17-AAG-Induced Activation of the Autophagic Pathway in Leishmania Is Associated with Parasite Death

The heat shock protein 90 (Hsp90) is thought to be an excellent drug target against parasitic diseases. The leishmanicidal effect of an Hsp90 inhibitor, 17-N-allylamino-17-demethoxygeldanamycin (17-AAG), was previously demonstrated in both in vitro and in vivo models of cutaneous leishmaniasis. Parasite death was shown to occur in association with severe ultrastructural alterations in Leishmania, suggestive of autophagic activation. We hypothesized that 17-AAG treatment results in the abnormal activation of the autophagic pathway, leading to parasite death. To elucidate this process, experiments were performed using transgenic parasites with GFP-ATG8-labelled autophagosomes. Mutant parasites treated with 17-AAG exhibited autophagosomes that did not entrap cargo, such as glycosomes, or fuse with lysosomes. ATG5-knockout (Δatg5) parasites, which are incapable of forming autophagosomes, demonstrated lower sensitivity to 17-AAG-induced cell death when compared to wild-type (WT) Leishmania, further supporting the role of autophagy in 17-AAG-induced cell death. In addition, Hsp90 inhibition resulted in greater accumulation of ubiquitylated proteins in both WT- and Δatg5-treated parasites compared to controls, in the absence of proteasome overload. In conjunction with previously described ultrastructural alterations, herein we present evidence that treatment with 17-AAG causes abnormal activation of the autophagic pathway, resulting in the formation of immature autophagosomes and, consequently, incidental parasite death.

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Mitochondrion-Dependent Cell Death in TDP-43 Proteinopathies

Biomedicines ◽

10.3390/biomedicines9040376 ◽

2021 ◽

Vol 9 (4) ◽

pp. 376

Author(s):

Chantal B. Lucini ◽

Ralf J. Braun

Keyword(s):

Cell Death ◽

Oxygen Species ◽

In Vivo Models ◽

Dependent Cell ◽

Cell Death Mechanisms ◽

Sting Pathway ◽

Mitochondrial Membrane Permeabilization

In the last decade, pieces of evidence for TDP-43-mediated mitochondrial dysfunction in neurodegenerative diseases have accumulated. In patient samples, in vitro and in vivo models have shown mitochondrial accumulation of TDP-43, concomitantly with hallmarks of mitochondrial destabilization, such as increased production of reactive oxygen species (ROS), reduced level of oxidative phosphorylation (OXPHOS), and mitochondrial membrane permeabilization. Incidences of TDP-43-dependent cell death, which depends on mitochondrial DNA (mtDNA) content, is increased upon ageing. However, the molecular pathways behind mitochondrion-dependent cell death in TDP-43 proteinopathies remained unclear. In this review, we discuss the role of TDP-43 in mitochondria, as well as in mitochondrion-dependent cell death. This review includes the recent discovery of the TDP-43-dependent activation of the innate immunity cyclic GMP-AMP synthase/stimulator of interferon genes (cGAS/STING) pathway. Unravelling cell death mechanisms upon TDP-43 accumulation in mitochondria may open up new opportunities in TDP-43 proteinopathy research.

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Humanin is an endogenous activator of chaperone-mediated autophagy

The Journal of Cell Biology ◽

10.1083/jcb.201606095 ◽

2017 ◽

Vol 217 (2) ◽

pp. 635-647 ◽

Cited By ~ 33

Author(s):

Zhenwei Gong ◽

Inmaculada Tasset ◽

Antonio Diaz ◽

Jaime Anguiano ◽

Emir Tas ◽

...

Keyword(s):

Quality Control ◽

Cell Death ◽

Heat Shock Protein 90 ◽

Protective Effects ◽

Neuroprotective Effects ◽

Selective Degradation ◽

Cytosolic Side ◽

Chaperone Mediated Autophagy

Chaperone-mediated autophagy (CMA) serves as quality control during stress conditions through selective degradation of cytosolic proteins in lysosomes. Humanin (HN) is a mitochondria-associated peptide that offers cytoprotective, cardioprotective, and neuroprotective effects in vivo and in vitro. In this study, we demonstrate that HN directly activates CMA by increasing substrate binding and translocation into lysosomes. The potent HN analogue HNG protects from stressor-induced cell death in fibroblasts, cardiomyoblasts, neuronal cells, and primary cardiomyocytes. The protective effects are lost in CMA-deficient cells, suggesting that they are mediated through the activation of CMA. We identified that a fraction of endogenous HN is present at the cytosolic side of the lysosomal membrane, where it interacts with heat shock protein 90 (HSP90) and stabilizes binding of this chaperone to CMA substrates as they bind to the membrane. Inhibition of HSP90 blocks the effect of HNG on substrate translocation and abolishes the cytoprotective effects. Our study provides a novel mechanism by which HN exerts its cardioprotective and neuroprotective effects.

