HSP90AB1 Gene

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">CDC3

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:

Structural Domains

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

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

• 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:

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

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

ATPase Cycle

HSP90AB1 undergoes conformational changes during its ATPase cycle:

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:

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

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

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

• 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):

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

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

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

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

Amyotrophic Lateral Sclerosis (ALS)

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

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

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

Huntington's Disease

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

• 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:

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

• PU-H71
• NVP-HSP990
• AT13387

• Radicicol
• Berbamine

Clinical Trials in Neurodegeneration

Challenges

Interaction Network

HSP90AB1 interacts with multiple co-chaperones:

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

• Blood levels indicate cellular stress
• Potential biomarker for neurodegeneration

• 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

Unresolved Questions

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.

See Also

• [Alzheimer's disease](/diseases/alzheimers-disease)
• [Parkinson's disease](/diseases/parkinsons-disease)

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

Pathway Diagram

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