Keratinocyte Wnt5β promotes dermal adipogenesis by simultaneously regulating adipocyte precursor cell conversion and adipogenic signaling

Skin is the largest organ in the body and comprises several types of cells. The intercellular plasticity of keratinocytes, fibroblasts, and skin adipocytes contributes to wound healing and dermal adipogenesis. Although keratinocyte activates dermal adipose tissue (dWAT) differentiation upon hair follicular cycle, regulating dWAT hyperplasia through keratinocyte reprogramming is still unknown. We used the CRISPR/Cas9 base editor to induce single nucleotide polymorphisms in Forkhead-box N1 (Foxn1) and identified the p.L19M variant that induced the formation of a thicker dWAT regardless of hair follicular cycle or wound healing. Foxn1 p.L19M activates Wnt5β through transcriptional activity. Wnt5β signaling induces the conversion of dWAT dermal fibroblasts into adipose precursor cells (APCs) and promotes APC adipocyte differentiation through keratinocyte epithelial-mesenchymal transition (EMT) and adipogenic signaling. Wnt5β is involved in the entire process of dWAT hyperplasia through APC supply and adipogenic signaling as a single factor. Foxn1 p.L19M and Wnt5β are expressed in keratinocytes, and a keratinocyte-derived adipogenic signal is critical for dermal adipogenesis. In addition, transient expression of Foxn1 p.L19M or Wnt5β using adeno-associated virus reproduced dermal adipocyte hyperplasia in mice. Considering the increasing importance of dWAT in functions such as the immune response, wound healing, hair follicle growth, and temperature control, this finding has potential applications in skin regeneration To investigate the keratinocyte function between Foxn1 and Foxn1 L19M in murine epidermis.