Dlk1-deficient mice achieve puberty despite low body weight and low levels of leptin and kisspeptin.

Loss-of-function mutations in DLK1, encoding Delta Like Non-Canonical Notch Ligand 1, have been linked to central precocious puberty (CPP) and increased body fat in girls, suggesting a role in the connection between metabolism and reproduction. DLK1 is located in the imprinted region of human chromosome 14, and mice lacking Dlk1 exhibit growth retardation and metabolic changes, phenotypes that overlap with Temple syndrome, an imprinting disorder associated with precocious puberty. However, the mechanisms by which DLK1 influences pubertal timing remain unclear. We investigated pubertal timing in Dlk1 knockout (KO) mice with either global or selective central nervous system (CNS) deletion of Dlk1, compared with control mice. Puberty onset and body weight were assessed, along with potential mediators of pubertal timing, including leptin and kisspeptin. Dlk1KO females reached puberty at the same age as controls, despite lower body weight. Dlk1KO males had delayed preputial separation but, like females, reached puberty at significantly lower body weight. Serum leptin and hypothalamic Socs3 mRNA, a downstream leptin effector, were lower peri-pubertally in Dlk1KO females than in controls. Kiss1 mRNA levels in the mediobasal hypothalamus were significantly lower in Dlk1KO females at puberty onset. Selective Dlk1 deletion in neurons and glial cells did not affect pubertal timing. These findings suggest that peripheral sources of Dlk1 contribute to the metabolic and endocrine regulation of pubertal timing. The absence of Dlk1 appears to alter the metabolic milieu in which puberty occurs, allowing activation of the reproductive axis despite low body weight and reduced hypothalamic kisspeptin expression.