Abstract
Hydroxysafflor Yellow A (HSYA), a most representative ingredient of Carthamus tinctorius L., had long been used in treating ischaemic cardiovascular diseases in China and exhibited prominently anticoagulant and pro‐angiogenic activities, but the underlying mechanisms remained largely unknown. This study aimed to further elucidate the pro‐angiogenic effect and mechanism of HSYA on ischaemic cardiac dysfunction. A C57 mouse model of acute myocardial infarction (AMI) was firstly established, and 25 mg/kg HSYA was intraperitoneally injected immediately after operation and given once, respectively, each morning and evening for 2 weeks. It was found that HSYA significantly improved ischaemia‐induced cardiac haemodynamics, enhanced the survival rate, alleviated the myocardial injury and increased the expressions of CD31, vascular endothelial growth factor‐A (VEGF‐A) and nucleolin in the ischaemic myocardium. In addition, HSYA promoted the migration and tube formation of human umbilical vein endothelial cells (HUVECs), enhanced the expressions of nucleolin, VEGF‐A and matrix metalloproteinase‐9 (MMP‐9) in a dose‐ and time‐dependent manner. However, down‐regulation of nucleolin expression sharply abrogated the effect mentioned above of HSYA. Further protein‐RNA coimmunoprecipitation and immunoprecipitation‐RT‐PCR assay showed that nucleolin binded to VEGF‐A and MMP‐9 mRNA and overexpression of nucleolin up‐regulated the mRNA expressions of VEGF‐A and MMP‐9 in the HUVECs through enhancing the stability of VEGF‐A and MMP‐9 mRNA. Furthermore, HSYA increased the mRNA expressions of VEGF‐A and MMP‐9 in the extract of antinucleolin antibody‐precipitated protein from the heart of AMI mice. Our data revealed that nucleolin mediated the pro‐angiogenic effect of HSYA through post‐transcriptional regulation of VEGF‐A and MMP‐9 expression, which contributed to the protective effect of HSYA on ischaemic cardiac dysfunction.
Highlights
Coronary artery heart disease has become the leading cause of death and disability globally in the last 15 years,[1] and it is mainly attributed to coronary artery stenosis or occlusion-induced myocardial hypoperfusion or ischaemia, which can result in acute myocardial infarction (AMI), myocardial fibrosis and further cardiac dysfunction
Protein-RNA coimmunoprecipitation was performed to determine the interaction between nucleolin and matrix metalloproteinase-9 (MMP-9), vascular endothelial growth factor-A (VEGF-A) mRNA as we reported previously.[18,23 5] lg of nucleolin antibody was added into the pre-cleared protein extract, followed by a period of 1 hour incubation at 4°C
We found that the expressions of MMP-9 and VEGF-A mRNA were significantly up-regulated by overexpression of nucleolin, whereas NCLsiRNA displayed contrary effect on the expressions of MMP-9 and VEGF-A mRNA in the human umbilical vein endothelial cells (HUVECs) (Figure 7E,F, P < .05)
Summary
Coronary artery heart disease has become the leading cause of death and disability globally in the last 15 years,[1] and it is mainly attributed to coronary artery stenosis or occlusion-induced myocardial hypoperfusion or ischaemia, which can result in acute myocardial infarction (AMI), myocardial fibrosis and further cardiac dysfunction. Nucleolin is a ubiquitously expressed and multifunctional DNA-, RNA- and protein-binding protein in the nucleolus of eukaryotic cells.[15,16] It is conserved in animals, plants and yeast and plays an essential role in various pathophysiological processes such as assembly of ribosomes, DNA and RNA metabolism, chromatin structure, rDNA transcription, rRNA maturation, nucleogenesis, cell proliferation and apoptosis, tumour growth and angiogenesis.[15]. Whether nucleolin mediates the proangiogenic effect of HSYA through post-transcriptional regulation of these angiogenesis-related genes is largely unknown. | 2693 the cardioprotective and pro-angiogenic effect of HSYA on the ischaemic cardiac dysfunction were firstly determined, and the role as well as the underlying mechanisms of nucleolin in the proangiogenic effect of HSYA was further investigated
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