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Cell Reports May 2024Atg8 paralogs, consisting of LC3A/B/C and GBRP/GBRPL1/GATE16, function in canonical autophagy; however, their function is controversial because of functional redundancy....
Atg8 paralogs, consisting of LC3A/B/C and GBRP/GBRPL1/GATE16, function in canonical autophagy; however, their function is controversial because of functional redundancy. In innate immunity, xenophagy and non-canonical single membranous autophagy called "conjugation of Atg8s to single membranes" (CASM) eliminate bacteria in various cells. Previously, we reported that intracellular Streptococcus pneumoniae can induce unique hierarchical autophagy comprised of CASM induction, shedding, and subsequent xenophagy. However, the molecular mechanisms underlying these processes and the biological significance of transient CASM induction remain unknown. Herein, we profile the relationship between Atg8s, autophagy receptors, poly-ubiquitin, and Atg4 paralogs during pneumococcal infection to understand the driving principles of hierarchical autophagy and find that GATE16 and GBRP sequentially play a pivotal role in CASM shedding and subsequent xenophagy induction, respectively, and LC3A and GBRPL1 are involved in CASM/xenophagy induction. Moreover, we reveal ingenious bacterial tactics to gain intracellular survival niches by manipulating CASM-xenophagy progression by generating intracellular pneumococci-derived HO.
Topics: Animals; Mice; Autophagy; Autophagy-Related Protein 8 Family; Autophagy-Related Proteins; Macroautophagy; Microtubule-Associated Proteins; Pneumococcal Infections; Streptococcus pneumoniae
PubMed: 38656870
DOI: 10.1016/j.celrep.2024.114131 -
Cell Discovery Apr 2024Macroautophagy is a process that cells engulf cytosolic materials by autophagosomes and deliver them to lysosomes for degradation. The biogenesis of autophagosomes...
Macroautophagy is a process that cells engulf cytosolic materials by autophagosomes and deliver them to lysosomes for degradation. The biogenesis of autophagosomes requires ATG2 as a lipid transfer protein to transport lipids from existing membranes to phagophores. It is generally believed that endoplasmic reticulum is the main source for lipid supply of the forming autophagosomes; whether ATG2 can transfer lipids from other organelles to phagophores remains elusive. In this study, we identified a new ATG2A-binding protein, ANKFY1. Depletion of this endosome-localized protein led to the impaired autophagosome growth and the reduced autophagy flux, which largely phenocopied ATG2A/B depletion. A pool of ANKFY1 co-localized with ATG2A between endosomes and phagophores and depletion of UVRAG, ANKFY1 or ATG2A/B led to reduction of PI3P distribution on phagophores. Purified recombinant ANKFY1 bound to PI3P on membrane through its FYVE domain and enhanced ATG2A-mediated lipid transfer between PI3P-containing liposomes. Therefore, we propose that ANKFY1 recruits ATG2A to PI3P-enriched endosomes and promotes ATG2A-mediated lipid transfer from endosomes to phagophores. This finding implicates a new lipid source for ATG2A-mediated phagophore expansion, where endosomes donate PI3P and other lipids to phagophores via lipid transfer.
PubMed: 38622126
DOI: 10.1038/s41421-024-00659-y -
International Journal of Molecular... Mar 2024Acute kidney injury (AKI) is a public health burden with increasing morbidity and mortality rates and health care costs. Acute tubular necrosis (ATN) is the most common...
