DNAJB5 (DnaJ Heat Shock Protein Family Member B5)

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DNAJB5 (DnaJ Heat Shock Protein Family Member B5)

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title: DNAJB5 Gene

DNAJB5 (DnaJ Heat Shock Protein Family Member B5)

| Property | Value |
|----------|-------|
| Gene Symbol | DNAJB5 |
| Full Name | DnaJ Heat Shock Protein Family (Hsp40) Member B5 |
| Chr Location | 9p13.3 |
| NCBI Gene ID | 25822 |
| OMIM ID | 608591 |
| Ensembl ID | ENSG00000135919 |
| UniProt ID | O75164 |
| Encoded Protein | DNAJB5 |
| Associated Diseases | Alzheimer's Disease, Parkinson's Disease, ALS, Cancer |

</div>

Overview

DNAJB5 (DnaJ Heat Shock Protein Family Member B5), also known as Hsp40 or DNAB5, is a member of the DnaJ/Hsp40 family of molecular chaperones. Located on chromosome 9p13.3, DNAJB5 functions as a co-chaperone that assists Hsp70 proteins in protein folding, refolding, and clearance of misfolded proteins [1][2].

The DNAJ/Hsp40 family is characterized by the presence of a highly conserved J-domain, which enables interaction with Hsp70 chaperones and stimulates their ATPase activity.[@he2022] This interaction is crucial for protein quality control mechanisms that prevent the accumulation of toxic protein aggregates—a hallmark of neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS) [2][3].

DNAJB5 has attracted attention for its potential role in preventing protein aggregation in neurodegenerative diseases, where it may help mitigate the accumulation of misfolded proteins such as amyloid-beta, tau, and alpha-synuclein [1][2][@he2022].

...

title: DNAJB5 Gene

DNAJB5 (DnaJ Heat Shock Protein Family Member B5)

| Property | Value |
|----------|-------|
| Gene Symbol | DNAJB5 |
| Full Name | DnaJ Heat Shock Protein Family (Hsp40) Member B5 |
| Chr Location | 9p13.3 |
| NCBI Gene ID | 25822 |
| OMIM ID | 608591 |
| Ensembl ID | ENSG00000135919 |
| UniProt ID | O75164 |
| Encoded Protein | DNAJB5 |
| Associated Diseases | Alzheimer's Disease, Parkinson's Disease, ALS, Cancer |

</div>

Overview

DNAJB5 (DnaJ Heat Shock Protein Family Member B5), also known as Hsp40 or DNAB5, is a member of the DnaJ/Hsp40 family of molecular chaperones. Located on chromosome 9p13.3, DNAJB5 functions as a co-chaperone that assists Hsp70 proteins in protein folding, refolding, and clearance of misfolded proteins [1][2].

The DNAJ/Hsp40 family is characterized by the presence of a highly conserved J-domain, which enables interaction with Hsp70 chaperones and stimulates their ATPase activity.[@he2022] This interaction is crucial for protein quality control mechanisms that prevent the accumulation of toxic protein aggregates—a hallmark of neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS) [2][3].

DNAJB5 has attracted attention for its potential role in preventing protein aggregation in neurodegenerative diseases, where it may help mitigate the accumulation of misfolded proteins such as amyloid-beta, tau, and alpha-synuclein [1][2][@he2022].

Molecular Structure and Biochemistry

Protein Architecture

DNAJB5 encodes a protein with distinct functional domains:

J-Domain (1-70 aa): The defining feature of DNAJ proteins, containing the conserved HPD motif
Gly/Phe-Rich Region (70-150 aa): Flexible linker region
C-terminal Substrate-Binding Domain (150-320 aa): Binds client proteins for targeting to Hsp70

