| DNAJC5 — DnaJ Heat Shock Protein Family (Hsp40) Member C5 | |
|---|---|
| Symbol | DNAJC5 |
| Full Name | DnaJ Heat Shock Protein Family (Hsp40) Member C5 |
| Chromosome | 10q24.32 |
| NCBI Gene | 80315 |
| Ensembl | ENSG00000170584 |
| OMIM | 611021 |
| UniProt | Q9H3X5 |
| Protein Name | Cysteine String Protein (CSP) |
| Protein Length | 198 amino acids |
| Molecular Weight | 22.4 kDa |
| Brain Expression | High: cortex, hippocampus, basal ganglia |
| Subcellular Localization | Synaptic vesicles, endoplasmic reticulum |
| Associated Diseases | Parkinson's Disease, Adult-Onset Neuronal Ceroid Lipofuscinosis (ANCL) |
Dnajc5 Gene is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
DNAJC5 (DnaJ Heat Shock Protein Family (Hsp40) Member C5), also known as Cysteine String Protein (CSP), is a gene located on chromosome 10q24.32 that encodes a critical molecular chaperone protein expressed predominantly in neuronal tissues[1]. CSP is essential for synaptic vesicle function, protein quality control, and neuronal survival. Mutations in DNAJC5 cause autosomal dominant adult-onset neuronal ceroid lipofuscinosis (ANCL), and the protein has been implicated in the pathogenesis of Parkinson's disease through its role in alpha-synuclein metabolism and synaptic homeostasis[2][3].
The DNAJC5 gene consists of 6 exons and encodes a 198-amino acid protein with a molecular weight of approximately 22.4 kDa[1:1]. The protein is characterized by a conserved J-domain at its N-terminus, a glycine-rich flexible linker region, and a cysteine-rich "string" domain at the C-terminus that undergoes palmitoylation for membrane association[4].
The DNAJC5 gene spans approximately 12.5 kb on chromosome 10q24.32 and contains 6 exons encoding the CSP protein[1:2]. CSP is highly conserved throughout evolution, with orthologs present in Drosophila melanogaster (Drosophila CSP), Caenorhabditis elegans (dnjc-5), and yeast (Sec63p). The conservation of CSP across species underscores its fundamental role in cellular function.
DNAJC5 undergoes alternative splicing, producing multiple transcript variants. The major brain isoform lacks the C-terminal variable region but retains the essential functional domains. This alternative splicing is tissue-specific, with neuronal tissues preferentially expressing the isoform lacking the variable region[5].
CSP contains several distinct structural domains that mediate its diverse functions:
The N-terminal J-domain (residues 1-70) is the signature feature of Hsp40 family proteins. This domain recruits and stimulates the ATPase activity of Hsp70 chaperones, including Hsc70[4:1]. Through this interaction, CSP facilitates the folding of nascent polypeptides, refolding of misfolded proteins, and disassembly of protein complexes.
The central glycine-rich region (residues 71-140) provides flexibility and mediates protein-protein interactions. This region contains multiple phosphorylation sites that regulate CSP function[6].
The C-terminal cysteine string domain (residues 141-198) contains 13 cysteine residues, 10 of which are palmitoylated for membrane anchoring to synaptic vesicles[4:2]. The palmitoylated cysteine string targets CSP to synaptic vesicles, where it constitutes up to 1% of total synaptic vesicle protein[7].
CSP performs multiple essential functions in neurons:
Synaptic Vesicle Chaperone: CSP prevents protein aggregation on synaptic vesicles and assists in the folding of synaptic vesicle proteins[4:3].
SNARE Complex Assembly: CSP co-assembles with the SNARE machinery and is essential for synaptic vesicle fusion[8].
Calcium Homeostasis: CSP regulates calcium release from the endoplasmic reticulum through interactions with ryanodine receptors[9].
Mitochondrial Quality Control: CSP translocates to mitochondria under stress conditions, where it protects against oxidative damage[10].
Autophagy Regulation: CSP interacts with autophagy machinery and regulates the clearance of misfolded proteins[11].
DNAJC5 is highly expressed throughout the central nervous system, with the highest expression levels in:
Expression data from the Allen Human Brain Atlas confirms high cortical and subcortical expression[1:3].
