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Disease Models & Mechanisms Oct 2023Invasive fungal infections represent a significant global health problem, and present several clinical challenges, including limited treatment options, increasing rates... (Review)
Review
Invasive fungal infections represent a significant global health problem, and present several clinical challenges, including limited treatment options, increasing rates of antifungal drug resistance and compounding comorbidities in affected patients. Metals, such as copper, iron and zinc, are critical for various biological and cellular processes across phyla. In mammals, these metals are important determinants of immune responses, but pathogenic microbes, including fungi, also require access to these metals to fuel their own growth and drive expression of major virulence traits. Therefore, host immune cells have developed strategies to either restrict access to metals to induce starvation of invading pathogens or deploy toxic concentrations within phagosomes to cause metal poisoning. In this Review, we describe the mechanisms regulating fungal scavenging and detoxification of copper, iron and zinc and the importance of these mechanisms for virulence and infection. We also outline how these metals are involved in host immune responses and the consequences of metal deficiencies or overloads on how the host controls invasive fungal infections.
Topics: Animals; Humans; Copper; Virulence; Metals; Iron; Zinc; Invasive Fungal Infections; Mammals
PubMed: 37905492
DOI: 10.1242/dmm.050393 -
The Journal of Cell Biology Mar 2024Leucine-rich repeat kinase 2 (LRRK2), a Rab kinase associated with Parkinson's disease and several inflammatory diseases, has been shown to localize to stressed...
Leucine-rich repeat kinase 2 (LRRK2), a Rab kinase associated with Parkinson's disease and several inflammatory diseases, has been shown to localize to stressed lysosomes and get activated to regulate lysosomal homeostasis. However, the mechanisms of LRRK2 recruitment and activation have not been well understood. Here, we found that the ATG8 conjugation system regulates the recruitment of LRRK2 as well as LC3 onto single membranes of stressed lysosomes/phagosomes. This recruitment did not require FIP200-containing autophagy initiation complex, nor did it occur on double-membrane autophagosomes, suggesting independence from canonical autophagy. Consistently, LRRK2 recruitment was regulated by the V-ATPase-ATG16L1 axis, which requires the WD40 domain of ATG16L1 and specifically mediates ATG8 lipidation on single membranes. This mechanism was also responsible for the lysosomal stress-induced activation of LRRK2 and the resultant regulation of lysosomal secretion and enlargement. These results indicate that the V-ATPase-ATG16L1 axis serves a novel non-autophagic role in the maintenance of lysosomal homeostasis by recruiting LRRK2.
Topics: Adenosine Triphosphatases; Autophagosomes; Autophagy; Cell Cycle Proteins; Lysosomes; Humans; Animals; Mice; Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; Autophagy-Related Proteins
PubMed: 38227290
DOI: 10.1083/jcb.202302067 -
The Journal of Cell Biology Jul 2023During autophagy, rapid membrane assembly expands small phagophores into large double-membrane autophagosomes. Theoretical modeling predicts that the majority of...
During autophagy, rapid membrane assembly expands small phagophores into large double-membrane autophagosomes. Theoretical modeling predicts that the majority of autophagosomal phospholipids are derived from highly efficient non-vesicular phospholipid transfer (PLT) across phagophore-ER contacts (PERCS). Currently, the phagophore-ER tether Atg2 is the only PLT protein known to drive phagophore expansion in vivo. Here, our quantitative live-cell imaging analysis reveals a poor correlation between the duration and size of forming autophagosomes and the number of Atg2 molecules at PERCS of starving yeast cells. Strikingly, we find that Atg2-mediated PLT is non-rate limiting for autophagosome biogenesis because membrane tether and the PLT protein Vps13 localizes to the rim and promotes the expansion of phagophores in parallel with Atg2. In the absence of Vps13, the number of Atg2 molecules at PERCS determines the duration and size of forming autophagosomes with an apparent in vivo transfer rate of ∼200 phospholipids per Atg2 molecule and second. We propose that conserved PLT proteins cooperate in channeling phospholipids across organelle contact sites for non-rate-limiting membrane assembly during autophagosome biogenesis.
