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1.
Annu Rev Biochem ; 93(1): 367-387, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38594929

ABSTRACT

Lysosomes are the degradative endpoints of material delivered by endocytosis and autophagy and are therefore particularly prone to damage. Membrane permeabilization or full rupture of lysosomal or late endosomal compartments is highly deleterious because it threatens cellular homeostasis and can elicit cell death and inflammatory signaling. Cells have developed a complex response to endo-lysosomal damage that largely consists of three branches. Initially, a number of repair pathways are activated to restore the integrity of the lysosomal membrane. If repair fails or if damage is too extensive, lysosomes are isolated and degraded by a form of selective autophagy termed lysophagy. Meanwhile, an mTORC1-governed signaling cascade drives biogenesis and regeneration of new lysosomal components to reestablish the full lysosomal capacity of the cell. This damage response is vital to counteract the effects of various conditions, including neurodegeneration and infection, and can constitute a critical vulnerability in cancer cells.


Subject(s)
Autophagy , Endosomes , Lysosomes , Mechanistic Target of Rapamycin Complex 1 , Signal Transduction , Lysosomes/metabolism , Humans , Animals , Mechanistic Target of Rapamycin Complex 1/metabolism , Mechanistic Target of Rapamycin Complex 1/genetics , Endosomes/metabolism , Endocytosis , Neoplasms/metabolism , Neoplasms/pathology , Neoplasms/genetics
2.
Cell ; 174(1): 88-101.e16, 2018 06 28.
Article in English | MEDLINE | ID: mdl-29909986

ABSTRACT

In colorectal cancer patients, a high density of cytotoxic CD8+ T cells in tumors is associated with better prognosis. Using a Stat3 loss-of-function approach in two wnt/ß-catenin-dependent autochthonous models of sporadic intestinal tumorigenesis, we unravel a complex intracellular process in intestinal epithelial cells (IECs) that controls the induction of a CD8+ T cell based adaptive immune response. Elevated mitophagy in IECs causes iron(II)-accumulation in epithelial lysosomes, in turn, triggering lysosomal membrane permeabilization. Subsequent release of proteases into the cytoplasm augments MHC class I presentation and activation of CD8+ T cells via cross-dressing of dendritic cells. Thus, our findings highlight a so-far-unrecognized link between mitochondrial function, lysosomal integrity, and MHC class I presentation in IECs and suggest that therapies triggering mitophagy or inducing LMP in IECs may prove successful in shifting the balance toward anti-tumor immunity in colorectal cancer.


Subject(s)
Adaptive Immunity , Mitophagy , Adaptive Immunity/drug effects , Animals , Azoxymethane/toxicity , CD8-Positive T-Lymphocytes/cytology , CD8-Positive T-Lymphocytes/drug effects , CD8-Positive T-Lymphocytes/metabolism , Cell Membrane Permeability , Colorectal Neoplasms/mortality , Colorectal Neoplasms/pathology , Cytokines/metabolism , Dendritic Cells/cytology , Dendritic Cells/immunology , Dendritic Cells/metabolism , Female , Ferrous Compounds/metabolism , Humans , Interferon-gamma/metabolism , Interferon-gamma/pharmacology , Intestinal Mucosa/cytology , Intestinal Mucosa/drug effects , Intestinal Mucosa/metabolism , Lysosomes/metabolism , Male , Mice , Mice, Knockout , Mitophagy/drug effects , STAT3 Transcription Factor/genetics , STAT3 Transcription Factor/metabolism , Survival Rate
3.
Cell ; 174(1): 187-201.e12, 2018 06 28.
Article in English | MEDLINE | ID: mdl-29779946

ABSTRACT

Widespread mRNA decay, an unappreciated feature of apoptosis, enhances cell death and depends on mitochondrial outer membrane permeabilization (MOMP), TUTases, and DIS3L2. Which RNAs are decayed and the decay-initiating event are unknown. Here, we show extensive decay of mRNAs and poly(A) noncoding (nc)RNAs at the 3' end, triggered by the mitochondrial intermembrane space 3'-to-5' exoribonuclease PNPT1, released during MOMP. PNPT1 knockdown inhibits apoptotic RNA decay and reduces apoptosis, while ectopic expression of PNPT1, but not an RNase-deficient mutant, increases RNA decay and cell death. The 3' end of PNPT1 substrates thread through a narrow channel. Many non-poly(A) ncRNAs contain 3'-secondary structures or bind proteins that may block PNPT1 activity. Indeed, mutations that disrupt the 3'-stem-loop of a decay-resistant ncRNA render the transcript susceptible, while adding a 3'-stem-loop to an mRNA prevents its decay. Thus, PNPT1 release from mitochondria during MOMP initiates apoptotic decay of RNAs lacking 3'-structures.


