Uremic toxins promote renal fatty acid synthesis and fibrosis via activating aryl hydrocarbon receptor.

Chronic kidney disease (CKD) affect about 10% of adults worldwide, with dyslipidemia being a common feature. Abnormalities in renal lipid metabolism have been strongly implicated in CKD progression; however, the mechanisms by which CKD leads to lipid metabolism disturbances remain underexplored. Here we show that following the accumulation of uremic toxins, the synthesis and deposition of lipids, along with the uremic toxin receptor aryl hydrocarbon receptor (AhR), are upregulated in the kidneys. Tubule-specific AhR knockout in male mice alleviates uremic toxin-induced increases in renal fatty acid (FA) synthesis, lipid accumulation and fibrosis. Immunoprecipitation‒mass spectrometry identifies nuclear receptor subfamily 1 group D member 1 (NR1D1) as an AhR-interacting protein. Co-immunoprecipitation confirms that AhR interacts with NR1D1 and promotes its ubiquitin-mediated degradation. As NR1D1 is an FA synthesis suppressor, its reduction relieves the transcriptional repressing effects on sterol regulatory element-binding protein 1 (SREBP1), thereby enhancing SREBP1/fatty acid synthase (FASN) pathway activity and FA synthesis. In summary, by acting on AhR, the accumulation of uremic toxins may accelerate renal fibrosis via the SREBP1/FASN pathway-mediated increase in FA synthesis.