The J-Domain Protein Family

DNAJB5 belongs to the DNAJ subfamily, which includes proteins with a full J-domain structure:

| Subfamily | Characteristics | Examples |
|-----------|-----------------|----------|
| DNAJA | Contain J-domain + Gly/Phe-rich + C-terminal | DNAJA1 (Hsp40), DNAJA2 |
| DNAJB | Contain J-domain + variable C-terminal | DNAJB5, DNAJB6, DNAJB8 |
| DNAJC | Contain J-domain + additional domains | DNAJC3, DNAJC13 |

Mechanism of Action

DNAJB5 functions through:

Hsp70 Recruitment: The J-domain recruits and activates Hsp70 proteins

Substrate Targeting: The C-terminal domain binds misfolded proteins

Handoff: Delivers substrates to Hsp70 for refolding or degradation

Aggregate Disaggregation: Can work with Hsp70 and Hsp110 to dissolve aggregates

Physiological Functions

Protein Folding Assistance

DNAJB5, in collaboration with Hsp70 family members, facilitates proper protein folding:

Co-translational folding assistance
Post-translational quality control
Prevention of misfolding during stress

Protein Quality Control

The DNAJB5-Hsp70 complex provides essential quality control functions [2][3]:

Proteasomal Degradation: Targets ubiquitinated misfolded proteins for degradation
Autophagic Clearance: Routes aggregates to autophagosomes
Aggregate Disassembly: Works with disaggregases to reverse aggregation

Stress Response

DNAJB5 expression is regulated by cellular stress:

Heat Shock Response: Upregulated under heat shock conditions
Oxidative Stress: Induced by reactive oxygen species
Proteotoxic Stress: Increased accumulation of misfolded proteins

Role in Neurodegenerative Diseases

Alzheimer's Disease

DNAJB5 has been implicated in Alzheimer's disease pathogenesis through its role in protein quality control [1][2]:

Amyloid-Beta Metabolism: May influence amyloid-beta production or clearance
Tau Pathology: Potential involvement in tau aggregation and clearance
Proteostasis Maintenance: Helps maintain neuronal proteostasis under stress

The accumulation of misfolded amyloid-beta and tau proteins is a hallmark of AD. DNAJB5 and other Hsp40 family members may provide protective functions by assisting in the clearance of these pathogenic proteins [2][3].

Parkinson's Disease

In Parkinson's disease, alpha-synuclein aggregation is a key pathological feature [1][2]. Research has shown that:

DNAJ proteins can interact with alpha-synuclein
Hsp40 overexpression reduces alpha-synuclein toxicity
DNAJ family members influence aggregation kinetics

The study by Hasegawa et al. (2018) specifically addressed the DnaJ/Hsp40 family in Parkinson's disease, highlighting the importance of these chaperones in maintaining dopaminergic neuron health [1].

Amyotrophic Lateral Sclerosis (ALS)

ALS is characterized by protein aggregation including TDP-43 and FUS [2][3]:

DNAJB5 expression is altered in ALS models
DNAJ proteins may help prevent toxic aggregation
Chaperone dysfunction may contribute to disease progression

Protective Mechanisms

DNAJ proteins provide neuroprotection through multiple mechanisms [3][4]:

Aggregate Prevention: Sequestration of aggregation-prone proteins

Disaggregation: Working with Hsp110 and Hsp70 to dissolve aggregates

Degradation Targeting: Directing misfolded proteins to the proteasome or autophagy

Membrane Repair: Assisting in repair of damaged membranes

Therapeutic Implications

Chaperone-Targeted Therapies

DNAJB5 represents a potential therapeutic target for neurodegenerative diseases [4]:

Small Molecule Activators: Compounds that enhance DNAJB5 activity
Gene Therapy: Viral delivery of DNAJB5 to neurons
Protein-Based Therapies: Recombinant DNAJB5 administration

Protein Disaggregases

The development of engineered protein disaggregases based on Hsp40-Hsp70-Hsp110 complexes represents a promising therapeutic approach [4]. These designer disaggregases could potentially reverse protein aggregation in neurodegenerative diseases.

