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Frontiers in Pharmacology 2023Humans are constantly exposed to various industrial, environmental, and endogenous particulates that result in inflammatory diseases. After being engulfed by immune...
Humans are constantly exposed to various industrial, environmental, and endogenous particulates that result in inflammatory diseases. After being engulfed by immune cells, viz. Macrophages, such particulates lead to phagolysosomal dysfunction, eventually inducing pyroptosis, a form of cell death accompanied by the release of inflammatory mediators, including members of the interleukin (IL)-1 family. Phagolysosomal dysfunction results in the activation of the nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, an immune complex that induces pyroptosis upon exposure to various external stimuli. However, several particulates induce pyroptosis even if the NLRP3 inflammasome is inhibited; this indicates that such inhibition is not always effective in treating diseases induced by particulates. Therefore, discovery of drugs suppressing particulate-induced NLRP3-independent pyroptosis is warranted. We screened compounds that inhibit silica particle (SP)-induced cell death and release of IL-1α using RAW264.7 cells, which are incapable of NLRP3 inflammasome formation. The candidates were tested for their ability to suppress particulate-induced pyroptosis and phagolysosomal dysfunction using mouse primary macrophages and alleviate SP-induced NLRP3-independent lung inflammation. Several Src family kinase inhibitors, including dasatinib, effectively suppressed SP-induced cell death and IL-1α release. Furthermore, dasatinib suppressed pyroptosis induced by other particulates but did not suppress that induced by non-particulates, such as adenosine triphosphate. Dasatinib reduced SP-induced phagolysosomal dysfunction without affecting phagocytosis of SPs. Moreover, dasatinib treatment strongly suppressed the increase in IL-1α levels and neutrophil counts in the lungs after intratracheal SP administration. Dasatinib suppresses particulate-induced pyroptosis and can be used to treat relevant inflammatory diseases.
PubMed: 37705538
DOI: 10.3389/fphar.2023.1250383 -
Frontiers in Immunology 2024() effectively manipulates the host processes to establish the deadly respiratory disease, Tuberculosis (TB). has developed key mechanisms to disrupt the host cell... (Review)
Review
() effectively manipulates the host processes to establish the deadly respiratory disease, Tuberculosis (TB). has developed key mechanisms to disrupt the host cell health to combat immune responses and replicate efficaciously. antigens such as ESAT-6, 19kDa lipoprotein, Hip1, and Hsp70 destroy the integrity of cell organelles (Mitochondria, Endoplasmic Reticulum, Nucleus, Phagosomes) or delay innate/adaptive cell responses. This is followed by the induction of cellular stress responses in the host. Such cells can either undergo various cell death processes such as apoptosis or necrosis, or mount effective immune responses to clear the invading pathogen. Further, to combat the infection progression, the host secretes extracellular vesicles such as exosomes to initiate immune signaling. The exosomes can contain as well as host cell-derived peptides that can act as a double-edged sword in the immune signaling event. The host-symbiont microbiota produces various metabolites that are beneficial for maintaining healthy tissue microenvironment. In juxtaposition to the above-mentioned mechanisms, dysregulates the gut and respiratory microbiome to support its replication and dissemination process. The above-mentioned interconnected host cellular processes of Immunometabolism, Cellular stress, Host Microbiome, and Extracellular vesicles are less explored in the realm of exploration of novel Host-directed therapies for TB. Therefore, this review highlights the intertwined host cellular processes to control survival and showcases the important factors that can be targeted for designing efficacious therapy.
Topics: Humans; Tuberculosis; Mycobacterium tuberculosis; Host-Pathogen Interactions; Signal Transduction; Apoptosis
PubMed: 38312835
DOI: 10.3389/fimmu.2024.1339467 -
Cells Jan 2024Autophagy is a major degradative pathway that plays a key role in sustaining cell homeostasis, integrity, and physiological functions. Macroautophagy, which ensures the... (Review)
Review
Autophagy is a major degradative pathway that plays a key role in sustaining cell homeostasis, integrity, and physiological functions. Macroautophagy, which ensures the clearance of cytoplasmic components engulfed in a double-membrane autophagosome that fuses with lysosomes, is orchestrated by a complex cascade of events. Autophagy has a particularly strong impact on the nervous system, and mutations in core components cause numerous neurological diseases. We first review the regulation of autophagy, from autophagosome biogenesis to lysosomal degradation and associated neurodevelopmental/neurodegenerative disorders. We then describe how this process is specifically regulated in the axon and in the somatodendritic compartment and how it is altered in diseases. In particular, we present the neuronal specificities of autophagy, with the spatial control of autophagosome biogenesis, the close relationship of maturation with axonal transport, and the regulation by synaptic activity. Finally, we discuss the physiological functions of autophagy in the nervous system, during development and in adulthood.
