Marta Sanz-Gómez, Beatriz Linillos-Pradillo, Rubén Fernández de la Rosa, Isabel Aránguez, Reinhold Kreutz, Antonia García, Coral Barbas, Adrián Plaza, María S Fernández-Alfonso
This study identifies citrate-dependent activation of acetyl-CoA carboxylase as a driver of renal lipid accumulation and remodeling independently of AMP-activated protein kinase, revealing a novel metabolic mechanism linking systemic citrate to kidney injury and potential therapeutic strategies.
BACKGROUND: Abnormal accumulation of lipids within the kidney contributes to the progression of chronic kidney disease, but the underlying metabolic mechanisms remain unclear. Citrate is a central metabolite in cellular energy regulation and is frequently elevated in advanced kidney disease, yet its impact on renal lipid metabolism has not been investigated. This study tested whether increased circulating citrate promotes lipid accumulation in the kidney by activating acetyl-CoA carboxylase independently of adenosine monophosphate-activated protein kinase.
METHODS: Male Munich Wistar Frömter rats, a genetic model of chronic kidney disease, were studied together with HEK293 cells exposed to citrate. Protein expression, phosphorylation, and polymerization were assessed using western blotting, q-RT-PCR, and native gel electrophoresis. Renal lipid composition was characterized by untargeted high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry, and citrate levels were semi-quantified using capillary electrophoresis-time-of-flight mass spectrometry.
RESULTS: MWF rats exhibited elevated plasma citrate, reduced vitamin D and bone mineral density, and increased renal fibrosis and mitochondrial dysfunction. Moreover, MWF showed higher expression of ATP-citrate lyase and fatty acid synthase, together with reduced phosphorylation of acetyl-CoA carboxylase and AMP-activated protein kinase, increased renal lipid deposition, and elevated fatty acid content. In HEK293, citrate treatment reproduced these effects, inducing acetyl-CoA carboxylase polymerization, lipid droplet formation, impaired mitochondrial activity, and increased superoxide production.
CONCLUSION: This study identifies citrate-dependent activation of acetyl-CoA carboxylase as a driver of renal lipid accumulation and remodeling independently of AMP-activated protein kinase, revealing a novel metabolic mechanism linking systemic citrate to kidney injury and potential therapeutic strategies.