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Member Publications
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Dec 27, 2024
Lysosomal damage due to cholesterol accumulation triggers immunogenic cell death
Karla Alvarez-Valadez, Allan Sauvat, Julien Diharce, Marion Leduc, Gautier Stoll, Lionel Guittat, Flavia Lambertucci, Juliette Paillet, Omar Motino, Lucille Ferret, Alexandra Muller, Sabrina Forveille, Maria Chiara Maiuri, Oliver Kepp, Alexandre G de Brevern, Harald Wodrich, Jonathan G Pol, Guido Kroemer, and Mojgan Djavaheri-Mergny
Cholesterol serves as a vital lipid that regulates numerous physiological processes. Nonetheless, its role in regulating cell death processes remains incompletely understood. In this study, we investigated the role of cholesterol trafficking in immunogenic cell death. Through cell-based drug screening, we identified two antidepressants, sertraline and indatraline, as potent inducers of the nuclear translocation of TFEB (transcription factor EB). Activation of TFEB was mediated through the autophagy-independent lipidation of MAP1LC3/LC3 (microtubule associated protein 1 light chain 3). Both compounds promoted cholesterol accumulation within lysosomes, resulting in lysosomal membrane permeabilization, disruption of autophagy and cell death that could be reversed by cholesterol depletion. Molecular docking analysis indicated that sertraline and indatraline have the potential to inhibit cholesterol binding to the lysosomal cholesterol transporters, NPC1 (NPC intracellular cholesterol transporter 1) and NPC2. This inhibitory effect might be further enhanced by the upregulation of NPC1 and NPC2 expression by TFEB. Both antidepressants also upregulated PLA2G15 (phospholipase A2 group XV), an enzyme that elevates lysosomal cholesterol. In cancer cells, sertraline and indatraline elicited immunogenic cell death, converting dying cells into prophylactic vaccines that were able to confer protection against tumor growth in mice. In a therapeutic setting, a single dose of each compound was sufficient to significantly reduce the outgrowth of established tumors in a T-cell-dependent manner. These results identify sertraline and indatraline as immunostimulatory agents for cancer treatment. More generally, this research shed light on novel therapeutic avenues harnessing lysosomal cholesterol transport to regulate immunogenic cell death.
Nov 9, 2024
Curcumin prevents cadmium or H2O2-induced oxidative stress via Nrf2/ ARE signaling and autophagy in myeloid cells
Maria Russo, Annamaria Di Giacomo, Federica Fiore, Carmela Spagnuolo, Virginia Carbone, Paola Minasi, Gian Luigi Russo
The evidence linking high levels of environmental pollutants to chronic degenerative diseases is alarming, with heavy metals (HM) identified as a key factor. Research suggests that certain phytochemicals in the diet can reduce HM levels and mitigate their adverse health effects.Curcumin (Curc), a natural polyphenol, is particularly effective in protecting against Cadmium (Cd) toxicity. The present study demonstrates that preincubation with low doses of Curc (1 μM) in differentiated HL-60 and K-562 human myeloid cells can significantly protect against cytotoxicity induced by Cd and or hydrogen peroxide (H2O2). Curc reduced the increased levels of Reactive Oxygen Species (ROS) generated by Cd or H2O2 by inducing a protective form of autophagy, a relevant process for the cellular homeostasis. Curc activated mild oxidative stress that triggers the expression of Nrf2-dependent transcripts, such as Nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent transcripts, such as human NADPH Quinone Oxidoreductase 1 (NQO1) and Heme Oxygenase (HO1). The potential chemopreventive effects of Curc against redox stress have been strengthened by the observation that free and unmetabolized Curc is detectable inside the cells after 5 min of treatment, and its presence parallels with increased levels of intracellular Glutathione (GSH). These findings suggest that supplementation with Curc in the form of nutraceuticals may represent a promising way to protect people living in highly polluted areas against the adverse effects of HM contaminants.
