| Background&Objective:Endothelial cell-derived secreted factors play a key role in maintaining homeostasis by affecting the behavior of other cells.When these factors are dysregulated,it may lead to the destruction of the physiological integrity of the mechanism and promote the occurrence of diseases in many different tissues and organs.Abdominal aortic aneurysm（AAA）is a degenerative disease that affects human health.Many of his pathogenesis is still unclear.In the current study,we investigated how targeted deletion of a chromatin remodeling protein,（Brahma-related gene 1,Brg1）,affects ApoE-knockout induced by angiotensin II（Ang II）(ApoE-/-)Pathogenesis of mouse AAA).Experimental method:By homozygous hybridization of homozygous ApoE-/-mice with Brg1 knockout mice,homozygous stable Brg1 was obtained from progeny;ApoE double knockout（DKO）mice were subjected to subsequent experimental grouping studies..The AAA mouse model was induced by Ang II.Male ApoE-/-mice of 8-10 weeks old and male（DKO）mice of 8-10 weeks old were fed for 1 week and then divided into WT group and KO.Group 2,10 in each group.The Ang II micro-osmotic pump was first configured in advance:the Ang II powder was dissolved in sterile 0.9%saline and loaded into the pump according to the animal’s body weight（1000 ng/kg/min infusion rate for 28days）and is now ready for use.In the WT group and the KO group,the Ang II-loaded sustained-release pump was implanted subcutaneously in the back and shoulders of the mice,and Ang II（200 ng·kg-1·min-1）was continuously released for 4 weeks.Four weeks later,Doppler ultrasound was used to detect changes in blood vessel diameter in mice;blood vessels were removed,photographed and histologically analyzed.After dehydration,embedding and sectioning,the vascular tissue was stained with Elastic tissue fiber Van Gieson（EVG）and HE.After staining,the microscope was used to analyze the image under the microscope.The blood vessel wall between the WT group and the KO group was observed.The extent of damage and histological analysis and statistics.Main results:1.ApoE-/-;Brg1（DKO）gene double knockout（DKO）mouse model construction1.1.Genotype identification results of mice:In the F2 generation,the 12th mouse of the obtained progeny mice was deleted with ApoE gene,and the Brg1 gene was also deleted,so this mouse was ApoE-/-;Brg1 double knock In addition to（DKO）mice.By identification,it was confirmed that ApoE-/-;Brg1（DKO）mice were successfully constructed.1.2 ApoE-/-;Brg1（DKO）mouse breeding results:the stable generation of stable genotypes can be maintained in the offspring,providing a guarantee for the experimental mouse model.2.The effect of the deletion of the endothelial-specific Brg1 gene on the anatomy of Ang II-induced abdominal aortic aneurysm in ApoE-/-mice:the abdominal aorta was dissected from the mouse,and the evaluation showed that the abdominal aorta of the WT group was significantly increased.Prompt that AAA has occurred.In contrast,the diameter of the aorta in the KO group was significantly decreased,and the incidence of the abdominal aorta was lower than that in the WT group.3.Loss of endothelial-specific Brg1 gene on Ang II-induced ApoE-/-mouse abdominal aortic aneurysm in echocardiographic measurement of vessel diameter:WT group mice have significantly larger vessel diameter than KO group.The statistical graph is a statistical analysis of the blood vessel diameters of the two groups of mice.It can be seen that the diameter of the aorta caused by the KO group is about 11%smaller than that of the WT group（*P<0.05）.4.Effect of endothelial-specific Brg1 gene deletion on Ang II-induced abdominal aortic aneurysm in ApoE-/-mice4.1 Effect on HE staining:As a result of the staining experiment,it can be seen that the degree of destruction of the middle layer of the blood vessel of the KO group was significantly reduced compared with the mouse of the WT group.4.2 Effects on the staining of vascular elastic fibers:The color results showed that the elasticity of elastin was much better in the KO group than in the WT group;the pathological grade also suggested that the elastin rupture in WT mice was more than that in KO mice.Severe,statistical analysis of elastin showed that the degree of elastin destruction in the KO group was significantly reduced compared with the WT group（*P<0.05）.In conclusion:Our results indicate that ApoE-/-;Brg1 double knockout（DKO）mice were successfully bred in F2 mice by hybridization,which provided a strong guarantee for subsequent experiments.In the ApoE-/-mouse abdominal aortic aneurysm（AAA）model induced by Ang II,the conditional deletion of the endothelial cell Brg1 gene can reduce the incidence of AAA,reduce the expansion of the aortic diameter,and reduce the damage of vascular fibrin.Thus,Ang II induced the development of AAA in ApoE-/-mice.Therefore,from the perspective of epigenetics,it can be concluded that the Brg1 gene may have a close relationship with the formation of AAA,and may be a role in promoting its development.The specific pathogenesis remains to be confirmed by further research. |
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