Cytokine-induced signal transduction is executed by natural biological switches, which among many others control immune-related processes. Here, we show that synthetic cytokine receptors (SyCyRs) can induce cytokine signaling using non-physiological ligands. High-affinity GFP- and mCherry-nanobodies were fused to transmembrane and intracellular domains of the IL-6/IL-11 and IL-23 cytokine receptors gp130 and IL-12Rβ1/IL-23R, respectively. Homo- and heterodimeric GFP:mCherry fusion proteins as synthetic cytokine-like ligands were able to induce canonical signaling in vitro and in vivo. Using SyCyR ligands, we show that IL-23 receptor homodimerization results in its activation and IL-23-like signal transduction. Moreover, trimeric receptor assembly induces trans-phosphorylation among cytokine receptors with associated Janus kinases. The SyCyR technology allows biochemical analyses of transmembrane receptor signaling in vitro and in vivo, cell-specific activation through SyCyR ligands using transgenic animals and possible therapeutic regimes involving non-physiological targets during immunotherapy.

ObjectivePost-traumatic stress disorder (PTSD) increases type 2 diabetes risk, yet the underlying mechanisms are unclear. We investigated how early-life exposure to chronic stress affects long-term insulin sensitivity.MethodsC57Bl/6J mice were exposed to chronic variable stress for 15 days (Cvs) and then recovered for three months without stress (Cvs3m).ResultsCvs mice showed markedly increased plasma corticosterone and hepatic insulin resistance. Cvs3m mice exhibited improved whole-body insulin sensitivity along with enhanced adipose glucose uptake and skeletal muscle mitochondrial function and fatty acid oxidation. Plasma FGF21 levels were substantially increased and associated with expression of genes involved in fatty acid oxidation and formation of brown-like adipocytes. In humans, serum FGF21 levels were associated with stress coping long time after the exposure.ConclusionsEarly-life exposure to chronic stress leads to long term improvements in insulin sensitivity, oxidative metabolism and adipose tissue remodeling. FGF21 contributes to a physiological memory mechanism to maintain metabolic homeostasis.