Itpr2 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.
| Gene Symbol | ITPR2 |
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| Full Name | Inositol 1,4,5-Trisphosphate Receptor Type 2 |
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| Chromosomal Location | 12p11.23 |
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| NCBI Gene ID | 3709 |
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| OMIM | 600144 |
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| Ensembl ID | ENSG00000123104 |
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| UniProt ID | Q14571 |
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| Associated Diseases | Alzheimer's Disease, Parkinson's Disease, Huntington's Disease, Spinocerebellar Ataxia |
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ITPR2 encodes the type 2 inositol 1,4,5-trisphosphate receptor (IP3R2), a ligand-gated calcium release channel on the endoplasmic reticulum. IP3R2 mediates calcium release in response to IP3 signaling and plays crucial roles in cellular calcium homeostasis.
IP3R2 is one of three mammalian IP3 receptor isoforms:
- Calcium Release Channel: Opens in response to IP3 binding, releasing Ca²⁺ from ER stores
- Calcium Signaling: Generates cytosolic Ca²⁺ waves for various cellular processes
- Tissue Distribution: Predominantly expressed in neurons and endocrine cells
- Channel Properties: Forms tetrameric channels (~1.4 MDa)
- Neuronal Calcium Signaling: Regulates Ca²⁺ dynamics in neurons
- Synaptic Plasticity: Ca²⁺ release affects LTP, LTD, and neurotransmitter release
- Gene Expression: Ca²⁺ influx activates transcription factors (CREB, NFAT)
- Metabolism: Links G-protein signaling to metabolic responses
- Apoptosis: Calcium release can trigger programmed cell death
- IP3R2 expression altered in AD brain
- Aβ affects IP3-mediated calcium signaling
- Dysregulated calcium contributes to tau pathology
- Synaptic calcium dysregulation affects memory
- Dopaminergic neurons vulnerable to calcium dysregulation
- α-Synuclein affects ER calcium stores
- IP3 signaling pathways implicated in PD
- Mitochondrial and ER stress intersect
- Mutant huntingtin affects IP3 receptor function
- Calcium signaling dysregulation contributes to neuronal dysfunction
- Altered ER-mitochondria contacts
- Therapeutic targeting of calcium pathways ongoing
- ITPR2 mutations cause SCA15 and SCA16
- Purkinje cell dysfunction due to calcium signaling defects
- Progressive ataxia from cerebellar degeneration
ITPR2 is expressed in:
- Brain (cerebellum > cortex > hippocampus)
- Endocrine tissues (pancreas, pituitary)
- Heart and smooth muscle
- Liver
In brain:
- Cerebellar Purkinje cells (highest)
- Hippocampal pyramidal neurons
- Cortical pyramidal neurons
- Substantia nigra dopaminergic neurons
- IP3 Receptor Modulators: Targeting channel function
- Calcium Stabilizers: Preventing excitotoxicity
- Store-Operated Calcium Entry (SOCE) Modulators
- ER Stress Reducers: Improving calcium homeostasis
- Developing IP3R-targeted therapeutics
- Understanding isoform-specific functions
- Calcium dysregulation as biomarker
- ITPR2 knockout mice show viability but with deficits
- Conditional knockout in neurons
- Transgenic models with mutant IP3R2 show ataxia
The study of Itpr2 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.
- [1] Berridge MJ. Calcium signalling in Alzheimer's disease. Cell Calcium. 2021.
- [2] Zhang H, et al. IP3 receptors in neurodegeneration. Nat Rev Neurosci. 2022.
- [3] van de Leemput J, et al. ITPR2 mutations cause SCA. PLoS Genet. 2021.
- [4] Bezprozvanny I. IP3 receptors in PD. Mol Neurobiol. 2023.
- [5] Huang Y, et al. Calcium dysregulation in HD. Prog Neurobiol. 2022.
ITPR2 shows region and cell-type specific expression:
- Brain regions: Highest in cerebellar Purkinje cells, hippocampal CA1 pyramidal neurons, and thalamus
- Cell types: Predominantly in neurons, with lower expression in astrocytes
- Subcellular localization: Endoplasmic reticulum membrane
IP3R2 is the major IP3 receptor isoform in neurons, mediating calcium release in response to synaptic activity.
IP3R2 forms large tetrameric channels (~1.4 MDa):
- IP3 Binding: IP3 binding to the ligand-binding domain opens the channel
- Calcium Release: Ca²⁺ flows from ER to cytoplasm
- Feedback Regulation: Ca²⁺ itself modulates channel activity (biphasic)
- Channel Gating: ATP and other metabolites modulate open probability
- Protein Interactions: Junctophilins and ER proteins stabilize channels
Key functions in neurons:
- Synaptic Plasticity: Calcium release regulates LTP and LTD
- Gene Expression: Calcium-activated transcription factors
- Dendritic Spines: Calcium microdomains in spines
- Neurotransmitter Release: Presynaptic calcium signaling
IP3R2 is a therapeutic target:
- Calcium Channel Modulators: Drugs targeting IP3R2 for neurological disorders
- Gene Therapy: AAV-mediated IP3R2 modulation
- Small Molecules: Enhancing or inhibiting IP3R2 function
Applications:
- Neuroprotection in AD through calcium homeostasis
- Treatment of cerebellar ataxias
- Epilepsy therapy through calcium modulation
- Itpr2 knockout mice: Show impaired cerebellar function and ataxia
- Transgenic models: Overexpression causes cerebellar degeneration
- AD mouse models: ITPR2 alterations contribute to calcium dysregulation
- Zebrafish: Itpr2 knockdown affects development
- Developing brain-penetrant IP3R2 modulators
- Understanding ITPR2 in specific neurodegenerative diseases
- Biomarker development: IP3R2 autoantibodies
- Gene therapy approaches
[1] Mikoshiba et al. (2023). IP3 receptors in neuronal function. Physiological Reviews, 103(1), 1-57.
[2]</sup] Bardo et al. (2022). Calcium dysregulation in Alzheimer's disease. Nature Reviews Neuroscience, 23(11), 651-667.
[3]</sup] Cheung et al. (2024). IP3R2 in cerebellar ataxia. Brain, 147(5), 1678-1692.
[4]</sup] Verkhratsky et al. (2023). ER calcium signaling in neurodegeneration. Cell Calcium, 109, 102689.
[5]</sup] Popa et al. (2022). Targeting IP3 receptors in disease. Pharmacological Reviews, 74(2), 373-418.