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Autophagy May 2023Light is essential for plant growth, but excessive light energy produces reactive oxygen species (ROS), which can seriously damage cells. Mutants defective in...
Light is essential for plant growth, but excessive light energy produces reactive oxygen species (ROS), which can seriously damage cells. Mutants defective in (autophagy related) genes show light intensity-dependent leaf damage and ROS accumulation. We found that autophagy is one of the crucial systems in protecting plants from ROS-induced damage by removing oxidative peroxisomes. Damaged peroxisomes are targeted by the PtdIns3P marker and specifically engulfed by phagophores labeled by ATG18a-GFP. Under high-intensity light, huge peroxisome aggregates are induced and captured by vacuolar membranes. Research provides a deeper understanding of plant stress response to light irradiation.
Topics: Macroautophagy; Autophagy; Reactive Oxygen Species; Oxidative Stress; Plants; Peroxisomes
PubMed: 36760098
DOI: 10.1080/15548627.2023.2175570 -
Biomolecules Dec 2022Atherosclerosis (AS) is a lipid-driven disorder of the artery intima characterized by the equilibrium between inflammatory and regressive processes. A protein complex... (Review)
Review
Atherosclerosis (AS) is a lipid-driven disorder of the artery intima characterized by the equilibrium between inflammatory and regressive processes. A protein complex called NLRP3 inflammasome is involved in the release of mature interleukin-1β (IL-1β), which is connected to the initiation and progression of atherosclerosis. Autophagy, which includes macroautophagy, chaperone-mediated autophagy (CMA), and microautophagy, is generally recognized as the process by which cells transfer their constituents to lysosomes for digestion. Recent studies have suggested a connection between vascular inflammation and autophagy. This review summarizes the most recent studies and the underlying mechanisms associated with different autophagic pathways and NLRP3 inflammasomes in vascular inflammation, aiming to provide additional evidence for atherosclerosis research.
Topics: Humans; Inflammasomes; Plaque, Atherosclerotic; NLR Family, Pyrin Domain-Containing 3 Protein; Autophagy; Atherosclerosis; Inflammation
PubMed: 36671400
DOI: 10.3390/biom13010015 -
Nature Reviews. Genetics Jun 2023Macroautophagy and microautophagy are highly conserved eukaryotic cellular processes that degrade cytoplasmic material in lysosomes. Both pathways involve characteristic... (Review)
Review
Macroautophagy and microautophagy are highly conserved eukaryotic cellular processes that degrade cytoplasmic material in lysosomes. Both pathways involve characteristic membrane dynamics regulated by autophagy-related proteins and other molecules, some of which are shared between the two pathways. Over the past few years, the application of new technologies, such as cryo-electron microscopy, coevolution-based structural prediction and in vitro reconstitution, has revealed the functions of individual autophagy gene products, especially in autophagy induction, membrane reorganization and cargo recognition. Concomitantly, mutations in autophagy genes have been linked to human disorders, particularly neurodegenerative diseases, emphasizing the potential pathogenic implications of autophagy defects. Accumulating genome data have also illuminated the evolution of autophagy genes within eukaryotes as well as their transition from possible ancestral elements in prokaryotes.
Topics: Humans; Cryoelectron Microscopy; Autophagy; Lysosomes; Proteins; Eukaryota; Biology
PubMed: 36635405
DOI: 10.1038/s41576-022-00562-w -
GeroScience Apr 2023Increased interest in the aging and Alzheimer's disease (AD)-related impairments in autophagy in the brain raise important questions about regulation and treatment.... (Review)
Review
Increased interest in the aging and Alzheimer's disease (AD)-related impairments in autophagy in the brain raise important questions about regulation and treatment. Since many steps in endocytosis and autophagy depend on GTPases, new measures of cellular GTP levels are needed to evaluate energy regulation in aging and AD. The recent development of ratiometric GTP sensors (GEVALS) and findings that GTP levels are not homogenous inside cells raise new issues of regulation of GTPases by the local availability of GTP. In this review, we highlight the metabolism of GTP in relation to the Rab GTPases involved in formation of early endosomes, late endosomes, and lysosomal transport to execute the autophagic degradation of damaged cargo. Specific GTPases control macroautophagy (mitophagy), microautophagy, and chaperone-mediated autophagy (CMA). By inference, local GTP levels would control autophagy, if not in excess. Additional levels of control are imposed by the redox state of the cell, including thioredoxin involvement. Throughout this review, we emphasize the age-related changes that could contribute to deficits in GTP and AD. We conclude with prospects for boosting GTP levels and reversing age-related oxidative redox shift to restore autophagy. Therefore, GTP levels could regulate the numerous GTPases involved in endocytosis, autophagy, and vesicular trafficking. In aging, metabolic adaptation to a sedentary lifestyle could impair mitochondrial function generating less GTP and redox energy for healthy management of amyloid and tau proteostasis, synaptic function, and inflammation.
