Calycosin attenuates renal fibrosis by modulating lipid metabolism via the PCK1/TWIST1/CPT1α axis.

Aims: Renal lipid metabolic dysregulation drives tubular injury and fibrosis in chronic kidney disease (CKD), yet endogenous targets governing tubular lipid homeostasis remain incompletely understood. This study aimed to elucidate how calycosin (CAL), an O-methylated isoflavone from Astragali Radix, corrects renal lipid metabolic dysregulation and attenuates fibrosis in CKD.

Materials and methods: An adenine-induced CKD mouse model and TGF-β1-stimulated HK-2 cells were treated with CAL. Lipidomics and network pharmacology screened candidate targets. Surface plasmon resonance (SPR) and molecular dynamics simulation validated target binding. Adeno-associated virus (AAV)-mediated renal phosphoenolpyruvate carboxykinase 1 (PCK1) overexpression in vivo and lentiviral overexpression in vitro established the regulatory relationship. The PCK1 inhibitor 3-mercaptopicolinic acid served as reverse validation.

Key findings: CAL improved renal function, alleviated fibrosis, and reduced lipid deposition both in vivo and in vitro. Lipidomics revealed that CAL bidirectionally modulated renal lipid metabolism by suppressing glycerophospholipid, sphingolipid, and glycerolipid accumulation while restoring omega-3 PUFA-enriched lipids and decreasing lipid saturation. SPR confirmed direct binding of CAL to PCK1. Gain-of-function experiments demonstrated that PCK1 negatively regulates Twist family BHLH transcription factor 1 (TWIST1) in the kidney. Accordingly, CAL activated the PCK1/TWIST1/carnitine palmitoyltransferase 1 A (CPT1α) axis, restoring fatty acid oxidation and suppressing lipid uptake, thereby attenuating lipotoxicity-driven oxidative stress and tubular apoptosis.

Significance: This study identifies PCK1 as an endogenous binding target of CAL in the kidney and delineates the PCK1/TWIST1/CPT1α axis as the downstream signaling circuitry through which CAL corrects tubular lipid metabolic disorders and attenuates renal fibrosis, providing mechanistic rationale for targeted CKD therapy.