| HSP70 (Heat Shock Protein 70 / HSPA1A) | |
|---|---|
| Gene | HSPA1A |
| UniProt | P0DMV8 |
| PDB Structures | 4B9Q, 5NRO, 2KHO |
| Molecular Weight | 70 kDa |
| Localization | Cytoplasm, nucleus (stress-induced) |
| Protein Family | Heat shock protein 70 family (HSP70 superfamily) |
| Diseases | Alzheimer's Disease, Parkinson's Disease, Huntington's Disease, ALS, FTD |
Hsp70 (Heat Shock Protein 70 Hspa1A) is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Heat Shock Protein 70 (HSP70) is a 70 kDa ATP-dependent molecular chaperone and a central node of the cellular [proteostasis] network. The human HSP70 family comprises at least 13 members, with HSPA1A (the major inducible form, also called HSP72 or HSP70-1) and HSPA8 (the constitutive form, also called HSC70 or HSP73) being the most relevant to neurodegeneration. HSPA1A is encoded by the HSPA1A gene on chromosome 6p21.33, within the major histocompatibility complex (MHC) class III region (Saxena et al., 2025).
HSP70 proteins are among the most highly conserved proteins across all domains of life and perform essential functions in protein folding, disaggregation, translocation, and degradation. In the context of neurodegeneration, HSP70 directly opposes the fundamental disease mechanism of [protein aggregation[/mechanisms/protein-aggregation — it binds to misfolded tau]/proteins/tau, [alpha-synuclein/proteins/[alpha-synuclein), [TDP-43[/proteins/tdp-43, [huntingtin[/proteins/huntingtin, and [SOD1[/proteins/sod1-protein to prevent their aggregation, disaggregate existing fibrils, and facilitate clearance via the [ubiquitin-proteasome system[/entities/ubiquitin-proteasome-system and [autophagy[/entities/autophagy (Kampinga & Bhatt, 2016; Bohush et al., 2019).
The decline of the heat shock response (HSR) with aging — and the consequent failure of HSP70-mediated proteostasis — is increasingly recognized as a convergent mechanism underlying [aging-associated neurodegeneration]. Conversely, pharmacological induction of HSP70 expression represents one of the most promising therapeutic strategies against protein misfolding diseases (Kalmar & Greensmith, 2023).
HSP70 proteins share a conserved three-domain architecture (~640 amino acids):
N-terminal Nucleotide-Binding Domain (NBD) (~40 kDa, residues 1–385):
Substrate-Binding Domain (SBD) (~15 kDa, residues 393–507):
C-terminal α-Helical Lid (~10 kDa, residues 508–641):
The HSP70 chaperone cycle is driven by ATP hydrolysis and regulated by co-chaperones:
| Feature | HSPA1A (HSP70/HSP72) | HSPA8 (HSC70/HSP73) |
|---|---|---|
| Expression | Stress-inducible (heat, oxidative, proteotoxic) | Constitutive, abundant in [neurons[/entities/neurons |
| Brain abundance | Low basal, highly upregulated by stress | High basal (~1% of total brain protein) |
| [Tau[/entities/tau-protein affinity | Higher affinity for tau | Lower affinity but more abundant |
| Key role | Emergency proteostasis response | Housekeeping protein quality control |
In aging and neurodegeneration, HSF1 (heat shock factor 1) — the master transcription factor controlling HSPA1A induction — becomes impaired, leading to an inadequate heat shock response and failure to upregulate HSP70 when most needed (Kalmar & Greensmith, 2023).
HSP70 is the central hub of the [protein quality control] network:
In [neurons[/entities/neurons, HSP70 provides multiple layers of protection:
HSP70 directly counters the two hallmark pathologies of AD:
Tau: The HSP70/HSP90 multichaperone complex buffers pathological tau]/proteins/tau through extensive intermolecular contacts that depend on tau's aggregation-prone repeat region (Nachman et al., 2022). HSP70 facilitates:
[Amyloid-Beta[/entities/amyloid-beta: HSP70 interacts with [Aβ[/proteins/Amyloid-Beta oligomers and modulates their aggregation:
HSP70 is a critical suppressor of [alpha-synuclein[/proteins/alpha-synuclein pathology:
However, the disaggregation process can paradoxically generate spreading-competent toxic α-synuclein species — small oligomeric fragments released during HSP110-mediated disaggregation can serve as seeds for [prion-like propagation] (Tittelmeier et al., 2020). This dual nature complicates therapeutic strategies.
HSP70 plays a protective role against [TDP-43 Proteinopathy[/mechanisms/tdp-43-proteinopathy:
Pharmacological activation of the heat shock response to upregulate HSP70 expression:
| Compound | Mechanism | Status |
|---|---|---|
| Arimoclomol | HSF1 co-activator; amplifies the natural HSR | Phase 2/3 in ALS (SOD1); failed primary endpoint but subgroup benefits observed |
| 17-AAG / BIIB021 | [HSP90[/proteins/hsp90 inhibitor → compensatory HSP70 induction via HSF1 | Preclinical/Phase 1 in neurodegeneration |
| Geranylgeranylacetone (GGA) | HSF1 activator; oral bioavailable | Preclinical in AD and PD models |
| Celastrol | Natural product HSF1 activator | Preclinical; reduces α-synuclein and tau aggregation |
| BGP-15 | Co-inducer of HSP70; hydroximic acid derivative | Phase 2 for insulin resistance; preclinical for neuroprotection |
The study of Hsp70 (Heat Shock Protein 70 Hspa1A) 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.