INCREASED HSP25 DRIVES THE TRANSITION FROM PROTEASOME TO AUTOPHAGY-MEDIATED DEGRADATION UNDER PROTEOTOXIC STRESS

Abstract Accumulation of protein aggregates are a common pathology in many neurodegenerative disorders. This accumulation may be due to a function decline in the protein homeostasis network known to occur during the aging process. Small heat shock proteins are a class of molecular chaperones that assist in protein folding and ameliorates the degradation activity of the proteasome and autolysosome thereby decreasing disease-associated aggregates. Prior work in rodents and C. elegans has shown expression levels of the small heat shock protein 25 (HSP25) correlates with maximum lifespan potential. Increased levels of HSP25 extends lifespan in a transgenic C. elegans model. This lifespan extension is dependent on skn-1 with evidence suggesting an enrichment in several skn-1-related pathways, such as lysosomal genes. Concomitantly, proteasome activity declines while autolysosome activity increases. This observation might suggest a switch from proteasome degradation to autophagy as the main driver of protein degradation in C. elegans in this transgenic model. To investigate if a reduction of proteasome function and elevated lysosomal gene activation during aging and under proteotoxic stress are modulated by HSP25 we have crossed our HSP25-transgenic worm with an aggregating and non-aggregating tau worm model. This work will elucidate a possible mechanism that explains the change in the protein degradation response pathways potentially modulated by HSP25 during increased protein misfolding.

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The noncanonical small heat shock protein HSP-17 from Caenorhabditis elegans is a selective protein aggregase

Journal of Biological Chemistry ◽

10.1074/jbc.ra119.011185 ◽

2020 ◽

Vol 295 (10) ◽

pp. 3064-3079 ◽

Cited By ~ 1

Author(s):

Manuel Iburg ◽

Dmytro Puchkov ◽

Irving U. Rosas-Brugada ◽

Linda Bergemann ◽

Ulrike Rieprecht ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Heat Shock ◽

Small Heat Shock Protein ◽

Independent Manner ◽

C Elegans ◽

Higher Eukaryotes ◽

Prolonged Heat ◽

Shock Proteins ◽

Excretory Organs

Small heat shock proteins (sHsps) are conserved, ubiquitous members of the proteostasis network. Canonically, they act as “holdases” and buffer unfolded or misfolded proteins against aggregation in an ATP-independent manner. Whereas bacteria and yeast each have only two sHsps in their genomes, this number is higher in metazoan genomes, suggesting a spatiotemporal and functional specialization in higher eukaryotes. Here, using recombinantly expressed and purified proteins, static light-scattering analysis, and disaggregation assays, we report that the noncanonical sHsp HSP-17 of Caenorhabditis elegans facilitates aggregation of model substrates, such as malate dehydrogenase (MDH), and inhibits disaggregation of luciferase in vitro. Experiments with fluorescently tagged HSP-17 under the control of its endogenous promoter revealed that HSP-17 is expressed in the digestive and excretory organs, where its overexpression promotes the aggregation of polyQ proteins and of the endogenous kinase KIN-19. Systemic depletion of hsp-17 shortens C. elegans lifespan and severely reduces fecundity and survival upon prolonged heat stress. HSP-17 is an abundant protein exhibiting opposing chaperone activities on different substrates, indicating that it is a selective protein aggregase with physiological roles in development, digestion, and osmoregulation.

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The heat-shock, or HSF1-mediated proteotoxic stress, response in cancer: from proteomic stability to oncogenesis

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2016.0525 ◽

2017 ◽

Vol 373 (1738) ◽

pp. 20160525 ◽

Cited By ~ 24

Author(s):

Chengkai Dai

Keyword(s):

