2499-P: Novel Hepatic PKCepsilon Interactors Display Specific Metabolic Associations in Lean and Obese Individuals without and with MASLD

Introduction and Objective: The protein kinase C ε (PKCε) is a pivotal mediator of lipid-induced hepatic insulin resistance, which is a central feature of metabolic dysfunction-associated steatotic liver disease (MASLD). Proteins interacting with PKCε may be therefore involved in the pathogenesis of MASLD and reveal new therapeutic targets. This study aims at identifying PKCε interactors and their associations with tissue-specific insulin resistance in humans. Methods: Proteomic analyses were used to detect PKCε interactors in insulin sensitive and lipid-induced insulin resistant HepG2 cells. The most abundant PKCε interactors were evaluated in liver samples from participants with class 3 obesity. The cohort comprised 17 individuals (lean, obese without or with histology-proven MASLD) who underwent hyperinsulinemic-euglycemic clamps. Associations between PKCε interactors and tissue-specific insulin sensitivity were assessed by correlations with the M-value, insulin-mediated suppression of endogenous glucose production (ΔEGP) and adipose tissue insulin resistance index (Adipo-IR). Results: We identified 3 previously unknown PKCε interactors: E3 ubiquitin-protein ligase TRIM21 (TRIM21) in insulin sensitive as well as testis-expressed protein 2 (TEX2) and propionyl-CoA carboxylase α-chain (PCCA) in insulin resistant HepG2 cells. In livers of individuals with obesity but without MASLD, TEX2 was lower than in lean individuals (p=0.020), while TRIM21 and PCCA were unchanged. However, TRIM21 associated negatively with the M-value (r=-0.825, p=0.003) and ΔEGP (r=-0.639, p=0.012) and positively with Adipo-IR (r=0.730, p=0.001) across the whole cohort. Conclusion: Novel protein interactors of PKCε were detected and differentially associated with tissue-specific insulin resistance in humans. These results suggest that PKCε interactors may modulate the role of PKCε during lipid-induced insulin resistance and MASLD. Disclosure M. Piribauer: None. P. Lipaeva: None. S. Lehr: None. S. Hartwig: None. L. Mastrototaro: None. B. Dewidar: None. S. Gancheva: None. S. Kahl: None. H. Al-Hasani: None. P. Schrauwen: Consultant; Current; AstraZeneca. Research Support; Ended; Pfizer Inc., MedImmune. B. Belgardt: None. S. Trenkamp: None. M. Roden: Advisory Panel; Current; AstraZeneca, Boehringer Ingelheim International GmbH, Lilly, Madrigal Pharmaceuticals, Inc., Novo Nordisk, Sanofi, Echosens. G. Heilmann: None.