Topics: Autophagy; Macroautophagy; Autophagosomes; Axonal Transport; Lysosomes
PubMed: 38201307
DOI: 10.3390/cells13010103 -
Aging Cell Oct 2023Autophagy is an intracellular degradative process with an important role in cellular homeostasis. Here, we show that the RNA binding protein (RBP), heterogeneous nuclear...
Autophagy is an intracellular degradative process with an important role in cellular homeostasis. Here, we show that the RNA binding protein (RBP), heterogeneous nuclear ribonucleoprotein Q (HNRNPQ)/SYNCRIP is required to stimulate early events in autophagosome biogenesis, in particular the induction of VPS34 kinase by ULK1-mediated beclin 1 phosphorylation. The RBPs HNRNPQ and poly(A) binding protein nuclear 1 (PABPN1) form a regulatory network that controls the turnover of distinct autophagy-related (ATG) proteins. We also show that oculopharyngeal muscular dystrophy (OPMD) mutations engender a switch from autophagosome stimulation to autophagosome inhibition by impairing PABPN1 and HNRNPQ control of the level of ULK1. The overexpression of HNRNPQ in OPMD patient-derived cells rescues the defective autophagy in these cells. Our data reveal a regulatory mechanism of autophagy induction that is compromised by PABPN1 disease mutations, and may thus further contribute to their deleterious effects.
Topics: Humans; Muscular Dystrophy, Oculopharyngeal; Autophagosomes; Mutation; Poly(A)-Binding Protein I
PubMed: 37559347
DOI: 10.1111/acel.13949 -
The Journal of Cell Biology Jul 2023Autophagy is a catabolic pathway required for the recycling of cytoplasmic materials. To define the mechanisms underlying autophagy it is critical to quantitatively...
Autophagy is a catabolic pathway required for the recycling of cytoplasmic materials. To define the mechanisms underlying autophagy it is critical to quantitatively characterize the dynamic behavior of autophagy factors in living cells. Using a panel of cell lines expressing HaloTagged autophagy factors from their endogenous loci, we analyzed the abundance, single-molecule dynamics, and autophagosome association kinetics of autophagy proteins involved in autophagosome biogenesis. We demonstrate that autophagosome formation is inefficient and ATG2-mediated tethering to donor membranes is a key commitment step in autophagosome formation. Furthermore, our observations support the model that phagophores are initiated by the accumulation of autophagy factors on mobile ATG9 vesicles, and that the ULK1 complex and PI3-kinase form a positive feedback loop required for autophagosome formation. Finally, we demonstrate that the duration of autophagosome biogenesis is ∼110 s. In total, our work provides quantitative insight into autophagosome biogenesis and establishes an experimental framework to analyze autophagy in human cells.
Topics: Humans; Autophagosomes; Autophagy; Autophagy-Related Proteins; Macroautophagy; Membrane Proteins
PubMed: 37115157
DOI: 10.1083/jcb.202210078 -
European Journal of Cell Biology Dec 2023Salmonella enterica serovar Typhimurium manipulates cellular Rho GTPases for host cell invasion by effector protein translocation via the Type III Secretion System...