Expression Pattern

Tissue Distribution

DNAJB5 exhibits broad tissue expression with notable brain localization:

Highest Expression: Hippocampus, cerebral cortex, cerebellum
Moderate Expression: Testis, ovary, heart
Cellular Localization: Cytosolic and membrane-associated

Brain Region Expression

Within the brain, DNAJB5 is expressed in:

Hippocampal neurons (CA1-CA3 pyramidal cells)
Cortical layer 2-4 neurons
Cerebellar Purkinje cells
Substantia nigra dopaminergic neurons

Regulation

DNAJB5 expression is regulated by:

Heat shock factor (HSF1)-dependent transcription
Cellular stress conditions
Developmental stage

Protein-Protein Interactions

Hsp70 Family Members

DNAJB5 interacts with multiple Hsp70 family proteins [9][10]:

HSPA1A (Hsp70-1): Major stress-inducible Hsp70
HSPA8 (Hsc70): Constitutively expressed chaperone
HSPA4 (Hsp110): Co-chaperone for disaggregation
HSPA5 (BiP/Grp78): ER-resident chaperone
HSPA9 (Mortalin): Mitochondrial Hsp70

Hsp90 Interaction

DNAJB5 can also interface with Hsp90 chaperone system:

Hsp90 client protein quality control
Coordination between Hsp70 and Hsp90 systems
Shared substrate targeting mechanisms

Other DNAJ Proteins

DNAJB5 may cooperate with other DNAJ family members [11]:

DNAJB1 (Hsp40): Canonical Hsp40 co-chaperone
DNAJB6: Brain-enriched Hsp40 with aggregation suppression
DNAJB8: Testis-specific Hsp40
DNAJC family members for broader proteostasis network

Mechanistic Role in Neurodegeneration

Protein Aggregation Pathways

The aggregation of misfolded proteins follows a characteristic cascade [3][4][12]:

Native State → Misfolding: Mutations, oxidative stress, or aging cause protein misfolding

Oligomer Formation: Misfolded proteins form transient oligomers

Nucleation: Oligomers serve as nuclei for further aggregation

Fibril Extension: Ordered fibrils grow through template-assisted polymerization

Amorphous Aggregation: Non-fibrillar aggregates accumulate

DNAJB5 intervenes at multiple points in this cascade:

Prevents initial misfolding through folding assistance
Captures early oligomers before they become nucleation-competent
Routes aggregates to degradation pathways
Works with disaggregases to reverse early fibril formation

Aggregate Clearance Mechanisms

DNAJB5 participates in multiple clearance pathways [13][14]:

Proteasomal Degradation (Ubiquitin-Proasome System):

Recognizes ubiquitinated misfolded proteins
Delivers substrates to the 26S proteasome
Facilitates unfolding and translocation into the proteasome
Works with Hsp70 to remove steric blocks

Autophagic Degradation:

Chaperone-mediated autophagy (CMA): Direct delivery to lysosomes via LAMP-2A
Macroautophagy: Bulk sequestration of aggregates into autophagosomes
Endosomal microautophagy: Selective uptake at endosomal membranes

Alternative Pathways:

Export to extracellular space
Sequestration into aggresomes for controlled storage

Membrane Protection and Repair

DNAJB5 contributes to membrane integrity [4]:

Associates with damaged membranes
Prevents aggregation of membrane-associated proteins
Aids in membrane fusion/fission events
Supports synaptic vesicle recycling

Role in Specific Neurodegenerative Diseases

Alzheimer's Disease

In Alzheimer's disease, DNAJB5 may modulate multiple pathological processes [1][2][15]:

Amyloid-Beta Metabolism:

May influence APP processing and Aβ production
Potential effects on α-secretase processing
Clearance of Aβ aggregates through proteostasis
Interaction with AChE and other Aβ-interacting proteins

Tau Pathology:

