| Summary: | 博士 === 國立交通大學 === 生物科技學系 === 101 === Renin-angiotensin system (RAS) is an important regulation system in the human circulatory system. The abnormal RAS is associated with the pathogenesis of cardiovascular diseases. Angiotensin II (Ang II), angiotensin 1-7 (Ang 1-7), angiotensin converting enzyme (ACE) and angiotensin converting enzyme II (ACE2) are the mainly members in RAS. Ang II stimulates inflammation, fibroblasts growth, cardiac myocyte apoptosis, fibrogenesis, and differentiation to cause tissue repair/remodeling, and it has been hydrolyzed by ACE2 to obtain the Ang 1-7 to against the disadvantageous effect of Ang II. ACE2 plays a significant role in RAS and heart diseases, but the regulation mechanisms of ACE2 in the heart and cardiac cells are unclear.
This study demonstrates the regulation mechanism of ACE2 and ace2 gene expression in cardiac cells, and the association between ACE2 and matrix metalloproteinases-2 (MMP-2) in the cells. The ACE2 expression in human cardiac fibroblasts (HCFs) treated with angiotensin peptides, Ang II and Ang 1-7, and analyzed the promoter activity of human ace2 using luciferase report assay to identify regulatory elements of ace2 gene. In addition, we also revealed the relationship with ACE2 and MMP-2 in HCFs utilized the technology of lentivirus to investigate the role of ACE2 regulation in cardiac cells.
The major results of this study are: (1) Ang II-AT1R and Ang 1-7-Mas axes were via ERK-MAPK signal pathway to regulate ACE2 expression, respectively; (2) the sequences of 5’-ATTTGGA-3’ within -516/-481 domain of the ace2 promoter could regulate ACE2 expression and this sequences was the binding site of the transcription factor; (3) Ang II regulated ACE2 expression through AT1R to activate ERK-MAPK signal pathway to stimulate the -516/+20 domain within the ace2 promoter; (4) the ace2 promoter activity was no significant response when HCFs treated with TGF-β1 and TNF-α; (5) ACE2 overexpression enhanced MMP-2 activity and Ang II-AT1R-ERK1/2 axis decreased MMP-2 activity; (6) compared to Ang II, Ang 1-7 through Mas receptor inhibited the activation of ERK1/2, but no significant effect of MMP-2 activity; (7) the tumor necrosis factor-α-converting enzyme (TACE or ADAM17) expression could be regulated through Ang II-AT1R-ERK1/2 and Ang 1-7-Mas-ERK1/2 axes to alter ACE2 shedding; (8) the ACE2 knockout (KO) mice were re-established in our laboratory, including the mice with ACE2+/-, ACE2-/- and ACE2-/y genotypes; (9) ACE2 deficiency enhances MMP-2 activity in heart tissue of ACE2 KO mice compared to WT mice.
This study reveals the ACE2 regulation by angiotensin peptides. Ang II and Ang 1-7 could enhance the ACE2 expression in HCFs and indicated that Ang II through the -516/+20 sequence domain within ace2 promoter to regulate ace2 gene expression. ACE2 overexpression enhances MMP-2 activity in HCFs, Ang II decrease the mRNA expression of ADAM17, MMP-2 activity and shed ACE2 activity in HCFs/ACE2. These results show ACE2 plays a protect role against the mechanism of heart remodeling by Ang II induction. Two mainly axes, Ang II-AT1R-ERK1/2 and Ang 1-7-Mas-ERK1/2, regulate the mRNA expression of ADAM17 and the activity of ACE2 and shed ACE2, and MMP-2 activity also could be regulated through Ang II-AT1R-ERK1/2 pathway.
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