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Autophagy triggers CTSD (cathepsin D) maturation and localization inside cells to promote apoptosis.Autophagy May 2021CTSD/CathD/CATD (cathepsin D) is a lysosomal aspartic protease. A distinguishing characteristic of CTSD is its dual functions of promoting cell proliferation via...
CTSD/CathD/CATD (cathepsin D) is a lysosomal aspartic protease. A distinguishing characteristic of CTSD is its dual functions of promoting cell proliferation via secreting a pro-enzyme outside the cells as a ligand, and promoting apoptosis via the mature form of this enzyme inside cells; however, the regulation of its secretion, expression, and maturation is undetermined. Using the lepidopteran insect , a serious agricultural pest, as a model, we revealed the dual functions and regulatory mechanisms of CTSD secretion, expression, and maturation. Glycosylation of asparagine 233 (N233) determined pro-CTSD secretion. The steroid hormone 20-hydroxyecdysone (20E) promoted CTSD expression. Macroautophagy/autophagy triggered CTSD maturation and localization inside midgut cells to activate CASP3 (caspase 3) and promote apoptosis. Pro-CTSD was expressed in the pupal epidermis and was secreted into the hemolymph to promote adult fat body endoreplication/endoreduplication, cell proliferation, and association. Our study revealed that the differential expression and autophagy-mediated maturation of CTSD in tissues determine its roles in apoptosis and cell proliferation, thereby determining the cell fates of tissues during lepidopteran metamorphosis. 20E: 20-hydroxyecdysone; 3-MA: 3-methyladenine; ACTB/β-actin: actin beta; AKT: protein kinase B; ATG1: autophagy-related 1; ATG4: autophagy-related 4; ATG5: autophagy-related 5; ATG7: autophagy-related 7; ATG14: autophagy-related 14; BSA: bovine serum albumin; CASP3: caspase 3; CQ: choroquine; CTSD: cathepsin D; DAPI: 4',6-diamidino-2-phenylindole; DMSO: dimethyl sulfoxide; DPBS: dulbecco's phosphate-buffered saline; DsRNA: double-stranded RNA; EcR: ecdysone receptor; EcRE: ecdysone response element; EdU: 5-ethynyl-2´-deoxyuridine; G-m-CTSD: glycosylated-mautre-CTSD; G-pro-CTSD: glycosylated-pro-CTSD; HaEpi: epidermal cell line; HE staining: hematoxylin and eosin staining; IgG: immunoglobin G; IM: imaginal midgut; JH: juvenile hormone; Kr-h1: krueppel homologous protein 1; LM: larval midgut; M6P: mannose-6-phosphate; PBS: phosphate-buffered saline; PCD: programmed cell death; PNGase: peptide-N-glycosidase F; RFP: red fluorescent protein; RNAi: RNA interference; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis; SYX17: syntaxin 17; USP1: ultraspiracle isoform 1.
Topics: Animals; Apoptosis; Autophagy; Cathepsin D; Cell Proliferation; Ecdysterone; Gene Knockdown Techniques; Lysosomes; Receptors, Steroid
PubMed: 32324083
DOI: 10.1080/15548627.2020.1752497 -
Palmitoylation promotes chaperone-mediated autophagic degradation of NLRP3 to modulate inflammation.Autophagy Oct 2023The critical intracellular pattern recognition receptor NLRP3 senses pathogenic organisms and endogenous danger signals via forming inflammasomes to orchestrate innate...
The critical intracellular pattern recognition receptor NLRP3 senses pathogenic organisms and endogenous danger signals via forming inflammasomes to orchestrate innate immune responses. Dysfunction of NLRP3 inflammasomes is implicated in several inflammatory disorders. Hence, it is important to uncover the mechanisms preventing sustained NLRP3 inflammasome activation. Recently, we revealed that ZDHHC12-mediated palmitoylation enhances NLRP3 degradation through the chaperone-mediated autophagy pathway, and identified gain-of-function variants of NLRP3 in autoinflammatory diseases, which induce excessive NLRP3 inflammasome activation through decreased NLRP3 palmitoylation level and impaired chaperone-mediated autophagic degradation of NLRP3.