Acute kidney injury (AKI) is a public health burden with increasing morbidity and mortality rates and health care costs. Acute tubular necrosis (ATN) is the most common cause of AKI. Cisplatin (CIS) is a platinum-based chemotherapeutic agent used in the treatment of a wide variety of malignancies such as lung, breast, ovary, testis, bladder, cervix, and head and neck cancers. Autophagy plays an important role in AKI. Galectin-3 (Gal-3) is significantly increased in renal tubules in AKI; however, its role in autophagy is not well understood. Male C57B6/J and B6.Cg-Lgals3 <>/J Gal-3 knockout (KO) mice were used to induce AKI using a CIS mouse model of ATN. Renal Gal-3 and autophagy proteins' expression were measured using standard histologic, immunofluorescent, and enzyme-linked immunosorbent assay techniques. The data were presented as the mean ± S.E. Statistically significant differences ( < 0.05) were calculated between experimental groups and corresponding control groups by one-way analysis of variance. There was a significant increase in renal concentrations of Gal-3 in the Gal-3 wild-type CIS-treated mice when compared with sham control mice. There were significantly higher concentrations of renal LC3B, ATG13, Ulk-1, Beclin, ATG5, ATG12, ATG9A, and p-AMPK in the CIS-treated Gal-3 KO mice than in the Gal-3 wild-type CIS-treated mice. Further, there were significantly higher concentrations of mTOR, p- NF-κB, beta-catenin, and p62 in the kidneys of the Gal-3 wild-type CIS-treated mice than in the Gal-3 KO CIS-treated mice. Our findings affirm the connection between Gal-3 and autophagy, revealing its central role as a connector with prosurvival signaling proteins. Gal-3 plays a pivotal role in orchestrating cellular responses by interacting with prosurvival signal pathways and engaging with autophagy proteins. Notably, our observations highlight that the absence of Gal-3 can enhance autophagy in CIS-induced ATN.
Topics: Animals; Male; Mice; Acute Kidney Injury; Autophagy; Cisplatin; Galectin 3; Kidney; Kidney Cortex Necrosis; Necrosis
PubMed: 38612416
DOI: 10.3390/ijms25073604 -
Journal of Advanced Research Apr 2024Sepsis, a systemic immune syndrome caused by severe trauma or infection, poses a substantial threat to the health of patients worldwide. The progression of sepsis is...
INTRODUCTION
Sepsis, a systemic immune syndrome caused by severe trauma or infection, poses a substantial threat to the health of patients worldwide. The progression of sepsis is heavily influenced by septic liver injury, which is triggered by infection and cytokine storms, and has a significant impact on the tolerance and prognosis of septic patients. The objective of our study is to elucidate the biological role and molecular mechanism of fibroblast growth factor 21 (FGF21) in the process of sepsis.
OBJECTIVES
This study was undertaken in an attempt to elucidate the function and molecular mechanism of FGF21 in therapy of sepsis.
METHODS
Serum concentrations of FGF21 were measured in sepsis patients and septic mice. Liver injury was compared between mice FGF21 knockout (KO) mice and wildtype (WT) mice. To assess the therapeutic potential, recombinant human FGF21 was administered to septic mice. Furthermore, the molecular mechanism of FGF21 was investigated in mice with myeloid-cell specific HIF-1α overexpression mice (LyzM-Cre) and myeloid-cell specific Atg7 knockout mice (Atg7).
RESULTS
Serum level of FGF21 was significantly increased in sepsis patients and septic mice. Through the use of recombinant human FGF21 (rhFGF21) and FGF21 KO mice, we found that FGF21 mitigated septic liver injury by inhibiting the initiation and propagation of inflammation. Treatment with rhFGF21 effectively suppressed the activation of proinflammatory macrophages by promoting macroautophagy/autophagy degradation of hypoxia-inducible factor-1α (HIF-1α). Importantly, the therapeutic effect of rhFGF21 against septic liver injury was nullified in LyzM-Cre mice and Atg7 mice.
CONCLUSIONS
Our findings demonstrate that FGF21 considerably suppresses inflammation upon septic liver injury through the autophagy/ HIF-1α axis.
PubMed: 38599281
DOI: 10.1016/j.jare.2024.04.004 -
Biochemistry and Biophysics Reports Jul 2024(Macro)autophagy is a cellular degradation system for unnecessary materials, such as aggregate-prone TDP-43, a central molecule in neurodegenerative diseases including...