Jun 18, 2024
Calorie restriction and calorie-restriction mimetics activate chaperone-mediated autophagy
Maryam Jafari, Adrián Macho-González, Antonio Diaz, Kristen Lindenau, Olaya Santiago-Fernández, Mei Zeng, Ashish C. Massey, Rafael de Cabo, Susmita Kaushik, and Ana Maria Cuervo
Chaperone-mediated autophagy (CMA) is part of the mammalian cellular proteostasis network that ensures protein quality control, maintenance of proteome homeostasis, and proteome changes required for the adaptation to stress. Loss of proteostasis is one of the hallmarks of aging. CMA decreases with age in multiple rodent tissues and human cell types. A decrease in lysosomal levels of the lysosome-associated membrane protein type 2A (LAMP2A), the CMA receptor, has been identified as a main reason for declined CMA in aging. Here, we report constitutive activation of CMA with calorie restriction (CR), an intervention that extends healthspan, in old rodent livers and in an in vitro model of CR with cultured fibroblasts. We found that CR-mediated upregulation of CMA is due to improved stability of LAMP2A at the lysosome membrane. We also explore the translational value of our observations using calorie-restriction mimetics (CRMs), pharmacologically active substances that reproduce the biochemical and functional effects of CR. We show that acute treatment of old mice with CRMs also robustly activates CMA in several tissues and that this activation is required for the higher resistance to lipid dietary challenges conferred by treatment with CRMs. We conclude that part of the beneficial effects associated with CR/CRMs could be a consequence of the constitutive activation of CMA mediated by these interventions.
May 6, 2024
Vaccinia virus subverts xenophagy through phosphorylation and nuclear targeting of p62
Melanie Krause, Jerzy Samolej, Artur Yakimovich, Janos Kriston-Vizi, Moona Huttunen, Samuel Lara-Reyna, Eva-Maria Frickel, and Jason Mercer.
Autophagy is an essential degradation program required for cell homeostasis. Among its functions is the engulfment and destruction of cytosolic pathogens, termed xenophagy. Not surprisingly, many pathogens use various strategies to circumvent or co-opt autophagic degradation. For poxviruses, it is known that infection activates autophagy, which however is not required for successful replication. Even though these complex viruses replicate exclusively in the cytoplasm, autophagy-mediated control of poxvirus infection has not been extensively explored. Using the prototypic poxvirus, vaccinia virus (VACV), we show that overexpression of the xenophagy receptors p62, NDP52, and Tax1Bp1 restricts poxvirus infection. While NDP52 and Tax1Bp1 were degraded, p62 initially targeted cytoplasmic virions before being shunted to the nucleus. Nuclear translocation of p62 was dependent upon p62 NLS2 and correlated with VACV kinase mediated phosphorylation of p62 T269/S272. This suggests that VACV targets p62 during the early stages of infection to avoid destruction and further implies that poxviruses exhibit multi-layered control of autophagy to facilitate cytoplasmic replication.
Apr 9, 2024
Alcohol-induced Golgiphagy is triggered by the downregulation of Golgi GTPase RAB3D
Amanda J. Macke, Taylor E. Divita, Artem N. Pachikov, Sundararajan Mahalingam, Ramesh Bellamkonda, Karuna Rasineni, Carol A. Casey & Armen Petrosyan
The development of alcohol-associated liver disease (ALD) is associated with disorganized Golgi apparatus and accelerated phagophore formation. While Golgi membranes may contribute to phagophores, association between Golgi alterations and macroautophagy/autophagy remains unclear. GOLGA4/p230 (golgin A4), a dimeric Golgi matrix protein, participates in phagophore formation, but the underlying mechanism is elusive. Our prior research identified ethanol (EtOH)-induced Golgi scattering, disrupting intra-Golgi trafficking and depleting RAB3D GTPase from the trans-Golgi. Employing various techniques, we analyzed diverse cellular and animal models representing chronic and chronic/binge alcohol consumption. In trans-Golgi of non-treated hepatocytes, we found a triple complex formed between RAB3D, GOLGA4, and MYH10/NMIIB (myosin, heavy polypeptide 10, non-muscle). However, EtOH-induced RAB3D downregulation led to MYH10 segregation from the Golgi, accompanied by Golgi fragmentation and tethering of the MYH10 isoform, MYH9/NMIIA, to dispersed Golgi membranes. EtOH-activated autophagic flux is evident through increased WIPI2 recruitment to the Golgi, phagophore formation, enhanced LC3B lipidation, and reduced SQSTM1/p62. Although GOLGA4 dimerization and intra-Golgi localization are unaffected, loss of RAB3D leads to an extension of the cytoplasmic N terminal domain of GOLGA4, forming GOLGA4-positive phagophores. Autophagy inhibition by hydroxychloroquine (HCQ) prevents alcohol-mediated Golgi disorganization, restores distribution of ASGR (asialoglycoprotein receptor), and mitigates COL (collagen) deposition and steatosis. In contrast to short-term exposure to HCQ, extended co-treatment with both EtOH and HCQ results in the depletion of LC3B protein via proteasomal degradation. Thus, (a) RAB3D deficiency and GOLGA4 conformational changes are pivotal in MYH9-driven, EtOH-mediated Golgiphagy, and (b) HCQ treatment holds promise as a therapeutic approach for alcohol-induced liver injury.