Topics: Humans; Inflammasomes; NLR Family, Pyrin Domain-Containing 3 Protein; Chaperone-Mediated Autophagy; Lipoylation; Autophagy; Inflammation
PubMed: 36927399
DOI: 10.1080/15548627.2023.2187957 -
Autophagy Aug 2022Senecavirus A (SVA), an important emerging porcine virus, has outbreaks in different regions and countries each year, becoming a virus with global prevalence. SVA...
Senecavirus A (SVA), an important emerging porcine virus, has outbreaks in different regions and countries each year, becoming a virus with global prevalence. SVA infection has been reported to induce macroautophagy/autophagy; however, the molecular mechanisms of autophagy induction and the effect of SVA on autophagy remain unknown. This study showed that SVA infection induced the autophagy process in the early stage of SVA infection, and the rapamycin-induced autophagy inhibited SVA replication by degrading virus 3 C protein. To counteract this, SVA utilized 2AB protein inhibiting the autophagy process from promoting viral replication in the late stage of SVA infection. Further study showed that SVA 2AB protein interacted with MARCHF8/MARCH8 and LC3 to degrade the latter and inhibit the autophagy process. In addition, we found that MARCHF8 was a positive regulator of type I IFN (IFN-I) signaling. During the autophagy process, the SVA 2AB protein targeted MARCHF8 and MAVS forming a large complex for degradation to deactivate IFN-I signaling. Together, our study reveals the molecular mechanisms of selective autophagy in the host against viruses and reveals potential viral strategies to evade the autophagic process and IFN-I signaling for successful pathogenesis. Baf A: bafilomycin A; Co-IP: co-immunoprecipitation; CQ: chloroquine; DAPI: 4',6-diamidino-2-phenylindole; hpi: hours post-infection; IFN: interferon; ISG: IFN-stimulated gene; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MARCHF8/MARCH8: membrane associated ring-CH-type finger 8; MAVS: mitochondrial antiviral signaling protein; MOI: multiplicity of infection; Rapa: rapamycin; RT: room temperature; siRNA: small interfering RNA; SVA: Senecavirus A; TCID: 50% tissue culture infectious doses.
Topics: Animals; Autophagy; Interferon Type I; Macroautophagy; Picornaviridae; Sirolimus; Swine
PubMed: 34964697
DOI: 10.1080/15548627.2021.2015740 -
Cell Reports Oct 2023Dysfunctional mitochondria are removed via multiple pathways, such as mitophagy, a selective autophagy process. Here, we identify an intracellular hybrid...
Dysfunctional mitochondria are removed via multiple pathways, such as mitophagy, a selective autophagy process. Here, we identify an intracellular hybrid mitochondria-lysosome organelle (termed the mitochondria-lysosome-related organelle [MLRO]), which regulates mitochondrial homeostasis independent of canonical mitophagy during hepatocyte dedifferentiation. The MLRO is an electron-dense organelle that has either a single or double membrane with both mitochondria and lysosome markers. Mechanistically, the MLRO is likely formed from the fusion of mitochondria-derived vesicles (MDVs) with lysosomes through a PARKIN-, ATG5-, and DRP1-independent process, which is negatively regulated by transcription factor EB (TFEB) and associated with mitochondrial protein degradation and hepatocyte dedifferentiation. The MLRO, which is galectin-3 positive, is reminiscent of damaged lysosome and could be cleared by overexpression of TFEB, resulting in attenuation of hepatocyte dedifferentiation. Together, results from this study suggest that the MLRO may act as an alternative mechanism for mitochondrial quality control independent of canonical autophagy/mitophagy involved in cell dedifferentiation.
Topics: Mitochondria; Organelles; Lysosomes; Autophagy; Mitophagy
PubMed: 37862166
DOI: 10.1016/j.celrep.2023.113291 -
Nature Aging Jun 2022The effects of aging on the brain are widespread and can have dramatic implications on the overall health of an organism. Mitochondrial dysfunction is a hallmark of...