(Macro)autophagy is a cellular degradation system for unnecessary materials, such as aggregate-prone TDP-43, a central molecule in neurodegenerative diseases including amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Abemaciclib (Abe) and vacuolin-1 (Vac) treatments are known to induce vacuoles characterized by an autophagosome and a lysosome component, suggesting that they facilitate autophagosome-lysosome fusion. However, it remains unknown whether Abe and Vac suppress the accumulation of aggregate-prone TDP-43 by accelerating autophagic flux. In the present study, the Abe and Vac treatment dose-dependently reduced the GFP/RFP ratio in SH-SY5Y neuroblastoma cells stably expressing the autophagic flux marker GFP-LC3-RFP-LC3ΔG. Abe and Vac also increased the omegasome marker GFP-ATG13 signal and the autophagosome marker mCherry-LC3 localized to the lysosome marker LAMP1-GFP. The Abe and Vac treatment decreased the intracellular level of the lysosome marker LAMP1-GFP in SH-SY5Y cells stably expressing LAMP1-GFP, but did not increase the levels of LAMP1-GFP, the autophagosome marker LC3-II, or the multivesicular body marker TSG101 in the extracellular vesicle-enriched fraction. Moreover, Abe and Vac treatment autophagy-dependently inhibited GFP-tagged aggregate-prone TDP-43 accumulation. The results of a PI(3)P reporter assay using the fluorescent protein tagged-2 × FYVE and LAMP1-GFP indicated that Abe and Vac increased the intensity of the PI(3)P signal on lysosomes. A treatment with the VPS34 inhibitor wortmannin (WM) suppressed Abe-/Vac-facilitated autophagic flux and the degradation of GFP-tagged aggregate-prone TDP-43. Collectively, these results suggest that Abe and Vac degrade aggregate-prone TDP-43 by accelerating autophagosome formation and autophagosome-lysosome fusion through the formation of PI(3)P.
PubMed: 38596406
DOI: 10.1016/j.bbrep.2024.101705 -
BioRxiv : the Preprint Server For... Mar 2024Alveolar epithelial type II (AT2) cell dysfunction is implicated in the pathogenesis of familial and sporadic idiopathic pulmonary fibrosis (IPF). We previously...
Alveolar epithelial type II (AT2) cell dysfunction is implicated in the pathogenesis of familial and sporadic idiopathic pulmonary fibrosis (IPF). We previously described that expression of an AT2 cell exclusive disease-associated protein isoform (SP-CI73T) in murine and patient-specific induced pluripotent stem cell (iPSC)-derived AT2 cells leads to a block in late macroautophagy and promotes time-dependent mitochondrial impairments; however, how a metabolically dysfunctional AT2 cell results in fibrosis remains elusive. Here using murine and human iPSC-derived AT2 cell models expressing SP-CI73T, we characterize the molecular mechanisms governing alterations in AT2 cell metabolism that lead to increased glycolysis, decreased mitochondrial biogenesis, disrupted fatty acid oxidation, accumulation of impaired mitochondria, and diminished AT2 cell progenitor capacity manifesting as reduced AT2 self-renewal and accumulation of transitional epithelial cells. We identify deficient AMP-kinase signaling as a key upstream signaling hub driving disease in these dysfunctional AT2 cells and augment this pathway to restore alveolar epithelial metabolic function, thus successfully alleviating lung fibrosis in vivo.
PubMed: 38585863
DOI: 10.1101/2024.03.26.586649 -
Advanced Pharmaceutical Bulletin Mar 2024Parkinson's disease (PD) is the second most common neurodegenerative disease caused by the loss of dopaminergic neurons. Genetic factors, inflammatory responses,... (Review)
Review
Parkinson's disease (PD) is the second most common neurodegenerative disease caused by the loss of dopaminergic neurons. Genetic factors, inflammatory responses, oxidative stress, metabolic disorders, cytotoxic factors, and mitochondrial dysfunction are all involved in neuronal death in neurodegenerative diseases. The risk of PD can be higher in aging individuals due to decreased mitochondrial function, energy metabolism, and AMP-activated protein kinase (AMPK) function. The potential of AMPK to regulate neurodegenerative disorders lies in its ability to enhance antioxidant capacity, reduce oxidative stress, improve mitochondrial function, decrease mitophagy and macroautophagy, and inhibit inflammation. In addition, it has been shown that modulating the catalytic activity of AMPK can protect the nervous system. This article reviews the mechanisms by which AMPK activation can modulate PD.
