The retromer complex promotes apoptotic cell degradation during efferocytosis
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE310776 | GEO | 2025/11/25
REPOSITORIES: GEO
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Project description:Phagocytes in different tissues recognize and remove apoptotic cells via the process of efferocytosis. Although it is well-established that efferocytosis elicits an anti-inflammatory response by phagocytes, the molecules and mechanisms that enforce this response in phagocytes are still being defined. In attempting to decipher gene programs induced after a phagocyte ingests a dying cell, we uncovered a chloride-sensing signaling pathway that controls both the ‘appetite’ of a phagocyte and how a phagocyte responds after corpse uptake. First, we noted that within phagocytes that have ingested a corpse, the solute carrier 12 (SLC12) family members SLC12A2 and SLC12A4 are actively modulated. Interfering with SLC12A2, either genetically or pharmacologically, led to significantly enhanced corpse uptake per phagocyte, while loss of SLC12A4 inhibited corpse uptake. Interestingly, when phagocytes with disrupted SLC12A2 engulfed apoptotic corpses, the typical homeostatic efferocytosis signature was perturbed, characterized by loss of the canonical anti-inflammatory program and replaced by pro-inflammatory and oxidative stress-associated gene programs. In further mechanistic studies, we observed efferocytosis was also regulated by the chloride-sensing pathway upstream of SLC12A2, including the kinases WNK1-OSR1-SPAK, and this involved chloride entry/exit across the plasma membrane of phagocytes during corpse engulfment. We also show that the ‘switch’ to pro-inflammatory sensing of apoptotic cells is specifically due to disruption of the chloride-sensing pathway and not due to corpse overload or poor degradation, and that the pro-inflammatory gene signature can be reversed using a chloride ionophore. Collectively, these data identify the WNK1-OSR1-SPAK-SLC12A2/SLC12A4 chloride-sensing pathway and chloride flux in phagocytes as key modifiers of how a phagocyte interprets an engulfed apoptotic corpse.
2020-03-24 | GSE131860 | GEO
Project description:Balancing the competing demands of phagolysosomal degradation and autophagy is a significant challenge for phagocytic tissues. Yet, how this plasticity is accomplished in health and disease is poorly understood. In the retina, circadian phagocytosis and degradation of photoreceptor outer segments by the postmitotic retinal pigment epithelium (RPE) is essential for healthy vision. Disrupted autophagy due to mTOR overactivation in the RPE is associated with blinding macular degenerations; however, outer segment degradation is unaffected in these diseases, indicating that distinct mechanisms regulate these clearance mechanisms. Here, using advanced imaging and mouse models, we identify optineurin as a key regulator that tunes phagocytosis and lysosomal capacity to meet circadian demands and helps prioritize outer segment clearance by the RPE in macular degenerations. High-resolution live-cell imaging implicates optineurin in scissioning outer segment tips prior to engulfment, analogous to microglial trogocytosis of neuronal processes. Optineurin is essential for recruiting LC3, which anchors outer segment phagosomes to microtubules and facilitates phagosome maturation and fusion with lysosomes. This dynamically activates transcription factor EB (TFEB) to induce lysosome biogenesis in an mTOR-independent, TRPML1 (transient receptor potential-mucolipin 1)-dependent manner. RNAseq analyses show that expression of TFEB target genes temporally tracks with optineurin recruitment, and that lysosomal and autophagy genes are controlled by distinct transcriptional programs in the RPE. The unconventional plasma membrane-to-nucleus signaling mediated by optineurin ensures outer segment degradation under conditions of impaired autophagy in macular degeneration models. Independent regulation of these critical clearance mechanisms would help safeguard metabolic fitness of the RPE through the organismal lifespan.
