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Cell Reports. Medicine Feb 2024Programmed cell death-1 (PD-1)/programmed cell death ligand-1 (PD-L1) blockade has become a mainstay of cancer immunotherapy. Targeting the PD-1/PD-L1 axis with small...
Programmed cell death-1 (PD-1)/programmed cell death ligand-1 (PD-L1) blockade has become a mainstay of cancer immunotherapy. Targeting the PD-1/PD-L1 axis with small molecules is an attractive approach to enhance antitumor immunity. Here, we identified a natural marine product, benzosceptrin C (BC), that enhances the cytotoxicity of T cells to cancer cells by reducing the abundance of PD-L1. Furthermore, BC exerts its antitumor effect in mice bearing MC38 tumors by activating tumor-infiltrating T cell immunity. Mechanistic studies suggest that BC can prevent palmitoylation of PD-L1 by inhibiting DHHC3 enzymatic activity. Subsequently, PD-L1 is transferred from the membrane to the cytoplasm and cannot return to the membrane via recycling endosomes, triggering lysosome-mediated degradation of PD-L1. Moreover, the combination of BC and anti-CTLA4 effectively enhances antitumor T cell immunity. Our findings reveal a previously unrecognized antitumor mechanism of BC and represent an alternative immune checkpoint blockade (ICB) therapeutic strategy to enhance the efficacy of cancer immunotherapy.
Topics: Animals; Mice; B7-H1 Antigen; Programmed Cell Death 1 Receptor; Neoplasms; Lysosomes; Imidazoles; Pyrroles
PubMed: 38237597
DOI: 10.1016/j.xcrm.2023.101357 -
Science Advances Sep 2023The mechanistic target of rapamycin complex 1 (mTORC1) is part of the amino acid sensing machinery that becomes activated on the endolysosomal surface in response to...
The mechanistic target of rapamycin complex 1 (mTORC1) is part of the amino acid sensing machinery that becomes activated on the endolysosomal surface in response to nutrient cues. Branched actin generated by WASH and Arp2/3 complexes defines endolysosomal microdomains. Here, we find mTORC1 components in close proximity to endolysosomal actin microdomains. We investigated for interactors of the mTORC1 lysosomal tether, RAGC, by proteomics and identified multiple actin filament capping proteins and their modulators. Perturbation of RAGC function affected the size of endolysosomal actin, consistent with a regulation of actin filament capping by RAGC. Reciprocally, the pharmacological inhibition of actin polymerization or alteration of endolysosomal actin obtained upon silencing of WASH or Arp2/3 complexes impaired mTORC1 activity. Mechanistically, we show that actin is required for proper association of RAGC and mTOR with endolysosomes. This study reveals an unprecedented interplay between actin and mTORC1 signaling on the endolysosomal system.
Topics: Mechanistic Target of Rapamycin Complex 1; Actins; Signal Transduction; Actin Cytoskeleton; Lysosomes
PubMed: 37703363
DOI: 10.1126/sciadv.add9084 -
IScience May 2024Lysosomes, the hub of metabolic signaling, are associated with various diseases and participate in autophagy by supplying nutrients to cells under nutrient starvation....
Lysosomes, the hub of metabolic signaling, are associated with various diseases and participate in autophagy by supplying nutrients to cells under nutrient starvation. However, their function and regulation under glucose starvation remain unclear and are studied herein. Under glucose starvation, lysosomal protein expression decreased, leading to the accumulation of damaged lysosomes. Subsequently, cell death occurred via ferroptosis and iron accumulation due to DMT1 degradation. GPX4, a key factor in ferroptosis inhibition located on the outer membrane of lysosomes, accumulated in lysosomes, especially under glucose starvation, to protect cells from ferroptosis. ALDOA, GAPDH, NAMPT, and PGK1 are also located on the outer membrane of lysosomes and participate in lysosomal function. These enzymes did not function effectively under glucose starvation, leading to lysosomal dysfunction and ferroptosis. These findings may facilitate the treatment of lysosomal-related diseases.
PubMed: 38706843
DOI: 10.1016/j.isci.2024.109735 -
Philosophical Transactions of the Royal... Apr 2024While causative mutations in complex disorders are rare, they can be used to extract a biological pathway whose pathogenicity can generalize to common forms of the... (Review)
Review
While causative mutations in complex disorders are rare, they can be used to extract a biological pathway whose pathogenicity can generalize to common forms of the disease. Here we begin by relying on the biological consequences of mutations in LRRK2 and VPS35, genetic causes of autosomal-dominant Parkinson's disease, to hypothesize that 'Retromer-dependent lysosomal stress' represents a pathway that can generalize to idiopathic Parkinson's disease. Next, we outline a series of studies that can test this hypothesis, including the development of biomarkers of pathway dysfunction. If validated, the hypothesis can suggest a unified mechanism of disease and might inform future diagnostic and therapeutic investigations. This article is part of a discussion meeting issue 'Understanding the endo-lysosomal network in neurodegeneration'.
