A Novel Hsp90 Inhibitor Activates Compensatory Heat Shock Protein Responses and Autophagy and Alleviates Mutant A53T<i>α</i>-Synuclein Toxicity

Xiong, Rui; Zhou, Wenbo; Siegel, David; Kitson, Russell R. A.; Freed, Curt R.; Moody, Christopher J.; Ross, David

doi:10.1124/mol.115.101451

Cited by 29 publications

(19 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By measuring LC3-II levels as a functional reporter of autophagy [48, 49], we first, transiently transfected SKBR3 with GFP-LC3 for 18 hours and scored by immunofluorescence the number of LC3 dots under different treatment conditions. We found that GA treatment reduced the number of LC3-II dots within cells (Figure 8A-8C), suggesting that HSP90 inhibition suppresses autophagy in contrast to previous studies in different experimental settings [50, 51]. To assess whether the LC3-II reduction resulted from either decreased autophagosomes synthesis, or from an increased degradation, we evaluated the autophagic flux in the presence of Baf, that is known to block autophagosome degradation [49, 52].…”

Section: Resultsmentioning

confidence: 87%

Identification of an HSP90 modulated multi-step process for ERBB2 degradation in breast cancer cells

et al. 2016

View full text Add to dashboard Cite

The receptor tyrosine kinase ERBB2 interacts with HSP90 and is overexpressed in aggressive breast cancers. Therapeutic HSP90 inhibitors, i.e. Geldanamycin (GA), target ERBB2 to degradation. We have previously shown that HSP90 is responsible for the missorting of recycling ERBB2 to degradation compartments. In this study, we used biochemical, immunofluorescence and electron microscopy techniques to demonstrate that in SKBR3 human breast cancer cells, GA strongly induces polyubiquitination and internalization of the full-length p185-ERBB2, and promotes its cleavage, with the formation of a p116-ERBB2 form in EEA1-positive endosomes (EE). p116-ERBB2 corresponds to a non-ubiquitinated, signaling-impaired, membrane-bound fragment, which is readily sorted to lysosomes and degraded. To define the sequence of events leading to p116-ERBB2 degradation, we first blocked the EE maturation/trafficking to late endosomes/lysosomes with wortmannin, and found an increase in GA-dependent formation of p116-ERBB2; we then inhibited the proteasome activity with MG-132 or lactacystin, and observed an efficient block of p185-ERBB2 cleavage, and its accumulation in EE, suggesting that p185-ERBB2 polyubiquitination is necessary for proteasome-dependent p116-ERBB2 generation occurring in EE. As polyubiquitination has also been implicated in autophagy-mediated degradation of ERBB2 under different experimental conditions, we exploited this possibility and demonstrate that GA strongly inhibits early autophagy, and reduces the levels of the autophagy markers atg5-12 and LC3-II, irrespective of GA-induced ERBB2 polyubiquitination, ruling out a GA-dependent autophagic degradation of ERBB2. In conclusion, we propose that HSP90 inhibition fosters ERBB2 polyubiquitination and proteasome-dependent generation of a non-ubiquitinated and inactive p116-ERBB2 form in EE, which is trafficked from altered EE to lysosomes.

show abstract

Section: Resultsmentioning

confidence: 87%

Identification of an HSP90 modulated multi-step process for ERBB2 degradation in breast cancer cells

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Previous studies that reported induction of autophagy by HSP90 inhibition relied mainly on accumulation of LC3-II, the ratio of LC3-II:LC3-I (as assessed by immunoblotting), and/or on an enhanced LC3 punctate appearance in treated cells. [46][47][48][49] Those studies did not monitor for autophagic flux, or incorrectly interpreted results obtained in the presence of lysosomal inhibition. 32,49 The autophagic repression documented in this study, is mediated by the downregulation of ATG7, and is demonstrated by both autophagy-specific assays and general measures of lysosomal activity.…”

Section: Discussionmentioning

confidence: 99%

HSP90 inhibition targets autophagy and induces a CASP9-dependent resistance mechanism in NSCLC

et al. 2018

View full text Add to dashboard Cite

Macroautophagy/autophagy has emerged as a resistance mechanism to anticancer drug treatments that induce metabolic stress. Certain tumors, including a subset of KRAS-mutant NSCLCs have been shown to be addicted to autophagy, and potentially vulnerable to autophagy inhibition. Currently, autophagy inhibition is being tested in the clinic as a therapeutic component for tumors that utilize this degradation process as a drug resistance mechanism. The current study provides evidence that HSP90 (heat shock protein 90) inhibition diminishes the expression of ATG7, thereby impeding the cellular capability of mounting an effective autophagic response in NSCLC cells. Additionally, an elevation in the expression level of CASP9 (caspase 9) prodomain in KRAS-mutant NSCLC cells surviving HSP90 inhibition appears to serve as a cell survival mechanism. Initial characterization of this survival mechanism suggests that the altered expression of CASP9 is mainly ATG7 independent; it does not involve the apoptotic activity of CASP9; and it localizes to a late endosomal and pre-lysosomal phase of the degradation cascade. HSP90 inhibitors are identified here as a pharmacological approach for targeting autophagy via destabilization of ATG7, while an induced expression of CASP9, but not its apoptotic activity, is identified as a resistance mechanism to the cellular stress brought about by HSP90 inhibition.

