Simplified Summary
IGF-1 LR3 is a modified form of IGF-1 in which an N-terminal extension and a single amino acid substitution dramatically reduce binding to the six IGF-binding proteins that normally regulate IGF-1 availability in biological systems. This reduced IGFBP binding results in a higher proportion of unbound, biologically active compound and an extended half-life compared to native IGF-1, making LR3 a useful research tool for studying IGF receptor signalling without the confounding effects of IGFBP-mediated sequestration.
In preclinical cell biology research, IGF-1 LR3 has been extensively used to study IGF-1 receptor (IGF-1R) signalling through the PI3K-Akt-mTOR and Ras-ERK pathways, which mediate cell survival, proliferation, and protein synthesis. Its extended activity window compared to native IGF-1 has made it a preferred research tool in cell culture systems where sustained IGF-1R stimulation is required for experimental paradigms.
Key Findings Reported in Preclinical Models
- Significantly reduced IGF-binding protein affinity compared to native IGF-1, characterised in binding assays with purified IGFBP proteins, resulting in extended free compound concentrations in biological systems.
- IGF-1 receptor activation and downstream PI3K-Akt-mTOR and Ras-MAPK signalling pathway characterisation in cell culture systems.
- Stimulation of protein synthesis and cell growth in skeletal muscle cell culture models including C2C12 myotubes.
- Anabolic effects in preclinical animal models with measurements of muscle mass, protein content, and growth-related biomarkers.
- Influence on satellite cell activation and muscle regeneration biology in relevant preclinical model systems.
Introduction
Insulin-like growth factor-1 is a primary mediator of growth hormone's anabolic effects, acting through IGF-1 receptors expressed throughout the body to stimulate cell growth, protein synthesis, and cell survival. Native IGF-1 in biological systems circulates largely bound to six distinct IGFBPs that regulate its bioavailability, half-life, and tissue distribution. IGF-1 LR3 was engineered to circumvent IGFBP sequestration, providing a research tool with more direct and sustained IGF-1R stimulation in both cell culture and animal model settings.
Research Applications
- IGF-1 receptor signalling pathway research in cell culture systems requiring extended IGF-1R stimulation without IGFBP interference.
- Skeletal muscle biology research examining anabolic signalling through mTOR and protein synthesis pathways in myotube culture models.
- Cell proliferation and survival research across diverse cell types using IGF-1 LR3 as a sustained IGF-1R agonist.
- Comparative pharmacology studies contrasting LR3's activity profile with native IGF-1 to characterise the functional consequences of IGFBP binding affinity.
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