HSP90AB1 Gene

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HSP90AB1 Gene

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HSP90AB1 Gene

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">hsp90ab1</th>
</tr>
<tr>
<td class="label">Category</td>
<td>Client Proteins</td>
</tr>
<tr>
<td class="label">Kinases</td>
<td>AKT, RAF, SRC</td>
</tr>
<tr>
<td class="label">Steroid receptors</td>
<td>ER, PR, AR</td>
</tr>
<tr>
<td class="label">Transcription factors</td>
<td>p53, HIF-1α</td>
</tr>
<tr>
<td class="label">Cell cycle</td>
<td>CDK4, CDK6</td>
</tr>
<tr>
<td class="label">Chaperones</td>
<td>HSP70, HSP40</td>
</tr>
<tr>
<td class="label">Disease</td>
<td>HSP90AB1 Role</td>
</tr>
<tr>
<td class="label">Prion Disease</td>
<td>Prion protein chaperone</td>
</tr>
<tr>
<td class="label">Frontotemporal Dementia</td>
<td>TDP-43 and FUS clients</td>
</tr>
<tr>
<td class="label">Multiple Sclerosis</td>
<td>Myelin protein folding</td>
</tr>
<tr>
<td class="label">Spinocerebellar Ataxia</td>
<td>Polyglutamine client</td>
</tr>
<tr>
<td class="label">Compound</td>
<td>Condition</td>
</tr>
<tr>
<td class="label">Tanespimycin</td>
<td>Alzheimer's Disease</td>
</tr>
<tr>
<td class="label">PU-H71</td>
<td>Parkinson's Disease</td>
</tr>
<tr>
<td class="label">Geldanamycin derivatives</td>
<td>ALS</td>
</tr>
<tr>
<td class="label">Co-chaperone</td>
<td>Function</td>
</tr>
<tr>
<td class="label">HOP</td>
<td>Client protein transfer</td>
</tr>
<tr>
<td class="label">CDC37</td>
<td>Kinase client recruitment</td>
</tr>
<tr>
<td class="label">AHA1</td>
<td>ATPase stimulation</td>
</tr>
<tr>
<td class="label">p23</td>
<td>Client protein folding</td>
</tr>
<tr>
<td class="label">HSP70</td>
<td>Cooperative chaperone</td>
</tr>
<tr>
<td class="label">FKBP4/5</td>
<td>Immunophilin client binding</td>
</tr>
<tr>
<td class="label">PP5</td>
<td>Dephosphorylation</td>
</tr>
<tr>
<td class="label">Protein</td>
<td>Interaction</td>
</tr>
<tr>
<td class="label">[SNCA](/genes/snca)</td>
<td>Modulates aggregation</td>
</tr>
<tr>
<td class="label">[PARK2](/genes/parkin)</td>
<td>Parkin co-chaperone</td>
</tr>
<tr>
<td class="label">[LRRK2](/genes/lrrk2)</td>
<td>LRRK2 client</td>
</tr>
<tr>
<td class="label">[MAPT](/genes/mapt)</td>
<td>Tau kinase client</td>
</tr>
<tr>
<td class="label">[SOD1](/genes/sod1)</td>
<td>Mutant SOD1 client</td>
</tr>
<tr>
<td class="label">[TARDBP](/genes/tardbp)</td>
<td>TDP-43 interaction</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a>, <a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a>, <a href="/wiki/dementia" style="color:#ef9a9a">Dementia</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">150 edges</a></td>
</tr>
</table>

Gene: HSP90AB1 | Protein: HSP90AB1 (Heat Shock Protein 90 Beta Family Member 1) | Aliases: HSP90B, HSP86, Hsp84, Hsp90, Hsp90-β

Introduction

The HSP90AB1 gene encodes HSP90AB1 (Heat Shock Protein 90 Beta Family Member 1), a member of the heat shock protein 90 (Hsp90) family of molecular chaperones. As a essential molecular chaperone, HSP90AB1 plays critical roles in protein folding, stability, and function, particularly for client proteins involved in signal transduction, cell cycle control, and stress response [1].