Salmonella enterica serovar Typhimurium manipulates cellular Rho GTPases for host cell invasion by effector protein translocation via the Type III Secretion System (T3SS). The two Guanine nucleotide exchange (GEF) mimicking factors SopE and -E2 and the inositol phosphate phosphatase (PiPase) SopB activate the Rho GTPases Rac1, Cdc42 and RhoA, thereby mediating bacterial invasion. S. Typhimurium lacking these three effector proteins are largely invasion-defective. Type III secretion is crucial for both early and later phases of the intracellular life of S. Typhimurium. Here we investigated whether and how the small GTPase RhoB, known to localize on endomembrane vesicles and at the invasion site of S. Typhimurium, contributes to bacterial invasion and to subsequent steps relevant for S. Typhimurium lifestyle. We show that RhoB is significantly upregulated within hours of Salmonella infection. This effect depends on the presence of the bacterial effector SopB, but does not require its phosphatase activity. Our data reveal that SopB and RhoB bind to each other, and that RhoB localizes on early phagosomes of intracellular S. Typhimurium. Whereas both SopB and RhoB promote intracellular survival of Salmonella, RhoB is specifically required for Salmonella-induced upregulation of autophagy. Finally, in the absence of RhoB, vacuolar escape and cytosolic hyper-replication of S. Typhimurium is diminished. Our findings thus uncover a role for RhoB in Salmonella-induced autophagy, which supports intracellular survival of the bacterium and is promoted through a positive feedback loop by the Salmonella effector SopB.
Topics: Humans; Salmonella Infections; Salmonella typhimurium; rho GTP-Binding Proteins; Autophagy; Phosphoric Monoester Hydrolases
PubMed: 37703749
DOI: 10.1016/j.ejcb.2023.151358 -
International Journal of Molecular... Oct 2023In recent years, efforts have been made to identify new anti-cancer therapies. Various types of nanomaterials, including silver nanoparticles (AgNPs), are being... (Review)
Review
In recent years, efforts have been made to identify new anti-cancer therapies. Various types of nanomaterials, including silver nanoparticles (AgNPs), are being considered as an option. In addition to its well-known antibacterial activity, AgNPs exhibit cytotoxic potential in both physiological and cancer cells by inducing stress-mediated autophagy and apoptotic cell death. A rapidly growing collection of data suggests that the proper regulation of autophagic machinery may provide an efficient tool for suppressing the development of cancer. In this light, AgNPs have emerged as a potential anti-cancer agent to support therapy of the disease. This review summarizes current data indicating the dual role of AgNP-induced autophagy and highlights factors that may influence its protective vs. its toxic potential. It also stresses that our understanding of the cellular and molecular mechanisms of autophagy machinery in cancer cells, as well as AgNP-triggered autophagy in both normal and diseased cells, remains insufficient.
Topics: Metal Nanoparticles; Silver; Autophagy; Autophagosomes; Cell Line, Tumor; Apoptosis
PubMed: 37895066
DOI: 10.3390/ijms242015386 -
BioRxiv : the Preprint Server For... Dec 2023Phagosome maturation arrest (PMA) imposed by ( ) is a classic tool that helps evade macrophage anti-bacterial responses. The exclusion of RAB7, a small GTPase, from...
Phagosome maturation arrest (PMA) imposed by ( ) is a classic tool that helps evade macrophage anti-bacterial responses. The exclusion of RAB7, a small GTPase, from -phagosomes underscores PMA. Here we report an unexpected mechanism that triggers crosstalk between the mitochondrial quality control (MQC) and the phagosome maturation pathways that reverses the PMA. CRISPR-mediated p62/SQSTM1 depletion ( ) blocks mitophagy flux without impacting mitochondrial quality. In cells, growth and survival are diminished, mainly through witnessing an increasingly oxidative environment and increased lysosomal targeting. The lysosomal targeting of is facilitated by enhanced TOM20 mitochondria-derived vesicles (MDVs) biogenesis, a key MQC mechanism. In cells, TOM20 -MDVs biogenesis is MIRO1/MIRO2-dependent and delivered to lysosomes for degradation in a RAB7-dependent manner. Upon infection in cells, TOM20 -MDVs get extensively targeted to -phagosomes, inadvertently facilitating RAB7 recruitment, PMA reversal and lysosomal targeting of . Triggering MQC collapse in cells further diminishes survival signifying cooperation between redox- and lysosome-mediated mechanisms. The MQC-anti-bacterial pathway crosstalk could be exploited for host-directed anti-tuberculosis therapies.
PubMed: 38076943
DOI: 10.1101/2023.12.01.569475 -
Autophagy May 2024Tripartite motif (TRIM) proteins are a large family of E3 ubiquitin ligases implicated in antiviral defense systems, tumorigenesis, and protein quality control. TRIM...