Subject(s)
Apoptosis , Exoribonucleases/metabolism , Mitochondria/metabolism , RNA, Messenger/metabolism , 3' Untranslated Regions , Apoptosis/drug effects , Caspase 3/metabolism , Cytochromes c/metabolism , Exoribonucleases/antagonists & inhibitors , Exoribonucleases/genetics , HCT116 Cells , Humans , Mitochondrial Membranes/metabolism , Nucleic Acid Conformation , Permeability , Poly(A)-Binding Protein I/chemistry , Poly(A)-Binding Protein I/metabolism , Protein Binding , Proto-Oncogene Proteins c-bcl-2/genetics , Proto-Oncogene Proteins c-bcl-2/metabolism , RNA Interference , RNA Stability/drug effects , RNA, Messenger/chemistry , RNA, Small Interfering/metabolism , RNA, Untranslated/chemistry , RNA, Untranslated/metabolism , TNF-Related Apoptosis-Inducing Ligand/pharmacology
4.
Cell ; 173(4): 851-863.e16, 2018 05 03.
Article in English | MEDLINE | ID: mdl-29576452

ABSTRACT

Hibernating mammals survive hypothermia (<10°C) without injury, a remarkable feat of cellular preservation that bears significance for potential medical applications. However, mechanisms imparting cold resistance, such as cytoskeleton stability, remain elusive. Using the first iPSC line from a hibernating mammal (13-lined ground squirrel), we uncovered cellular pathways critical for cold tolerance. Comparison between human and ground squirrel iPSC-derived neurons revealed differential mitochondrial and protein quality control responses to cold. In human iPSC-neurons, cold triggered mitochondrial stress, resulting in reactive oxygen species overproduction and lysosomal membrane permeabilization, contributing to microtubule destruction. Manipulations of these pathways endowed microtubule cold stability upon human iPSC-neurons and rat (a non-hibernator) retina, preserving its light responsiveness after prolonged cold exposure. Furthermore, these treatments significantly improved microtubule integrity in cold-stored kidneys, demonstrating the potential for prolonging shelf-life of organ transplants. Thus, ground squirrel iPSCs offer a unique platform for bringing cold-adaptive strategies from hibernators to humans in clinical applications. VIDEO ABSTRACT.


Subject(s)
Adaptation, Physiological , Induced Pluripotent Stem Cells/metabolism , Neurons/metabolism , Animals , Cell Differentiation , Cold Temperature , Humans , Induced Pluripotent Stem Cells/cytology , Kidney/drug effects , Kidney/metabolism , Lysosomes/metabolism , Mice , Mice, Inbred C57BL , Mitochondria/metabolism , Neurons/cytology , Oxidative Stress , Protease Inhibitors/pharmacology , Rats , Reactive Oxygen Species/metabolism , Retina/metabolism , Sciuridae , Transcriptome , Tubulin/chemistry , Tubulin/genetics , Tubulin/metabolism
5.
Mol Cell ; 84(8): 1556-1569.e10, 2024 Apr 18.
Article in English | MEDLINE | ID: mdl-38503285

ABSTRACT

Cells respond to lysosomal membrane permeabilization by membrane repair or selective macroautophagy of damaged lysosomes, termed lysophagy, but it is not fully understood how this decision is made. Here, we uncover a pathway in human cells that detects lipid bilayer perturbations in the limiting membrane of compromised lysosomes, which fail to be repaired, and then initiates ubiquitin-triggered lysophagy. We find that SPG20 binds the repair factor IST1 on damaged lysosomes and, importantly, integrates that with the detection of damage-associated lipid-packing defects of the lysosomal membrane. Detection occurs via sensory amphipathic helices in SPG20 before rupture of the membrane. If lipid-packing defects are extensive, such as during lipid peroxidation, SPG20 recruits and activates ITCH, which marks the damaged lysosome with lysine-63-linked ubiquitin chains to initiate lysophagy and thus triages the lysosome for destruction. With SPG20 being linked to neurodegeneration, these findings highlight the relevance of a coordinated lysosomal damage response for cellular homeostasis.


