Neuronal PAS Domain 2 (Npas2)‐Deficient Fibroblasts Accelerate Skin Wound Healing and Dermal Collagen Reconstruction

Abstract

The circadian clock, which consists of endogenous self-sustained and cellautonomous oscillations in mammalian cells, is known to regulate a wide range of peripheral tissues. The unique upregulation of a clock gene, neuronal PAS domain protein 2 (Npas2), observed along with fibroblast aging prompted us to investigate the role of Npas2 in the homeostasis of dermal structure using in vivo and in vitro wound healing models. Time-course healing of a fullthickness skin punched wound exhibited significantly faster wound closure in Npas2−/− mice than wild-type (WT) C57Bl/6J mice. Dorsal skin fibroblasts isolated from WT, Npas2+/−, and Npas2−/− mice exhibited consistent profiles of core clock gene expression except for Npas2 and Per2. In vitro behavioral characterizations of dermal fibroblasts revealed that Npas2−/− mutation was associated with increased proliferation, migration, and cell contraction measured by floating collagen gel contraction and single-cell force contraction assays. Npas2 knockout fibroblasts carrying sustained the high expression level of type XII and XIV FAICT collagens and synthesized dermis-like thick collagen fibers in vitro. Confocal laser scanning microscopy demonstrated the reconstruction of dermis-like collagen architecture in the wound healing area of Npas2−/− mice. This study indicates that the induced Npas2 expression in fibroblasts may interfere with skin homeostasis, wound healing, and dermal tissue reconstruction, providing a basis for novel therapeutic target and strategy.

The circadian clock and diseases of the skin

“…Intriguingly, the expression level of Acta2 and Actb, along with other integrin genes, does not differ among the genotypes. Some collagen genes (Col12a1 and Col14a1) are upregulated in cultured Npas2 À/À and Npas2 À/À fibroblasts, in agreement with promoted collagen fiber formation observed in those knockout cells [134].…”

LncRNA Nuclear-Enriched Abundant Transcript 1 Regulates Atrial Fibrosis via the miR-320/NPAS2 Axis in Atrial Fibrillation

“…Our study demonstrated that Ang II decreased miR-320 expression, whereas NEAT1 knockdown increased it. NPAS2-deficient fibroblasts expedite skin wound healing and dermal collagen reconstruction ( Sasaki et al, 2020 ), and NPAS2 promotes liver fibrosis via direct transcriptional activation of Hes1 in hepatic stellate cells ( Yang et al, 2019 ). In our study, we demonstrated that miR-320 overexpression suppressed NPAS2 expression and miR-320 inhibition reversed the suppressive effect of shNEAT1 on NPAS2 expression.…”

The Impact of the Circadian Clock on Skin Physiology and Cancer Development

“…Summarized in Figure 4 , these processes range from stem cell function and wound healing to immune defense and responses to environmental exposure. For example, cell cycle progression [ 72 ], keratinocyte proliferation [ 48 ], and stem cell function [ 73 , 74 ] have all been reported to show rhythmicity that likely influences reported circadian differences in processes, such as wound healing, through a variety of mechanisms [ 75 , 76 , 77 , 78 ]. Similarly, the clock has even been reported to affect hair follicles [ 79 ], such that hair growth is reported to occur faster in the morning [ 80 ] and be disrupted by the loss of core circadian genes [ 81 , 82 ].…”