Molecular signature of early obesity-associated insulin resistance: Adipocyte-derived extracellular vesicle proteins reveal stage-specific candidates for metabolic dysfunction

Visceral obesity is closely related to insulin resistance (IR), a key process in developing metabolic diseases. Adipocyte-derived extracellular vesicles (AdEVs) have emerged as mediators of intercellular communication, carrying signals reflecting adipose tissue's functional state. This study aimed to perform a comparative proteomic analysis of AdEVs to propose a molecular fingerprint of specific biomarker candidates for IR in early-onset obesity. AdEVs were isolated from epididymal adipocytes of 16-week-old male Wistar rats on a high-fat diet (HFD) and controls and analyzed by mass spectrometry coupled to a multi-software protein identification bioinformatics strategy. For relative quantification using the label-free method, more than 1200 proteins were identified, with 431 being overrepresented and unique to HFD, associated explicitly with energy metabolism, cellular stress, and insulin signaling. Based on biological plausibility, and/or the best log2FC and p-value scores, six proteins were proposed as part of the IR molecular fingerprint: Atp5f1b, Anxa6, Myo1c, GLUT4, Anxa5, and Aoc3. Phosphoproteomic analysis revealed key modifications in phosphorylated proteins such as CaATPase (S663), PLIN (S130), and PPM1H (S260,265). The results suggest that AdEVs reflect early mitochondrial alterations related to IR, which could be employed as potential non-invasive biomarker candidates for metabolic dysfunction and follow-up in early overweight or obesity.

Significance

In this study, we demonstrate that adipocyte-derived extracellular vesicles (AdEVs) encapsulate a stage-resolved molecular signature that reflects key pathophysiological events underlying the early development of insulin resistance in obesity. These vesicles carry proteins linked to lipotoxicity, mitochondrial and endoplasmic reticulum stress, and impaired vesicular trafficking, offering mechanistic insight into how local adipocyte dysfunction may trigger systemic metabolic impairment. This EV-based proteomic fingerprint advances our understanding of insulin resistance pathogenesis and identifies potential biomarker candidates for early metabolic risk stratification.