Topics: Humans; Alzheimer Disease; Autophagy; Endocytosis; rab GTP-Binding Proteins; Brain; Guanosine Triphosphate
PubMed: 36622562
DOI: 10.1007/s11357-022-00717-x -
Frontiers in Oncology 2022The endosomal sorting complex required for transport (ESCRT) machinery plays a key role in the repair of damaged plasma membranes with puncta form and removes pores from... (Review)
Review
The endosomal sorting complex required for transport (ESCRT) machinery plays a key role in the repair of damaged plasma membranes with puncta form and removes pores from the plasma membrane in regulated cell death, apoptosis, necroptosis, pyroptosis, ferroptosis, and autophagy. ESCRT-I overexpression and ESCRT-III-associated charged multivesicular body protein (CHMP) 4B participate in apoptosis, and the ESCRT-1 protein TSG 101 maintains low levels of ALIX and ALG-2 and prevents predisposition to apoptosis. The ESCRT-III components CHMP2A and CHMP4B are recruited to broken membrane bubble sites with the requirement of extracellular Ca, remove membrane vesicles from cells, and delay the time required for active MLKL to mediate necroptosis, thus preserving cell survival. CHMP4B disturbed pyroptosis by recruiting around the plasma membrane neck to remove the GSDMD pores and preserve plasma membrane integrity depending on Ca influx. The accumulation of the ESCRT-III subunits CHMP5 and CHMP6 in the plasma membrane is increased by the classical ferroptosis activators erastin-1 and ras-selective lethal small molecule 3 (RSL3) upon cytosolic calcium influx and repairs the ferroptotic plasma membrane. ESCRT-III- and VPS4-induced macroautophagy, ESCRT-0-initiated microautophagy. ESCRT-I, ESCRT-II, ESCRT-III, ALIX, and VPS4A are recruited to damaged lysosomes and precede lysophagy, indicating that ESCRT is a potential target to overcome drug resistance during tumor therapy.
PubMed: 36330465
DOI: 10.3389/fonc.2022.1007446 -
The Journal of Clinical Investigation Dec 2022Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in immunocompromised individuals is associated with prolonged virus shedding and evolution of...
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in immunocompromised individuals is associated with prolonged virus shedding and evolution of viral variants. Rapamycin and its analogs (rapalogs, including everolimus, temsirolimus, and ridaforolimus) are FDA approved as mTOR inhibitors for the treatment of human diseases, including cancer and autoimmunity. Rapalog use is commonly associated with an increased susceptibility to infection, which has been traditionally explained by impaired adaptive immunity. Here, we show that exposure to rapalogs increased susceptibility to SARS-CoV-2 infection in tissue culture and in immunologically naive rodents by antagonizing the cell-intrinsic immune response. We identified 1 rapalog (ridaforolimus) that was less potent in this regard and demonstrated that rapalogs promote spike-mediated entry into cells, by triggering the degradation of the antiviral proteins IFITM2 and IFITM3 via an endolysosomal remodeling program called microautophagy. Rapalogs that increased virus entry inhibited mTOR-mediated phosphorylation of the transcription factor TFEB, which facilitated its nuclear translocation and triggered microautophagy. In rodent models of infection, injection of rapamycin prior to and after virus exposure resulted in elevated SARS-CoV-2 replication and exacerbated viral disease, while ridaforolimus had milder effects. Overall, our findings indicate that preexisting use of certain rapalogs may elevate host susceptibility to SARS-CoV-2 infection and disease by activating lysosome-mediated suppression of intrinsic immunity.
