Feto-maternal cholesterol transport regulated by β-Klotho–FGF15 axis is essential for fetal growth

Abstract

β-Klotho (β-KL) is indispensable to regulate lipid, glucose, and energy metabolism in adult animals. β-KL is highly expressed in the yolk sac, but its role in the developmental stages has not been established. We hypothesized that β-KL is required for metabolic regulation in the embryo and aimed to clarify the role of β-KL during development. Here, we show that β-KL regulates feto-maternal cholesterol transport through the yolk sac by mediating FGF 15 signaling, and also that impairment of the β-KL–FGF15 axis causes fetal growth restriction (FGR). Embryos ofβ-klknockout (β-kl−/−) mice were morphologically normal but exhibited FGR before placental maturation. The body weight ofβ-kl−/− mice remained lower after birth. β-KL deletion reduced cholesterol supply from the maternal blood and led to lipid shortage in the embryos. These phenotypes were similar to those of embryos lacking FGF15, indicating that β-KL–FGF15 axis is essential for growth and lipid regulation in the embryonic stages. Our findings suggest that lipid abnormalities in early gestation provoke FGR, leading to reduced body size in later life.