: Ten patients were identified for inclusion in the study. The average age of the 5 male and 5 female patients was 16.2 ± 2.33 years. Average clinical follow-up period was 31 ± 6.5 months. Visual analogue scale scores improved from 5.33 ± 3.50 preoperatively to 1.44 ± 2.0 postoperatively, ASES scores improved from 52.2 ± 18.7 to 85.9 ± 14.9 and simple shoulder test improved from 8.17 ± 3.19 to 11.4 ± 1.01. All of the functional evaluation scores improved postoperatively (P < 0.05). There was no case of postoperative dislocation or subluxation, all reported excellent subjective outcome, and all those who played sports returned to their previous level. CONCLUSIONS: Good and excellent outcomes can be obtained with arthroscopic stabilization for patients with voluntary instability. Improved results from previous reports may be related to improved patient selection, surgical technique, and postoperative rehabilitation. Although long-term follow-up and comparative studies are necessary, arthroscopic stabilization seems to be an acceptable treatment option for patients who fail nonoperative treatment. LEVEL OF EVIDENCE: Level IV, case series, retrospective review.
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Artroscopia/métodos , Instabilidade Articular/cirurgia , Articulação do Ombro/cirurgia , Adolescente , Feminino , Seguimentos , Humanos , Masculino , Dor/etiologia , Medição da Dor , Satisfação do Paciente , Seleção de Pacientes , Amplitude de Movimento Articular , Estudos Retrospectivos , Articulação do Ombro/patologia , Inquéritos e Questionários , Resultado do TratamentoRESUMO
Synthetic gene circuits that precisely control human cell function could expand the capabilities of gene- and cell-based therapies. However, platforms for developing circuits in primary human cells that drive robust functional changes in vivo and have compositions suitable for clinical use are lacking. Here, we developed synthetic zinc finger transcription regulators (synZiFTRs), which are compact and based largely on human-derived proteins. As a proof of principle, we engineered gene switches and circuits that allow precise, user-defined control over therapeutically relevant genes in primary T cells using orthogonal, US Food and Drug Administration-approved small-molecule inducers. Our circuits can instruct T cells to sequentially activate multiple cellular programs such as proliferation and antitumor activity to drive synergistic therapeutic responses. This platform should accelerate the development and clinical translation of synthetic gene circuits in diverse human cell types and contexts.
Assuntos
Terapia Baseada em Transplante de Células e Tecidos , Redes Reguladoras de Genes , Genes Sintéticos , Linfócitos T , Fatores de Transcrição , Dedos de Zinco , Humanos , Terapia Baseada em Transplante de Células e Tecidos/métodos , Biologia Sintética/métodos , Linfócitos T/metabolismo , Linfócitos T/transplante , Engenharia GenéticaRESUMO
Apoptosis of cells and their subsequent removal through efferocytosis occurs in nearly all tissues during development, homeostasis, and disease. However, it has been difficult to track cell death and subsequent corpse removal in vivo. We developed a genetically encoded fluorescent reporter, CharON (Caspase and pH Activated Reporter, Fluorescence ON), that could track emerging apoptotic cells and their efferocytic clearance by phagocytes. Using Drosophila expressing CharON, we uncovered multiple qualitative and quantitative features of coordinated clearance of apoptotic corpses during embryonic development. When confronted with high rates of emerging apoptotic corpses, the macrophages displayed heterogeneity in engulfment behaviors, leading to some efferocytic macrophages carrying high corpse burden. Overburdened macrophages were compromised in clearing wound debris. These findings reveal known and unexpected features of apoptosis and macrophage efferocytosis in vivo.
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Apoptose , Rastreamento de Células , Drosophila/embriologia , Desenvolvimento Embrionário , Macrófagos/fisiologia , Fagocitose , Animais , Concentração de Íons de HidrogênioRESUMO
Epithelial tissues such as lung and skin are exposed to the environment and therefore particularly vulnerable to damage during injury or infection. Rapid repair is therefore essential to restore function and organ homeostasis. Dysregulated epithelial tissue repair occurs in several human disease states, yet how individual cell types communicate and interact to coordinate tissue regeneration is incompletely understood. Here, we show that pannexin 1 (Panx1), a cell membrane channel activated by caspases in dying cells, drives efficient epithelial regeneration after tissue injury by regulating injury-induced epithelial proliferation. Lung airway epithelial injury promotes the Panx1-dependent release of factors including ATP, from dying epithelial cells, which regulates macrophage phenotype after injury. This process, in turn, induces a reparative response in tissue macrophages that includes the induction of the soluble mitogen amphiregulin, which promotes injury-induced epithelial proliferation. Analysis of regenerating lung epithelium identified Panx1-dependent induction of Nras and Bcas2, both of which positively promoted epithelial proliferation and tissue regeneration in vivo. We also established that this role of Panx1 in boosting epithelial repair after injury is conserved between mouse lung and zebrafish tailfin. These data identify a Panx1-mediated communication circuit between epithelial cells and macrophages as a key step in promoting epithelial regeneration after injury.