Mar 21, 2024
An LIR motif in the Rift Valley fever virus NSs protein is critical for the interaction with LC3 family members and inhibition of autophagy
Kaylee Petraccione, Mohamed G. H. Ali, Normand Cyr, Haytham M. Wahba, Timothy Stocker, Maryna Akhrymuk, Ivan Akhrymuk, Lauren Panny, Nicole Bracci, Raphaël Cafaro, Danuta Sastre, Andrew Silberfarb, Paul O’Maille, James Omichinski, Kylene Kehn-Hall
Rift Valley fever virus (RVFV) is a viral zoonosis that causes severe disease in ruminants and humans. The nonstructural small (NSs) protein is the primary virulence factor of RVFV that suppresses the host’s antiviral innate immune response. Bioinformatic analysis and AlphaFold structural modeling identified four putative LC3-interacting regions (LIR) motifs (NSs 1–4) in the RVFV NSs protein, which suggest that NSs interacts with the host LC3-family proteins. Using, isothermal titration calorimetry, X-ray crystallography, co-immunoprecipitation, and co-localization experiments, the C-terminal LIR motif (NSs4) was confirmed to interact with all six human LC3 proteins. Phenylalanine at position 261 (F261) within NSs4 was found to be critical for the interaction of NSs with LC3, retention of LC3 in the nucleus, as well as the inhibition of autophagy in RVFV infected cells. These results provide mechanistic insights into the ability of RVFV to overcome antiviral autophagy through the interaction of NSs with LC3 proteins.
Jan 27, 2024
Mitophagy curtails cytosolic mtDNA-dependent activation of cGAS/STING inflammation during aging
Juan Ignacio Jiménez-Loygorri, Beatriz Villarejo-Zori, Álvaro Viedma-Poyatos, Juan Zapata-Muñoz, Rocío Benítez-Fernández, María Dolores Frutos-Lisón, Francisco A. Tomás-Barberán, Juan Carlos Espín, Estela Area-Gómez, Aurora Gomez-Duran & Patricia Boya
Macroautophagy decreases with age, and this change is considered a hallmark of the aging process. It remains unknown whether mitophagy, the essential selective autophagic degradation of mitochondria, also decreases with age. In our analysis of mitophagy in multiple organs in the mito-QC reporter mouse, mitophagy is either increased or unchanged in old versus young mice. Transcriptomic analysis shows marked upregulation of the type I interferon response in the retina of old mice, which correlates with increased levels of cytosolic mtDNA and activation of the cGAS/STING pathway. Crucially, these same alterations are replicated in primary human fibroblasts from elderly donors. In old mice, pharmacological induction of mitophagy with urolithin A attenuates cGAS/STING activation and ameliorates deterioration of neurological function. These findings point to mitophagy induction as a strategy to decrease age-associated inflammation and increase healthspan.