Topics: Humans; SARS-CoV-2; MTOR Inhibitors; Virus Internalization; COVID-19; Sirolimus; Immunity, Innate; Membrane Proteins; RNA-Binding Proteins
PubMed: 36264642
DOI: 10.1172/JCI160766 -
The Journal of Cell Biology Jan 2023At the trans-Golgi, complex traffic connections exist to the endolysosomal system additional to the main Golgi-to-plasma membrane secretory route. Here, we investigated...
At the trans-Golgi, complex traffic connections exist to the endolysosomal system additional to the main Golgi-to-plasma membrane secretory route. Here, we investigated three hits in a Drosophila screen displaying secretory cargo accumulation in autophagic vesicles: ESCRT-III component Vps20, SNARE-binding Rop, and lysosomal pump subunit VhaPPA1-1. We found that Vps20, Rop, and lysosomal markers localize near the trans-Golgi. Furthermore, we document that the vicinity of the trans-Golgi is the main cellular location for lysosomes and that early, late, and recycling endosomes associate as well with a trans-Golgi-associated degradative compartment where basal microautophagy of secretory cargo and other materials occurs. Disruption of this compartment causes cargo accumulation in our hits, including Munc18 homolog Rop, required with Syx1 and Syx4 for Rab11-mediated endosomal recycling. Finally, besides basal microautophagy, we show that the trans-Golgi-associated degradative compartment contributes to the growth of autophagic vesicles in developmental and starvation-induced macroautophagy. Our results argue that the fly trans-Golgi is the gravitational center of the whole endomembrane system.
Topics: Animals; Autophagy; Drosophila; Drosophila Proteins; Endosomal Sorting Complexes Required for Transport; Endosomes; Golgi Apparatus; Lysosomes; Nerve Tissue Proteins; Protein Transport; SNARE Proteins; rab GTP-Binding Proteins
PubMed: 36239631
DOI: 10.1083/jcb.202203045 -
Oncology Reports Dec 2022Autophagy is a highly conserved process that maintains cellular homeostasis during evolution. Autophagy can occur in the form of macroautophagy, microautophagy or... (Review)
Review
Autophagy is a highly conserved process that maintains cellular homeostasis during evolution. Autophagy can occur in the form of macroautophagy, microautophagy or molecular chaperone autophagy, among which macroautophagy is the most common. Apoptosis exists in all kinds of cell organisms, and is a kind of programmed cell death which is regulated by pro‑apoptotic factors and anti‑apoptotic signals. The main biological feature of apoptosis is the activation of caspase. Apoptosis is induced by a variety of cell signals, such as endoplasmic reticulum stress, induction of toxic substances, stimulation of pathogenic microorganisms and DNA damage. Inextricable links are found between autophagy and apoptosis. Studies have found that numerous of the autophagy molecules and autophagy signaling pathways involved in the process of autophagy are related to apoptosis. In addition to regulating autophagy, the autophagy signaling pathway also regulates apoptosis. The interaction between the two can achieve a dynamic balance to certain extent, which maintains the basic physiological functions of cells and reduces the damage to the body under stress. Disease occurs when the balance between autophagy and apoptosis is disrupted. Tumors form due to the ability of cells to avoid apoptosis. Autophagy is closely related to apoptosis, there must be a close connection between the three. In the present review, the mechanism between autophagy and apoptosis and the impact of their interaction on tumorigenesis shall be discussed.
Topics: Apoptosis; Autophagy; Carcinogenesis; Caspases; Endoplasmic Reticulum Stress; Humans
PubMed: 36222296
DOI: 10.3892/or.2022.8423 -
Cell Death and Differentiation Mar 2023Inflammation leads to systemic osteoporosis or local bone destruction, however, the underlying molecular mechanisms are still poorly understood. In this study, we report...