Topics: Humans; Parkinson Disease; Vesicular Transport Proteins; Mutation; Lysosomes
PubMed: 38368937
DOI: 10.1098/rstb.2022.0376 -
Life Science Alliance Aug 2023SLIT/ROBO signaling impacts many aspects of tissue development and homeostasis, in part, through the regulation of cell growth and proliferation. Recent studies have...
SLIT/ROBO signaling impacts many aspects of tissue development and homeostasis, in part, through the regulation of cell growth and proliferation. Recent studies have also linked SLIT/ROBO signaling to the regulation of diverse phagocyte functions. However, the mechanisms by which SLIT/ROBO signaling acts at the nexus of cellular growth control and innate immunity remain enigmatic. Here, we show that SLIT2-mediated activation of ROBO1 leads to inhibition of mTORC1 kinase activity in macrophages, leading to dephosphorylation of its downstream targets, including transcription factor EB and ULK1. Consequently, SLIT2 augments lysosome biogenesis, potently induces autophagy, and robustly promotes the killing of bacteria within phagosomes. Concordant with these results, we demonstrate decreased lysosomal content and accumulated peroxisomes in the spinal cords of embryos from , double knockout mice. We also show that impediment of auto/paracrine SLIT-ROBO signaling axis in cancer cells leads to hyperactivation of mTORC1 and inhibition of autophagy. Together, these findings elucidate a central role of chemorepellent SLIT2 in the regulation of mTORC1 activity with important implications for innate immunity and cancer cell survival.
Topics: Animals; Mice; Nerve Tissue Proteins; Receptors, Immunologic; Lysosomes; Bacteria; Mechanistic Target of Rapamycin Complex 1
PubMed: 37311584
DOI: 10.26508/lsa.202301964 -
Cell Reports Aug 2023Amino acid (aa) metabolism is closely correlated with the pathogenesis of psoriasis; however, details on aa transportation during this process are barely known. Here, we...
Amino acid (aa) metabolism is closely correlated with the pathogenesis of psoriasis; however, details on aa transportation during this process are barely known. Here, we find that SLC38A5, a sodium-dependent neutral aa transporter that counter-transports protons, is markedly upregulated in the psoriatic skin of both human patients and mouse models. SLC38A5 deficiency significantly ameliorates the pathogenesis of psoriasis, indicating a pathogenic role of SLC38A5. Surprisingly, SLC38A5 is almost exclusively expressed in dendritic cells (DCs) when analyzing the psoriatic lesion and mainly locates on the lysosome. Mechanistically, SLC38A5 potentiates lysosomal acidification, which dictates the cleavage and activation of TLR7 with ensuing production of pro-inflammatory cytokines such as interleukin-23 (IL-23) and IL-1β from DCs and eventually aggravates psoriatic inflammation. In summary, this work uncovers an auxiliary mechanism in driving lysosomal acidification, provides inspiring insights for DC biology and psoriasis etiology, and reveals SLC38A5 as a promising therapeutic target for treating psoriasis.
Topics: Animals; Mice; Humans; Dendritic Cells; Skin; Psoriasis; Inflammation; Disease Models, Animal; Lysosomes; Hydrogen-Ion Concentration; Amino Acid Transport Systems, Neutral
PubMed: 37531255
DOI: 10.1016/j.celrep.2023.112910 -
Journal of Translational Medicine Dec 2023Mounting attention has been focused on defects of the autophagy-lysosomal pathway in sepsis, however, the precise mechanisms governing the autophagy-lysosomal process in...
Mounting attention has been focused on defects of the autophagy-lysosomal pathway in sepsis, however, the precise mechanisms governing the autophagy-lysosomal process in sepsis are poorly known. We have previously reported that Erbin deficiency aggravated the inflammatory response and organ injuries caused by sepsis. In the present study, we found that Erbin knockout impaired the autophagy process in both muramyl dipeptide (MDP)-induced bone marrow-derived macrophages (BMDMs) and sepsis mouse liver and lung, as detected by the accumulation of LC3-II and SQSTM1/p62, and autophagosomes. Pretreatment with autophagy inhibitor chloroquine (CQ) further aggravated inflammatory response and organ injuries in vivo and in vitro sepsis model. We also observed that the impaired lysosomal function mediated autophagic blockade, as detected by the decreased expression of ATP6V, cathepsin B (CTSB) and LAMP2 protein. Immunoprecipitation revealed that the C-terminal of Erbin (aa 391-964) interacts with the N-terminal of transcription factor EB (TFEB) (aa 1-247), and affects the stability of TFEB-14-3-3 and TFEB-PPP3CB complexes and the phosphorylation status of TFEB, thereby promote the nucleus translocation of TFEB and the TFEB target genes transcription. Thus, our study suggested that Erbin alleviated sepsis-induced inflammatory responses and organ injuries by rescuing dysfunction of the autophagy-lysosomal pathway through TFEB-14-3-3 and TFEB-PPP3CB pathway.