Subject(s)
Lysosomes , Macroautophagy , Humans , Autophagy/physiology , Intracellular Membranes/metabolism , Lipids , Lysosomes/metabolism , Ubiquitin/genetics , Ubiquitin/metabolism
6.
Trends Biochem Sci ; 49(8): 717-728, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38906725

ABSTRACT

Lytic cell death culminates in cell swelling and plasma membrane rupture (PMR). The cellular contents released, including proteins, metabolites, and nucleic acids, can act as danger signals and induce inflammation. During regulated cell death (RCD), lysis is actively initiated and can be preceded by an initial loss of membrane integrity caused by pore-forming proteins, allowing small molecules and cytokines to exit the cell. A recent seminal discovery showed that ninjurin1 (NINJ1) is the common executioner of PMR downstream of RCD, resulting in the release of large proinflammatory molecules and representing a novel target of cell death-associated lysis. We summarize recent developments in understanding membrane integrity and rupture of the plasma membrane with a focus on NINJ1.


Subject(s)
Cell Adhesion Molecules, Neuronal , Cell Membrane , Humans , Cell Membrane/metabolism , Cell Adhesion Molecules, Neuronal/metabolism , Animals , Nerve Growth Factors/metabolism , Apoptosis
7.
Mol Cell ; 79(1): 68-83.e7, 2020 07 02.
Article in English | MEDLINE | ID: mdl-32533918

ABSTRACT

BAX is a pro-apoptotic protein that transforms from a cytosolic monomer into a toxic oligomer that permeabilizes the mitochondrial outer membrane. How BAX monomers assemble into a higher-order conformation, and the structural determinants essential to membrane permeabilization, remain a mechanistic mystery. A key hurdle has been the inability to generate a homogeneous BAX oligomer (BAXO) for analysis. Here, we report the production and characterization of a full-length BAXO that recapitulates physiologic BAX activation. Multidisciplinary studies revealed striking conformational consequences of oligomerization and insight into the macromolecular structure of oligomeric BAX. Importantly, BAXO enabled the assignment of specific roles to particular residues and α helices that mediate individual steps of the BAX activation pathway, including unexpected functionalities of BAX α6 and α9 in driving membrane disruption. Our results provide the first glimpse of a full-length and functional BAXO, revealing structural requirements for the elusive execution phase of mitochondrial apoptosis.


Subject(s)
Apoptosis , Mitochondria/pathology , Mitochondrial Membranes/metabolism , Protein Multimerization , bcl-2-Associated X Protein/chemistry , bcl-2-Associated X Protein/metabolism , Animals , Biological Transport , Cell Membrane Permeability , Cytosol/metabolism , Humans , Mice , Mitochondria/metabolism , Models, Molecular , Protein Conformation , Proto-Oncogene Proteins c-fos
8.
J Cell Sci ; 137(9)2024 05 01.
Article in English | MEDLINE | ID: mdl-38578235

ABSTRACT

Endosomal-lysosomal trafficking is accompanied by the acidification of endosomal compartments by the H+-V-ATPase to reach low lysosomal pH. Disruption of the correct pH impairs lysosomal function and the balance of protein synthesis and degradation (proteostasis). Here, we treated mammalian cells with the small dipeptide LLOMe, which is known to permeabilize lysosomal membranes, and find that LLOMe also impacts late endosomes (LEs) by neutralizing their pH without causing membrane permeabilization. We show that LLOMe leads to hyperactivation of Rab7 (herein referring to Rab7a), and disruption of tubulation and mannose-6-phosphate receptor (CI-M6PR; also known as IGF2R) recycling on pH-neutralized LEs. pH neutralization (NH4Cl) and expression of Rab7 hyperactive mutants alone can both phenocopy the alterations in tubulation and CI-M6PR trafficking. Mechanistically, pH neutralization increases the assembly of the V1G1 subunit (encoded by ATP6V1G1) of the V-ATPase on endosomal membranes, which stabilizes GTP-bound Rab7 via RILP, a known interactor of Rab7 and V1G1. We propose a novel pathway by which V-ATPase and RILP modulate LE pH and Rab7 activation in concert. This pathway might broadly contribute to pH control during physiologic endosomal maturation or starvation and during pathologic pH neutralization, which occurs via lysosomotropic compounds and in disease states.


