| BackgroundMyocardial infarction(MI)is a kind of serious disease that seriously endangers human health.Although there are many methods for its treatment,such as drugs,thrombolysis and coronary intervention,it can only save the myocardial cells and heart function of close to necrosis,hibermation or myocardial stunning,and the loss of cardiac function caused by myocardial necrosis,is unable to recover.How to save the heart function of the necrotic myocardium?At present,there are many researches for this aspects,such as cell reprogramming,tissue engineering repair,and myocardial regeneration.Although there have been many studies,the first two are not effective due to various conditions.Endogenous myocardial regeneration has won the attention of researchers more and more because of its unique biological effects such as no immune rejection and more responsive to physiological developmental patterns.Previous studies in this area have shown that non-coding RNA plays a very important role.lt has been found that long-chain non-coding RNA(IncRNA)has been widely involved in many biological processes such as epigenetic regulation,cell cycle regulation and cell differentiation,and plays a key role in regulating biological development.It has become a research hotspot.More and more LncRNAs are currently being discovered and confirmed to be involved in cardiovascular processes.However,due to its linear structure,LncRNA is poorly stable in the body,easily degraded by nucleases,and has a short biological activity cycle,so its effect is limited to some extent.Because the non-coding RNA Circular RNA(CirRNA)is a Circular closed structure,it is not easily degraded by endonuclease,has strong stability in vivo,and has long biological activity,avoiding the above defects,so it may be a kind of prospective non-coding RNA.Blood vessels are an important part of heart tissue,which can promote the supply of oxygen and nutrients in the myocardium,take away the metabolites,and participate in the metabolism of myocardium.A large number of studies have confirmed that neovascularization is closely related to myocardial regeneration and recovery of cardiac function.Promoting neovascularization can promote the recovery of myocardial infarction and inhibit the expansion of the marginal zone of the myocardial infarction.Therefore,;in combination with the above-mentioned,searching for a Circular RNA associated with blood vessel proliferation,may be make sure an expected effect,theoretically.Through the CircRNA expression profiling,which suggest that CireHipk3 is a kind of Circular RNA with high expression in neonatal rat heart,low expression in adult rat heart,and high homology in human and mouse.Combined with previous studies,which indicated that it has the role of regulating and promoting endothelial and vascular proliferation and cell proliferation.For this reason,we speculate that it may play an important role in myocardial regeneration.On the basis of that,in vitro pre-experiment showed that it is an ideal target gene.To this end,we carried out functional verification in vivo and in vitro,and explored the molecular mechanism.Methods??function experimentWe isolated the cardiomyocytes of suckling mice and adult rats by collagen fiber digestion.The establishment of the myocardial infarction rmodel was performed by anterior descending branch ligation,and the success of the myocardial infarction model was verified by ST-segment elevation of the electrocardiogram and later echocardiography.Cardiac function assessment was performed by echocardiography;fibrosis after myocardial infarction was detected by Masson staining;myocardial perfusion after myocardial infarction was detected by PETCT.??mechanismQuantitative PCR and in situ hybridization were used to determine the differential expression of CircHipk3 in the heart of suckling mice and adult rats.Protein detection was performed using western.Electrophoretic mobility shift assay was used to detect Gata4-mediated regulation of CircHipk3 expression.RNA pulldown and luciferase assays were used to study the interaction of CircHipk3 with proteins and miRNAs,respectively.??Result(1)Knockdown and overexpression of CircHipk3 inhibited and promoted the proliferation of cardiomyocytes in cardiomyocytes in vitro.Overexpression of CircHipk3 in adult mouse myocardial infarction model improved cardiac function after myocardial infarction;Knocking down CircHipk3 in a rat model of myocardial infarction attenuated the recovery of cardiac function after myocardial infarction.(2)Knockdown and overexpression of CircHipk3 inhibits and promotes endothelial cell migration and tube formation in human coronary artery endothelial cells in vitro;overexpression of CircHipk3 in an adult mouse myocardial infarction model promotes the enhancement of neovascularization.CircHipk3 is regulated by the transcription factor GATA4.CircHipk3 promotes eardiomyocyte proliferation by increasing the acetylation of Notch1,increasing the stability of Notch1 and preventing its degradation.At the same time,CircHipk3 acts as a sponge of miR-133a,promotes the expression of CTGF,and activates endothelial cells to promote neovascularization.Conclusion:CircHipk3,which is regulated by the transcription factor Gata4,synergistically induces CM proliferation and angiogenesis by activating Notch 1 signaling and inhibiting miR-133a activity,respectively,leading to improved cardiac funetion post MI. |
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