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Background and Purpose Migration and differentiation of epidermal cells are essential for epidermal regeneration during wound healing. Fibroblast growth factor 21 (FGF21) plays key roles in mediating a variety of biological activities. However, its role in skin wound healing remains unknown. Experimental Approach Fgf21 knockout (Fgf21 KO) mice were used to determine the effect of FGF21 on wound healing. The source of FGF21 and its target cells were determined by immunohistochemistry, immunoblotting, and ELISA assay. Moreover, Sirt1flox/flox and Atg7flox/flox mice were constructed and injected with the epidermal‐specific Cre virus to elucidate the underlying mechanisms. Migration and differentiation of keratinocytes were evaluated in vitro by cell scratch assays, immunofluorescence, and qRT‐RCR. The effects were further assessed when SIRT1, ATG7, ATG5, BECN1, and P53 were silenced. Interactions between SIRT1 and autophagy‐related genes were assessed using immunoprecipitation assays. Key Results FGF21 was active in fibroblasts and promoted migration and differentiation of keratinocytes following injury. After wounding, SIRT1 expression and autophagosome synthesis were lower in Fgf21 KO mice. Depletion of ATG7 in keratinocytes counteracted the FGF21‐induced increases in migration and differentiation, suggesting that autophagy is required for the FGF21‐mediated pro‐healing effects. Furthermore, epithelial‐specific Sirt1 knockout abolished the FGF21‐mediated improvements of autophagy and wound healing. Silencing of SIRT1 in keratinocytes, which decreased deacetylation of p53 and autophagy‐related proteins, revealed that FGF21‐induced autophagy during wound healing was SIRT1‐dependent. Conclusions and implications FGF21 is a key regulator of keratinocyte migration and differentiation during wound healing. FGF21 may be a novel therapeutic target to accelerate would healing.

Background and Aims: Chronic liver diseases are associated with the development of liver fibrosis. Without treatment, liver fibrosis commonly leads to cirrhosis and HCC. FGF12 is an intracrine factor belonging to the FGF superfamily, but its role in liver homeostasis is largely unknown. This study aimed to investigate the role of FGF12 in the regulation of liver fibrosis.Approach and Results: FGF12 was up-regulated in bile duct ligation (BDL)-induced and CCL 4 -induced liver fibrosis mouse models. Expression of FGF12 was specifically up-regulated in nonparenchymal liver cells, especially in hepatic macrophages. By constructing myeloid-specific FGF12 knockout mice, we found that deletion of FGF12 in macrophages protected against BDL-induced and CCL 4 -induced liver fibrosis. Further results revealed that FGF12 deletion dramatically decreased the population of lymphocyte antigen 6 complex locus C high macrophages in mouse fibrotic liver tissue and reduced the expression of proinflammatory cytokines and chemokines. Meanwhile, loss-of-function and gain-of-function approaches revealed that FGF12 promoted the proinflammatory activation of macrophages, thus inducing HSC activation mainly through the monocyte chemoattractant protein-1/chemokine (C-C motif) receptor 2 axis. Further experiments indicated that the regulation of macrophage activation by FGF12 was mainly mediated through the Janus kinase-signal transducer of activators of transcription pathway. Finally, the results revealed that FGF12 expression correlates with the severity of fibrosis across the spectrum of fibrogenesis in human liver samples.

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