Neurons expressing the insulin-like growth factor 1 receptor (IGF1R) represent a critical population for neuronal survival, development, and function throughout the lifespan. IGF1R is a receptor tyrosine kinase that binds insulin-like growth factor 1 (IGF-1) with high affinity, as well as IGF-2 and insulin at lower affinity [1]. These neurons are widely distributed in the brain and play essential roles in neuroprotection, synaptic plasticity, metabolism, and myelination. The IGF-1 system has emerged as a major therapeutic target for neurodegenerative diseases, particularly Alzheimer's disease and ALS.
The IGF1R gene is located on chromosome 15q26.3 in humans and encodes a 1,367-amino acid receptor precursor that is cleaved to form the mature heterotetrameric receptor [2]. The receptor consists of:
IGF1R binds multiple ligands with different affinities:
| Ligand | Affinity | Primary Role |
|---|---|---|
| IGF-1 | Highest | Neuroprotection, development |
| IGF-2 | High | Fetal development |
| Insulin | Low | Metabolic regulation |
IGF1R activates multiple intracellular cascades:
IGF1R-expressing neurons are found throughout the CNS:
| Brain Region | Expression Level | Function |
|---|---|---|
| Cortex | High | Synaptic plasticity |
| Hippocampus | High | Memory, neuroprotection |
| Cerebellum | High | Motor learning |
| Brainstem | Moderate | Various functions |
| Spinal Cord | Moderate | Motor neuron function |
| Hypothalamus | Moderate | Metabolic control |
IGF1R neurons are protected against various insults:
In the cortex and hippocampus:
IGF-1 promotes oligodendrocyte function:
In the hypothalamus:
IGF1R dysfunction is central to Alzheimer's disease pathogenesis:
IGF-1 Signaling Deficit:
Amyloid Relationship:
Therapeutic Strategies:
IGF-1 is a major therapeutic target in ALS:
Motor Neuron Protection:
Therapeutic Approaches:
IGF-1 may be beneficial in Parkinson's disease:
IGF-1 is neuroprotective after injury:
Clinical Use:
Investigational:
Side Effects:
Delivery:
Bondy, C.A., & Cheng, C.M. (2004). Signaling by insulin-like growth factor 1 in brain. European Journal of Pharmacology, 490(1-3), 25-31 ↩︎
Torres-Aleman, I. (2010). Toward a comprehensive therapy for Alzheimer's disease. CNS Drugs, 24(4), 289-301 ↩︎
Carro, E., et al. (2002). IGF-1 and Alzheimer's disease: where do we stand? Journal of Alzheimer's Disease, 4(6), 463-474 ↩︎
Lai, E.C., et al. (1997). Effect of recombinant human insulin-like growth factor-I on progression of ALS. Neurology, 49(6), 1621-1630 ↩︎