FKBP5/FKBP51 on weight watch: central FKBP5 links regulatory WIPI protein networks to autophagy and metabolic control

Stress and changes in energy stores are perceived by hormone- and nutrient-sensing nuclei of the hypothalamus, which orchestrate an adaptive physiological body response to maintain homeostasis. Macroautophagy/autophagy is a fundamental lysosomal degradation system contributing to preservation of proteome balance and metabolic homeostasis. Its dysregulation is linked to diverse human pathologies, including neuropsychiatric and metabolic disorders. Autophagy is coordinated by cellular nutrient sensors, including AMPK and MTORC1 that interact with WIPI proteins. Studies suggest that WDR45/WIPI4 interacts with the stress-sensitive co-chaperone FKBP5/FKBP51, which has emerged as a key autophagy scaffold. However, the impact of FKBP5 on autophagy signaling in response to metabolic challenges, such as a high-fat diet, is elusive. Therefore, we manipulated FKBP5 in the mediobasal hypothalamus (MBH) and studied autophagy signaling and protein interactions in their physiological context. We identified FKBP5 as a scaffold of the STK11/LKB1-AMPK complex with WDR45/WIPI4 and TSC2 with WDR45B/WIPI3 in response to metabolic challenges, positioning FKBP5 in major nutrient-sensing and autophagy-regulating networks. Intriguingly, we could demonstrate that FKBP5 deletion in the MBH strongly induces obesity, whereas its overexpression protects against high-fat diet-induced obesity. Our findings suggest a crucial regulatory and adaptive function of FKBP5-regulated autophagy within the MBH in response to metabolic challenges.Abbreviations: AKT: thymoma viral proto-oncogene; AMPK: AMP-activated protein kinase; BECN1: beclin 1, autophagy related; eWAT: epididymal white adipose tissue; FKBP5/FKBP51: FK506 binding protein 5; KO, knockout; MBH, mediobasal hypothalamus; MTORC1, mechanistic target of rapamycin kinase complex 1; p: phosphorylated; PHLPP: PH domain and leucine rich repeat protein phosphatase; RPS6KB/p70S6K: ribosomal protein S6 kinase; SKP2: S-phase kinase-associated protein 2; SM: soleus muscle; SQSTM1/p62, sequestosome 1; STK11/LKB1: serine/threonine kinase 11; TSC: TSC complex; ULK1: unc-51 like kinase 1; WIPI: WD repeat domain, phosphoinositide interacting; WT: wild type.