HSP90AB1 is one of the most abundant proteins in the cell, comprising 1-2% of total cellular protein. It is essential for cellular viability and has emerged as an important therapeutic target in cancer and neurodegenerative diseases. The protein is highly conserved across eukaryotes, reflecting its fundamental cellular functions.

Gene Structure and Expression

Genomic Location

The HSP90AB1 gene is located on chromosome 6p21.1 in humans, within the major histocompatibility complex (MHC) class III region. This locus also contains other heat shock proteins including [HSP90AA1](/genes/hsp90aa1).

Promoter Structure

The HSP90AB1 promoter contains several regulatory elements:

HSE (Heat Shock Element): Multiple HSEs allow heat shock-induced transcription
GC-rich regions: Multiple Sp1 binding sites for constitutive expression
TATA box: Present but not essential for expression
Intron/exon structure: 11 exons encoding the functional protein

Alternative Splicing

HSP90AB1 produces multiple transcript variants:

Variant 1 (canonical): Full-length protein encoding the predominant isoform
Variant 2: Alternative splicing in 5'UTR affecting translation efficiency
Isoforms: Multiple N-terminal isoforms with tissue-specific expression

Tissue Distribution

HSP90AB1 is ubiquitously expressed at high levels:

Brain: Particularly high in neurons, especially in synapses
Liver: High expression in hepatocytes
Muscle: Abundant in skeletal and cardiac muscle
Immune cells: High expression in activated lymphocytes

Protein Structure and Biochemistry

Domain Architecture

HSP90AB1 is a 724-amino acid dimeric protein with distinct domains:

Mermaid diagram (expand to render)

Structural Domains

N-terminal domain (1-230 aa):

Contains the ATP-binding pocket
Binds ATP and ADP
Site for geldanamycin and other Hsp90 inhibitors

Middle domain (231-600 aa):

Contains the client protein binding site
Interacts with protein substrates
Contains the catalytic site for ATP hydrolysis

C-terminal domain (601-724 aa):

Mediates dimerization
Contains the EEVD motif for co-chaperone binding
Site for post-translational modifications

Dimer Structure

HSP90AB1 functions as a homodimer:

Each monomer contains the three domains described above
Dimerization occurs through C-terminal interactions
The dimer creates a molecular "clamp" for client proteins
Conformational changes during the ATPase cycle

Post-Translational Modifications

HSP90AB1 undergoes extensive post-translational modifications:

Phosphorylation: Multiple serine/threonine phosphorylation sites

Tyr-124 phosphorylation affects client binding
Ser-231 and Ser-263 are regulatory sites

Acetylation: Lysine acetylation regulates function

Lys-294 acetylation affects ATPase activity
Lys-546 acetylation influences co-chaperone interactions

Sumoylation: SUMO modification affects stability

Ubiquitination: Regulates degradation

Nitrosylation: Affects chaperone function under stress

ATPase Cycle

HSP90AB1 undergoes conformational changes during its ATPase cycle:

Open state: Apo-Hsp90, client protein binding

Closed state: ATP binding, client protein encapsulation

Hydrolysis: ATP hydrolysis drives conformational changes

Release: ADP release, client release

Biological Functions

Molecular Chaperone Activity

HSP90AB1 serves as a molecular chaperone:

Protein folding: Assists in proper protein folding
Stabilization: Prevents aggregation of misfolded proteins
Complex assembly: Facilitates assembly of multi-protein complexes
Quality control: Targets damaged proteins for degradation

Client Proteins

HSP90AB1 interacts with hundreds of client proteins:

Role in Protein Quality Control

HSP90AB1 is central to cellular protein quality control:

Folding assistance: Helps proteins achieve native conformation
Aggregate prevention: Prevents toxic protein aggregation
Degradation targeting: Works with E3 ubiquitin ligases for degradation
Stress response: Critical for surviving proteotoxic stress

HSP90AB1 in Neurodegenerative Diseases

Alzheimer's Disease

In [Alzheimer's disease](/diseases/alzheimers-disease), HSP90AB1 plays complex roles:

Tau Pathology: HSP90AB1 is involved in tau folding and aggregation

Modulates tau phosphorylation through client kinases
Can be recruited to neurofibrillary tangles
Therapeutic targeting may reduce tau pathology

Amyloid-β Handling: HSP90AB1 affects Aβ production and clearance

Client proteins include γ-secretase components
Chaperone activity can reduce Aβ toxicity
HSP90 inhibitors show promise in AD models

Synaptic Function: Essential for synaptic protein maintenance

HSP90 is required for synaptic vesicle cycling
Local translation at synapses requires HSP90
Loss of HSP90 affects long-term potentiation

Therapeutic Targeting:

HSP90 inhibitors reduce AD pathology in models
17-AAG (tanespimycin) has been studied in clinical trials
Combination approaches show enhanced effects

Parkinson's Disease

HSP90AB1 is particularly relevant to [Parkinson's disease](/diseases/parkinsons-disease):

Alpha-Synuclein: HSP90AB1 interacts with α-synuclein ([SNCA](/genes/snca))

Modulates aggregation propensity
Can target mutant SNCA for degradation
HSP90 inhibition reduces aggregation

Parkin Function: HSP90AB1 is a co-chaperone for parkin ([PRNK](/genes/parkin))

Essential for parkin E3 ligase activity
Mutations affecting this interaction contribute to PD
Therapeutic modulation is under investigation

Dopaminergic Neuron Survival:

HSP90 protects dopaminergic neurons from stress
Client proteins include key survival factors
Targeting HSP90 shows neuroprotective effects

LRRK2: HSP90AB1 is a client for LRRK2

LRRK2 mutations common in familial PD
HSP90 inhibition affects LRRK2 stability
Therapeutic implications are being explored

Amyotrophic Lateral Sclerosis (ALS)

SOD1: HSP90AB1 interacts with mutant SOD1

Mutant SOD1 is a HSP90 client protein
HSP90 inhibitors accelerate mutant SOD1 degradation
Shows therapeutic potential in ALS models

FUS and TDP-43: HSP90AB1 affects ALS-associated proteins

HSP90 inhibitors reduce toxicity
Both FUS and TDP-43 are HSP90 clients

Motor Neuron Protection:

HSP90 induction is neuroprotective
Heat shock response is impaired in ALS
Therapeutic approaches targeting HSP90 are promising

Huntington's Disease

Mutant Huntingtin: HSP90AB1 binds mutant Htt

Contributes to aggregation
HSP90 inhibition reduces aggregation
Client proteins include kinases affecting Htt toxicity

Therapeutic Targeting:

HSP90 inhibitors show benefits in HD models
Reduce mutant Htt aggregation
Improve motor function in models

Other Neurodegenerative Conditions

Therapeutic Targeting of HSP90

HSP90 Inhibitors

HSP90 inhibitors have been extensively studied:

Geldanamycin derivatives:

17-AAG (tanespimycin)
17-DMAG (alvespimycin)
Retaspimycin (IPI-504)

Synthetic inhibitors:

PU-H71
NVP-HSP990
AT13387

Natural compounds:

Radicicol
Berbamine

Clinical Trials in Neurodegeneration

Challenges

Cancer effects: HSP90 inhibitors have anti-cancer effects

CNS penetration: Many inhibitors have poor brain penetration

Toxicity: Off-target effects and toxicity issues

Client protein diversity: Broad client protein network

Interaction Network

HSP90AB1 interacts with multiple co-chaperones:

Mermaid diagram (expand to render)

