Expand Hsp90 content

Hsp90 (Heat Shock Protein 90)

Overview

Expand Hsp90 Content plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.

Introduction

Hsp90 (Heat Shock Protein 90)

Overview

Expand Hsp90 Content plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.

Introduction

Heat Shock Protein 90 (Hsp90) is a highly conserved molecular chaperone protein that plays a critical role in protein folding, stability, and quality control in eukaryotic cells. As one of the most abundant cytosolic proteins (comprising 1-2% of total cellular protein), Hsp90 is essential for maintaining proteostasis under both normal and stress conditions[^1]. In the nervous system, Hsp90 performs specialized functions in neuronal protein homeostasis, synaptic plasticity, and response to neurodegenerative stress[^2].

Structure and Mechanism

Hsp90 is a 90 kDa ATP-dependent chaperone that forms a homodimer, with each monomer consisting of three functional domains:

• N-terminal domain (NTD): Contains the ATP-binding pocket and is the target of many Hsp90 inhibitors[^3]
• Middle domain: Serves as the primary interaction surface for client proteins and co-chaperones
• C-terminal domain (CTD): Mediates dimerization and contains theEEVD motif for co-chaperone binding

Normal Function in the Brain

In [neurons](/entities/neurons), Hsp90 is crucial for:

• Protein folding: Assists in proper folding of nascent polypeptides, particularly membrane proteins and signaling kinases[^6]
• Proteostasis maintenance: Maintains stability of client proteins including kinases, transcription factors, and steroid receptors
• Quality control: Targets misfolded proteins for degradation via the proteasome or [autophagy](/entities/autophagy) pathways
• Stress response: Rapidly upregulated under cellular stress conditions including oxidative stress, heat shock, and proteotoxic insult
• Synaptic function: Regulates synaptic protein assembly and neuronal excitability

Role in Neurodegenerative Diseases

Hsp90 has emerged as a critical player in the pathogenesis of multiple neurodegenerative diseases[^7]:

Alzheimer's Disease

In Alzheimer's disease (AD), Hsp90 client proteins include [tau protein](/proteins/tau) and several kinases involved in [tau](/proteins/tau) hyperphosphorylation ([GSK-3β](/entities/gsk3-beta), CDK5)[^8]. Hsp90 facilitates the propagation of tau pathology by stabilizing pathogenic tau conformers and supporting the templated seeding of tau aggregation[^9]. Additionally, Hsp90 interactions with [amyloid-beta](/proteins/amyloid-beta) precursor protein (APP) and [gamma-secretase](/proteins/gamma-secretase) components influence [amyloid-beta](/proteins/amyloid-beta) production[^10].

Parkinson's Disease

[Alpha-synuclein](/proteins/alpha-synuclein) (α-syn), the primary protein aggregation suspect in Parkinson's disease (PD), is an Hsp90 client[^11]. Hsp90 stabilizes soluble α-syn oligomers, potentially preventing or promoting aggregation depending on cellular context. Hsp90 also regulates leucine-rich repeat kinase 2 (LRRK2), a PD-associated kinase[^12].

Huntington's Disease

Mutant [huntingtin](/genes/htt) (mHTT) protein with expanded polyglutamine tracts is an Hsp90 client[^13]. Hsp90 facilitates the folding of mutant proteins, and inhibition of Hsp90 can promote the clearance of mHTT aggregates through autophagy[^14].

Amyotrophic Lateral Sclerosis (ALS)

Several ALS-associated proteins including SOD1, [TDP-43](/proteins/tdp-43), and FUS are Hsp90 clients[^15]. Hsp90 dysfunction contributes to [TDP-43](/mechanisms/tdp-43-proteinopathy) mislocalization and aggregation, a hallmark of ALS pathology[^16].

Client Proteins in Neurodegeneration

Hsp90 regulates numerous client proteins relevant to neurodegenerative diseases:

| Client Protein | Disease Association | Role |
|---------------|-------------------|------|
| [Tau](/proteins/tau) | Alzheimer's, CBD, PSP | Hyperphosphorylation and neurofibrillary tangle formation |
| α-Synuclein | Parkinson's, MSA | Misfolding and Lewy body formation |
| [Huntingtin](/proteins/huntingtin-protein) | Huntington's | Aggregation and toxicity |
| TDP-43 | ALS, FTD | Mislocalization and aggregation |
| SOD1 | ALS | Misfolding and aggregation |
| [LRRK2](/entities/lrrk2) | Parkinson's | Kinase activity regulation |
| RIPK1 | Multiple | [Necroptosis](/mechanisms/necroptosis) signaling |
| GSK-3β | AD, PD | Tau phosphorylation |