Topics: Autophagosomes; Phospholipids; Endoplasmic Reticulum; Autophagy; Saccharomyces cerevisiae; Autophagy-Related Proteins; Saccharomyces cerevisiae Proteins
PubMed: 37115156
DOI: 10.1083/jcb.202211039 -
Molecular Cell May 2024Aggregation of proteins containing expanded polyglutamine (polyQ) repeats is the cytopathologic hallmark of a group of dominantly inherited neurodegenerative diseases,...
Aggregation of proteins containing expanded polyglutamine (polyQ) repeats is the cytopathologic hallmark of a group of dominantly inherited neurodegenerative diseases, including Huntington's disease (HD). Huntingtin (Htt), the disease protein of HD, forms amyloid-like fibrils by liquid-to-solid phase transition. Macroautophagy has been proposed to clear polyQ aggregates, but the efficiency of aggrephagy is limited. Here, we used cryo-electron tomography to visualize the interactions of autophagosomes with polyQ aggregates in cultured cells in situ. We found that an amorphous aggregate phase exists next to the radially organized polyQ fibrils. Autophagosomes preferentially engulfed this amorphous material, mediated by interactions between the autophagy receptor p62/SQSTM1 and the non-fibrillar aggregate surface. In contrast, amyloid fibrils excluded p62 and evaded clearance, resulting in trapping of autophagic structures. These results suggest that the limited efficiency of autophagy in clearing polyQ aggregates is due to the inability of autophagosomes to interact productively with the non-deformable, fibrillar disease aggregates.
Topics: Peptides; Autophagy; Humans; Huntingtin Protein; Autophagosomes; Sequestosome-1 Protein; Amyloid; Huntington Disease; Protein Aggregates; Cryoelectron Microscopy; Animals; Protein Aggregation, Pathological
PubMed: 38759629
DOI: 10.1016/j.molcel.2024.04.018 -
The Journal of Cell Biology Aug 2023In macroautophagy, cellular components are sequestered within autophagosomes and transported to lysosomes/vacuoles for degradation. Although phosphatidylinositol...
In macroautophagy, cellular components are sequestered within autophagosomes and transported to lysosomes/vacuoles for degradation. Although phosphatidylinositol 3-kinase complex I (PI3KCI) plays a pivotal role in the regulation of autophagosome biogenesis, little is known about how this complex localizes to the pre-autophagosomal structure (PAS). In Saccharomyces cerevisiae, PI3KCI is composed of PI3K Vps34 and conserved subunits Vps15, Vps30, Atg14, and Atg38. In this study, we discover that PI3KCI interacts with the vacuolar membrane anchor Vac8, the PAS scaffold Atg1 complex, and the pre-autophagosomal vesicle component Atg9 via the Atg14 C-terminal region, the Atg38 C-terminal region, and the Vps30 BARA domain, respectively. While the Atg14-Vac8 interaction is constitutive, the Atg38-Atg1 complex interaction and the Vps30-Atg9 interaction are enhanced upon macroautophagy induction depending on Atg1 kinase activity. These interactions cooperate to target PI3KCI to the PAS. These findings provide a molecular basis for PAS targeting of PI3KCI during autophagosome biogenesis.
Topics: Autophagosomes; Autophagy; Autophagy-Related Proteins; Membrane Proteins; Phosphatidylinositol 3-Kinases; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Vesicular Transport Proteins
PubMed: 37436710
DOI: 10.1083/jcb.202210017 -
Moschus ameliorates glutamate-induced cellular damage by regulating autophagy and apoptosis pathway.Scientific Reports Oct 2023Alzheimer's disease (AD), a neurodegenerative disorder, causes short-term memory and cognition declines. It is estimated that one in three elderly people die from AD or...