Subject(s)
Adaptor Proteins, Signal Transducing , Endosomes , Vacuolar Proton-Translocating ATPases , rab7 GTP-Binding Proteins , Animals , Humans , Endosomes/metabolism , HeLa Cells , Hydrogen-Ion Concentration , Lysosomes/metabolism , Protein Transport , Receptor, IGF Type 2/metabolism , Receptor, IGF Type 2/genetics , Vacuolar Proton-Translocating ATPases/metabolism , Vacuolar Proton-Translocating ATPases/genetics
9.
Immunity ; 44(2): 221-31, 2016 Feb 16.
Article in English | MEDLINE | ID: mdl-26885855

ABSTRACT

Some forms of regulated cell death, such as apoptosis, are precipitated by the activation of cysteine proteases of the caspase family, including caspase 8, 9, and 3. Other caspases, such as caspase 1 and 4, are well known for their pro-inflammatory functions but regulate cell death in a limited number of pathophysiological settings. Accumulating evidence suggests that the most conserved function of mammalian caspases is not to control cell death sensu stricto, but to regulate inflammatory and immune reactions to dying cells and infectious challenges. Here, we review the molecular and cellular mechanisms though which mammalian caspases connect cell-death signaling to the maintenance of organismal homeostasis.


Subject(s)
Caspases/physiology , Cell Death , Homeostasis , Animals , Humans , Signal Transduction
10.
Antimicrob Agents Chemother ; : e0075324, 2024 Sep 05.
Article in English | MEDLINE | ID: mdl-39235250

ABSTRACT

Gram-negative bacteria (GNB) pose a major global public health challenge as they exhibit a remarkable level of resistance to antibiotics. One of the factors responsible for promoting resistance against a wide range of antibiotics is the outer membrane (OM) of Gram-negative bacteria. The OM acts as a barrier that prevents the entry of numerous antibiotics by reducing their influx (due to membrane impermeability) and enhancing their efflux (with the help of efflux pumps). Our study focuses on analyzing the effect of IMT-P8, a cell-penetrating peptide (CPP), to enhance the influx of various Gram-positive specific antibiotics in multi-drug resistant Gram-negative pathogens. In the mechanistic experiments, IMT-P8 permeabilizes the OM at the same concentrations at which it enhances the activity of various antibiotics against GNB. Cytoplasmic membrane permeabilization was also observed at these concentrations, indicating that IMT-P8 acts on both the outer and cytoplasmic membranes. IMT-P8 interferes with the intrinsic resistance mechanism of GNB and has the potential to make Gram-positive specific antibiotics effective against GNB. IMT-P8 extends the post-antibiotic effect and in combination with antibiotics shows anti-persister activity. The IMT-P8/fusidic acid combination is effective in eliminating intracellular pathogens. IMT-P8 with negligible toxicity displayed good efficacy in murine lung and thigh infection models. Based on these findings, IMT-P8 is a potential antibiotic adjuvant to treat Gram-negative bacterial infections that pose a health hazard.

11.
Mol Pharm ; 21(6): 2993-3005, 2024 Jun 03.
Article in English | MEDLINE | ID: mdl-38722865

ABSTRACT

The susceptibility of lysosomal membranes in tumor cells to cationic amphiphilic drugs (CADs) enables CADs to induce lysosomal membrane permeabilization (LMP) and trigger lysosome-dependent cell death (LDCD), suggesting a potential antitumor therapeutic approach. However, the existence of intrinsic lysosomal damage response mechanisms limits the display of the pharmacological activity of CADs. In this study, we report that low concentrations of QS-21, a saponin with cationic amphiphilicity extracted from Quillaja Saponaria tree, can induce LMP but has nontoxicity to tumor cells. QS-21 and MAP30, a type I ribosome-inactivating protein, synergistically induce apoptosis in tumor cells at low concentrations of both. Mechanistically, QS-21-induced LMP helps MAP30 escape from endosomes or lysosomes and subsequently enter the endoplasmic reticulum, where MAP30 downregulates the expression of autophagy-associated LC3 proteins, thereby inhibiting lysophagy. The inhibition of lysophagy results in the impaired clearance of damaged lysosomes, leading to the leakage of massive lysosomal contents such as cathepsins into the cytoplasm, ultimately triggering LDCD. In summary, our study showed that coadministration of QS-21 and MAP30 amplified the lysosomal disruption and can be a new synergistic LDCD-based antitumor therapy.