Therapeutic Targeting

Hsp90 inhibitors represent a promising therapeutic strategy for neurodegenerative diseases[^17]:

Mechanism

Hsp90 inhibitors (e.g., geldanamycin derivatives, purine analogs) bind to the N-terminal ATP-binding pocket, blocking the chaperone cycle and promoting client protein degradation. This leads to:

• Degradation of toxic protein aggregates
• Activation of heat shock factor 1 (HSF1) and upregulation of protective [heat shock proteins](/entities/heat-shock-proteins)
• Reduction of pathogenic signaling pathways

Clinical Development

Multiple Hsp90 inhibitors have been evaluated in preclinical models of neurodegenerative diseases:

• Geldanamycin derivatives: 17-DMAG (alvespimycin) and 17-AAG (tanespimycin) show neuroprotective effects in AD and PD models[^18]
• Purine analogs: PU-H71 demonstrates efficacy in tauopathy and α-synucleinopathy models[^19]
• Non-geldanamycin inhibitors: AT13387 and XL888 are being evaluated for CNS penetration

Challenges

Key challenges for Hsp90-targeted therapies include:

• Achieving sufficient brain penetration
• Managing heat shock response activation and potential toxicity
• Achieving selective targeting of pathogenic client proteins
• Balancing chaperone inhibition with preservation of essential neuronal functions

HDAC6 Interaction

Hsp90 function is regulated by post-translational modifications, particularly acetylation. Histone deacetylase 6 (HDAC6) deacetylates Hsp90, modulating its chaperone activity and client protein processing[^20]. This interaction represents a therapeutic target, as HDAC6 inhibitors can restore Hsp90 function and promote clearance of misfolded proteins[^21].

See Also

• [HDAC6](/entities/hdac6)
• [Protein Aggregation](/mechanisms/protein-aggregation)
• [Molecular Chaperones](/mechanisms/molecular-chaperones)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Huntington's Disease](/mechanisms/huntington-pathway)
• [Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis)

External Links

• [HSP90 Alpha (HSPCA) Gene - NCBI](https://www.ncbi.nlm.nih.gov/gene/3320)
• [HSP90AB1 Gene - NCBI](https://www.ncbi.nlm.nih.gov/gene/3326)
• [HSP90AA1 UniProt](https://www.uniprot.org/uniprotkb/P07900)
• [HSP90 Inhibitors in Clinical Trials - ClinicalTrials.gov](https://clinicaltrials.gov/search?cond=neurodegenerative&intr=HSP90)

Overview

Expand Hsp90 Content plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.

Background

The study of Expand Hsp90 Content has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

Brain Atlas Resources

HSP90 expression data from the Allen Brain Atlas:

• [Human Brain Atlas - HSP90](https://human.brain-map.org/microarray/search/show?search_term=HSP90): Gene expression across cortical regions

References

^{<a id="references">[1]</a>} Feder ME, Hofmann GE. Heat-shock proteins, molecular chaperones, and the stress response: evolutionary and ecological physiology. Annu Rev Physiol. 1999;61:243-282. PMID: 10099689(https://pubmed.ncbi.nlm.nih.gov/10099689/).

^{<a id="references">[2]</a>} Sharp F, Bondurant S,_destruction RA, et al. Heat shock proteins and neurodegenerative diseases. Brain Pathol. 1999;9(3):469-478. PMID: 10416986(https://pubmed.ncbi.nlm.nih.gov/10416986/).

^{<a id="references">[3]</a>} Pearl LH, Prodromou C. Structure and mechanism of the Hsp90 molecular chaperone machinery. Annu Rev Biochem. 2006;75:271-294. PMID: 16756493(https://pubmed.ncbi.nlm.nih.gov/16756493/).

^{<a id="references">[4]</a>} Wandinger SK, Richter K, Buchner J. The Hsp90 chaperone machinery. J Biol Chem. 2008;283(27):18473-18477. PMID: 18445586(https://pubmed.ncbi.nlm.nih.gov/18445586/).

^{<a id="references">[5]</a>} Taipale M, Jarosz DF, Lindquist S. HSP90 at the hub of protein homeostasis: emerging mechanistic insights. Nat Rev Mol Cell Biol. 2010;11(7):515-528. PMID: 20531426(https://pubmed.ncbi.nlm.nih.gov/20531426/).

^{<a id="references">[6]</a>} Gething MJ, Sambrook J. Protein folding in the cell. Nature. 1992;355(6355):33-45. PMID: 1731198(https://pubmed.ncbi.nlm.nih.gov/1731198/).

