H19在心肌肥厚中的功能研究
[Abstract]:The heart is one of the earliest organs of the human body in the development stage of the embryo, and is one of the most important organs of the human body. The heart is composed of cardiac muscle cells and other cells (fibroblasts, lymphatic vessels, blood vessels, etc.), and the quantity of the cardiac muscle cells is about 25% of the total quantity, but the volume accounts for about 75% of the volume of the heart. Heart failure is one of the important causes of human death, and heart failure is often derived from the development of cardiac hypertrophy, so it is of great practical significance to study the pathogenesis of cardiac hypertrophy. Myocardial hypertrophy is an adaptive response of the heart to various pressures and to maintain cardiac function at an early stage. However, persistent cardiac hypertrophy and concomitant myocardial remodeling often lead to heart failure, and the risk of cardiac death is increased. Although various specific peptide hormones, growth factors and small RNAs have been shown to be involved in the regulation of cardiac hypertrophy, the mechanism of cardiac hypertrophy is not fully understood. Long noncoding RNA (lncRNA) is a class of RNA which has a length of more than 200 nucleotides and cannot encode proteins, which plays an important and complex role in the process of life, and is involved in such processes as RNA processing, cell fate determination, chromatin modification, and the like. It has been found that lncRNA can also function as a competitive endogenous RNA (cRNA). In recent years, it has been found that lncRNA is involved in the regulation of the development and disease process of the heart. Braveheart lncRNA can stimulate the transformation of stem cells into cardiac cells during the differentiation of mouse embryonic stem cells. The mutation of the MIAT on exon 5 increases the transcription of MIAT and may be associated with the occurrence of myocardial infarction. LncRNA ANRIL is located at 9p21, and its offset can cause abnormal proliferation of myocardial cells and coronary artery disease. It was found that the expression of lncRNA in the early stage of cardiac hypertrophy and the stage of heart failure was significantly changed, suggesting that the lncRNA played an important role in cardiac hypertrophy and heart failure. Therefore, lncRNA has gradually become a new focus and focus of the cardiovascular and clinical research. As the earliest discovered imprinting gene, lncRNA H19 has been demonstrated to play an important role in the development and tumorigenesis of mammalian embryos. The first exon of H19 is capable of encoding miR-675, and it has been found that the function of H19 in many pathophysiological processes is mediated by miR-675. A number of studies in recent years have shown that the H19 expression level is up-regulated when screening for differentially expressed lncRNA in a pathological myocardial hypertrophy mouse model, suggesting that it may play a role in cardiac hypertrophy, However, the specific functions and related mechanisms of H19 in cardiac tissue have been reported to date. The purpose of this study was to explore the function of H19 in the course of myocardial hypertrophy and to explore its related mechanism. We first examined the expression of H19 and its coded miR-675 in different types of cardiac hypertrophy mouse model and human heart failure specimen, and found that the expression level of H19 and its coded miR-675 was up-regulated in pathological myocardial hypertrophy model and heart failure sample. While the expression of the two was down-regulated in the motion-induced physiological cardiac hypertrophy mouse model. In order to study the function of H19 in myocardial cells, we construct and package an adenovirus for overexpression of H19 and use it to infect isolated primary cardiomyocytes in vitro. It is found that the expression of H19 can inhibit the hypertrophy and growth of the cardiac muscle cells in vitro by the detection of the morphological analysis of the cardiac muscle and the expression level of the hypertrophy marker gene. On the other hand, we have also found the expression of endogenous h19 in the low primary cardiac muscle cells by transfecting si-h19 in vitro, and it is found that the knockdown of h19 can promote the hypertrophy and growth of the cardiac muscle cells. To understand the mechanism of h19 to inhibit the growth of cardiac myocyte hypertrophy, we have adopted the following strategy to explore whether the function of h19 in a cardiac muscle cell is mediated by mir-675. First, we overexpress or knock low mir-675 in an in vitro primary myocardial cell, and it is found that the mir-675 can also inhibit the growth of the hypertrophy of the cardiac muscle cells in vitro. Further, the detection of the simultaneous knockdown of mir-675, the morphological analysis of the cardiac myocyte and the level of the expression of the hypertrophy marker gene in primary myocardial cells shows that the knockdown of mir-675 can effectively save the decrease in the size of the myocardial cells due to the overexpression of h19. In addition, we also packaged the h19-tru and the h19-mut adenovirus containing the h19-truncated (h19-tru) and the mutant mir-675 precursor sequence of the mir-675 precursor sequence, respectively, and the infection of the cardiac muscle cells, respectively. It was found that both forms of adenovirus can effectively express h19 in the cardiac muscle cell, but it has no significant effect on the expression of mir-675 in the cardiac muscle cells. The morphological analysis and the detection of the expression level of the hypertrophy marker gene showed that both h19-tru and h19-mut both lost the ability to inhibit the growth of cardiac myocyte hypertrophy. All of these results show that mir-675 is capable of mediating the function of h19 to inhibit the growth of cardiac muscle cells. We have further explored the mechanism of the action of h19/ mir-675. The target molecules that are likely to act with the mir-675 are predicted using the targetscan, from which a system analysis of the calcium/ calmodulin-dependent protein kinase ii (camkii) with the function of promoting the cardiac hypertrophy is selected. First, we constructed a luciferase reporter vector containing normal and mutant camkii-3 '-utr and co-transfected 293T cells with mir-675. The results show that the mir-675 can effectively inhibit the 3 '-utr activity of camkiii, while the mir-675 has a loss of this inhibitory effect on the mutant vector. Further detection of the expression level of camkii showed that the mir-675 was able to significantly inhibit the expression of camkii in mrna and protein levels. These results show that camkii is a direct target molecule for mir-675. in order to verify whether the function of h19 in the cardiac muscle cell is mediated by camkii, we tap the low h19 in the in vitro primary myocardial cell and tap the camkii antigen, finding that the low-energy portion of the camkii antigen alleviates the increase in the size of the cardiac muscle resulting from the low h19 knockdown, It is shown that camkii can partially mediate the function of h19 to inhibit the growth of cardiac myocyte hypertrophy. In order to study the function of h19/ mir-675 in the steady-state maintenance of heart in vivo, we examined the effect of the expression of mir-675 in vivo on the cardiac hypertrophy caused by the tac operation. We performed a tac procedure on c57 males at 2 months of age, and after 1 week of post-operation, cardiac hypertrophy was confirmed, the mir-675 inhibitor (antagomir-675) was injected via the tail of the mouse, and the heart was taken and analyzed after 3 weeks of injection. We found that antagomir-675 was used in vivo to effectively relieve the increase in the level of mir-675 expression induced by the tac operation and to increase the cardiac hypertrophy induced by the stress load, suggesting that the inhibition of mir-675 in vivo would promote the occurrence of cardiac hypertrophy. To sum up, our study first revealed that h19/ mir-675 can provide a new theoretical basis for understanding the pathogenesis of cardiac hypertrophy by targeting camkii to inhibit cardiac hypertrophy, and provide a new target for the treatment of heart disease.
【學(xué)位授予單位】:中國(guó)人民解放軍軍事醫(yī)學(xué)科學(xué)院
【學(xué)位級(jí)別】:博士
【學(xué)位授予年份】:2016
【分類(lèi)號(hào)】:R542.2
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