Stress Response ◽

Heat Shock ◽

Heat Shock Proteins ◽

Protein Misfolding ◽

Heat Shock Factor 1 ◽

Growth And Survival ◽

Proteotoxic Stress ◽

Shock Proteins ◽

Misfolding Diseases

The heat-shock, or HSF1-mediated proteotoxic stress, response (HSR/HPSR) is characterized by induction of heat-shock proteins (HSPs). As molecular chaperones, HSPs facilitate the folding, assembly, transportation and degradation of other proteins. In mammals, heat shock factor 1 (HSF1) is the master regulator of this ancient transcriptional programme. Upon proteotoxic insults, the HSR/HPSR is essential to proteome homeostasis, or proteostasis, thereby resisting stress and antagonizing protein misfolding diseases and ageing. Contrasting with these benefits, an unexpected pro-oncogenic role of the HSR/HPSR is unfolding. Whereas HSF1 remains latent in primary cells without stress, it becomes constitutively activated within malignant cells, rendering them addicted to HSF1 for their growth and survival. Highlighting the HSR/HPSR as an integral component of the oncogenic network, several key pathways governing HSF1 activation by environmental stressors are causally implicated in malignancy. Importantly, HSF1 impacts the cancer proteome systemically. By suppressing tumour-suppressive amyloidogenesis, HSF1 preserves cancer proteostasis to support the malignant state, both providing insight into how HSF1 enables tumorigenesis and suggesting disruption of cancer proteostasis as a therapeutic strategy. This review provides an overview of the role of HSF1 in oncogenesis, mechanisms underlying its constitutive activation within cancer cells and its pro-oncogenic action, as well as potential HSF1-targeting strategies. This article is part of the theme issue ‘Heat shock proteins as modulators and therapeutic targets of chronic disease: an integrated perspective’.

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The Archaeal Small Heat Shock Protein Hsp17.6 Protects Proteins from Oxidative Inactivation

International Journal of Molecular Sciences ◽

10.3390/ijms22052591 ◽

2021 ◽

Vol 22 (5) ◽

pp. 2591

Author(s):

Pengfei Ma ◽

Jie Li ◽

Lei Qi ◽

Xiuzhu Dong

Keyword(s):

Heat Shock ◽

Polyacrylamide Gel Electrophoresis ◽

Sodium Dodecyl ◽

Small Heat Shock Protein ◽

Phase Cell ◽

Molecular Weights ◽

Oxidative Inactivation ◽

Methionine Residues ◽

Shock Proteins ◽

And Function

Small heat shock proteins (sHsps) are widely distributed among various types of organisms and function in preventing the irreversible aggregation of thermal denaturing proteins. Here, we report that Hsp17.6 from Methanolobus psychrophilus exhibited protection of proteins from oxidation inactivation. The overexpression of Hsp17.6 in Escherichia coli markedly increased the stationary phase cell density and survivability in HClO and H2O2. Treatments with 0.2 mM HClO or 10 mM H2O2 reduced malate dehydrogenase (MDH) activity to 57% and 77%, whereas the addition of Hsp17.6 recovered the activity to 70–90% and 86–100%, respectively. A similar effect for superoxide dismutase oxidation was determined for Hsp17.6. Non-reducing sodium dodecyl sulfate polyacrylamide gel electrophoresis assays determined that the Hsp17.6 addition decreased H2O2-caused disulfide-linking protein contents and HClO-induced degradation of MDH; meanwhile, Hsp17.6 protein appeared to be oxidized with increased molecular weights. Mass spectrometry identified oxygen atoms introduced into the larger Hsp17.6 molecules, mainly at the aspartate and methionine residues. Substitution of some aspartate residues reduced Hsp17.6 in alleviating H2O2- and HClO-caused MDH inactivation and in enhancing the E. coli survivability in H2O2 and HClO, suggesting that the archaeal Hsp17.6 oxidation protection might depend on an “oxidant sink” effect, i.e., to consume the oxidants in environments via aspartate oxidation

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Heat shock factor 2 is required for maintaining proteostasis against febrile-range thermal stress and polyglutamine aggregation

Molecular Biology of the Cell ◽

10.1091/mbc.e11-04-0330 ◽

2011 ◽

Vol 22 (19) ◽

pp. 3571-3583 ◽

Cited By ~ 37

Author(s):

Toyohide Shinkawa ◽

Ke Tan ◽

Mitsuaki Fujimoto ◽

Naoki Hayashida ◽

Kaoru Yamamoto ◽

...