Sep 5, 2023
Astrovirus replication is dependent on induction of double-membrane vesicles through a PI3K-dependent, LC3-independent pathway
Theresa Bub, Virginia Hargest, Shaoyuan Tan, Maria Smith, Ana Vazquez-Pagan, Tim Flerlage, Pamela Brigleb, Victoria Meliopoulos, Brett Lindenbach, Harish N. Ramanathan, Valerie Cortez, Jeremy Chase Crawford, Stacey Schultz-Cherry
Human astrovirus is a positive-sense, single-stranded RNA virus. Astrovirus infection causes gastrointestinal symptoms and can lead to encephalitis in immunocompromised patients. Positive-strand RNA viruses typically utilize host intracellular membranes to form replication organelles, which are potential antiviral targets. Many of these replication organelles are double-membrane vesicles (DMVs). Here, we show that astrovirus infection leads to an increase in DMV formation through a replication-dependent mechanism that requires some early components of the autophagy machinery. Results indicate that the upstream class III phosphatidylinositol 3-kinase (PI3K) complex, but not LC3 conjugation machinery, is utilized in DMV formation. Both chemical and genetic inhibition of the PI3K complex lead to significant reduction in DMVs, as well as viral replication. Elucidating the role of autophagy machinery in DMV formation during astrovirus infection reveals a potential target for therapeutic intervention for immunocompromised patients.
Aug 24, 2023
Autophagy deficiency protects against ocular hypertension and neurodegeneration in experimental and spontaneous glaucoma mouse models
Angela Dixon, Myoung Sup Shim, April Nettesheim, Aislyn Coyne, Chien-Chia Su, Haiyan Gong & Paloma B. Liton
Glaucoma is a group of diseases that leads to chronic degeneration of retinal ganglion cell (RGC) axons and progressive loss of RGCs, resulting in vision loss. While aging and elevated intraocular pressure (IOP) have been identified as the main contributing factors to glaucoma, the molecular mechanisms and signaling pathways triggering RGC death and axonal degeneration are not fully understood. Previous studies in our laboratory found that overactivation of autophagy in DBA/2J::GFP-LC3 mice led to RGC death and optic nerve degeneration with glaucomatous IOP elevation. We found similar findings in aging GFP-LC3 mice subjected to chronic IOP elevation. Here, we further investigated the impact of autophagy deficiency on autophagy-deficient DBA/2J-Atg4bko and DBA/2J-Atg4b+/− mice, generated in our laboratory via CRISPR/Cas9 technology; as well as in Atg4bko mice subjected to the experimental TGFβ2 chronic ocular hypertensive model. Our data shows that, in contrast to DBA/2J and DBA/2J-Atg4b+/− littermates, DBA/2J-Atg4bko mice do not develop glaucomatous IOP elevation. Atg4b deficiency also protected against glaucomatous IOP elevation in the experimental TGFβ2 chronic ocular hypertensive model. Atg4 deletion did not compromise RGC or optic nerve survival in Atg4bko mice. Moreover, our results indicate a protective role of autophagy deficiency against RGC death and ON atrophy in the hypertensive DBA/2J-Atg4b+/− mice. Together, our data suggests a pathogenic role of autophagy activation in ocular hypertension and glaucoma.
Jul 20, 2023
Shear stress induces autophagy in Schlemm’s canal cells via primary cilia-mediated SMAD2/3 signaling pathway
Myoung Sup Shim, Angela Dixon, April Nettesheim, Kristin M. Perkumas, W. Daniel Stamer, Yang Sun and Paloma B. Liton
The Schlemm’s canal (SC) is a circular, lymphatic-like vessel located at the limbus of the eye that participates in the regulation of aqueous humor drainage to control intraocular pressure (IOP). Circumferential flow of aqueous humor within the SC lumen generates shear stress, which regulates SC cell behaviour. Using biochemical analysis and real-time live cell imaging techniques, we have investigated the activation of autophagy in SC cells by shear stress. We report, for the first time, the primary cilium (PC)-dependent activation of autophagy in SC cells in response to shear stress. Moreover, we identified PC-dependent shear stress-induced autophagy to be positively regulated by phosphorylation of SMAD2 in its linker and C-terminal regions. Additionally, SMAD2/3 signaling was found to transcriptionally activate LC3B, ATG5 and ATG7 in SC cells. Intriguingly, concomitant to SMAD2-dependent activation of autophagy, we also report here the activation of mTOR pathway, a classical autophagy inhibi-tor, in SC cells by shear stress. mTOR activation was found to also be dependent on the PC. Moreover, pharmacological inhibition of class I PI3K increased phosphorylation of SMAD2 at the linker and activated autophagy. Together, our data indicates an interplay between PI3K and SMAD2/3 signaling pathways in the regulation of PC-dependent shear stress-induced autophagy in SC cells.