Subject(s)
Antineoplastic Agents , Apoptosis , Autophagy , Lysosomes , Ribosome Inactivating Proteins, Type 1 , Saponins , Animals , Humans , Mice , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Autophagy/drug effects , Cell Line, Tumor , Drug Synergism , Lysosomes/drug effects , Lysosomes/metabolism , Quillaja/chemistry , Ribosome Inactivating Proteins, Type 1/pharmacology , Saponins/pharmacology
12.
Arch Microbiol ; 206(6): 257, 2024 May 11.
Article in English | MEDLINE | ID: mdl-38734773

ABSTRACT

There is a growing imperative for research into alternative compounds for the treatment of the fungal infections. Thus, many studies have focused on the analysis of antifungal proteins and peptides from different plant sources. Among these molecules are protease inhibitors (PIs). Previously, PIs present in the peptide-rich fractions called PEF1, PEF2 and PEF3 were identified from Capsicum chinense seeds, which have strong activity against phytopathogenic fungi. The aim of this study was to evaluate the mechanism of action and antimicrobial activity of PIs from PEF2 and PEF3 on the growth of yeasts of the genus Candida. In this work, analyses of their antimicrobial activity and cell viability were carried out. Subsequently, the mechanism of action by which the PIs cause the death of the yeasts was evaluated. Cytotoxicity was assessed in vitro by erythrocytes lysis and in vivo in Galleria mellonella larvae. PEF2 and PEF3 caused 100% of the growth inhibition of C. tropicalis and C. buinensis. For C. albicans inhibition was approximately 60% for both fractions. The PEF2 and PEF3 caused a reduction in mitochondrial functionality of 54% and 46% for C. albicans, 26% and 30% for C. tropicalis, and 71% and 68% for C. buinensis, respectively. These fractions induced morphological alterations, led to membrane permeabilization, elevated ROS levels, and resulted in necrotic cell death in C. tropicalis, whilst demonstrating low toxicity toward host cells. From the results obtained here, we intend to contribute to the understanding of the action of PIs in the control of fungal diseases of medical importance.


Subject(s)
Antifungal Agents , Candida , Protease Inhibitors , Antifungal Agents/pharmacology , Candida/drug effects , Candida/growth & development , Protease Inhibitors/pharmacology , Microbial Sensitivity Tests , Animals , Capsicum/microbiology , Reactive Oxygen Species/metabolism , Seeds/growth & development , Plant Extracts/pharmacology , Plant Extracts/chemistry , Erythrocytes/drug effects , Larva/microbiology , Larva/growth & development , Larva/drug effects
13.
Fish Shellfish Immunol ; 146: 109406, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38278338

ABSTRACT

Hepcidin, initially identified in human blood ultrafiltrate as cysteine rich Liver Expressed Antimicrobial Peptide (LEAP-1), is a core molecular conduit between iron trafficking and immune response. Though a great share of studies has been focused on the iron regulatory function of hepcidins, investigations on the antimicrobial aspects are relatively less. The present study is aimed at identification of hepcidin from a teleost fish, Alepes djedaba followed by its recombinant expression, testing antibacterial property, stability and evaluation of cytotoxicity. Modes of action on bacterial pathogens were also examined. A novel hepcidin isoform, Ad-Hep belonging to the HAMP1 (Hepcidin antimicrobial peptide 1) group of hepcidins was identified from the shrimp scad, Alepes djedaba. Ad-Hep with 2.9 kDa size was found to be a cysteine rich, cationic peptide (+4) with antiparallel beta sheet conformation, a furin cleavage site (RXXR) and 'ATCUN' motif. It was heterologously expressed in E. coli Rosettagami B(DE3)PLysS cells and the recombinant peptide, rAd-Hep was found to have significant antibacterial activity, especially against Edwardsiella tarda, Vibrio parahaemolyticus and Escherichia coli. Membrane depolarization followed by membrane permeabilization and Reactive Oxygen Species (ROS) production were found to be the modes of action of rAd-Hep on bacterial cells. Ad-Hep was found to be non-haemolytic to hRBC and non-cytotoxic in mammalian cell line. Stability of the peptide at varying temperature, pH and metal salts qualify them for applications in vivo. With significant bactericidal activity coupled with direct killing mechanisms, the rAd-Hep can be a promising drug candidate for therapeutic applications in medicine and fish culture systems.