Tau is an Hsp70 client protein
DNAJB5 may assist in tau refolding/degradation
Modulation of tau phosphorylation states
Prevention of tau aggregate formation

Synaptic Proteostasis:

Critical for synaptic protein quality control
Supports AMPA receptor trafficking
Maintains neurotransmitter release machinery
Preserves synaptic plasticity under stress

Neuroinflammation Modulation:

Modulates heat shock response in glia
May regulate inflammatory cytokine expression
Supports neuronal survival in inflammatory environments

Parkinson's Disease

In Parkinson's disease, alpha-synuclein aggregation is central [1][16]:

Alpha-Synuclein Homeostasis:

DNAJ proteins including DNAJB5 interact with α-synuclein
Prevents α-synuclein oligomerization
May slow fibril extension kinetics
Supports autophagic clearance of α-synuclein

Dopaminergic Neuron Vulnerability:

High metabolic demand increases proteostatic stress
Mitochondrial dysfunction amplifies protein damage
DNAJB5 helps maintain proteostasis under these conditions
May provide neuroprotection in SN neurons

LRRK2 Interaction:

LRRK2 mutations are common in familial PD
Hsp40 proteins may modulate LRRK2 aggregation
Potential therapeutic modulation strategies
Interaction with other PD-associated proteins

Amyotrophic Lateral Sclerosis (ALS)

ALS features protein aggregation in motor neurons [2][3]:

TDP-43 Pathology:

TDP-43 is a major aggregating protein in ALS
DNAJ proteins may modulate TDP-43 aggregation
Hsp40 family members show altered expression in ALS
Potential for therapeutic intervention

FUS Proteinopathy:

FUS is another aggregating protein in ALS
Hsp40 proteins can interact with FUS
DNAJB5 may modulate FUS aggregation
Related to RNA processing dysfunction

C9orf72 Hexanucleotide Expansion:

Most common genetic cause of ALS/FTD
Produces toxic dipeptide repeats
DNAJ proteins may counteract this toxicity
Potential for modifier-based therapy

Huntington's Disease

Huntington's disease involves mutant huntingtin aggregation [17][18]:

Huntingtin Quality Control:

Mutant huntingtin has expanded polyglutamine tract
DNAJB5 can triage mutant huntingtin aggregates
Prevents toxic oligomer formation
Routes to degradation pathways

Modulation of Aggregation Kinetics:

Slows nucleation phase
Reduces fibril growth rate
Decreases overall aggregate burden
Maintains proteostasis longer

Therapeutic Strategies

Small Molecule Approaches

Hsp70/Hsp40 Modulators:

Agonists that enhance chaperone activity
Compounds that increase DNAJB5 expression
Allosteric activators of J-domain function

Disaggregation Enhancers:

Support Hsp110-Hsp70-Hsp40 system
Increase aggregate dissolution rates
Synergy with autophagy induction

Gene Therapy Approaches

Viral Vector Delivery:

AAV-mediated DNAJB5 overexpression
Targeting specific brain regions
Cell type-specific promoters
Regulated expression systems

Gene Editing:

Enhance endogenous DNAJB5 expression
Modify regulatory elements
Optimize codon usage for better translation

Protein-Based Therapies

Recombinant Protein Delivery:

Purified DNAJB5 protein administration
Engineered variants with enhanced activity
Cell-penetrating variants
Targeted delivery to neurons

Peptide-Based Approaches:

J-domain peptides for Hsp70 activation
Substrate-binding domain fragments
Cell-permeable chaperone mimetics

Combination Strategies

Chaperone + Degradation:

Combine DNAJB5 enhancement with proteasome/ autophagy activators
Coordinated clearance of existing aggregates
Prevention of new aggregate formation

Chaperone + Anti-aggregation:

Small molecule aggregation inhibitors
Antibody-based approaches
Multi-target combination therapy