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HSP90 is a chaperone for DLK and is required for axon injury signaling

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1805351115 ◽

2018 ◽

Vol 115 (42) ◽

pp. E9899-E9908 ◽

Cited By ~ 10

Author(s):

Scott Karney-Grobe ◽

Alexandra Russo ◽

Erin Frey ◽

Jeffrey Milbrandt ◽

Aaron DiAntonio

Keyword(s):

Leucine Zipper ◽

Axon Regeneration ◽

Heat Shock Protein 90 ◽

Hsp90 Inhibitor ◽

Loss Of Function ◽

Hsp90 Inhibition ◽

Axon Injury ◽

Evolutionarily Conserved ◽

The Stability

Peripheral nerve injury induces a robust proregenerative program that drives axon regeneration. While many regeneration-associated genes are known, the mechanisms by which injury activates them are less well-understood. To identify such mechanisms, we performed a loss-of-function pharmacological screen in cultured adult mouse sensory neurons for proteins required to activate this program. Well-characterized inhibitors were present as injury signaling was induced but were removed before axon outgrowth to identify molecules that block induction of the program. Of 480 compounds, 35 prevented injury-induced neurite regrowth. The top hits were inhibitors to heat shock protein 90 (HSP90), a chaperone with no known role in axon injury. HSP90 inhibition blocks injury-induced activation of the proregenerative transcription factor cJun and several regeneration-associated genes. These phenotypes mimic loss of the proregenerative kinase, dual leucine zipper kinase (DLK), a critical neuronal stress sensor that drives axon degeneration, axon regeneration, and cell death. HSP90 is an atypical chaperone that promotes the stability of signaling molecules. HSP90 and DLK show two hallmarks of HSP90–client relationships: (i) HSP90 binds DLK, and (ii) HSP90 inhibition leads to rapid degradation of existing DLK protein. Moreover, HSP90 is required for DLK stability in vivo, where HSP90 inhibitor reduces DLK protein in the sciatic nerve. This phenomenon is evolutionarily conserved in Drosophila. Genetic knockdown of Drosophila HSP90, Hsp83, decreases levels of Drosophila DLK, Wallenda, and blocks Wallenda-dependent synaptic terminal overgrowth and injury signaling. Our findings support the hypothesis that HSP90 chaperones DLK and is required for DLK functions, including proregenerative axon injury signaling.

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The HSP90 inhibitor Onalespib exerts synergistic anti-cancer effects when combined with radiotherapy: an in vitro and in vivo approach

Scientific Reports ◽

10.1038/s41598-020-62293-4 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 2

Author(s):

Diana Spiegelberg ◽

Andris Abramenkovs ◽

Anja Charlotte Lundgren Mortensen ◽

Sara Lundsten ◽

Marika Nestor ◽

...

Keyword(s):

Tumor Growth ◽

External Beam Radiotherapy ◽

Heat Shock Protein 90 ◽

Hsp90 Inhibitor ◽

Control Group ◽

A431 Cells ◽

Anti Cancer ◽

Client Proteins

AbstractOncogenic client-proteins of the chaperone Heat shock protein 90 (HSP90) insure unlimited tumor growth and are involved in resistance to chemo- and radiotherapy. The HSP90 inhibitor Onalespib initiates the degradation of oncoproteins, and might also act as a radiosensitizer. The aim of this study was therefore to evaluate the efficacy of Onalespib in combination with external beam radiotherapy in an in vitro and in vivo approach. Onalespib downregulated client proteins, lead to increased apoptosis and caused DNA-double-strands. Monotherapy and combination with radiotherapy reduced colony formation, proliferation and migration assessed in radiosensitive HCT116 and radioresistant A431 cells. In vivo, a minimal treatment regimen for 3 consecutive days of Onalespib (3 × 10 mg/kg) doubled survival, whereas Onalespib with radiotherapy (3 × 2 Gy) caused a substantial delay in tumor growth and prolonged the survival by a factor of 3 compared to the HCT116 xenografted control group. Our results demonstrate that Onalespib exerts synergistic anti-cancer effects when combined with radiotherapy, most prominent in the radiosensitive cell models. We speculate that the depletion and downregulation of client proteins involved in signalling, migration and DNA repair mechanisms is the cause. Thus, individually, or in combination with radiotherapy Onalespib inhibits tumor growth and has the potential to improve radiotherapy outcomes, prolonging the overall survival of cancer patients.

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Ganetespib (STA-9090), a Nongeldanamycin HSP90 Inhibitor, Has Potent Antitumor Activity in In Vitro and In Vivo Models of Non–Small Cell Lung Cancer

Clinical Cancer Research ◽

10.1158/1078-0432.ccr-11-2967 ◽

2012 ◽

Vol 18 (18) ◽

pp. 4973-4985 ◽

Cited By ~ 93

Author(s):

Takeshi Shimamura ◽

Samanthi A. Perera ◽

Kevin P. Foley ◽

Jim Sang ◽

Scott J. Rodig ◽

...