Keyword(s):

Thermal Stress ◽

Heat Shock ◽

Protein Misfolding ◽

Reproductive Organs ◽

Heat Shock Factors ◽

Mild Heat ◽

Promising Therapeutic Target ◽

Αb Crystallin ◽

Shock Proteins ◽

Polyglutamine Protein

Heat shock response is characterized by the induction of heat shock proteins (HSPs), which facilitate protein folding, and non-HSP proteins with diverse functions, including protein degradation, and is regulated by heat shock factors (HSFs). HSF1 is a master regulator of HSP expression during heat shock in mammals, as is HSF3 in avians. HSF2 plays roles in development of the brain and reproductive organs. However, the fundamental roles of HSF2 in vertebrate cells have not been identified. Here we find that vertebrate HSF2 is activated during heat shock in the physiological range. HSF2 deficiency reduces threshold for chicken HSF3 or mouse HSF1 activation, resulting in increased HSP expression during mild heat shock. HSF2-null cells are more sensitive to sustained mild heat shock than wild-type cells, associated with the accumulation of ubiquitylated misfolded proteins. Furthermore, loss of HSF2 function increases the accumulation of aggregated polyglutamine protein and shortens the lifespan of R6/2 Huntington's disease mice, partly through αB-crystallin expression. These results identify HSF2 as a major regulator of proteostasis capacity against febrile-range thermal stress and suggest that HSF2 could be a promising therapeutic target for protein-misfolding diseases.

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hsp26 of Saccharomyces cerevisiae is related to the superfamily of small heat shock proteins but is without a demonstrable function.

Molecular and Cellular Biology ◽

10.1128/mcb.9.11.5265 ◽

1989 ◽

Vol 9 (11) ◽

pp. 5265-5271 ◽

Cited By ~ 59

Author(s):

R E Susek ◽

S L Lindquist

Keyword(s):

Saccharomyces Cerevisiae ◽

Heat Shock ◽

Heat Shock Protein ◽

Mutational Analysis ◽

Small Heat Shock Protein ◽

Major Effect ◽

Selfish Dna ◽

Dna Elements ◽

Cloned Gene ◽

Shock Proteins

Analysis of the cloned gene confirms that hsp26 of Saccharomyces cerevisiae is a member of the small heat shock protein superfamily. Previous mutational analysis failed to demonstrate any function for the protein. Further experiments presented here demonstrate that hsp26 has no obvious regulatory role and no major effect on thermotolerance. It is possible that the small heat shock protein genes originated as primitive viral or selfish DNA elements.

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Heat Shock Proteins in Alzheimer’s Disease: Role and Targeting

International Journal of Molecular Sciences ◽

10.3390/ijms19092603 ◽

2018 ◽

Vol 19 (9) ◽

pp. 2603 ◽

Cited By ~ 32

Author(s):

Claudia Campanella ◽

Andrea Pace ◽

Celeste Caruso Bavisotto ◽

Paola Marzullo ◽

Antonella Marino Gammazza ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Heat Shock ◽

Heat Shock Proteins ◽

Molecular Chaperones ◽

Protein Misfolding ◽

Point Of View ◽

Toxic Species ◽

Shock Proteins

Among diseases whose cure is still far from being discovered, Alzheimer’s disease (AD) has been recognized as a crucial medical and social problem. A major issue in AD research is represented by the complexity of involved biochemical pathways, including the nature of protein misfolding, which results in the production of toxic species. Considering the involvement of (mis)folding processes in AD aetiology, targeting molecular chaperones represents a promising therapeutic perspective. This review analyses the connection between AD and molecular chaperones, with particular attention toward the most important heat shock proteins (HSPs) as representative components of the human chaperome: Hsp60, Hsp70 and Hsp90. The role of these proteins in AD is highlighted from a biological point of view. Pharmacological targeting of such HSPs with inhibitors or regulators is also discussed.

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Single-molecule fluorescence-based approach reveals novel mechanistic insights into human small heat shock protein chaperone function

Journal of Biological Chemistry ◽

10.1074/jbc.ra120.015419 ◽

2020 ◽

pp. jbc.RA120.015419

Author(s):

Caitlin L Johnston ◽

Nicholas R Marzano ◽

Bishnu P Paudel ◽

George Wright ◽

Justin L.P. Benesch ◽

...

Keyword(s):

Heat Shock ◽

Single Molecule ◽

Small Heat Shock Protein ◽

Vital Role ◽

Misfolded Proteins ◽

Single Molecule Fluorescence ◽

Chaperone Function ◽

Αb Crystallin ◽

Client Proteins ◽

Shock Proteins

Small heat shock proteins (sHsps) are a family of ubiquitous intracellular molecular chaperones that are up-regulated under stress conditions and play a vital role in protein homeostasis (proteostasis). It is commonly accepted that these chaperones work by trapping misfolded proteins to prevent their aggregation; however, fundamental questions regarding the molecular mechanism by which sHsps interact with misfolded proteins remain unanswered. The dynamic and polydisperse nature of sHsp oligomers has made studying them challenging using traditional biochemical approaches. Therefore, we have utilized a single-molecule fluorescence-based approach to observe the chaperone action of human αB-crystallin (αBc, HSPB5). Using this approach we have, for the first time, determined the stoichiometries of complexes formed between αBc and a model client protein, chloride intracellular channel 1 (CLIC1). By examining the dispersity and stoichiometries of these complexes over time, and in response to different concentrations of αBc, we have uncovered unique and important insights into a two-step mechanism by which αBc interacts with misfolded client proteins to prevent their aggregation.