show abstract

“…HSP90 has been recently identified as the predominant chaperone implicated in α-synuclein-induced PD pathologies [36,37], which could prevent α-synuclein misfolding, oligomerization, and aggregation to suppress α-synuclein misfolding-induced PD toxicity [38]. In addition, HSP90 could regulate the proliferative and senescent client proteins [14], including PI3K, AKT, MAPKs, CDK4, Cyclin D1, and VEGF, which also indicated that HSP90 played an important role in the PD [24,25,38,39].…”

Section: Discussionmentioning

confidence: 99%

“…In addition, HSP90 could regulate the proliferative and senescent client proteins [14], including PI3K, AKT, MAPKs, CDK4, Cyclin D1, and VEGF, which also indicated that HSP90 played an important role in the PD [24,25,38,39]. Quantitative proteomics technique is a reliable and precise method to predict the disease-specific targets and underlying mechanism [21].…”

Section: Discussionmentioning

confidence: 99%

Uncaria rhynchophylla Ameliorates Parkinson’s Disease by Inhibiting HSP90 Expression: Insights from Quantitative Proteomics

Lan

Zhou

Liu

et al. 2018

Cell Physiol Biochem

View full text Add to dashboard Cite

Background/Aims: Uncaria rhynchophylla, known as “Gou-teng”, is a traditional Chinese medicine (TCM) used to extinguish wind, clear heat, arrest convulsions, and pacify the liver. Although U. rhynchophylla has a long history of being often used to treat central nervous system (CNS) diseases, its efficacy and potential mechanism are still uncertain. This study investigated neuroprotective effect and the underlying mechanism of U. rhynchophylla extract (URE) in MPP⁺-induced SH-SY5Y cells and MPTP-induced mice. Methods: MPP⁺-induced SH-SY5Y cells and MPTP-induced mice were used to established Parkinson’s disease (PD) models. Quantitative proteomics and bioinformatics were used to uncover proteomics changes of URE. Western blotting was used to validate main differentially expressed proteins and test HSP90 client proteins (apoptosis-related, autophagy-related, MAPKs, PI3K, and AKT proteins). Flow cytometry and JC-1 staining assay were further used to confirm the effect of URE on MPP⁺-induced apoptosis in SH-SY5Y cells. Gait analysis was used to detect the behavioral changes in MPTP-induced mice. The levels of dopamine (DA) and their metabolites were examined in striatum (STR) by HPLC-EC. The positive expression of tyrosine hydroxylase (TH) was detected by immunohischemical staining and Western blotting. Results: URE dose-dependently increased the cell viability in MPP⁺-induced SH-SY5Y cells. Quantitative proteomics and bioinformatics results confirmed that HSP90 was an important differentially expressed protein of URE. URE inhibited the expression of HSP90, which further reversed MPP⁺-induced cell apoptosis and autophagy by increasing the expressions of Bcl-2, Cyclin D1, p-ERK, p-PI3K p85, PI3K p110α, p-AKT, and LC3-I and decreasing cleaved caspase 3, Bax, p-JNK, p-p38, and LC3-II. URE also markedly decreased the apoptotic ratio and elevated mitochondrial transmembrane potential (DΨ_m). Furthermore, URE treatment ameliorated behavioral impairments, increased the contents of DA and its metabolites and elevated the positive expressions of TH in SN and STR as well as the TH protein. Conclusions: URE possessed the neuroprotective effect in vivo and in vitro, regulated MAPK and PI3K-AKT signal pathways, and inhibited the expression of HSP90. U. rhynchophylla has potentials as therapeutic agent in PD treatment.

show abstract

A Novel Hsp90 Inhibitor Activates Compensatory Heat Shock Protein Responses and Autophagy and Alleviates Mutant A53Tα-Synuclein Toxicity

Cited by 29 publications

References 53 publications

Identification of an HSP90 modulated multi-step process for ERBB2 degradation in breast cancer cells

Identification of an HSP90 modulated multi-step process for ERBB2 degradation in breast cancer cells

HSP90 inhibition targets autophagy and induces a CASP9-dependent resistance mechanism in NSCLC

Uncaria rhynchophylla Ameliorates Parkinson’s Disease by Inhibiting HSP90 Expression: Insights from Quantitative Proteomics

Contact Info

Product

Resources

About