| Objective:The skin is the largest organ of the human body and the necessary way for external irradiation to act on the human body.People are exposed to ionizing radiation in the event of terrorist attacks,nuclear accidents,loss of radioactive sources,etc.,and it is likely to cause radiation composite skin damage.Radiation combined skin injury is difficult to heal,and the mechanism is still unclear.There is no unified treatment plan and effective therapeutic drugs in clinic.Amphibian skin can produce bioactive peptides with a variety of biological functions to protect the skin from microbes,parasites,ultraviolet rays and the like.These peptides are stored in the granule glands of the skin,when the skin was exposed to external stimulican,peptides can be released into the skin secretions at high concentrations.The exploration of functional peptides of amphibian skin secretions and their biological functions is important for the development of new therapeutic agents.The aim of this study was to investigate the radiation-induced Pelophylax nigromaculatus skin polypeptides and functions,and to provide new ideas for the development of effective therapeutic drugs for radiological composite skin damage.Method:Establish a whole body irradiation model of Pelophylax nigromaculatus and observe its survival period.A model of local radiation damage of Pelophylax nigromaculatus was established and its skin damage was observed.Skin section HE staining was used to observe changes in skin structure after irradiation.Ultraviolet spectroscopy of the frog skin extract was used to observe changes in skin composition after irradiation.Second-generation sequencing technology was used to analyze RNA changes in frog skin tissue after exposure.The polypeptide whose expression is up-regulated in the skin tissue of Pelophylax nigromaculatus after irradiation is identified and screened by polypeptideomics.At the cellular level,the total antioxidant capacity of the body fluid of polypeptides was determined by DPPH-and ABTS-based free radical scavenging experiments.The reactive oxygen species of the skin cells after irradiation were detected by a cell reactive oxygen species test.The viability of the skin cells after irradiation was examined by the CCK-8 assay.The lactate dehydrogenase cytotoxicity assay was used to examine the release of lactate dehydrogenase from skin cells after irradiation.The cell scratch test was used to examine the migration of skin cells after irradiation.A radiation composite skin damage model was established on BALB/c mice to observe the effect of polypeptides on the progression and repair of radiation composite skin damage.Result:The black-spotted frog has strong radiation resistance.Some 50Gy irradiated Pelophylax nigromaculatus developed skin damage.The skin section HE staining shows that the skin structure is incomplete,microvascular congestion,and secretory gland disappear.After the Pelophylax nigromaculatus skin was sequenced,536 up-regulated genes and 875 down-regulated genes were screened.Through polypeptideomics,54 peptides which were signif-icantly differentially expressed in the skin of the Pelophylax nigromaculatus after irradiation were screened,of which 27 were up-regulated and 27 were down-regulated.The 10 lost significant up-regulated peptides were selected for further study at the cellular level,and the free radical scavenging ability of the peptide itself was found to be different.These polypeptides can increase the vitality of the skin cells after irradiation,and reduce the levels of lactate dehydrogenase and reactive oxygen species in the skin cells after irradiation.Promotes the migration of skin cells after irradiation,while promoting the healing of radiation composite skin damage of mice.Conclusion:Ionizing radiation can cause skin damage of the Pelophylax nigromaculatus and change the structure of the skin;Ionizing radiation can cause changes in the RNA and polypeptide of the skin of Pelophylax nigromaculatus;The selected radiation-induced frog skin polypeptide has antioxidant capacity,can reduce the release of reactive oxygen species and lactate dehydrogenase from skin cells after irradiation,enhance cell viability,promote migration,and accelerate the healing of radiation composite skin damage.It provides new ideas for the development of therapeutic drugs for radiation composite skin damage. |
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