Research Methods and Tools

Protein-Protein Interaction Studies

Co-immunoprecipitation: Identify DNAJB5 interacting partners
Yeast two-hybrid screening: Map interaction domains
Surface plasmon resonance: Measure binding affinities
Fluorescence resonance energy transfer (FRET): Monitor complex formation in cells

Aggregation Assays

Thioflavin T fluorescence: Quantify fibril formation
Electron microscopy: Visualize aggregate structures
Atomic force microscopy: Measure aggregate morphology
Sedimentation assays: Separate soluble from aggregated protein

Cellular Models

Neuronal cell lines: SH-SY5Y, PC12, N2a
Primary neuron cultures: Mouse cortical neurons
iPSC-derived neurons: Patient-specific models
Organoid systems: Brain organoids for complex models

Animal Models

Transgenic mice: Models of protein aggregation diseases
Knockout mice: DNAJB5 loss-of-function studies
Viral transduction: Local overexpression in brain
Behavioral testing: Cognitive and motor assessments

Evolutionary Conservation

Species Distribution

DNAJB5 is evolutionarily conserved across eukaryotes:

| Species | Homolog | Conservation |
|---------|---------|--------------|
| Human | DNAJB5 | Reference |
| Mouse | Dnajb5 | Very high (95%+) |
| Zebrafish | dnajb5 | High |
| D. melanogaster | dnaJ-1 | Moderate |
| C. elegans | dnj-10 | Moderate |
| S. cerevisiae | YDJ1 | Lower |

Functional Conservation

Key functional domains are highly conserved:

J-domain: Nearly identical across species
Gly/Phe-rich region: Variable but present
C-terminal domain: Moderately conserved

Genetic Variations and Polymorphisms

Known Variants

DNAJB5 genetic variations have been studied:

SNPs: Various single nucleotide polymorphisms identified
Population frequency: Common variants in population databases
Functional effects: Most variants have mild effects
Disease associations: Limited direct evidence

Clinical Significance

Currently, DNAJB5 variants are not strongly associated with:

Rare monogenic diseases
Strong risk factors for complex diseases
Pharmacogenomic considerations

However, DNAJB5 expression and common variants may modify:

Neurodegenerative disease progression
Response to chaperone-based therapies
Protein aggregation disease severity

Future Directions

Research Gaps

In vivo function: Better understanding of DNAJB5 in living organisms

Cell-type specificity: Which neurons benefit most from DNAJB5

Aggregate specificity: Does DNAJB5 prefer specific aggregate types

Therapeutic windows: Optimal timing for intervention

Biomarkers: Surrogate markers for chaperone activity

Emerging Approaches

Cryo-EM structures: High-resolution chaperone-substrate complexes

Single-molecule studies: Real-time observation of chaperone action

Systems biology: Integration into cellular proteostasis networks

Synthetic biology: Engineered chaperones with enhanced properties

Clinical translation: Moving basic science to therapies

External Links

[NCBI Gene: DNAJB5](https://www.ncbi.nlm.nih.gov/gene/25822)
[UniProt: O75164](https://www.uniprot.org/uniprot/O75164)
[OMIM: 608591](https://www.omim.org/entry/608591)
[Ensembl: ENSG00000135919](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000135919)

References

[Hasegawa et al., DnaJ/Hsp40 Family and Parkinson's Disease (2018)](https://pubmed.ncbi.nlm.nih.gov/29367843/)

[He & Wang, The roles of HSP40/DNAJ protein family in neurodegenerative diseases (2022)](https://pubmed.ncbi.nlm.nih.gov/36581576/)

[Zarouchlioti et al., DNAJ Proteins in neurodegeneration: essential and protective factors (2018)](https://pubmed.ncbi.nlm.nih.gov/29203718/)

[Shorter, Designer protein disaggregases to counter neurodegenerative disease (2017)](https://pubmed.ncbi.nlm.nih.gov/28208059/)

[Pang et al., Critical role of zebrafish dnajb5 in myocardial proliferation and regeneration (2020)](https://pubmed.ncbi.nlm.nih.gov/33191150/)

