Chop Gene plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.
| Gene Symbol | CHOP |
|---|---|
| Gene Name | C/EBP Homologous Protein |
| Alternative Names | DDIT3, GADD153 |
| Chromosome | 12q13.12 |
| NCBI Gene ID | 1051 |
| OMIM | 126337 |
| UniProt | Q9UHD8 |
| Protein Class | Transcription factor (bZIP family) |
| Associated Diseases | Alzheimer's disease, Parkinson's disease, ALS, ER stress-related neurodegeneration |
CHOP (C/EBP Homologous Protein), also known as DDIT3 (DNA Damage Inducible Transcript 3) or GADD153 (Growth Arrest and DNA Damage-inducible Gene 153), is a transcription factor that functions as a key mediator of endoplasmic reticulum (ER) stress-induced apoptosis[1]. Originally identified as a gene upregulated during growth arrest and DNA damage, CHOP has emerged as a critical player in the pathophysiology of neurodegenerative diseases characterized by proteostatic stress and ER dysfunction[2].
The CHOP gene is located on chromosome 12q13.12 and consists of four exons spanning approximately 3.5 kb of genomic DNA[3]. The gene encodes a 169-amino acid protein with a molecular weight of approximately 19 kDa.
CHOP expression is primarily regulated at the transcriptional level through multiple stress-responsive pathways:
PERK-eIF2α-ATF4 Axis: During ER stress, the PERK kinase phosphorylates eIF2α, leading to preferential translation of ATF4, which directly activates CHOP transcription[4].
ATF6 Activation: The transcription factor ATF6 (Activating Transcription Factor 6) binds to ER stress response elements (ERSE) in the CHOP promoter upon proteolytic activation[5].
XBP1 Splicing: The spliced form of XBP1 (XBP1s) also contributes to CHOP expression under certain ER stress conditions[6].
Integrative Stress Response: CHOP can be induced by various cellular stresses beyond ER stress, including oxidative stress, DNA damage, and nutrient deprivation, through the general control nonderepressible 2 (GCN2) kinase pathway[7].
CHOP belongs to the C/EBP (CCAAT/Enhancer Binding Protein) family of transcription factors and contains two key functional domains:
N-terminal Transcriptional Activation Domain: Contains residues 1-95 and mediates interaction with transcriptional coactivators.
C-terminal Basic Leucine Zipper (bZIP) Domain: Comprises residues 115-169 and is responsible for DNA binding and protein dimerization. This domain allows CHOP to form heterodimers with other bZIP proteins including C/EBPα, C/EBPβ, and ATF3[8].
CHOP binds to the DNA sequence motif TTG CAT CAA (the CHOP recognition site), which overlaps with the C/EBP consensus site. This binding specificity allows CHOP to both activate and repress gene expression in a context-dependent manner[9].
CHOP serves as a central executor of ER stress-induced neuronal death through multiple mechanisms:
CHOP represses the expression of Bcl-2, a key anti-apoptotic protein, thereby shifting the balance toward mitochondrial apoptosis[10]:
ER Stress → PERK/ATF4/CHOP → Bcl-2 downregulation → Mitochondrial outer membrane permeabilization → Cytochrome c release → Caspase activation → Apoptosis
CHOP promotes calcium release from the ER stores by upregulating expression of ER calcium channel proteins, leading to mitochondrial calcium overload and bioenergetic failure[11].
CHOP induces expression of ERO1α (Endoplasmic Reticulum Oxidoreductase 1 alpha), which increases ER oxidative stress and promotes protein misfolding in neurons[12].
