PERK eIF2α Kinase Regulates Neonatal Growth by Controlling the Expression of Circulating Insulin-Like Growth Factor-I Derived from the Liver

Humans afflicted with the Wolcott-Rallison syndrome and mice deficient for PERK (pancreatic endoplasmic reticulum eIF2α kinase) show severe postnatal growth retardation. In mice, growth retardation in Perk−/− mutants is manifested within the first few days of neonatal development. Growth parameters of Perk−/− mice, including comparison of body weight to length and organ weights, are consistent with proportional dwarfism. Tibia growth plates exhibited a reduction in proliferative and hypertrophic chondrocytes underlying the longitudinal growth retardation. Neonatal Perk−/− deficient mice show a 75% reduction in liver IGF-I mRNA and serum IGF-I within the first week, whereas the expression of IGF-I mRNA in most other tissues is normal. Injections of IGF-I partially reversed the growth retardation of the Perk−/− mice, whereas GH had no effect. Transgenic rescue of PERK activity in the insulin- secreting β-cells of the Perk−/− mice reversed the juvenile but not the neonatal growth retardation. We provide evid...