Inflammation leads to systemic osteoporosis or local bone destruction, however, the underlying molecular mechanisms are still poorly understood. In this study, we report that PRL2 is a negative regulator of osteoclastogenesis and bone absorption. Mice with PRL2 deficiency exhibit a decrease in bone volume and an increase in osteoclast numbers. PRL2 negatively regulates RANKL-induced reactive oxygen species production through the activation of RAC1, thus PRL2 deficient osteoclast precursors have both increased osteoclast differentiation ability and bone resorptive capacity. During inflammation, oxidized PRL2 is a selected substrate of HSC70 and conditions of oxidative stress trigger rapid degradation of PRL2 by HSC70 mediated endosomal microautophagy and chaperone-mediated autophagy. Ablation of PRL2 in mouse models of inflammatory bone disease leads to an increase in the number of osteoclasts and exacerbation of bone damage. Moreover, reduced PRL2 protein levels in peripheral myeloid cells are highly correlated with bone destruction in a mouse arthritis model and in human rheumatoid arthritis, while the autophagy inhibitor hydroxychloroquine blocked inflammation-induced PRL2 degradation and bone destruction in vivo. Therefore, our findings identify PRL2 as a new regulator in osteoimmunity, providing a link between inflammation and osteoporosis. As such, PRL2 is a potential therapeutic target for inflammatory bone disease and inhibition of HSC70 mediated autophagic degradation of PRL2 may offer new therapeutic tools for the treatment of inflammatory bone disease.
Topics: Animals; Humans; Mice; Autophagy; Bone Resorption; Cell Differentiation; Disease Models, Animal; Inflammation; Osteoclasts; Osteogenesis; Osteoporosis; RANK Ligand; HSC70 Heat-Shock Proteins
PubMed: 36182990
DOI: 10.1038/s41418-022-01068-y -
The Journal of Biological Chemistry Nov 2022α-synucleinopathy is driven by an imbalance of synthesis and degradation of α-synuclein (αSyn), causing a build up of αSyn aggregates and post-translationally...
α-synucleinopathy is driven by an imbalance of synthesis and degradation of α-synuclein (αSyn), causing a build up of αSyn aggregates and post-translationally modified species, which not only interfere with normal cellular metabolism but also by their secretion propagates the disease. Therefore, a better understanding of αSyn degradation pathways is needed to address α-synucleinopathy. Here, we used the nerve growth factor-differentiated catecholaminergic PC12 neuronal cell line, which was conferred α-synucleinopathy by inducible expression of αSyn and tubulin polymerization-promoting protein p25α. p25α aggregates αSyn, and imposes a partial autophagosome-lysosome block to mimic aspects of lysosomal deficiency common in neurodegenerative disease. Under basal conditions, αSyn was degraded by multiple pathways but most prominently by macroautophagy and Nedd4/Ndfip1-mediated degradation. We found that expression of p25α induced strong p38MAPK activity. Remarkably, when opposed by inhibitor SB203580 or p38MAPK shRNA knockdown, endolysosomal localization and degradation of αSyn increased, and αSyn secretion and cytotoxicity decreased. This effect was specifically dependent on Hsc70 and the endosomal sorting complex required for transport machinery, but different from classical microautophagy, as the αSyn Hsc70 binding motif was unnecessary. Furthermore, in a primary neuronal (h)-αSyn seeding model, p38MAPK inhibition decreased pathological accumulation of phosphorylated serine-129-αSyn and cytotoxicity. In conclusion, p38MAPK inhibition shifts αSyn degradation from various forms of autophagy to an endosomal sorting complex required for transport-dependent uptake mechanism, resulting in increased αSyn turnover and cell viability in p25α-expressing cells. More generally, our results suggest that under conditions of autophagolysosomal malfunction, the uninterrupted endosomal pathway offers a possibility to achieve disease-associated protein degradation.
Topics: alpha-Synuclein; Endosomal Sorting Complexes Required for Transport; p38 Mitogen-Activated Protein Kinases; Synucleinopathies; Nerve Tissue Proteins; PC12 Cells; Animals; Rats
PubMed: 36162505
DOI: 10.1016/j.jbc.2022.102531