The effects of aging on the brain are widespread and can have dramatic implications on the overall health of an organism. Mitochondrial dysfunction is a hallmark of brain aging, but, the interplay between mitochondrial quality control, neuronal aging, and organismal health is not well understood. Here, we show that aging leads to a decline in mitochondrial autophagy (mitophagy) in the brain with a concomitant increase in mitochondrial content. We find that induction of BCL2-interacting protein 3 (BNIP3), a mitochondrial outer membrane protein, in the adult nervous system induces mitophagy and prevents the accumulation of dysfunctional mitochondria in the aged brain. Importantly, neuronal induction of BNIP3-mediated mitophagy increases organismal longevity and healthspan. Furthermore, BNIP3-mediated mitophagy in the nervous system improves muscle and intestinal homeostasis in aged flies, indicating cell non-autonomous effects. Our findings identify BNIP3 as a therapeutic target to counteract brain aging and prolong overall organismal health with age.
Topics: Animals; Mitophagy; Drosophila; Aging; Autophagy; Mitochondria
PubMed: 36213625
DOI: 10.1038/s43587-022-00214-y -
Neuron Aug 2023Autophagy disorders prominently affect the brain, entailing neurodevelopmental and neurodegenerative phenotypes in adolescence or aging, respectively. Synaptic and...
Autophagy disorders prominently affect the brain, entailing neurodevelopmental and neurodegenerative phenotypes in adolescence or aging, respectively. Synaptic and behavioral deficits are largely recapitulated in mouse models with ablation of autophagy genes in brain cells. Yet, the nature and temporal dynamics of brain autophagic substrates remain insufficiently characterized. Here, we immunopurified LC3-positive autophagic vesicles (LC3-pAVs) from the mouse brain and proteomically profiled their content. Moreover, we characterized the LC3-pAV content that accumulates after macroautophagy impairment, validating a brain autophagic degradome. We reveal selective pathways for aggrephagy, mitophagy, and ER-phagy via selective autophagy receptors, and the turnover of numerous synaptic substrates, under basal conditions. To gain insight into the temporal dynamics of autophagic protein turnover, we quantitatively compared adolescent, adult, and aged brains, revealing critical periods of enhanced mitophagy or degradation of synaptic substrates. Overall, this resource unbiasedly characterizes the contribution of autophagy to proteostasis in the maturing, adult, and aged brain.
Topics: Animals; Mice; Autophagy; Mitophagy; Macroautophagy; Aging; Brain
PubMed: 37279748
DOI: 10.1016/j.neuron.2023.05.011 -
Autophagy Apr 2022While the functions of STING1 (stimulator of interferon response cGAMP interactor 1) during DNA virus infection had been well documented, the roles STING1 plays during...
While the functions of STING1 (stimulator of interferon response cGAMP interactor 1) during DNA virus infection had been well documented, the roles STING1 plays during RNA viruses infection is obscure. Infection with foot-and-mouth disease virus (FMDV), a well-known picornavirus, induces endoplasmic reticulum (ER) stress response and autophagy. Here, we found that the FMDV-induced integrated stress response originates from the cellular pattern recognition receptor DDX58/RIG-I (DExD/H-box helicase 58). DDX58 transmits signals to the ER-anchored adaptor protein STING1, which specifically activates the EIF2AK3/PERK (eukaryotic translation initiation factor 2A)-dependent integrated stress response and finally leads to reticulophagy and degradation of STING1 itself. Knockdown/knockout of STING1 or EIF2AK3 suppresses FMDV genome replication and viral protein expression. Reticulophagy induction by STING1 does not require its translocation to the Golgi or IFN response activation. However, STING1 polymerization is necessary for the FMDV-induced integrated stress response and reticulophagy. Our work illustrated the signaling cascades that mediate the cellular stress response to FMDV infection and indicated that induction of autophagy in response to both DNA and RNA virus infection may be an evolutionarily conserved function of STING1. ATF6: activating transcription factor 6; CGAS: cyclic GMP-AMP synthase; DDX58/RIG-I: DExD/H-box helicase 58; EIF2A/eIF2α: eukaryotic translation initiation factor 2A; EIF2AK3/PERK: eukaryotic translation initiation factor 2 alpha kinase 2; ER: endoplasmic reticulum; ERN1/IRE1: endoplasmic reticulum to nucleus signaling 1; FMD: foot-and-mouth disease; FMDV: foot-and-mouth disease virus; IFIH1/MDA5: interferon induced with helicase C domain 1; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MAVS: mitochondrial antiviral signaling protein; MOI: multiplicity of infection; RETREG1/FAM134B: reticulophagy regulator 1; STING1: stimulator of interferon response cGAMP interactor 1; TCID50: 50% tissue culture infectious dose; XBP1: X-box binding protein 1.