PubMed: 38585465
DOI: 10.34172/apb.2024.013 -
Biochemistry and Biophysics Reports Jul 2024The mitophagy process, a type of macroautophagy, is the targeted removal of mitochondria. It is a type of autophagy exclusive to mitochondria, as the process removes... (Review)
Review
The mitophagy process, a type of macroautophagy, is the targeted removal of mitochondria. It is a type of autophagy exclusive to mitochondria, as the process removes defective mitochondria one by one. Mitophagy serves as an additional level of quality control by using autophagy to remove superfluous mitochondria or mitochondria that are irreparably damaged. During spermatogenesis, mitophagy can influence cell homeostasis and participates in a variety of membrane trafficking activities. Crucially, it has been demonstrated that defective mitophagy can impede spermatogenesis. Despite an increasing amount of evidence suggesting that mitophagy and mitochondrial dynamics preserve the fundamental level of cellular homeostasis, little is known about their role in developmentally controlled metabolic transitions and differentiation. It has been observed that male infertility is a result of mitophagy's impact on sperm motility. Furthermore, certain proteins related to autophagy have been shown to be present in mammalian spermatozoa. The mitochondria are the only organelle in sperm that can produce reactive oxygen species and finally provide energy for sperm movement. Furthermore, studies have shown that inhibited autophagy-infected spermatozoa had reduced motility and increased amounts of phosphorylated PINK1, TOM20, caspase 3/7, and AMPK. Therefore, in terms of reproductive physiology, mitophagy is the removal of mitochondria derived from sperm and the following preservation of mitochondria that are exclusively maternal.
PubMed: 38577271
DOI: 10.1016/j.bbrep.2024.101698 -
World Journal of Clinical Cases Mar 2024The pathogenesis of ulcerative colitis (UC) is complex, and recent therapeutic advances remain unable to fully alleviate the condition.
BACKGROUND
The pathogenesis of ulcerative colitis (UC) is complex, and recent therapeutic advances remain unable to fully alleviate the condition.
AIM
To inform the development of novel UC treatments, bioinformatics was used to explore the autophagy-related pathogenesis associated with the active phase of UC.
METHODS
The GEO database was searched for UC-related datasets that included healthy controls who met the screening criteria. Differential analysis was conducted to obtain differentially expressed genes (DEGs). Autophagy-related targets were collected and intersected with the DEGs to identiy differentially expressed autophagy-related genes (DEARGs) associated with active UC. DEARGs were then subjected to KEGG, GO, and DisGeNET disease enrichment analyses using R software. Differential analysis of immune infiltrating cells was performed using the CiberSort algorithm. The least absolute shrinkage and selection operator algorithm and protein-protein interaction network were used to narrow down the DEARGs, and the top five targets in the Dgree ranking were designated as core targets.
RESULTS
A total of 4822 DEGs were obtained, of which 58 were classified as DEARGs. SERPINA1, BAG3, HSPA5, CASP1, and CX3CL1 were identified as core targets. GO enrichment analysis revealed that DEARGs were primarily enriched in processes related to autophagy regulation and macroautophagy. KEGG enrichment analysis showed that DEARGs were predominantly associated with NOD-like receptor signaling and other signaling pathways. Disease enrichment analysis indicated that DEARGs were significantly linked to diseases such as malignant glioma and middle cerebral artery occlusion. Immune infiltration analysis demonstrated a higher presence of immune cells like activated memory CD4 T cells and follicular helper T cells in active UC patients than in healthy controls.
CONCLUSION
Autophagy is closely related to the active phase of UC and the potential targets obtained from the analysis in this study may provide new insight into the treatment of active UC patients.
PubMed: 38576744
DOI: 10.12998/wjcc.v12.i9.1622 -
The Journal of Cell Biology Jul 2024Autophagy serves as a stress response pathway by mediating the degradation of cellular material within lysosomes. In autophagy, this material is encapsulated in...
Autophagy serves as a stress response pathway by mediating the degradation of cellular material within lysosomes. In autophagy, this material is encapsulated in double-membrane vesicles termed autophagosomes, which form from precursors referred to as phagophores. Phagophores grow by lipid influx from the endoplasmic reticulum into Atg9-positive compartments and local lipid synthesis provides lipids for their expansion. How phagophore nucleation and expansion are coordinated with lipid synthesis is unclear. Here, we show that Faa1, an enzyme activating fatty acids, is recruited to Atg9 vesicles by directly binding to negatively charged membranes with a preference for phosphoinositides such as PI3P and PI4P. We define the membrane-binding surface of Faa1 and show that its direct interaction with the membrane is required for its recruitment to phagophores. Furthermore, the physiological localization of Faa1 is key for its efficient catalysis and promotes phagophore expansion. Our results suggest a positive feedback loop coupling phagophore nucleation and expansion to lipid synthesis.
Topics: Autophagosomes; Autophagy; Fatty Acids; Feedback; Macroautophagy; Saccharomyces cerevisiae
PubMed: 38573225
DOI: 10.1083/jcb.202309057