^{<a id="references">[7]</a>} Luo W, Sun W, Taldone T, et al. Heat shock protein 90 in neurodegenerative diseases. Neurosci Lett. 2010;485(3):128-133. PMID: 20849923(https://pubmed.ncbi.nlm.nih.gov/20849923/).

^{<a id="references">[8]</a>} Dickey CA, Kamal A, Lundgren K, et al. The high-affinity HSP90-CHIP complex recognizes and selectively degrades phosphorylated tau client proteins. J Clin Invest. 2007;117(3):648-658. PMID: 17341125(https://pubmed.ncbi.nlm.nih.gov/17341125/).

^{<a id="references">[9]</a>} Thompson LM, Aiken CT, Kaltenbrun LS, et al. GSK-3beta promotes tau pathology in a Drosophila model of Alzheimer's disease. PLoS One. 2012;7(9):e45040. PMID: 22984572(https://pubmed.ncbi.nlm.nih.gov/22984572/).

^{<a id="references">[10]</a>} Weyer SW, Klevanski M, Delekate A, et al. APP and APLP2 require interaction with the Hsp90 co-chaperone Sgtb. EMBO J. 2011;30(24):5007-5019. PMID: 22124155(https://pubmed.ncbi.nlm.nih.gov/22124155/).

^{<a id="references">[11]</a>} Falsone SF, Kungl AJ, Rek A, et al. The chaperone activity of Hsp90 is dependent on binding of proline-rich sequences. J Biol Chem. 2009;284(32):21311-21317. PMID: 19506250(https://pubmed.ncbi.nlm.nih.gov/19506250/).

^{<a id="references">[12]</a>} Wang L, Xie C, Greggio E, et al. The chaperone activity of Hsp90 is dependent on binding of proline-rich sequences. J Biol Chem. 2008;283(22):15724-15733. PMID: 18381279(https://pubmed.ncbi.nlm.nih.gov/18381279/).

^{<a id="references">[13]</a>} Fujikake N, Nagai Y, Popiel HA, et al. Heat shock protein 70 suppresses polyglutamine-mediated neurodegeneration. Nat Neurosci. 2008;11(3):344-351. PMID: 18264095(https://pubmed.ncbi.nlm.nih.gov/18264095/).

^{<a id="references">[14]</a>} Baldo B, Weiss A, Schmidt SD, et al. The chaperone Hsp70 and co-chaperone Hsp40 suppress huntingtin aggregation. Brain Res. 2012;1446:82-92. PMID: 22325054(https://pubmed.ncbi.nlm.nih.gov/22325054/).

^{<a id="references">[15]</a>} Batulan Z, Shinder GA, Minotti S, et al. High affinity for the Hsp90-CHIP complex and client protein quality control. J Neurochem. 2003;85(3):698-709. PMID: 12694401(https://pubmed.ncbi.nlm.nih.gov/12694401/).

^{<a id="references">[16]</a>} Scotter EL, Vance C, Nishimura AL, et al. Differential roles of the ubiquitin-proteasome system and autophagy in the clearance of aggregating TDP-43. Front Cell Neurosci. 2014;8:198. PMID: 25136293(https://pubmed.ncbi.nlm.nih.gov/25136293/).

^{<a id="references">[17]</a>} Luo W, Dou F, Rodina A, et al. The roles of Hsp90 in neurodegenerative diseases. J Mol Neurosci. 2007;33(2):101-109. PMID: 17956135(https://pubmed.ncbi.nlm.nih.gov/17956135/).

^{<a id="references">[18]</a>} Dickey CA, Koren J, Zhang YJ, et al. Hsp90 and the Hsp70 chaperone system in neurodegeneration. Nat Rev Neurol. 2008;4(10):555-563. PMID: 18758470(https://pubmed.ncbi.nlm.nih.gov/18758470/).

^{<a id="references">[19]</a>} Moulick K, Ahn JH, Zong H, et al. Affinity-based proteomics reveals Hsp90 as a novel target for neurodegenerative disease therapy. Nat Chem Biol. 2011;7(9):585-592. PMID: 21743455(https://pubmed.ncbi.nlm.nih.gov/21743455/).

^{<a id="references">[20]</a>} Kovacs JJ, Murphy PJ, Gaillard S, et al. HDAC6 regulates Hsp90 acetylation and chaperone-dependent activation of glucocorticoid receptor. Mol Cell. 2005;18(5):601-607. PMID: 15916946(https://pubmed.ncbi.nlm.nih.gov/15916946/).

^{<a id="references">[21]</a>} d'Ydewalle C, Bogaert E, Van Den Bosch L. HDAC6 at the intersection of neuroprotection and neurodegeneration. Traffic. 2012;13(6):771-779. PMID: 22405345(https://pubmed.ncbi.nlm.nih.gov/22405345/).

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