Topics: Animals; Autophagy; Endoplasmic Reticulum Stress; Interferons; RNA; RNA Viruses
PubMed: 34338134
DOI: 10.1080/15548627.2021.1959086 -
Autophagy Apr 2022Until recently, the ubiquitin-proteasome system (UPS) and macroautophagy/autophagy were considered to be two independent systems that target proteins for degradation by...
Until recently, the ubiquitin-proteasome system (UPS) and macroautophagy/autophagy were considered to be two independent systems that target proteins for degradation by proteasomes or via lysosomes, respectively. Here, we report that TRIM44 (tripartite motif containing 44) is a novel link that connects the UPS system with the autophagy degradation pathway. Suppressing the UPS degradation pathway leads to TRIM44 upregulation, which further promotes aggregated protein clearance through the binding of K48 ubiquitin chains on proteins. TRIM44 expression activates autophagy via promoting SQSTM1/p62 oligomerization, which rapidly increases the rate of aggregate protein removal. Overall, our data reveal that TRIM44 is a newly identified link between the UPS system and the autophagy pathway. Delineating the cross-talk between these two degradation pathways may reveal new mechanisms of targeting aggregate-prone diseases, such as cancer and neurodegenerative disease.: 3-MA: 3-methyladenine; ACTB: actin beta; ATG5: autophagy related 5; BB: B-box domain; BECN1: beclin1; BM: bone marrow; CC: coiled-coil domain; CFTR: cystic fibrosis transmembrane conductance regulator; CON: control; CQ: chloroquine; DOX: doxycycline; DSP: dithiobis(succinimidly propionate); ER: endoplasmic reticulum; FI: fluorescence intensity; FL: full length; HIF1A/HIF-1#x3B1;: hypoxia inducible factor 1 subunit alpha; HSC: hematopoietic stem cells; HTT: huntingtin; KD: knockdown; KD-CON: knockdown construct control; MM: multiple myeloma; MTOR: mechanistic target of rapamycin kinase; NP-40: nonidet P-40; NFE2L2/NRF2: nuclear factor, erythroid 2 like 2; OE: overexpression; OE-CON: overexpression construct control; PARP: poly (ADP-ribose) polymerase; SDS: sodium dodecyl sulfate; SQSTM1/p62: sequestosome 1; Tet-on: tetracycline; TRIM44: tripartite motif containing 44; UPS: ubiquitin-proteasome system; ZF: zinc-finger.
Topics: Autophagy; Humans; Intracellular Signaling Peptides and Proteins; Macroautophagy; Neurodegenerative Diseases; Proteasome Endopeptidase Complex; Sequestosome-1 Protein; Tripartite Motif Proteins; Ubiquitin
PubMed: 34382902
DOI: 10.1080/15548627.2021.1956105 -
Autophagy Aug 2021TMEM41B and VMP1, two endoplasmic reticulum (ER)-resident transmembrane proteins, play important roles in regulating the formation of lipid droplets (LDs), autophagy... (Review)
Review
TMEM41B and VMP1, two endoplasmic reticulum (ER)-resident transmembrane proteins, play important roles in regulating the formation of lipid droplets (LDs), autophagy initiation, and viral infection. However, the biochemical functions of TMEM41B and VMP1 are unclear. A lipids distribution screen suggested TMEM41B and VMP1 are critical to the normal distribution of cholesterol and phosphatidylserine. Biochemical analyses unveiled that TMEM41B and VMP1 have scramblase activity. These findings shed light on the mechanism by which TMEM41B and VMP1 regulate LD formation, lipids distribution, macroautophagy, and viral infection.
Topics: Animals; Autophagosomes; Autophagy; Humans; Macroautophagy; Membrane Proteins; Phospholipid Transfer Proteins
PubMed: 34074213
DOI: 10.1080/15548627.2021.1937898 -
Cells Jan 2021Ubiquitin-proteasome and lysosome-autophagy are the two main cellular degradation systems controlling cellular homeostasis in eukaryotes [...].
Ubiquitin-proteasome and lysosome-autophagy are the two main cellular degradation systems controlling cellular homeostasis in eukaryotes [...].
Topics: Autophagy; Plants
PubMed: 33478039
DOI: 10.3390/cells10010194