Lipidomic Profiling of Kidney Cortical Tubule Segments Identifies Lipotypes with Physiological Implications

Abstract

A detailed knowledge of the lipid composition of components of nephrons is crucial for understanding physiological processes and the development of kidney diseases. However, the lipidomic composition of kidney tubular segments is unknown. We manually isolated the proximal convoluted tubule (PCT), the cortical thick ascending limb of Henle's loop (cTAL) and the cortical collecting duct (CCD) from five lean and obese mice and subjected the samples to shotgun lipidomics analysis by high resolution mass spectrometry acquisition. Across all samples, more than five hundred lipid species were identified, quantified and compared. We observed significant compositional differences among the three tubular segments, which serve as true signatures. These intrinsic lipidomic features are associated with a distinct proteomic program that regulates highly specific physiological functions. The distinctive lipidomic features of each of the three segments are mostly based on the relative composition of neutral lipids, long-chain polyunsaturated fatty acids, sphingolipids, and ether phospholipids. These features support the hypothesis of a lipotype assigned to specific tubular segments. Obesity profoundly impacts the lipotype of proximal convoluted tubules. In conclusion, we present a comprehensive lipidomic analysis of three cortical segments of mouse kidney tubules. This valuable resource provides unparalleled detail that enhances our understanding of tubular physiology and the potential impact of pathological conditions.