Genetic Aspects

Polymorphisms

HSP90AB1 polymorphisms have been studied:

Promoter polymorphisms: Affect expression levels
Coding polymorphisms: May affect client protein interactions
Disease associations: Some variants linked to neurodegeneration risk

Epigenetic Regulation

HSP90AB1 expression is epigenetically regulated:

Promoter methylation: Can silence expression
Histone modifications: Affect transcription
Age-related changes: Expression changes with aging

Animal Models

Knockout Studies

Hsp90ab1 knockout: Embryonic lethal in mice
Conditional knockout: Reveals tissue-specific functions
Neuron-specific knockout: Shows neuronal phenotypes

Transgenic Models

HSP90 overexpression: Protective in neurodegeneration models
Mutant client proteins: Model various diseases

Biomarkers

HSP90 as a Biomarker

Extracellular HSP90: Released from cells under stress

Blood levels indicate cellular stress
Potential biomarker for neurodegeneration

HSP90 complexes: Different client-bound complexes

Indicate specific pathway activation
May have diagnostic value

Cross-Linking to Other Neurodegeneration Pathways

Protein Quality Control Network

HSP90AB1 is part of the protein quality control network:

Works with HSP70/HSP40 for protein folding
Links to ubiquitin-proteasome system
Intersects with autophagy pathway
Essential for maintaining proteostasis

Connections to Specific Neurodegeneration Proteins

HSP90 in Normal Brain Function

Synaptic Plasticity

HSP90AB1 is essential for synaptic function:

Required for AMPA receptor trafficking
Essential for NMDA receptor function
Involved in synaptic vesicle cycling
Critical for learning and memory

Axonal Transport

HSP90AB1 participates in axonal transport:

Client proteins include motor proteins
Required for organelle transport
Axonal protection under stress

Heat Shock Response

The heat shock response is neuroprotective:

HSP90 induction protects neurons
Transcriptional regulation via HSF1
Declines with age

Comparative Biology

HSP90 is highly conserved:

Yeast: Essential for viability
Drosophila: Essential for development
Zebrafish: Brain development requires HSP90
Mice: Embryonic lethal knockout

Future Directions

Emerging Therapies

Next-generation inhibitors: Improved specificity and brain penetration

Co-chaperone targeting: More selective modulation

Combination therapies: With other neuroprotective agents

Unresolved Questions

How does HSP90 client specificity change in disease?

Can we develop neuron-specific HSP90 modulators?

What determines client protein selection?

How does HSP90 interact with aging?

Summary

HSP90AB1 is an essential molecular chaperone with critical roles in protein folding, stability, and cellular proteostasis. In neurodegenerative diseases, HSP90AB1 interacts with disease-associated proteins including α-synuclein, tau, mutant SOD1, and parkin. Therapeutic modulation of HSP90AB1 represents a promising approach for treating AD, PD, ALS, and related conditions. The protein's central role in maintaining cellular proteostasis makes it an attractive target for neuroprotective strategies.

External Links

[NCBI Gene: HSP90AA1](https://www.ncbi.nlm.nih.gov/gene/?term=HSP90AA1)
[GeneCards: HSP90AA1](https://www.genecards.org/cgi-bin/carddisp.pl?gene=HSP90AA1)
[OMIM: HSP90AA1](https://omim.org/search?search=HSP90AA1)
[Ensembl: HSP90AA1](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=HSP90AA1)
[Allen Brain Atlas: HSP90AA1](https://human.brain-map.org/microarray/search/show?search_term=HSP90AA1)

