Cholesterol Insensitive Kir2.1 is Protective Against Obesity as a Result of Improved Endothelial Function in Resistance Arteries

Background: Inwardly Rectifying Potassium Channel 2.1 (Kir2.1) plays a key role in the maintenance of membrane potential in a variety of cell types and is critical for flow-induced vasodilation (FIV) in resistance arteries of mice and humans. Our earlier studies showed that Kir2.1 is suppressed by hypercholesterolemia and discovered a point mutation that renders the channels to be cholesterol insensitive, the substitution of leucine 222 to isoleucine. Objective: Here, our goal is to determine whether a CRISPR mouse expressing Kir2.1 L222I is protected against high fat diet (HFD)-induced impairment of FIV and against obesity. Methods: Kir2.1 L222I mice were fed HFD for 15 weeks after which mesenteric arteries were isolated for FIV, AFM, and electrophysiological recordings on freshly isolated endothelial cells. The obesity phenotype was characterized by NMR to determine body composition, analysis of plasma lipid panels, metabolomics, liver histology and analysis of feeding behavior, as well as fecal excretion and respiratory exchange rate. Results: We found that Kir2.1 L222I mice are protected against HFD induced suppression of FIV in mesenteric resistance arteries, which correlated with the protection of Kir2.1 currents in freshly-isolated endothelial cells. Furthermore, we found that obesity-associated palmitic acid (PA) suppresses Kir2.1 current and flow-sensitivity in WT mesenteric endothelial cells. Notably, both HFD in vivo and exposure to PA in vitro resulted in shortening of the endothelial glycocalyx, as assessed by the AFM, which we found earlier to play an important role in the flow-sensitivity of Kir2.1. In terms of the global effects of Kir2.1 L222I on obesity, we found that Kir2.1 L222I mice are protected against excessive weight gain and associated changes in the body composition, as well as liver steatosis. These protective effects Kir2.1 L222I mice were independent of the feeding behavior or excretion but were accompanied with increased respiration exchange rate and increased time in the running wheel, which suggests increased energy consumption. Furthermore, metabolomics analysis showed increased amino acid metabolism, specifically, methionine, and a reduction of obesity-associated pro-inflammatory lipid metabolites, specifically choline derivatives, which is consistent with the protection against obesity. Conclusions: Our findings support a model where lipid insensitive Kir2.1 facilitates improved vascular function under metabolic challenge. This improved vasculature contributes to protection against obesity and associated disease phenotypes. This research is supported by NIH T32HL144909 and NIH T32HL007829 (KB), RO1HL073965 (IL), R01HL141120 (IL), and R01HL083298 (IL). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.