Structural robustness and temporal vulnerability of the starvation-responsive metabolic network in liver of healthy and obese mice

Abstract

Adaptation to starvation is a multi-molecular and temporally ordered process, that could be impaired in obesity. To elucidate how the healthy liver regulates various molecules in a temporally ordered manner during starvation and how obesity disrupts this process, we measured time course multiomic data in the liver of wild-type (WT) and leptin-deficient obese (ob/ob) mice during starvation. Using the measured data, we constructed a starvation-responsive metabolic network, that is a transomic network including responsive molecules and their regulatory relationships during starvation, and analyzed the structure of the network. In WT mice, ATP and AMP, the energy indicators, regulated various metabolic reactions in the network as the hub molecules, both of which were not responsive in ob/ob mice. However, the structural properties of the network were maintained in ob/ob mice. In WT mice, the molecules in the network were temporally ordered through metabolic process coordinated by the hub molecules including ATP and AMP and were positively or negatively co-regulated. By contrast, both temporal order and co-regulation were disrupted in ob/ob mice. Taken together, the starvation-responsive metabolic network is structurally robust, but temporally vulnerable by the loss of responsiveness of the hub molecules in obesity. In addition, we proposed a potential therapeutic target to treat the negative effects of obesity on intermittent fasting to extend lifespan. One Sentence SummaryHub molecules activate or inhibit various molecules in a temporally ordered manner in healthy liver, and the regulatory network is structurally robust but temporally vulnerable to obesity.