[Ago et al., A redox-dependent pathway for regulating class II HDACs and cardiac hypertrophy (2008)](https://pubmed.ncbi.nlm.nih.gov/18555775/)

[Lampis et al., MIR21 Drives Resistance to Heat Shock Protein 90 Inhibition in Cholangiocarcinoma (2018)](https://pubmed.ncbi.nlm.nih.gov/29113809/)

[Schulze et al., Gene expression in IBD (2008)](https://pubmed.ncbi.nlm.nih.gov/18340362/)

[Kampinga et al., Guidelines for the nomenclature of the human heat shock proteins (2010)](https://pubmed.ncbi.nlm.nih.gov/20019750/)

[Chen et al., The HSP40 family in neurodegenerative diseases (2019)](https://pubmed.ncbi.nlm.nih.gov/31153615/)

[Chen et al., Autophagy-modulating proteins in neurodegeneration (2020)](https://pubmed.ncbi.nlm.nih.gov/32065043/)

[Jackson et al., Hsp40 proteins triage mutant huntingtin (2018)](https://pubmed.ncbi.nlm.nih.gov/29896949/)

[Goloubinoff et al., How do small heat shock proteins work? (2009)](https://pubmed.ncbi.nlm.nih.gov/19609937/)

[Liberek et al., The Hsp70/Hsp40 chaperone system (2008)](https://pubmed.ncbi.nlm.nih.gov/18537416/)

[Mayer et al., Hsp70 chaperone dynamics (2010)](https://pubmed.ncbi.nlm.nih.gov/20805477/)

[Vodermayer et al., Human Hsp40/DNAJ proteins in neurodegeneration (2009)](https://pubmed.ncbi.nlm.nih.gov/19192389/)

[Terryn et al., The role of DNAJB proteins in protein homeostasis (2018)](https://pubmed.ncbi.nlm.nih.gov/30104758/)

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DNAJB5

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📊 Evidence Profile Foundational

Evidence Balance

+0%

Certainty

85%

Debates

0

Incoming

17

Outgoing

17

0 supporting 0 contradicting 0 neutral

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📗 Cite This Artifact

DNAJB5 (DnaJ Heat Shock Protein Family Member B5)

DNAJB5 (DnaJ Heat Shock Protein Family Member B5)

Overview

DNAJB5 (DnaJ Heat Shock Protein Family Member B5)

Overview

Molecular Structure and Biochemistry

Protein Architecture

The J-Domain Protein Family

Mechanism of Action

Physiological Functions

Protein Folding Assistance

Protein Quality Control

Stress Response

Role in Neurodegenerative Diseases

Alzheimer's Disease

Parkinson's Disease

Amyotrophic Lateral Sclerosis (ALS)

Protective Mechanisms

Therapeutic Implications

Chaperone-Targeted Therapies

Protein Disaggregases

Expression Pattern

Tissue Distribution

Brain Region Expression

Regulation

Protein-Protein Interactions

Hsp70 Family Members

Hsp90 Interaction

Other DNAJ Proteins

Mechanistic Role in Neurodegeneration

Protein Aggregation Pathways

Aggregate Clearance Mechanisms

Membrane Protection and Repair

Role in Specific Neurodegenerative Diseases

Alzheimer's Disease

Parkinson's Disease

Amyotrophic Lateral Sclerosis (ALS)

Huntington's Disease

Therapeutic Strategies

Small Molecule Approaches

Gene Therapy Approaches

Protein-Based Therapies

Combination Strategies

Research Methods and Tools

Protein-Protein Interaction Studies

Aggregation Assays

Cellular Models

Animal Models

Evolutionary Conservation

Species Distribution

Functional Conservation

Genetic Variations and Polymorphisms

Known Variants

Clinical Significance

Future Directions

Research Gaps

Emerging Approaches

See Also

External Links

References

💬 Discussion