2023-08-15 | GSE237291 | GEO
Project description:Balancing the competing demands of phagolysosomal degradation and autophagy is a significant challenge for phagocytic tissues. Yet, how this plasticity is accomplished in health and disease is poorly understood. In the retina, circadian phagocytosis and degradation of photoreceptor outer segments by the postmitotic retinal pigment epithelium (RPE) is essential for healthy vision. Disrupted autophagy due to mTOR overactivation in the RPE is associated with blinding macular degenerations; however, outer segment degradation is unaffected in these diseases, indicating that distinct mechanisms regulate these clearance mechanisms. Here, using advanced imaging and mouse models, we identify optineurin as a key regulator that tunes phagocytosis and lysosomal capacity to meet circadian demands and helps prioritize outer segment clearance by the RPE in macular degenerations. High-resolution live-cell imaging implicates optineurin in scissioning outer segment tips prior to engulfment, analogous to microglial trogocytosis of neuronal processes. Optineurin is essential for recruiting LC3, which anchors outer segment phagosomes to microtubules and facilitates phagosome maturation and fusion with lysosomes. This dynamically activates transcription factor EB (TFEB) to induce lysosome biogenesis in an mTOR-independent, TRPML1 (transient receptor potential-mucolipin 1)-dependent manner. RNAseq analyses show that expression of TFEB target genes temporally tracks with optineurin recruitment, and that lysosomal and autophagy genes are controlled by distinct transcriptional programs in the RPE. The unconventional plasma membrane-to-nucleus signaling mediated by optineurin ensures outer segment degradation under conditions of impaired autophagy in macular degeneration models. Independent regulation of these critical clearance mechanisms would help safeguard metabolic fitness of the RPE through the organismal lifespan.
2023-08-15 | GSE237292 | GEO
Project description:Apoptotic cell clearance (efferocytosis), a process essential for organismal homeostasis, is performed by phagocytes that inhabit a wide range of environments, including physiologic hypoxia. Here, we find macrophages, the predominant tissue-resident phagocyte, display enhanced efferocytosis under chronic hypoxia, characterized by increased internalization and accelerated degradation of apoptotic cells. Analysis of mRNA and protein programs revealed that chronic hypoxia induces two distinct but complimentary states in macrophages. The first, ‘primed’ state consists of concomitant induction of transcriptional and translational programs broadly associated with metabolism in apoptotic cell-naïve macrophages that persist during efferocytosis. The second, ‘poised’ state consists of transcription, but not translation, of phagocyte function programs in apoptotic cell-naïve macrophages that are subsequently translated during efferocytosis. We discovered that one such primed state consists of the efficient flux of glucose into a noncanonical pentose phosphate pathway (PPP) loop, whereby PPP-derived intermediates cycle back through the PPP to enhance production of NADPH. Mechanistically, we found that PPP-derived NADPH directly supports enhanced efferocytosis under chronic hypoxia via its role in phagolysosomal maturation, while simultaneously maintaining cellular redox homeostasis. Thus, macrophages adapt to chronic hypoxia by adopting states that both support cell fitness and ensure ability to rapidly and safely perform essential homeostatic functions.
2022-12-30 | GSE192969 | GEO
Project description:Phagocytosis is an essential process for the microbicidal function of professional phagocytes, in which phagosome maturation plays a critical role. Macrophage activation by interferons (IFN) increases their microbicidal activity, but delays phagosomal maturation. Here, we investigated the role of ubiquitylation in phagosome functions. We show that phagosomal proteins are ubiquitylated and that phagosomes contain diverse ubiquitin chain types, including atypical ubiquitin chains. IFN-γ activation of macrophages substantially enhanced phagosomal ubiquitylation of both innate immune response proteins and vesicle trafficking proteins. We identified the E3 ubiquitin ligase RNF115, which is enriched on phagosomes of IFN-γ activated macrophages, as an important regulator of phagosomal maturation. Loss of RNF115 protein or ubiquitin ligase activity facilitated enhanced phagosomal maturation, and increased cytokine responses to Staphylococcus aureus. Our data suggests that both innate immune signalling and phagolysosomal trafficking are controlled through ubiquitylation. In conclusion, we identify RNF115 and ubiquitylation as important regulators of innate immune signalling from the phagosome during bacterial infections.
