Authors
Hua Deng, Zhi-Hui Zhou, Yi Lyu, Xin-Yi Zhou, Jia-Yu Wen, Qi-Wen Xiang, Cheng Peng, Chao-Long Rao, Ji-Hai Gao
Published in
Zhongguo Zhong yao za zhi = Zhongguo zhongyao zazhi = China journal of Chinese materia medica. Volume 51. Issue 12. Pages 3497-3509.
Abstract
This study aims to investigate the phototoxic effects of imperatorin(IMO) and its potential mechanisms of inducing skin photodamage and cellular senescence. A phototoxicity model was established on the dorsal skin of SD rats, which were randomly divided into a control group, an IMO group(0.8 mg·cm~(-2)), a long-wave ultraviolet A(UVA) group(10 J·cm~(-2)), and an IMO + UVA group. The rats were continuously observed for 72 h, and Draize skin scores were assessed. Hematoxylin-eosin(HE) staining was used to observe histopathological changes, and Verhoeff-Van Gieson(VVG) staining was utilized to evaluate changes in dermal elastic and collagen fibers. Human dermal fibroblasts(HDF) were cultured in vitro and divided into control, IMO, UVA(1 J·cm~(-2)), and groups of IMO with low, medium, and high doses(1, 2.5, and 5 μg·mL~(-1)) + UVA. The CCK-8 assay was used to assess the cell viability. Transcriptomics by RNA-seq was used to analyze the changes in gene expression. Real-time quantitative PCR(RT-qPCR) was used to detect the mRNA expressions of the top 10 senescence-associated genes. Enzyme-linked immunosorbent assay(ELISA) was used to detect the levels of senescence-associated secretory phenotype(SASP) factors like matrix metalloproteinase-3(MMP-3), interleukin(IL)-6, and IL-8. Immunofluorescence was used to evaluate the senescence-associated heterochromatin foci(SAHF) markers like heterochromatin protein 1γ(HP1γ) and trimethylation of histone H3 at lysine 9(H3K9me3). Senescence-associated β-galactosidase(SA-β-gal) staining was performed to detect the senescent cells, and Western blot was used to detect the expression and localization of growth arrest and DNA damage-inducible alpha(GADD45A), G_2/M phase-specific cyclin B1(Cyclin B1), and cyclin-dependent kinase 1(CDK1) proteins. Flow cytometry was used to analyze the cell cycle. The siRNA was used to silence GADD45A gene to verify its function. In vivo results show that, compared to the control group, the IMO + UVA group has significantly higher skin damage scores, with stratum corneum loss, inflammatory cell infiltration, reduced collagen fiber density, and abnormal deposition of elastic fibers. In vitro results demonstrate that IMO + UVA significantly inhibits the cell viability of HDF(P<0.05). RNA-seq and RT-qPCR verifications indicate that IMO + UVA significantly upregulate the expressions of senescence-associated genes, with GADD45A gene showing the most significant change. The IMO + UVA group also shows significant increases in SASP factor secretion, SA-β-gal activity, SAHF formation, and the proportion of cells in the G_2/M phase(P<0.05). Western blot results demonstrate that IMO + UVA promote the expression of GADD45A protein and inhibit nuclear translocation of Cyclin B1, thereby reducing the kinase activity of the Cyclin B1-CDK1 complex. Silencing GADD45A gene effectively alleviates G_2/M phase arrest and cellular senescence phenotype. In summary, IMO in combination with UVA can induce photodamage to the skin and accelerate cellular senescence, and the mechanism may involve G_2/M phase arrest mediated by the activation of the GADD45A/Cyclin B1/CDK1 axis.
PMID:
42543309
Bibliographic data and abstract were imported from PubMed on 03 Aug 2026.
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