Keyword(s):

Lung Cancer ◽

Antitumor Activity ◽

Small Cell Lung Cancer ◽

Cell Lung Cancer ◽

Hsp90 Inhibitor ◽

Small Cell ◽

Small Cell Lung ◽

In Vivo Models

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Mineralocorticoid receptor degradation is promoted by Hsp90 inhibition and the ubiquitin-protein ligase CHIP

AJP Renal Physiology ◽

10.1152/ajprenal.00285.2010 ◽

2010 ◽

Vol 299 (6) ◽

pp. F1462-F1472 ◽

Cited By ~ 29

Author(s):

Nourdine Faresse ◽

Dorothée Ruffieux-Daidie ◽

Mélanie Salamin ◽

Celso E. Gomez-Sanchez ◽

Olivier Staub

Keyword(s):

Mineralocorticoid Receptor ◽

Nuclear Translocation ◽

Heat Shock Protein 90 ◽

Hsp90 Inhibition ◽

Interacting Protein ◽

Ubiquitin Protein Ligase ◽

The Stability ◽

Benzoquinone Ansamycin

The mineralocorticoid receptor (MR) plays a crucial role in the regulation of Na+ balance and blood pressure, as evidenced by gain of function mutations in the MR of hypertensive families. In the kidney, aldosterone binds to the MR, induces its nuclear translocation, and promotes a transcriptional program leading to increased transepithelial Na+ transport via the epithelial Na+ channel. In the unliganded state, MR is localized in the cytosol and part of a multiprotein complex, including heat shock protein 90 (Hsp90), which keeps it ligand-binding competent. 17-Allylamino-17-demethoxygeldanamycin (17-AAG) is a benzoquinone ansamycin antibiotic that binds to Hsp90 and alters its function. We investigated whether 17-AAG affects the stability and transcriptional activity of MR and consequently Na+ reabsorption by renal cells. 17-AAG treatment lead to reduction of MR protein level in epithelial cells in vitro and in vivo, thereby interfering with aldosterone-dependent transcription. Moreover, 17-AAG inhibited aldosterone-induced Na+ transport, possibly by interfering with MR availability for the ligand. Finally, we identified the ubiquitin-protein ligase, COOH terminus of Hsp70-interacting protein, as a novel partner of the cytosolic MR, which is responsible for its polyubiquitylation and proteasomal degradation in presence of 17-AAG. In conclusion, 17-AAG may represent a novel pharmacological tool to interfere with Na+ reabsorption and hypertension.

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3.235 ISOTHIOCYANATES PROTECT AGAINST DOPAMINERGIC CELL DEATH IN IN VITRO AND IN VIVO MODELS OF PARKINSON'S DISEASE

Parkinsonism & Related Disorders ◽

10.1016/s1353-8020(11)70907-5 ◽

2012 ◽

Vol 18 ◽

pp. S212

Author(s):

F. Morroni ◽

P. Hrelia ◽

C. Bolondi ◽

G. Cantelli-Forti ◽

A. Tarozzi

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Cell Death ◽

In Vivo Models ◽

Dopaminergic Cell

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Paradoxical Effects of Microbial-Derived Butyrate: The Influences on Colonic Wnt/β-catenin Signaling and Cell Kinetics in In Vitro and In Vivo Models

Current Developments in Nutrition ◽

10.1093/cdn/nzaa044_032 ◽

2020 ◽

Vol 4 (Supplement_2) ◽

pp. 333-333

Author(s):

Ting-chun Lin ◽

Leah Healey ◽

Anand Soorneedi ◽

Jinchao Li ◽

Matthew Moore ◽

...

Keyword(s):

Cell Death ◽

Epithelial Cells ◽

Wnt Signaling ◽

Cancer Cells ◽

Cell Kinetics ◽

Dietary Factors ◽

In Vivo Models ◽

Genetic Components

Abstract Objectives Butyrate is considered as an important mediator in the complex etiology of colorectal cancer (CRC) that integrates gut microbiota with dietary factors and genetic components. However, how microbial-derived butyrate mediates colonic tumorigenesis remains unclear, with contradictory results from only limited experimental studies. Methods In current studies, we examined the fecal concentration of butyrate in high and low fat-fed animals and its associations with Wnt-signaling and cell kinetics in the in vivo normal epithelial cells. We further examined the influence butyrate and its receptor gene, Free Fatty Acid Receptor 2 (FFAR2), on those molecular parameters in the in vitro Caco-2 cancer cells. Results Our results showed a diminished level of fecal butyrate concentration in the high fat-fed animals, and in parallel with it are the increased Wnt/β-catenin signaling, indicated by increased active β-catenin and Wnt-signaling downstream gene expressions (p < 0.05), and altered cell kinetics, manifested by increased Ki-67 and decreased apoptosis. Whereas the results from the Caco-2 cancer cells demonstrated that the addition of butyrate surprisingly increased Wnt-signaling (p < 0.05), but was associated with cell death (p < 0.05), and the knockdown of FFAR2 by siRNA reversed the effect of butyrate on Wnt/β-catenin signaling and cell death (p < 0.05). Conclusions These paradoxical results demonstrated that butyrate may have disparate effects on tumorigenesis, depending on whether it is exerting a direct effect on normal or tumor epithelial cells, and other genetic or environmental factors. This study provided critical evidence to inform the necessity to wisely apply butyrate for cancer protection and to avoid its potential cancer-promoting effect in other circumstances. Funding Sources This project was supported by the US Department of Agriculture Hatch funding (1,013,548).

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