Molecular Mechanism

HSP90AB1 operates as a master molecular chaperone within neurons, forming a dynamic cycle with HSP70 and co-chaperones to facilitate folding of nascent polypeptides and rescue of stress-denatured proteins. The chaperone cycle involves ATP-dependent conformational changes—open apo-state, closed ATP-bound state, and ADP-post-hydrolysis state—driven by HSP90AB1's intrinsic ATPase activity, which is modulated by co-chaperones including CDC37 (kinase recruitment), AHA1 (ATPase stimulation), and p23 (stabilization of the closed state). In neurodegeneration, HSP90AB1 interfaces directly with disease-relevant client proteins: it binds phosphorylated tau (MAPT) to regulate its folding and aggregation propensity; it engages α-synuclein (SNCA) to either suppress or exacerbate aggregation depending on the client-bound conformation; it serves as a critical co-chaperone for parkin (PRKN/PARK2), stabilizing the E3 ligase in an active state required for mitophagy of damaged mitochondria; and it interacts with LRRK2 (leucine-rich repeat kinase 2), a protein heavily implicated in familial Parkinson's disease pathogenesis. Pharmacologically, HSP90AB1 is targeted by PU-H71 and tanespimycin (17-AAG), which compete for the N-terminal ATP-binding pocket and trap the chaperone in a closed, client-release-incompetent state, thereby promoting degradation of mutant client proteins. Notably, brain penetration of HSP90 inhibitors remains a major challenge, limiting therapeutic translation. The HSP90AB1 system also crosstalk with the ubiquitin-proteasome system through shared client substrates and with the autophagy machinery through HSF1-mediated transcriptional induction of HSP70. Evidence from post-mortem Alzheimer's disease brain tissue shows altered HSP90AB1 distribution in hippocampal subfields, with increased expression in glia and reduced neuronal staining, consistent with a compensatory neuroprotective response to proteotoxic stress. PMID: 30133257 PMID: 17431395 PMID: 23431407 PMID: 27580824 PMID: 40436281

References

[Taipale et al., HSP90: the crucial hub of the HSP90 network (2010) (2010)](https://doi.org/10.1016/j.tibs.2010.05.001)

[Pratt et al., The HSP90-based client protein interaction network (2010) (2010)](https://pubmed.ncbi.nlm.nih.gov/20562811/)

[Luo et al., HSP90 and neurodegeneration (2019) (2019)](https://doi.org/10.1016/j.neurobiolaging.2019.04.010)

[Unknown, Tatu and Helenius, HSP90 and protein quality control (2019) (2019)](https://doi.org/10.1016/j.jmb.2019.04.015)

[Wang et al., HSP90 inhibitors in Alzheimer's disease (2020) (2020)](https://doi.org/10.3233/JAD-190856)

Pathway Diagram

The following diagram shows the key molecular relationships involving HSP90AB1 Gene discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

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HSP90AB1 Gene

HSP90AB1 Gene

HSP90AB1 Gene

Introduction

Gene Structure and Expression

Genomic Location

Promoter Structure

Alternative Splicing

Tissue Distribution

Protein Structure and Biochemistry

Domain Architecture

Structural Domains

Dimer Structure

Post-Translational Modifications

ATPase Cycle

Biological Functions

Molecular Chaperone Activity

Client Proteins

Role in Protein Quality Control

HSP90AB1 in Neurodegenerative Diseases

Alzheimer's Disease

Parkinson's Disease

Amyotrophic Lateral Sclerosis (ALS)

Huntington's Disease

Other Neurodegenerative Conditions

Therapeutic Targeting of HSP90

HSP90 Inhibitors

Clinical Trials in Neurodegeneration

Challenges

Interaction Network

Genetic Aspects

Polymorphisms

Epigenetic Regulation

Animal Models

Knockout Studies

Transgenic Models

Biomarkers

HSP90 as a Biomarker

Cross-Linking to Other Neurodegeneration Pathways

Protein Quality Control Network

Connections to Specific Neurodegeneration Proteins

HSP90 in Normal Brain Function

Synaptic Plasticity

Axonal Transport

Heat Shock Response

Comparative Biology

Future Directions

Emerging Therapies

Unresolved Questions

Summary

See Also

External Links

Molecular Mechanism

References

Pathway Diagram