Subject(s)
Escherichia coli , Hepcidins , Animals , Humans , Cysteine , Fishes/metabolism , Protein Isoforms , Anti-Bacterial Agents/pharmacology , Iron , Peptides , Mammals/metabolism
14.
Bioorg Chem ; 145: 107227, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38387400

ABSTRACT

Multidrug-resistant (MDR) pathogens are severely impacting our ability to successfully treat common infections. Here we report the synthesis of a panel of adarotene-related retinoids showing potent antimicrobial activity on Staphylococcus aureus strains (including multidrug-resistant ones). Fluorescence and molecular dynamic studies confirmed that the adarotene analogues were able to induce conformational changes and disfunctions to the cell membrane, perturbing the permeability of the phospholipid bilayer. Since the major obstacle for developing retinoids is their potential cytotoxicity, a selected candidate was further investigated to evaluate its activity on a panel of human cell lines. The compound was found to be well tolerated, with IC50 5-15-fold higher than the MIC on S. aureus strains. Furthermore, the adarotene analogue had a good pharmacokinetic profile, reaching a plasma concentration of about 6 µM after 0.5 h after administration (150 mg/kg), at least twice the MIC observed against various bacterial strains. Moreover, it was demonstrated that the compound potentiated the growth-inhibitory effect of the poorly bioavailable rifaximin, when used in combination. Overall, the collected data pave the way for the development of synthetic retinoids as potential therapeutics for hard-to-treat infectious diseases caused by antibiotic-resistant Gram-positive pathogens.


Subject(s)
Methicillin-Resistant Staphylococcus aureus , Staphylococcal Infections , Humans , Staphylococcus aureus , Anti-Bacterial Agents , Retinoids/pharmacology , Staphylococcal Infections/drug therapy , Microbial Sensitivity Tests
15.
Cell Mol Biol Lett ; 29(1): 116, 2024 Sep 05.
Article in English | MEDLINE | ID: mdl-39237893

ABSTRACT

Lysosomes are acidic organelles involved in crucial intracellular functions, including the degradation of organelles and protein, membrane repair, phagocytosis, endocytosis, and nutrient sensing. Given these key roles of lysosomes, maintaining their homeostasis is essential for cell viability. Thus, to preserve lysosome integrity and functionality, cells have developed a complex intracellular system, called lysosome quality control (LQC). Several stressors may affect the integrity of lysosomes, causing Lysosomal membrane permeabilization (LMP), in which membrane rupture results in the leakage of luminal hydrolase enzymes into the cytosol. After sensing the damage, LQC either activates lysosome repair, or induces the degradation of the ruptured lysosomes through autophagy. In addition, LQC stimulates the de novo biogenesis of functional lysosomes and lysosome exocytosis. Alterations in LQC give rise to deleterious consequences for cellular homeostasis. Specifically, the persistence of impaired lysosomes or the malfunctioning of lysosomal processes leads to cellular toxicity and death, thereby contributing to the pathogenesis of different disorders, including neurodegenerative diseases (NDs). Recently, several pieces of evidence have underlined the importance of the role of lysosomes in NDs. In this review, we describe the elements of the LQC system, how they cooperate to maintain lysosome homeostasis, and their implication in the pathogenesis of different NDs.


Subject(s)
Lysosomes , Neurodegenerative Diseases , Lysosomes/metabolism , Humans , Neurodegenerative Diseases/metabolism , Animals , Homeostasis , Autophagy
16.
Cell Mol Life Sci ; 80(6): 160, 2023 May 20.
Article in English | MEDLINE | ID: mdl-37210406

