IGF-2

The second member of the insulin-like growth factor family, encoded by an imprinted gene primarily expressed from the paternal allele. While IGF-1 is the dominant postnatal growth mediator, IGF-2 plays important roles in muscle development, satellite cell self-renewal, and the early stages of muscle regeneration. It signals through the IGF-1 receptor, the insulin receptor isoform A, and has its own clearance receptor (IGF-2R/mannose-6-phosphate receptor).

• Binds IGF-1 receptor to activate PI3K/Akt and MAPK/ERK pathways
• Binds insulin receptor isoform A (IR-A), particularly relevant in muscle progenitor cells
• Promotes asymmetric satellite cell division, maintaining the stem cell niche while generating committed myoblasts
• Cleared by IGF-2R (mannose-6-phosphate receptor) which directs it to lysosomes
• Regulated by imprinting — loss of imprinting (LOI) is associated with pathological overgrowth

• Active malignancy or history of IGF-2-overexpressing tumors
• Beckwith-Wiedemann syndrome or other imprinting disorders
• Diabetes or insulin-dependent conditions
• Pregnancy or breastfeeding

Store at 2–8°C (36–46°F) for up to 3 months. For long-term storage, keep at -20°C (-4°F) to -80°C (-112°F). Once reconstituted, refrigerate and use within 7 days. Very sensitive to degradation.

IGF-2 has been studied primarily in developmental biology and cancer research. Seminal work by Merrick et al. demonstrated IGF-2's role in satellite cell self-renewal during muscle regeneration in mice. Unlike IGF-1, which drives differentiation, IGF-2 maintains the regenerative capacity of the satellite cell pool. While preclinical evidence is promising for muscle repair applications, no clinical trials for musculoskeletal indications exist. Its complex regulation through genomic imprinting adds a layer of biological nuance absent in other IGF family peptides.