Tripartite motif (TRIM) proteins are a large family of E3 ubiquitin ligases implicated in antiviral defense systems, tumorigenesis, and protein quality control. TRIM proteins contribute to protein quality control by regulating the ubiquitin-proteasome system, endoplasmic reticulum-associated degradation, and macroautophagy/autophagy. However, the detailed mechanisms through which various TRIM proteins regulate downstream events have not yet been fully elucidated. Herein, we identified a novel function of TRIM22 in the regulation of autophagy. TRIM22 promotes autophagosome-lysosome fusion by mediating the association of GABARAP family proteins with PLEKHM1, thereby inducing the autophagic clearance of protein aggregates, independent of its E3 ubiquitin ligase activity. Furthermore, a TRIM22 variant associated with early-onset familial Alzheimer disease interferes with autophagosome-lysosome fusion and autophagic clearance. These findings suggest TRIM22 as a critical autophagic regulator that orchestrates autophagosome-lysosome fusion by scaffolding autophagy-related proteins, thus representing a potential therapeutic target in neurodegenerative diseases. AD: Alzheimer disease; ADAOO: AD age of onset; AICD: APP intracellular domain; APP: amyloid beta precursor protein; BSA: bovine serum albumin; cDNAs: complementary DNAs; CQ: chloroquine; CTF: carboxyl-terminal fragment; EBSS: Earle's balanced salt solution; GABARAP: GABA type A receptor-associated protein; GST: glutathione S-transferase; HA: hemagglutinin; HOPS: homotypic fusion and protein sorting; IFN: interferon; IL1A/IL-1α: interleukin 1 alpha; KO: knockout; MTORC1: mechanistic target of rapamycin kinase complex 1; NFKBIA/IκBα: NFKB inhibitor alpha; NFE2L2/NRF2: NFE2 like bZIP transcription factor; PBS: phosphate-buffered saline; PI3K: class I phosphoinositide 3-kinase; PLA: proximity ligation assay; PLEKHM1: pleckstrin homology and RUN domain containing M1; PSEN1: presenilin 1; SEM: standard errors of the means; SNAREs: soluble N-ethylmaleimide-sensitive factor attachment protein receptors; SNCA: synuclein alpha; SNP: single nucleotide polymorphism; TBS: tris-buffered saline; TNF/TNF-α: tumor necrosis factor; TRIM: tripartite motif; ULK1: unc-51 like autophagy activating kinase 1; WT: wild-type.
Topics: Autophagosomes; Humans; Lysosomes; Autophagy; Tripartite Motif Proteins; Membrane Fusion; Adaptor Proteins, Signal Transducing; Microtubule-Associated Proteins; HEK293 Cells; Apoptosis Regulatory Proteins; Alzheimer Disease; Protein Binding; Animals; Autophagy-Related Proteins; Repressor Proteins; Minor Histocompatibility Antigens
PubMed: 38009729
DOI: 10.1080/15548627.2023.2287925 -
EMBO Reports Mar 2024Human rhinovirus is the most frequently isolated virus during severe exacerbations of chronic respiratory diseases, like chronic obstructive pulmonary disease. In this...
Human rhinovirus is the most frequently isolated virus during severe exacerbations of chronic respiratory diseases, like chronic obstructive pulmonary disease. In this disease, alveolar macrophages display significantly diminished phagocytic functions that could be associated with bacterial superinfections. However, how human rhinovirus affects the functions of macrophages is largely unknown. Macrophages treated with HRV16 demonstrate deficient bacteria-killing activity, impaired phagolysosome biogenesis, and altered intracellular compartments. Using RNA sequencing, we identify the small GTPase ARL5b to be upregulated by the virus in primary human macrophages. Importantly, depletion of ARL5b rescues bacterial clearance and localization of endosomal markers in macrophages upon HRV16 exposure. In permissive cells, depletion of ARL5b increases the secretion of HRV16 virions. Thus, we identify ARL5b as a novel regulator of intracellular trafficking dynamics and phagolysosomal biogenesis in macrophages and as a restriction factor of HRV16 in permissive cells.
Topics: Humans; Rhinovirus; Macrophages; Macrophages, Alveolar; Phagocytosis; Bacteria
PubMed: 38332148
DOI: 10.1038/s44319-024-00069-x