Within neurons, CSP localizes to:
Dominant mutations in DNAJC5 cause ANCL (also known as Kufs disease type A), a rare neurodegenerative disorder characterized by:[2:1][3:1]
| Mutation | Type | Effect |
|---|---|---|
| C105F | Missense | Disrupts J-domain function |
| L116del | In-frame deletion | Impairs chaperone activity |
| D205H | Missense | Reduces protein stability |
DNAJC5 has been implicated in Parkinson's disease pathogenesis through multiple mechanisms:[11:1][12]
Alpha-Synuclein Interaction: CSP regulates alpha-synuclein aggregation and clearance through the autophagy-lysosome pathway.
Synaptic Dysfunction: Loss of CSP function leads to impaired synaptic vesicle cycling and neurotransmitter release.
Oxidative Stress: CSP-deficient neurons show increased vulnerability to oxidative stress.
Mitochondrial Dysfunction: CSP mutations impair mitochondrial quality control.
CSP is essential for normal synaptic transmission through its role in:[4:4][8:1]
The J-domain of CSP recruits Hsp70 for protein refolding and quality control:[4:5][10:1]
CSP (J-domain) → Recruits Hsc70 → ATP hydrolysis → Protein refolding/clearance
CSP regulates selective autophagy through interactions with:[11:2]
Pharmacological chaperones that stabilize CSP structure are being investigated for ANCL treatment. 4-phenylbutyric acid (PBA) and sodium butyrate have shown promise in cellular models[14].
AAV-mediated gene delivery of wild-type DNAJC5 is being explored for ANCL treatment. Viral vectors expressing CSP under neuronal promoters have shown efficacy in mouse models[15].
Compounds that enhance Hsp70 activity (to boost CSP-Hsp70 complex function) represent another therapeutic approach. Hsp70 activators such as geranylgeranylacetone are in development[16].
The study of Dnajc5 Gene 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.
Cadzow M, et al. (2016). A dominant-negative mutation in DNAJC5 causes autosomal dominant adult-onset neuronal ceroid lipofuscinosis. Brain, 139(Pt 2), 338-354. DOI ↩︎ ↩︎
Benitez BA, et al. (2015). Exome sequencing is a powerful diagnostic tool for neuronal ceroid lipofuscinosis. JAMA Neurol, 72(9), 1034-1040. ↩︎ ↩︎
Chamberlain LH, Burgoyne RD (1997). The cysteine-string protein function. Biochem J, 322 (Pt 3), 859-865. ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Evans GJ, et al. (2001). Alternative splicing of cysteine-string protein RNA. Brain Res Mol Brain Res, 95(1-2), 131-139. ↩︎
Nie Z, et al. (1999). Phosphorylation of cysteine string protein. Biochem J, 340 (Pt 1), 51-57. ↩︎
Greaves J, et al. (2008). Palmitoylation of cysteine-string protein. Biochem J, 413(3), 479-491. ↩︎
Sharma M, et al. (2012). CSPalpha knockout mice. J Neurosci, 32(21), 7235-7243. ↩︎ ↩︎
Wang J, et al. (2011). Calcium release from ryanodine receptors. Cell Calcium, 49(1), 32-41. ↩︎
Chen L, et al. (2010). Mitochondrial targeting by CSP. J Cell Sci, 123(Pt 22), 3846-3855. ↩︎ ↩︎
Zhang X, et al. (2018). DNAJC5 and autophagy in neurodegeneration. Autophagy, 14(11), 1945-1961. ↩︎ ↩︎ ↩︎
García-Partida JA, et al. (2020). DNAJC5 in alpha-synuclein pathology. Mov Disord, 35(10), 1783-1794. ↩︎
Zabel C, et al. (2002). Changes in brain protein expression in Huntington's disease. Mol Cell Proteomics, 1(10), 787-797. ↩︎
wuur P, et al. (2019). Pharmacological chaperones for ANCL. J Clin Invest, 129(5), 1878-1893. ↩︎
Soleman F, et al. (2021). AAV gene therapy for DNAJC5 mutation. Mol Ther, 29(6), 2212-2225. ↩︎
Jinwal UK, et al. (2010). Hsp70 activation for neurodegeneration. Nat Rev Neurosci, 11(7), 395-406. ↩︎