Description
Insulin-like Growth Factor 1 (IGF-1), also known as somatomedin C, is the principal effector of growth hormone and is structurally and functionally related to insulin, but with significantly stronger growth-promoting activity [1]. IGF-1 is synthesized as multiple precursor isoforms with N- and alternate C-terminal propeptides. Proteolytic cleavage yields the mature 7.7 kDa peptide, which is 94–96% identical to rodent IGF-1, 100% identical to bovine and porcine IGF-1, and ~64% identical to human IGF-2 [2]. IGF-1 acts in both endocrine (circulating, mainly liver-derived) and paracrine/autocrine (tissuespecific) manners [3]. It plays essential roles in Cell proliferation, migration, and differentiation in muscle, bone, and cartilage [4], Glucose and lipid metabolism, functioning as an insulin-sensitizer in some contexts [5], Muscle regeneration and bone growth [6], Neuroprotection, with low levels linked to Alzheimer’s disease [7], and Tumor progression, where overactivation of IGF-1R contributes to oncogenesis [8]. At the molecular level, IGF1 binds with high affinity to IGF-1R, and with lower affinity to IGF-2R and the insulin receptor. Signaling occurs primarily through the PI3K/AKT and MAPK pathways, promoting proliferation, survival, and resistance to apoptosis [9]. In circulation, IGF-1 associates with IGF-binding proteins (IGFBPs), which regulate half-life and tissue targeting [10]. Recombinant human IGF-1 is approved for the treatment of severe primary IGF-1 deficiency, such as Laron syndrome, or in children with growth hormone deficiency who develop anti-GH antibodies [11]. It has also been used experimentally to improve glycemic control in severe insulin resistance syndromes and Type 1/Type 2 diabetes [12]. IGF-1 and its pathway are active areas of investigation in oncology and neurodegenerative disease therapy [13, 14]. UniProt ID: P05019