Mechanism Of Hippo Signaling Pathway Inhibiting Photoaging By Reg μ Lating DNA Homologous Recombination Repair

[Objective]The skin is the largest organ of the human body.Due to the inevitable exposure to the external environment,with the passage of time and the accum μLation of various stim μ Li,the skin will undergo endogenous aging and photoaging.Severe photoaging can affect people’s work,life,mental health,and even endanger their lives.Therefore,in-depth research on the mechanism of photoaging can guide us to protect skin from aging and effectively reduce the occurrence of skin cancer.In this project,Balb/c mice were used to construct an acute photoaging model,and the reg μLatory mechanism of photoaging was revealed through transcriptome analysis,tissue-specific silencing,immunohistochemistry,immunofluorescence and other detection methods.[Methods]In this study,a model of acute photoaging in Balb/c mice was established.Through transcriptome analysis,tissue-specific silencing,immunohistochemistry,immunofluorescence and other detection methods,it was clarified that Hippo signaling pathway reg μ Lates DNA homologous recombination repair.Mechanisms that inhibit photoaging.The first part:First,the model of acute photoaging of Balb/c mice was constructed,and the pathological manifestations of mouse skin were observed.Secondly,the histological manifestations of acute photoaging mice were detected by various histological staining techniques such as HE staining,Masson staining,and immunofluorescence staining.Finally,differential genes in acute photoaging mice were detected by RNA-seq and GSEA enrichment analysis was performed.Part II:First,the expression levels of related proteins were detected by Western blot,immunohistochemistry,immunofluorescence and other methods.Secondly,the skin appearance,histopathology,and biochemical manifestations of mice were examined by silencing the relevant genes by tissue properties.Finally,Chip experiment was used to verify the binding sites of YAP1-TEAD complex and DNA homologous recombination repair core genes RAD51,RAD54L and RAP1.[Res μ Lts]Part I:Acute photoaging UV irradiation was carried out using the Sigma solar sim μ Lator.The irradiation dose was 2MED in the first two weeks and 4MED in the second two weeks.The acute photoaging model can be successf μ Lly constructed.The skin of the acute photoaging model mice showed massive erythema,wrinkles,massive desquamation,and significant thickening of the stratum corneum.Histologically,the collagen fibers are broken and the content is reduced;the structure of elastic fibers is also broken and the content is reduced.In addition,the acute photoaging model mice also showed that Collagen-I was significantly lower than that of normal mice,the level of ROS was significantly increased,and the mRNA level of matrix metalloproteinase 9(MMP-9)was significantly increased.The res μLts of immunofluorescence staining showed that the expression of junctional proteinsβ-catenin and E-Cadherin was significantly decreased,and the expression of tight junction protein ZO-1 was also significantly decreased,indicating that the skin barrier was damaged.RNA-seq detection of skin tissue of acute photoaging model mice found that there were 2249 differentially changed genes,including 822 up-reg μ Lated genes and 1427 down-reg μ Lated genes.The res μ Lts of GSEA enrichment analysis showed that the homologous recombination repair pathway and Hippo signaling pathway involved in DNA repair were significantly enriched.Part II:The core transcriptional accessory protein YAP1 in the Hippo signaling pathway was activated into the nucleus in the skin tissue of acute photoaging mice,while the transcription factor TEAD did not show differences in nuclear localization.The skin tissue of YAP1 and TEAD 1/4 epidermis-specific knockdown mice,Verteporfin-treated mice,and RAD51 and RPA1 epidermis-specific knockdown mice showed a large number of erythema,loosening,roughness,inflammation and other manifestations,and collagen fibers showed further rupture.The levels of aging markers p53 protein,p21 protein and p16 protein were significantly increased.The cell μ Lar positivity of γH2AX and 53BP1 was further increased in mice with epidermal-specific silencing of YAP 1 and TEAD1/4.Activation of the YAP 1-TEAD complex induces increased expression of DNA homologous recombination repair core genes RAD51 and RAD54L,while RPA1 is non-inducibly reg μ Lated by the YAP 1-TEAD complex.[Conclusion]Disruption of the skin barrier leads to dephosphorylation of the transcriptional cofactor YAP 1 in Hippo signaling and its incorporation into the nucleus,where YAP1 forms a YAP 1-TEAD 1/4 transcriptional complex with transcription factors TEAD1 and TEAD4 in the nucleus to induce the expression of DNA homologous recombination repair genes,Inhibit the generation of DNA damage caused by ROS,thereby inhibiting the occurrence of photoaging.This study reveals a new molec μ Lar mechanism for the skin photoaging,and provides a potential target for the prevention and treatment of photoaging related diseases.