2022-07-20 | PXD026843 | Pride
Project description:Macrophages can adjust their phenotype and function in response to environmental cues, such as encountering apoptotic cells or pathogens. After tissue injury or inflammation, macrophages must successively engulf and process multiple apoptotic corpses (via efferocytosis) to achieve tissue homeostasis. How macrophages may rapidly adapt their transcription to achieve continued corpse uptake is incompletely understood. Transcriptional pause/release is an evolutionarily conserved process wherein RNA polymerase II (Pol II), after initiating transcription for 20-60 nucleotides, gets ‘paused’ for seconds to hours; paused Pol II then gets ‘released’ to complete transcription to make full-length mRNA. Here we show that macrophages, within minutes of corpse encounter, use transcriptional pause/release as a mechanism to unleash a rapid transcriptional response. For human and murine macrophages, the Pol II pause/release was crucial for continued efferocytosis of corpses in vitro and in vivo. Interestingly, blocking Pol II pause/release did not impede FcR-mediated phagocytosis, yeast uptake, or bacterial phagocytosis. Integrating data from three complementary genomic approaches of PRO-seq, RNA-seq, and ATAC-seq on efferocytic macrophages at different time points, we found that Pol II pause/release controls expression of select transcription factors and downstream target genes. Further mechanistic studies on transcription factor Egr3, one of the genes prominently affected by pause/release, uncovered Egr3-related reprogramming of macrophage genes involved in cytoskeleton and corpse processing. Via lysosomal probes and a newly designed genetic fluorescent reporter, we identify a key role for pause/release in phagosome acidification during efferocytosis. Further, microglia from egr3-deficient zebrafish embryos displayed reduced phagocytosis of apoptotic neurons and fewer maturing endosomes, supporting a defect in corpse processing. Collectively, these data advance a novel concept that macrophages use Polymerase II pause/release as a mechanism to rapidly alter their transcriptional programs for efficient processing of the ingested apoptotic corpse and for successive efferocytosis.
2024-01-25 | GSE253577 | GEO
Project description:Macrophages can adjust their phenotype and function in response to environmental cues, such as encountering apoptotic cells or pathogens. After tissue injury or inflammation, macrophages must successively engulf and process multiple apoptotic corpses (via efferocytosis) to achieve tissue homeostasis. How macrophages may rapidly adapt their transcription to achieve continued corpse uptake is incompletely understood. Transcriptional pause/release is an evolutionarily conserved process wherein RNA polymerase II (Pol II), after initiating transcription for 20-60 nucleotides, gets ‘paused’ for seconds to hours; paused Pol II then gets ‘released’ to complete transcription to make full-length mRNA. Here we show that macrophages, within minutes of corpse encounter, use transcriptional pause/release as a mechanism to unleash a rapid transcriptional response. For human and murine macrophages, the Pol II pause/release was crucial for continued efferocytosis of corpses in vitro and in vivo. Interestingly, blocking Pol II pause/release did not impede FcR-mediated phagocytosis, yeast uptake, or bacterial phagocytosis. Integrating data from three complementary genomic approaches of PRO-seq, RNA-seq, and ATAC-seq on efferocytic macrophages at different time points, we found that Pol II pause/release controls expression of select transcription factors and downstream target genes. Further mechanistic studies on transcription factor Egr3, one of the genes prominently affected by pause/release, uncovered Egr3-related reprogramming of macrophage genes involved in cytoskeleton and corpse processing. Via lysosomal probes and a newly designed genetic fluorescent reporter, we identify a key role for pause/release in phagosome acidification during efferocytosis. Further, microglia from egr3-deficient zebrafish embryos displayed reduced phagocytosis of apoptotic neurons and fewer maturing endosomes, supporting a defect in corpse processing. Collectively, these data advance a novel concept that macrophages use Polymerase II pause/release as a mechanism to rapidly alter their transcriptional programs for efficient processing of the ingested apoptotic corpse and for successive efferocytosis.
2024-01-25 | GSE253576 | GEO
Project description:Macrophages can adjust their phenotype and function in response to environmental cues, such as encountering apoptotic cells or pathogens. After tissue injury or inflammation, macrophages must successively engulf and process multiple apoptotic corpses (via efferocytosis) to achieve tissue homeostasis. How macrophages may rapidly adapt their transcription to achieve continued corpse uptake is incompletely understood. Transcriptional pause/release is an evolutionarily conserved process wherein RNA polymerase II (Pol II), after initiating transcription for 20-60 nucleotides, gets ‘paused’ for seconds to hours; paused Pol II then gets ‘released’ to complete transcription to make full-length mRNA. Here we show that macrophages, within minutes of corpse encounter, use transcriptional pause/release as a mechanism to unleash a rapid transcriptional response. For human and murine macrophages, the Pol II pause/release was crucial for continued efferocytosis of corpses in vitro and in vivo. Interestingly, blocking Pol II pause/release did not impede FcR-mediated phagocytosis, yeast uptake, or bacterial phagocytosis. Integrating data from three complementary genomic approaches of PRO-seq, RNA-seq, and ATAC-seq on efferocytic macrophages at different time points, we found that Pol II pause/release controls expression of select transcription factors and downstream target genes. Further mechanistic studies on transcription factor Egr3, one of the genes prominently affected by pause/release, uncovered Egr3-related reprogramming of macrophage genes involved in cytoskeleton and corpse processing. Via lysosomal probes and a newly designed genetic fluorescent reporter, we identify a key role for pause/release in phagosome acidification during efferocytosis. Further, microglia from egr3-deficient zebrafish embryos displayed reduced phagocytosis of apoptotic neurons and fewer maturing endosomes, supporting a defect in corpse processing. Collectively, these data advance a novel concept that macrophages use Polymerase II pause/release as a mechanism to rapidly alter their transcriptional programs for efficient processing of the ingested apoptotic corpse and for successive efferocytosis.