ABSTRACT

We previously reported that permanent ischemia induces marked dysfunction of the autophagy-lysosomal pathway (ALP) in rats, which is possibly mediated by the transcription factor EB (TFEB). However, it is still unclear whether signal transducer and activator of transcription 3 (STAT3) is responsible for the TFEB-mediated dysfunction of ALP in ischemic stroke. In the present study, we used AAV-mediated genetic knockdown and pharmacological blockade of p-STAT3 to investigate the role of p-STAT3 in regulating TFEB-mediated ALP dysfunction in rats subjected to permanent middle cerebral occlusion (pMCAO). The results showed that the level of p-STAT3 (Tyr705) in the rat cortex increased at 24 h after pMCAO and subsequently led to lysosomal membrane permeabilization (LMP) and ALP dysfunction. These effects can be alleviated by inhibitors of p-STAT3 (Tyr705) or by STAT3 knockdown. Additionally, STAT3 knockdown significantly increased the nuclear translocation of TFEB and the transcription of TFEB-targeted genes. Notably, TFEB knockdown markedly reversed STAT3 knockdown-mediated improvement in ALP function after pMCAO. This is the first study to show that the contribution of p-STAT3 (Tyr705) to ALP dysfunction may be partly associated with its inhibitory effect on TFEB transcriptional activity, which further leads to ischemic injury in rats.


Subject(s)
Autophagy , STAT3 Transcription Factor , Animals , Rats , Autophagy/genetics , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/genetics , Ischemia/metabolism , Lysosomes/metabolism , Phosphorylation , STAT3 Transcription Factor/genetics , STAT3 Transcription Factor/metabolism
17.
Ecotoxicol Environ Saf ; 274: 116195, 2024 Apr 01.
Article in English | MEDLINE | ID: mdl-38479315

ABSTRACT

Fluoride is known to induce nephrotoxicity; however, the underlying mechanisms remain incompletely understood. Therefore, this study aims to explore the roles and mechanisms of lysosomal membrane permeabilization (LMP) and the GSDME/HMGB1 axis in fluoride-induced nephrotoxicity and the protective effects of rutin. Rutin, a naturally occurring flavonoid compound known for its antioxidative and anti-inflammatory properties, is primarily mediated by inhibiting oxidative stress and reducing proinflammatory markers. To that end, we established in vivo and in vitro models. In the in vivo study, rats were exposed to sodium fluoride (NaF) throughout pregnancy and up until 2 months after birth. In parallel, we employed in vitro models using HK-2 cells treated with NaF, n-acetyl-L-cysteine (NAC), or rutin. We assessed lysosomal permeability through immunofluorescence and analyzed relevant protein expression via western blotting. Our findings showed that NaF exposure increased ROS levels, resulting in enhanced LMP and increased cathepsin B (CTSB) and D (CTSD) expression. Furthermore, the exposure to NaF resulted in the upregulation of cleaved PARP1, cleaved caspase-3, GSDME-N, and HMGB1 expressions, indicating cell death and inflammation-induced renal damage. Rutin mitigates fluoride-induced nephrotoxicity by suppressing ROS-mediated LMP and the GSDME/HMGB1 axis, ultimately preventing fluoride-induced renal toxicity occurrence and development. In conclusion, our findings suggest that NaF induces renal damage through ROS-mediated activation of LMP and the GSDME/HMGB1 axis, leading to pyroptosis and inflammation. Rutin, a natural antioxidative and anti-inflammatory dietary supplement, offers a novel approach to prevent and treat fluoride-induced nephrotoxicity.


Subject(s)
Fluorides , HMGB1 Protein , Kidney Diseases , Rutin , Animals , Rats , Anti-Inflammatory Agents/pharmacology , Antioxidants/metabolism , Caspase 3/metabolism , Fluorides/metabolism , Fluorides/toxicity , HMGB1 Protein/drug effects , HMGB1 Protein/metabolism , Inflammation/metabolism , Lysosomes/drug effects , Pyroptosis/drug effects , Reactive Oxygen Species/metabolism , Reactive Oxygen Species/toxicity , Rutin/pharmacology , Sodium Fluoride/toxicity , Kidney Diseases/chemically induced , Kidney Diseases/drug therapy , Gasdermins/drug effects , Gasdermins/metabolism
18.
Environ Toxicol ; 2024 Jul 19.
Article in English | MEDLINE | ID: mdl-39031462

