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Retinoic acid receptor‐related orphan receptor RORα regulates differentiation and survival of keratinocytes during hypoxia

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Journal of Cellular Physiology

Published online on


Low O2 pressures present in the microenvironment of epidermis control keratinocyte differentiation and epidermal barrier function through hypoxia inducible factors (HIFs) dependent gene expression. This study focuses on investigating relations of the retinoic acid receptor‐related orphan receptor alpha (RORα) to HIF‐1α in keratinocytes under hypoxic conditions. The expression level of RORα is significantly elevated under hypoxia in both human and murine keratinocytes. Gene silencing of RORA attenuates hypoxia‐stimulated expression of genes related to late differentiation and epidermal barrier function, and leads to an enhanced apoptotic response. While the hypoxic induction of RORα is dependent on HIF‐1α, RORα is in turn critical for nuclear accumulation of HIF‐1α and activation of HIF transcriptional activity. These results collectively suggest that RORα functions as an important mediator of HIF‐1α activities in regulating keratinocyte differentiation/survival and epidermal barrier function during the oxygen sensing stage. We have identified RORα as a regulator imperative to HIF‐1α activities in promoting terminal differentiation, epidermal barrier function, and survival of keratinocytes under low O2 tension. Given highly diversified functions of HIF targets in maintaining skin homeostasis, manipulations of HIF activities through RORα ligands can represent a novel strategy for therapeutic treatment of pathophysiological conditions such as cutaneous diseases related to defective epidermal barrier functions and wound healing.