Alzheimer's disease (AD), a neurodegenerative disorder, causes short-term memory and cognition declines. It is estimated that one in three elderly people die from AD or other dementias. Chinese herbal medicine as a potential drug for treating AD has gained growing interest from many researchers. Moschus, a rare and valuable traditional Chinese animal medicine, was originally documented in Shennong Ben Cao Jing and recognized for its properties of reviving consciousness/resuscitation. Additionally, Moschus has the efficacy of "regulation of menstruation with blood activation, relief of swelling and pain" and is used for treating unconsciousness, stroke, coma, and cerebrovascular diseases. However, it is uncertain whether Moschus has any protective effect on AD patients. We explored whether Moschus could protect glutamate (Glu)-induced PC12 cells from cellular injury and preliminarily explored their related action mechanisms. The chemical compounds of Moschus were analyzed and identified by GC-MS. The Glu-induced differentiated PC12 cell model was thought to be the common AD cellular model. The study aims to preliminarily investigate the intervention effect of Moschus on Glu-induced PC12 cell damage as well as their related action mechanisms. Cell viability, lactate dehydrogenase (LDH), mitochondrial reactive oxygen species, mitochondrial membrane potential (MMP), cell apoptosis, autophagic vacuoles, autolysosomes or autophagosomes, proteins related to apoptosis, and the proteins related to autophagy were examined and analyzed. Seventeen active compounds of the Moschus sample were identified based on GC-MS analysis. In comparison to the control group, Glu stimulation increased cell viability loss, LDH release, mitochondrial damage, loss of MMP, apoptosis rate, and the number of cells containing autophagic vacuoles, and autolysosomes or autophagosomes, while these results were decreased after the pretreatment with Moschus and 3-methyladenine (3-MA). Furthermore, Glu stimulation significantly increased cleaved caspase-3, Beclin1, and LC3II protein expression, and reduced B-cell lymphoma 2/BAX ratio and p62 protein expression, but these results were reversed after pretreatment of Moschus and 3-MA. Moschus has protective activity in Glu-induced PC12 cell injury, and the potential mechanism might involve the regulation of autophagy and apoptosis. Our study may promote research on Moschus in the field of neurodegenerative diseases, and Moschus may be considered as a potential therapeutic agent for AD.
Topics: Animals; Rats; Female; Humans; Aged; Glutamic Acid; Autophagy; Reactive Oxygen Species; Autophagosomes; Apoptosis; Alzheimer Disease; PC12 Cells; Cell Survival
PubMed: 37903904
DOI: 10.1038/s41598-023-45878-7 -
Journal of Biochemistry Dec 2023Iron is involved in many biochemical processes including oxygen transport, ATP production, DNA synthesis and antioxidant defense. The importance of iron also applies to... (Review)
Review
Iron is involved in many biochemical processes including oxygen transport, ATP production, DNA synthesis and antioxidant defense. The importance of iron also applies to Leishmania parasites, an intracellular protozoan pathogen causing leishmaniasis. Leishmania are heme-auxotrophs, devoid of iron storage proteins and the heme synthesis pathway. Acquisition of iron and heme from the surrounding niche is thus critical for the intracellular survival of Leishmania inside the host macrophages. Moreover, Leishmania parasites are also exposed to oxidative stress within phagolysosomes of macrophages in mammalian hosts, and they need iron superoxide dismutase for overcoming this stress. Therefore, untangling the strategy adopted by these parasites for iron acquisition and utilization can be good targets for the development of antileishmanial drugs. Here, in this review, we will address how Leishmania parasites acquire and utilize iron and heme during infection to macrophages.
Topics: Animals; Leishmania; Iron; Parasites; Leishmaniasis; Heme; Mammals
PubMed: 37830941
DOI: 10.1093/jb/mvad082 -
Science Bulletin Dec 2023Increased mitochondrial damage plays a critical role in many neurodegeneration-related diseases such as Parkinson's disease (PD) and Down syndrome (DS). Thus,...
Increased mitochondrial damage plays a critical role in many neurodegeneration-related diseases such as Parkinson's disease (PD) and Down syndrome (DS). Thus, enhancement of mitochondrial degradation by small molecule compounds may provide promising new strategies to tackle these diseases. Here, we explored the strategy to induce clearance of mitochondria by targeting them to the autophagy machinery by autophagy-tethering compounds (ATTECs). We provided the proof-of-concept evidence demonstrating that the bifunctional compound (mT1) binding to both the outer mitochondrial membrane protein TSPO and the autophagosome protein LC3B simultaneously may enhance the engulfment of damaged mitochondria by autophagosomes and subsequent autophagic degradation of them. In addition, preliminary experiments suggest that mT1 attenuated disease-relevant phenotypes in both a PD cellular model and a DS organoid model. Taken together, we demonstrate the possibility of degrading mitochondria by bifunctional ATTECs, which confirms the capability of degrading organelles by ATTECs and provides potential new strategies in the intervention of mitochondria-related disorders.
