Leptin is an adipocyte-derived hormone that stimulates hypothalamic neurons to strongly inhibit food intake. Leptin signaling in the hypothalamus, a part of the mid-brain, thus plays a crucial role in the regulation of body weight: Leptin resistance, in which leptin signaling is disrupted, is a major obstacle to the improvement of obesity. However, the exact mechanisms underlying leptin resistance in obese patients have yet to be elucidated.

The research group of Professor Masaharu Noda, Associate Professor Takafumi Shintani, and a graduate student Satoru Higashi of the National Institute for Basic Biology (NIBB) demonstrated that protein tyrosine phosphatase receptor type J (PTPRJ) inhibits leptin signaling and that induction of PTPRJ in the hypothalamus is a cause of leptin resistance.