Paternal Insulin-like Growth Factor 2 (Igf2) Regulates Stem Cell Activity During Adulthood

Paternal Igf2 regulates stem cells frequency and activity lifelong following a spatio-temporal gradient of expression. Upper panel: Igf2 high and broad expression during pre-natal life drops after weaning then becomes restricted to tissue stem cells. Lowering paternal Igf2 has no obvious effect on life span. However, lowering Igf2 levels delays the end of post-natal growth and the onset of adulthood. Lower panel: Igf2 deficiency avoids the age-related decrease of the stem cells pool by reducing stem cells activity and differentiation. Therefore, Igf2 function would be to regulate stem cells by maintaining their capacity to support hematopoiesis and to interact with their environment, which is coherent with the presence of Igf2 in the IGF/Insulin longevity pathway. The activity of stem cells during development, homeostasis and regeneration, would follow an innate mechanism involving Igf2. Igf2 level would give stem cells a temporal identity and act as a timing regulator of their activity life long.128