Jul 18, 2023
Autophagy protein 5 controls flow-dependent endothelial functions
Pierre Nivoit, Thomas Mathivet, Junxi Wu, Yann Salemkour, Devanarayanan Siva Sankar, Véronique Baudrie, Jennifer Bourreau, Anne-Laure Guihot, Emilie Vessieres, Mathilde Lemitre, Cinzia Bocca, Jérémie Teillon, Morgane Le Gall, Anna Chipont, Estelle Robidel, Neeraj Dhaun, Eric Camerer, Pascal Reynier, Etienne Roux, Thierry Couffinhal, Patrick W. F. Hadoke, Jean-Sébastien Silvestre, Xavier Guillonneau, Philippe Bonnin, Daniel Henrion, Joern Dengjel, Pierre-Louis Tharaux & Olivia Lenoir
Dysregulated autophagy is associated with cardiovascular and metabolic diseases, where impaired flow-mediated endothelial cell responses promote cardiovascular risk. The mechanism by which the autophagy machinery regulates endothelial functions is complex. We applied multi-omics approaches and in vitro and in vivo functional assays to decipher the diverse roles of autophagy in endothelial cells. We demonstrate that autophagy regulates VEGF-dependent VEGFR signaling and VEGFR-mediated and flow-mediated eNOS activation. Endothelial ATG5 deficiency in vivo results in selective loss of flow-induced vasodilation in mesenteric arteries and kidneys and increased cerebral and renal vascular resistance in vivo. We found a crucial pathophysiological role for autophagy in endothelial cells in flow-mediated outward arterial remodeling, prevention of neointima formation following wire injury, and recovery after myocardial infarction. Together, these findings unravel a fundamental role of autophagy in endothelial function, linking cell proteostasis to mechanosensing.
Apr 21, 2023
Cell-autonomous immune dysfunction driven by disrupted autophagy in C9orf72-ALS iPSC-derived microglia contributes to neurodegeneration
Poulomi Banerjee, Arpan R Mehta, Raja S Nirujogi, James Cooper, Owen G James, Jyoti Nanda, James Longden, Karen Burr, Karina McDade, Andrea Salzinger, Evdokia Paza, Judith Newton, David Story, Suvankar Pal, Colin Smith, Dario R Alessi, Bhuvaneish T Selvaraj, Josef Priller, Siddharthan Chandran
Although microglial activation is widely found in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), the underlying mechanism(s) are poorly understood. Here, using human-induced pluripotent stem cell-derived microglia-like cells (hiPSC-MG) harboring the most common ALS/FTD mutation (C9orf72, mC9-MG), gene-corrected isogenic controls (isoC9-MG), and C9orf72 knockout hiPSC-MG (C9KO-MG), we show that reduced C9ORF72 protein is associated with impaired phagocytosis and an exaggerated immune response upon stimulation with lipopolysaccharide. Analysis of the C9ORF72 interactome revealed that C9ORF72 interacts with regulators of autophagy and functional studies showed impaired initiation of autophagy in mC9-MG and C9KO-MG. Coculture studies with motor neurons (MNs) demonstrated that the autophagy deficit in mC9-MG drives increased vulnerability of mC9-MNs to excitotoxic stimulus. Pharmacological activation of autophagy ameliorated both cell-autonomous functional deficits in hiPSC-MG and MN death in MG-MN coculture. Together, these findings reveal an important role for C9ORF72 in regulating immune homeostasis and identify dysregulation in myeloid cells as a contributor to neurodegeneration in ALS/FTD.
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