2024-01-25 | GSE253574 | GEO
Project description:Mycobacterium tuberculosis’success as a pathogen comes from itsability to evade degradation by macrophages. Normally macro-phages clear microorganisms that activate pathogen-recognitionreceptors (PRRs) through a lysosomal-trafficking pathway called“LC3-associated phagocytosis”(LAP). AlthoughM.tuberculosisac-tivates numerous PRRs, for reasons that are poorly understoodLAP does not substantially contribute toM.tuberculosiscontrol.LAP depends upon reactive oxygen species (ROS) generated byNADPH oxidase, butM.tuberculosisfails to generate a robustoxidative response. Here, we show that CpsA, a LytR-CpsA-Psr(LCP) domain-containing protein, is required forM.tuberculosisto evade killing by NADPH oxidase and LAP. Unlike phagosomescontaining wild-type bacilli, phagosomes containing theΔcpsAmutant recruited NADPH oxidase, produced ROS, associated withLC3, and matured into antibacterial lysosomes. Moreover, CpsAwas sufficient to impair NADPH oxidase recruitment to fungal par-ticles that are normally cleared by LAP. Intracellular survival of theΔcpsAmutant was largely restored in macrophages missing LAPcomponents (Nox2,Rubicon,Beclin,Atg5,Atg7,orAtg16L1) butnot in macrophages defective in a related, canonical autophagypathway (Atg14,Ulk1,orcGAS). TheΔcpsAmutant was highlyimpaired in vivo, and its growth was partially restored in micedeficient in NADPH oxidase,Atg5,orAtg7, demonstrating thatCpsA makes a significant contribution to the resistance ofM.tu-berculosisto NADPH oxidase and LC3 trafficking in vivo. Overall,our findings reveal an essential role of CpsA in innate immuneevasion and suggest that LCP proteins have functions beyond theirpreviously known role in cell-wall metabolism.
2019-12-13 | GSE141931 | GEO
Project description:On a daily basis, we turnover billions of apoptotic cells that are removed by professional and non-professional phagocytes1-10. While characterizing the transcriptional program of phagocytes, we discovered a novel solute carrier family (SLC) gene signature (33 SLC members) that is specifically modified during engulfment of apoptotic cells (efferocytosis) but not during antibody-mediated phagocytosis. When we assessed the functional relevance of these SLCs, we noted robust induction of an aerobic glycolysis program in engulfing phagocytes, initiated by SLC2A1-mediated glucose uptake, and suppression of oxidative phosphorylation program. Interestingly, the different steps of phagocytosis10,11, i.e. smell (‘find-me’ signals / sensing factors released by apoptotic cells), taste (phagocyte- apoptotic cell contact), and ingestion (corpse internalization), activated different molecules to promote this glycolytic process. Further, lactate, a natural by-product of aerobic glycolysis12,13, was released from engulfing phagocytes via SLC16A1, an SLC member activated after corpse uptake. While glycolysis within phagocytes contributed to actin polymerization and the continued uptake of corpses, the lactate released via SLC16A1 influenced the establishment of an anti-inflammatory environment. Collectively, these data reveal a novel SLC program activated during efferocytosis, identify a previously unknown reliance on aerobic glycolysis during apoptotic cell uptake, and that glycolytic byproducts of efferocytosis can also influence other cells in the microenvironment.
2018-11-30 | GSE119273 | GEO