High-fat diet remodels plasma membrane rigidity to potentiate colonocyte stemness in mice.

BACKGROUND & AIMS: Obesity and consumption of a high-fat diet (HFD) are established risk factors for colorectal cancer (CRC). However, the cellular mechanisms linking dietary lipid exposure to intestinal stem cell (ISC) dysregulation remain incompletely defined. We therefore investigated whether HFD perturbs plasma membrane homeostasis to potentiate colonocyte stemness in mice. METHODS: Mice were placed on a chronic 12-week HFD or control (low-fat diet; LFD) feeding regimen, or a short-term 1-week HFD exposure. In addition, genetically obese leptin receptor-deficient (db/db) versus (db/+) wildtype mice were examined. Membrane free cholesterol and rigidity were quantified in colonic crypts and Lgr5+ ISCs utilizing Filipin III and Di-4-ANEPPDHQ dyes, respectively. Membrane receptor nanoclustering of epidermal growth factor receptor (EGFR) and low-density lipoprotein receptor-related protein 6 (LRP6) was assessed by super-resolution microscopy. β-catenin activation, stem cell frequency, proliferation, and organoid-forming efficiency were also evaluated by immunostaining, flow cytometry, and ex vivo organoid assays. RESULTS: Chronic HFD feeding in mice increased membrane free cholesterol content and rigidity in colonic stem cells, and enhanced EGFR and LRP6 receptor nanoclustering. This alteration in plasma membrane homeostasis resulted in the overactivation of β-catenin and expansion of the ISC niche, e.g., stem cell proliferation and organoid-forming efficiency. Notably, genetically induced obesity in db/db mice did not recapitulate the HFD membrane phenotype, highlighting a diet-specific effect. CONCLUSIONS: Collectively, these findings identify plasma membrane remodeling as a previously unrecognized mechanism linking dietary lipids to aberrant ISC homeostasis and CRC risk.