Topics: Humans; Autophagy; Mitochondria; Autophagosomes; Mitophagy; Mitochondrial Membranes; Parkinson Disease; Neurodegenerative Diseases; Receptors, GABA
PubMed: 37940449
DOI: 10.1016/j.scib.2023.10.021 -
Frontiers in Immunology 2023Bacterial infections still impose a significant burden on humanity, even though antimicrobial agents have long since been developed. In addition to individual severe... (Review)
Review
Bacterial infections still impose a significant burden on humanity, even though antimicrobial agents have long since been developed. In addition to individual severe infections, the f fatality rate of sepsis remains high, and the threat of antimicrobial-resistant bacteria grows with time, putting us at inferiority. Although tremendous resources have been devoted to the development of antimicrobial agents, we have yet to recover from the lost ground we have been driven into. Looking back at the evolution of treatment for cancer, which, like infectious diseases, has the similarity that host immunity eliminates the lesion, the development of drugs to eliminate the tumor itself has shifted from a single-minded focus on drug development to the establishment of a treatment strategy in which the de-suppression of host immunity is another pillar of treatment. In infectious diseases, on the other hand, the development of therapies that strengthen and support the immune system has only just begun. Among innate immunity, the first line of defense that bacteria encounter after invading the host, the molecular mechanisms of the phagolysosome pathway, which begins with phagocytosis to fusion with lysosome, have been elucidated in detail. Bacteria have a large number of strategies to escape and survive the pathway. Although the full picture is still unfathomable, the molecular mechanisms have been elucidated for some of them, providing sufficient clues for intervention. In this article, we review the host defense mechanisms and bacterial evasion mechanisms and discuss the possibility of host-directed therapy for bacterial infection by intervening in the phagolysosome pathway.
Topics: Humans; Bacterial Infections; Immunity, Innate; Anti-Infective Agents; Bacteria; Phagosomes; Communicable Diseases
PubMed: 37841276
DOI: 10.3389/fimmu.2023.1227467 -
Autophagy Aug 2023The precursors to mammalian autophagosomes originate from preexisting membranes contributed by a number of sources, and subsequently enlarge through intermembrane lipid...
The precursors to mammalian autophagosomes originate from preexisting membranes contributed by a number of sources, and subsequently enlarge through intermembrane lipid transfer, then close to sequester the cargo, and merge with lysosomes to degrade the cargo. Using cellular and in vitro membrane fusion analyses coupled with proteomic and biochemical studies we show that autophagosomes are formed from a hybrid membrane compartment referred to as a prophagophore or HyPAS (hybrid preautophagosomal structure). HyPAS is initially LC3-negative and subsequently becomes an LC3-positive phagophore. The prophagophore emerges through fusion of RB1CC1/FIP200-containing vesicles, derived from the cis-Golgi, with endosomally derived ATG16L1 membranes. A specialized Ca-responsive apparatus controls prophagophore biogenesis and can be modulated by pharmacological agents such as SIGMAR1 agonists and antagonists including chloroquine. Autophagic prophagophore formation is inhibited during SARS-CoV-2 infection and is recapitulated by expression of SARS-CoV-2 nsp6. These findings show that mammalian autophagosomal prophagophores emerge via the convergence of secretory and endosomal pathways in a process that is targeted by microbial factors including coronaviral membrane proteins. CLEM, correlative light and electron microscopy; CQ, chloroquine; HyPAS, hybrid preautophagosomal; strcuture/prophagophore; LC3, microtubule associated protein 1 light chain 3; RUPEX, a combination of RUSH and APEX2 systems; SARS-CoV-2, SARS-CoV-2 virus, causative agent of COVID19.
Topics: Humans; Animals; Autophagosomes; Autophagy; Proteomics; COVID-19; SARS-CoV-2; Mammals
PubMed: 36571474
DOI: 10.1080/15548627.2022.2161728