CPT1B-Mediated Fatty Acid Oxidation Induces Pigmentation in Solar Lentigo

Abstract

Introduction: Cellular senescence is associated with altered lipid metabolism, including increased cellular lipid uptake, upregulated lipid biosynthesis, and deregulated lipid breakdown. Previous studies have reported that carnitine palmitoyltransferase (CPT), the rate-limiting enzyme in fatty acid oxidation that catalyzes the conversion of acyl-CoA to acylcarnitine, is involved in various senescence-related diseases. Although solar lentigo (SL) is an age-related pigmentary disorder characterized by the accumulation of senescent cells, its role in metabolic dysregulation has rarely been investigated. Methods and Results: Integrated transcriptomic profiling of SL skin samples, combining mRNA sequencing, differential gene expression, pathway enrichment analyses, metabolic flux simulations, and protein-protein interaction analysis, was conducted to demonstrate the molecular alterations in SL compared to perilesional normal skin. We found transcriptomic alterations in mitochondrial energy metabolism-associated genes. Metabolic flux simulations revealed that carnitine-associated reactions involved in fatty acid oxidation were upregulated. Using a multi-omics approach, CPT1B was selected as a potential marker for SL, which was confirmed via its overexpression in immunohistochemical studies. Using a zebrafish model, CPT1B was implicated in melanogenesis. Discussion: CPT1B-mediated metabolic alteration is a key driver of SL pathogenesis. Targeting CPT1B and the associated lipid metabolism pathways is a novel therapeutic approach for managing SL and age-related pigmentation disorders.