Topics: Animals; Mice; Autophagosomes; Autophagy; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Cell Nucleus; Inflammation; Lysosomes; Sepsis; Intracellular Signaling Peptides and Proteins
PubMed: 38105228
DOI: 10.1186/s12967-023-04796-y -
The Journal of Cell Biology Jul 2024Bacteria, omnipresent in our environment and coexisting within our body, exert dual beneficial and pathogenic influences. These microorganisms engage in intricate... (Review)
Review
Bacteria, omnipresent in our environment and coexisting within our body, exert dual beneficial and pathogenic influences. These microorganisms engage in intricate interactions with the human body, impacting both human health and disease. Simultaneously, certain organelles within our cells share an evolutionary relationship with bacteria, particularly mitochondria, best known for their energy production role and their dynamic interaction with each other and other organelles. In recent years, communication between bacteria and mitochondria has emerged as a new mechanism for regulating the host's physiology and pathology. In this review, we delve into the dynamic communications between bacteria and host mitochondria, shedding light on their collaborative regulation of host immune response, metabolism, aging, and longevity. Additionally, we discuss bacterial interactions with other organelles, including chloroplasts, lysosomes, and the endoplasmic reticulum (ER).
Topics: Animals; Humans; Bacteria; Endoplasmic Reticulum; Host-Pathogen Interactions; Lysosomes; Mitochondria; Organelles
PubMed: 38748249
DOI: 10.1083/jcb.202310134 -
Cell Death and Differentiation Jan 2024Mixed lineage kinase-like protein (MLKL) forms amyloid-like polymers to promote necroptosis; however, the mechanism through which these polymers trigger cell death is...
Mixed lineage kinase-like protein (MLKL) forms amyloid-like polymers to promote necroptosis; however, the mechanism through which these polymers trigger cell death is not clear. We have determined that activated MLKL translocates to the lysosomal membrane during necroptosis induction. The subsequent polymerization of MLKL induces lysosome clustering and fusion and eventual lysosomal membrane permeabilization (LMP). This LMP leads to the rapid release of lysosomal contents into the cytosol, resulting in a massive surge in cathepsin levels, with Cathepsin B (CTSB) as a significant contributor to the ensuing cell death as it cleaves many proteins essential for cell survival. Importantly, chemical inhibition or knockdown of CTSB protects cells from necroptosis. Furthermore, induced polymerization of the MLKL N-terminal domain (NTD) also triggers LMP, leading to CTSB release and subsequent cell death. These findings clearly establish the critical role of MLKL polymerization induced lysosomal membrane permeabilization (MPI-LMP) in the process of necroptosis.
Topics: Protein Kinases; Necroptosis; Polymerization; Lysosomes; Polymers; Receptor-Interacting Protein Serine-Threonine Kinases
PubMed: 37996483
DOI: 10.1038/s41418-023-01237-7 -
Nature Communications Jan 2024Accumulation of advanced glycation end products (AGEs) on biopolymers accompanies cellular aging and drives poorly understood disease processes. Here, we studied how...
Accumulation of advanced glycation end products (AGEs) on biopolymers accompanies cellular aging and drives poorly understood disease processes. Here, we studied how AGEs contribute to development of early onset Parkinson's Disease (PD) caused by loss-of-function of DJ1, a protein deglycase. In induced pluripotent stem cell (iPSC)-derived midbrain organoid models deficient for DJ1 activity, we find that lysosomal proteolysis is impaired, causing AGEs to accumulate, α-synuclein (α-syn) phosphorylation to increase, and proteins to aggregate. We demonstrated these processes are at least partly driven by astrocytes, as DJ1 loss reduces their capacity to provide metabolic support and triggers acquisition of a pro-inflammatory phenotype. Consistently, in co-cultures, we find that DJ1-expressing astrocytes are able to reverse the proteolysis deficits of DJ1 knockout midbrain neurons. In conclusion, astrocytes' capacity to clear toxic damaged proteins is critical to preserve neuronal function and their dysfunction contributes to the neurodegeneration observed in a DJ1 loss-of-function PD model.
Topics: Humans; Parkinson Disease; Proteostasis; Astrocytes; Proteolysis; Mesencephalon; Organoids; Lysosomes
PubMed: 38200091
DOI: 10.1038/s41467-024-44732-2