IGF-2
Growth Hormone AxisAlso known as: Insulin-Like Growth Factor 2, Somatomedin A, IGF-II
Mechanism
IGF-2 (Insulin-Like Growth Factor 2) is a growth factor primarily important during fetal development and early growth. Unlike IGF-1 which is mainly GH-dependent, IGF-2 production is largely GH-independent and regulated by genomic imprinting. It plays roles in placental growth, fetal organ development, and metabolic regulation. It is less studied than IGF-1 for therapeutic applications.
Technical detail
IGF-2 is a 67-amino-acid peptide with 62% sequence homology to IGF-1. It signals primarily through the IGF-1R (with lower affinity than IGF-1), the insulin receptor isoform A (IR-A), and the IGF-2R (which functions primarily as a clearance receptor). IGF-2 is subject to genomic imprinting — it is expressed exclusively from the paternal allele, with the maternal allele silenced via methylation. Dysregulated IGF-2 expression is implicated in Beckwith-Wiedemann syndrome (overgrowth), Wilms tumor, and non-islet cell tumor hypoglycemia (NICTH) where ectopic tumor production of big-IGF-2 causes refractory hypoglycemia.