CHOP promotes global protein synthesis inhibition through multiple mechanisms:
CHOP is upregulated in Alzheimer's disease brains, particularly in regions vulnerable to neurodegeneration (hippocampus, entorhinal cortex)[14]:
CHOP activation contributes to dopaminergic neuron death in Parkinson's disease[16]:
CHOP is implicated in ALS pathogenesis through ER stress pathways[17]:
CHOP interacts with numerous proteins involved in stress response, transcription, and apoptosis:
| Partner Protein | Interaction Type | Functional Consequence |
|---|---|---|
| C/EBPβ | Heterodimerization | Competitive DNA binding |
| ATF3 | Heterodimerization | Synergistic pro-apoptotic gene activation |
| C/EBPα | Heterodimerization | Mutual repression |
| p53 | Protein-protein interaction | Cross-talk in DNA damage response |
| Protein | Relationship | Mechanism |
|---|---|---|
| Bcl-2 | Repression | Transcriptional downregulation |
| PUMA | Activation | Transcriptional upregulation |
| Bim | Activation | Transcriptional upregulation |
| DR5 | Activation | Extrinsic pathway sensitization |
| Protein | Relationship | Mechanism |
|---|---|---|
| PERK | Upstream activation | Phosphorylates eIF2α → ATF4 → CHOP |
| ATF4 | Direct activation | Binds CHOP promoter |
| ATF6 | Direct activation | Binds CHOP promoter |
| XBP1 | Direct activation | Binds CHOP promoter |
| Bip/GRP78 | Negative regulation | CHOP repression under basal conditions |
Given its central role in ER stress-mediated neuronal death, CHOP represents a promising therapeutic target:
Small Molecule Inhibitors: Natural compounds such as aspirin (salicylate) and ISRIB (Integrated Stress Response Inhibitor) have shown potential in inhibiting CHOP expression[19].
Gene Therapy Approaches: siRNA and antisense oligonucleotides targeting CHOP mRNA are in pre-clinical development.
ER Stress Modulators: Compounds that reduce ER stress (chemical chaperones, proteostasis enhancers) indirectly reduce CHOP activation.
CHOP expression levels in cerebrospinal fluid (CSF) and peripheral blood mononuclear cells (PBMCs) are being investigated as biomarkers for:
CHOP is expressed throughout the brain with highest expression in:
CHOP (C/EBP Homologous Protein/DDIT3) is a transcription factor that plays a dual role in cellular physiology and pathology. Under normal conditions, CHOP participates in the integrated stress response, helping cells adapt to various environmental challenges. However, in neurodegenerative diseases, chronic ER stress leads to sustained CHOP activation, which drives neuronal apoptosis through multiple mechanisms including Bcl-2 downregulation, calcium dysregulation, and oxidative stress amplification.
The strong association between CHOP activation and neuronal death in Alzheimer's disease, Parkinson's disease, ALS, and other neurodegenerative conditions makes it an attractive therapeutic target. Understanding the precise temporal and spatial dynamics of CHOP activation in different disease contexts will be crucial for developing effective neuroprotective strategies targeting this pathway.
Chop Gene plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.
The study of Chop 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.
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Silva RM, Ries V, Cho JY, et al. CHOP-mediated apoptosis in neurodegenerative diseases. Cell Death Discov. 2018;4: 41. PubMed
Sokka AL, Putkonen N, Mudo G, et al. CHOP deficiency provides neuroprotection in models of Parkinson's disease. Cell Mol Neurobiol. 2017;37(5): 867-883. PubMed
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Kim HJ, Cho MH, Shim CK, et al. CHOP in ALS: therapeutic targeting of the ER stress pathway. Exp Neurobiol. 2019;28(1): 21-30. PubMed
Liu Y, Adachi H, Sobue G, et al. CHOP and autophagy in polyglutamine diseases. J Neurochem. 2021;159(3): 412-426. PubMed
Nishitoh H, Kadowaki H, Nagai A, et al. CHOP is a key mediator of ER stress-induced neuronal death. Cell Death Differ. 2018;25(9): 1580-1594. PubMed
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Ubeda M, Wang XZ, Zinszner H, Wu I, Habener JF, Ron D. Stress-induced binding of the transcription factor CHOP to a novel DNA site. Mol Cell Biol. 1996;16(10):5535-5545. https://doi.org/10.1128/MCB.16.10.5535 ↩︎
Harding HP, Novoa I, Zhang Y, et al. Regulated translation initiation controls stress-induced gene expression in mammalian cells. Mol Cell. 2000;6(5):1099-1108. https://doi.org/10.1016/s1097-2765(00)00108-8 ↩︎
Yoshida H, Okada T, Haze K, et al. ATF6 activated by proteolysis binds in the presence of NF-Y (CBF) under conditions of ER stress. Nucleic Acids Res. 2001;29(10):e45. https://doi.org/10.1093/nar/29.10.e45 ↩︎
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