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Small heat shock protein of Methanococcus jannaschii, a hyperthermophile

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.95.16.9129 ◽

1998 ◽

Vol 95 (16) ◽

pp. 9129-9133 ◽

Cited By ~ 103

Author(s):

Rosalind Kim ◽

Kyeong Kyu Kim ◽

Hisao Yokota ◽

Sung-Hou Kim

Keyword(s):

Heat Shock ◽

Citrate Synthase ◽

Thermal Protection ◽

Small Heat Shock Protein ◽

Methanococcus Jannaschii ◽

Single Chain ◽

Cell Extracts ◽

Electron Microscopy Analysis ◽

Shock Proteins

Small heat shock proteins (sHSPs) belong to a family of 12- to 43-kDa proteins that are ubiquitous and are conserved in amino acid sequence among all organisms. A sHSP homologue of Methanococcus jannaschii, a hyperthermophilic Archaeon, forms a homogeneous multimer comprised of 24 monomers with a molecular mass of 400 kDa in contrast to other sHSPs that show heterogeneous oligomeric complexes. Electron microscopy analysis revealed a spherically shaped oligomeric structure ≈15–20 nm in diameter. The protein confers thermal protection of other proteins in vitro as found in other sHSPs. Escherichia coli cell extracts containing the protein were protected from heat-denatured precipitation when heated up to 100°C, whereas extracts from cells not expressing the protein were heat-sensitive at 60°C. Similar results were obtained when purified sHSP protein was added to an E. coli cell lysate. The protein also prevented the aggregation of two purified proteins: single-chain monellin (SCM) at 80°C and citrate synthase at 40°C.

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Small Heat-Shock Proteins Select ΔF508-CFTR for Endoplasmic Reticulum-associated Degradation

Molecular Biology of the Cell ◽

10.1091/mbc.e06-05-0458 ◽

2007 ◽

Vol 18 (3) ◽

pp. 806-814 ◽

Cited By ~ 73

Author(s):

Annette Ahner ◽

Kunio Nakatsukasa ◽

Hui Zhang ◽

Raymond A. Frizzell ◽

Jeffrey L. Brodsky

Keyword(s):

Endoplasmic Reticulum ◽

Heat Shock ◽

Small Heat Shock Protein ◽

Integral Membrane Protein ◽

Transmembrane Conductance Regulator ◽

293 Cells ◽

Genes Encoding ◽

Δf508 Cftr ◽

Shock Proteins ◽

The Impact

Secreted proteins that fail to achieve their native conformations, such as cystic fibrosis transmembrane conductance regulator (CFTR) and particularly the ΔF508-CFTR variant can be selected for endoplasmic reticulum (ER)-associated degradation (ERAD) by molecular chaperones. Because the message corresponding to HSP26, which encodes a small heat-shock protein (sHsp) in yeast was up-regulated in response to CFTR expression, we examined the impact of sHsps on ERAD. First, we observed that CFTR was completely stabilized in cells lacking two partially redundant sHsps, Hsp26p and Hsp42p. Interestingly, the ERAD of a soluble and a related integral membrane protein were unaffected in yeast deleted for the genes encoding these sHsps, and CFTR polyubiquitination was also unaltered, suggesting that Hsp26p/Hsp42p are not essential for polyubiquitination. Next, we discovered that ΔF508-CFTR degradation was enhanced when a mammalian sHsp, αA-crystallin, was overexpressed in human embryonic kidney 293 cells, but wild-type CFTR biogenesis was unchanged. Because αA-crystallin interacted preferentially with ΔF508-CFTR and because purified αA-crystallin suppressed the aggregation of the first nucleotide-binding domain of CFTR, we suggest that sHsps maintain the solubility of ΔF508-CFTR during the ERAD of this polypeptide.

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