Igf1R 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.
| Full Name | IGF1R (Insulin-like Growth Factor 1 Receptor) |
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| Chromosome | chr15 |
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| Location | 15q26.3 |
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| NCBI Gene ID | 3480 |
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| OMIM | 147370 |
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| Ensembl | ENSG00000140443 |
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| UniProt | P08069 |
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| Associated Diseases | Alzheimer's Disease, Parkinson's Disease, ALS, Cancer, Laron Syndrome |
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| Protein Class | Receptor Tyrosine Kinase |
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| Expression | Ubiquitous, high in brain |
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IGF1R (Insulin-like Growth Factor 1 Receptor) is a heterotetrameric receptor tyrosine kinase that binds IGF1 and IGF2 with high affinity. It is essential for normal brain development, neuronal survival, synaptic plasticity, and overall nervous system function. IGF1R is widely expressed throughout the brain, with particularly high levels in the hippocampus, cortex, and olfactory bulb during development. As the primary mediator of IGF1's neuroprotective effects, IGF1R activates the PI3K/Akt and MAPK/ERK signaling cascades that promote cell survival, growth, and differentiation. Dysregulation of IGF1R signaling has been implicated in neurodegenerative diseases, making it an important therapeutic target.
The IGF1R gene is located on chromosome 15q26.3 and spans approximately 100 kb. The gene consists of 21 exons and produces a single major transcript encoding the precursor protein. The gene promoter contains multiple transcription factor binding sites, allowing regulation by growth factors, hormones, and cellular stress:
- Exon 1-2: 5' UTR and signal peptide
- Exons 3-11: α-subunit (extracellular ligand-binding domain)
- Exons 12-21: β-subunit (transmembrane and intracellular domains)
- Alternative splicing: Produces variants with tissue-specific expression
The mature IGF1R is a heterotetramer consisting of two α-subunits and two β-subunits:
- α-Subunit (706 aa each): Extracellular ligand-binding domain containing multiple cysteine-rich repeats
- β-Subunit (626 aa each): Single transmembrane helix and intracellular tyrosine kinase domain
- Disulfide bonds: Link the two α- and two β-subunits
¶ Key Domains
- Cysteine-rich region: Ligand binding
- Fibronectin type III repeats: Structural
- Tyrosine kinase domain: Catalytic activity
- C-terminal tail: Multiple phosphorylation sites
IGF1R activation involves:
- Ligand (IGF1 or IGF2) binding to extracellular α-subunits
- Receptor dimerization (pre-formed or induced)
- Autophosphorylation of intracellular tyrosine residues
- Recruitment of adapter proteins (IRS-1/2, Shc)
- Activation of downstream signaling pathways
Primary pro-survival signaling:
- Akt phosphorylation inhibits pro-apoptotic proteins
- mTORC1 activation promotes protein synthesis
- GSK-3β inhibition affects tau phosphorylation
- FOXO transcription factor regulation
Growth and differentiation signaling:
- Ras/Raf/MEK/ERK cascade activation
- Gene transcription
- Cell growth and proliferation
- Synaptic plasticity modulation
- Neurogenesis regulation
- Neuronal survival
- Synaptic plasticity and LTP
- Myelination support
- Astrocyte function
IGF1R signaling is significantly altered in AD:
- Decreased IGF1R expression in hippocampus and cortex
- Impaired downstream signaling (PI3K/Akt deficits)
- Reduced IRS-1/2 function (insulin resistance)
- Therapeutic potential of IGF1R modulation
- IGF1R protects dopaminergic neurons
- Reduced signaling in substantia nigra
- Therapeutic delivery of IGF1 shows promise
- Receptor as drug target
- Motor neurons vulnerable to IGF1R deficits
- Gene therapy approaches targeting IGF1R
- Neuroprotective effects demonstrated
- Clinical trials ongoing
IGF1R is frequently overexpressed in cancers:
- Promotes tumor growth and metastasis
- Resistance to chemotherapy
- Therapeutic targeting with antibodies and small molecules
- Dual targeting with IGF1R/IR inhibitors
- IGF1R mutations cause GH insensitivity
- Severe growth deficiency
- Neurodevelopmental consequences
IGF1R exhibits widespread expression:
- Highest Expression: Embryonic brain, adult hippocampus (CA1-CA3), cortex, olfactory bulb
- Moderate Expression: Cerebellum, basal ganglia, thalamus
- Cell Types: Neurons, astrocytes, oligodendrocytes, microglia
Expression is highest during development and decreases with age, correlating with age-related vulnerability to neurodegeneration.
IGF1R autophosphorylation sites:
- Tyrosine 1131: Major activation site
- Tyrosine 1135/1136: Kinase domain
- Tyrosine 1250/1251: Docking sites
- IRS-1/2: PI3K/Akt pathway
- Shc: MAPK/ERK pathway
- Grb10: Negative regulation
- Insulin Receptor (IR): Hybrid receptors
- Integrins: Cell adhesion signaling
- Other growth factor receptors
- Protein tyrosine phosphatases (PTPs)
- SOCS proteins
- Endocytosis and degradation
- Recombinant IGF1: Mecasermin
- IGF1 mimetics: Selective activation
- Allosteric modulators
- Blocking antibodies: Picropodophyllin
- Small molecule inhibitors: NVP-AEW541
- IGF1/IGF2 neutralizers
- AAV-IGF1R modulation
- CRISPR approaches
- siRNA targeting
- IGF1R + PI3K modulators
- IGF1R + neurotrophic factors
- Targeted delivery to brain
- Complete KO: Embryonic lethal, growth deficiency
- Neuron-specific KO: Learning/memory deficits
- Conditional KO: Age-related phenotypes
- Overexpression: Enhanced neurogenesis
- Disease models: AD, PD, HD
- Reporter lines
- Brain-penetrant IGF1R modulators
- Selective agonists vs. antagonists
- Delivery across BBB
- Biomarker development
- Clinical translation
The study of Igf1R 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.