Fatty acid oxidation fuels mitochondrial respiration to drive epidermal stem cell fate and differentiation.

Skin barrier function relies on the epidermis, whose integrity is maintained by basal stem cells that continuously renew and differentiate into a multilayered architecture. Disrupted epidermal differentiation underlies numerous hyperproliferative and inflammatory skin disorders. While transcriptional and epigenetic mechanisms are known to regulate late differentiation, the molecular events driving early commitment remain elusive. Here, we reveal that early mitochondrial reprogramming, characterized by the activation of oxidative phosphorylation, is a determinant of differentiation initiation. We identify fatty acid oxidation as the primary metabolic pathway fueling oxidative phosphorylation during this process. Pharmacological and genetic inhibition of fatty acid oxidation, in vitro and in vivo, disrupts differentiation and compromises stratification, causing defective responses to physical insults. Mechanistically, fatty acid oxidation enables ATP production in committed epidermal cells to support the differentiation process, linking lipid metabolism and epidermal homeostasis. These results uncover an unrecognized role for metabolic reprogramming in epidermal stem cell fate and highlight fatty acid oxidation as a promising therapeutic target for restoring differentiation defects in disease.