ABSTRACT

In sepsis, bacterial components, particularly lipopolysaccharide (LPS), trigger organ injuries such as liver dysfunction. Although sepsis induces hepatocyte damage, the mechanisms underlying sepsis-related hepatic failure remain unclear. In this study, we demonstrated that the LPS-treated rat hepatocyte cell line Clone 9 not only induced reactive oxygen species (ROS) generation and apoptosis but also increased the expression of the autophagy marker proteins LC3-II and p62, and decreased the expression of intact Lamp2A, a lysosomal membrane protein. Additionally, LPS increased lysosomal membrane permeability and galectin-3 puncta formation, and promoted lysosomal alkalization in Clone 9 cells. Pharmacological inhibition of caspase-8 and cathepsin D (CTSD) suppressed the activation of caspase-3 and rescued the viability of LPS-treated Clone 9 cells. Furthermore, LPS induced CTSD release associated with lysosomal leakage and contributed to caspase-8 activation. Pretreatment with the antioxidant N-acetylcysteine (NAC) not only diminished ROS generation and increased the cell survival rate, but also decreased the expression of activated caspase-8 and caspase-3 and increased the protein level of Lamp2A in LPS-treated Clone 9 cells. These results demonstrate that LPS-induced ROS causes lysosomal membrane permeabilization and lysosomal cell death, which may play a crucial role in hepatic failure in sepsis. Our results may facilitate the development of new strategies for sepsis management.

19.
Nano Lett ; 23(23): 10657-10666, 2023 Dec 13.
Article in English | MEDLINE | ID: mdl-38018769

ABSTRACT

CaO2 nanoparticles (CNPs) can produce toxic Ca2+ and H2O2 under acidic pH, which accounts for their intrinsic anticancer activity but at the same time raises safety concerns upon systemic exposure. Simultaneously realizing minimized Ca2+/H2O2 production and enhanced anticancer activity poses a dilemma. Herein, we introduce a "crystallinity gradient-based selective etching" (CGSE) strategy, which is realized by creating a crystallinity gradient in a CNP formed by self-assembled nanocrystals. The nanocrystals distributed in the outer layer have a higher crystallinity and thus are chemically more robust than those distributed in the inner layer, which can be selectively etched. CGSE not only leads to CNPs with tailored single- and double-shell hollow structures and metal-doped compositions but more surprisingly enables significantly enhanced anticancer activity as well as tumor growth inhibition under limited Ca2+/H2O2 production, which is attributed to an alkalinity-reinforced lysosome-dependent cell death pathway.


Subject(s)
Nanoparticles , Nanostructures , Neoplasms , Humans , Hydrogen Peroxide/metabolism , Nanostructures/chemistry , Neoplasms/drug therapy , Nanoparticles/chemistry
20.
Int J Mol Sci ; 25(11)2024 May 28.
Article in English | MEDLINE | ID: mdl-38892068

ABSTRACT

Food-grade titanium dioxide (E171) and zinc oxide nanoparticles (ZnO NPs) are common food additives for human consumption. We examined multi-organ toxicity of both compounds on Wistar rats orally exposed for 90 days. Rats were divided into three groups: (1) control (saline solution), (2) E171-exposed, and (3) ZnO NPs-exposed. Histological examination was performed with hematoxylin-eosin (HE) staining and transmission electron microscopy (TEM). Ceramide (Cer), 3-nitrotyrosine (NT), and lysosome-associated membrane protein 2 (LAMP-2) were detected by immunofluorescence. Relevant histological changes were observed: disorganization, inflammatory cell infiltration, and mitochondrial damage. Increased levels of Cer, NT, and LAMP-2 were observed in the liver, kidney, and brain of E171- and ZnO NPs-exposed rats, and in rat hearts exposed to ZnO NPs. E171 up-regulated Cer and NT levels in the aorta and heart, while ZnO NPs up-regulated them in the aorta. Both NPs increased LAMP-2 expression in the intestine. In conclusion, chronic oral exposure to metallic NPs causes multi-organ injury, reflecting how these food additives pose a threat to human health. Our results suggest how complex interplay between ROS, Cer, LAMP-2, and NT may modulate organ function during NP damage.


Subject(s)
Ceramides , Metal Nanoparticles , Rats, Wistar , Titanium , Zinc Oxide , Animals , Zinc Oxide/toxicity , Titanium/toxicity , Titanium/adverse effects , Rats , Ceramides/metabolism , Metal Nanoparticles/chemistry , Metal Nanoparticles/toxicity , Male , Administration, Oral , Lysosomal-Associated Membrane Protein 2/metabolism , Tyrosine/analogs & derivatives , Tyrosine/metabolism , Liver/drug effects , Liver/metabolism , Liver/pathology , Kidney/drug effects , Kidney/metabolism , Kidney/pathology
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