ABSTRACT
Objective:To investigate the role and mechanism of N 6-methyladenosine (m 6A) methyltransferase-like 3 (METTL3) in vascular calcification (VC) of chronic kidney disease (CKD) through apoptosis-associated protein. Methods:(1) Real-time fluorescence quantitative PCR was used to test METTL3 mRNA in serum of maintenance hemodialysis (MHD) patients. (2) Western blotting was used to detect the expression of METTL3 protein in high-phosphorus stimulated vascular smooth muscle cells (VSMCs), and immunofluorescence double lable was used to observe the distribution of METTL3 and Runt-related transcription factor 2 (Runx2). The METTL3 overexpressed and knockdown plasmids were constructed and transfected into VSMCs. Alizarin red staining was used to detect calcification degree. Western blotting was used to detect the expressions of osteogenic markers [Runx2, bone morphogenetic protein-2(BMP-2), collagen Ⅰ] and apoptosis- related proteins Bax and Bcl-2. (3) SD rats were randomly divided into control group, CKD-VC group and S-adenosylhomocysteine (SAH) intervention group. The calcification of thoracic aorta was evaluated by von Kossa staining, and the protein expressions of Runx2, Bax and Bcl-2 were detected by immunohistochemistry and Western blotting.Results:(1) METTL3 mRNA expression in MHD patients with VC was significantly lower than that in non-VC patients ( P<0.05), and was negatively correlated with coronary artery calcium score ( r=-0.65, P<0.001). (2) The expression of METTL3 in VSMCs stimulated by high phosphorus was decreased and showed a time dependence. Immunofluorescence double label showed that METTL3 and Runx2 were co-expressed in the nucleus. METTL3 was overexpressed in high-phosphorus induced VSMCs, and the expressions of Runx2, collagen I and BMP-2 were significantly decreased, accompanied by the decrease of calcified nodules and Bax/Bcl-2 ratio (all P<0.05). Conversely, METTL3 knockdown aggravated VSMCs calcification by inducing apoptosis. (3) Furthermore, METTL3 inhibitor SAH was administered in vivo, and it was found that inhibition of METTL3 expression significantly increased the calcification of rat thoracic aorta, and the Bax/Bcl-2 ratio and Runx2 expression were up-regulated. Conclusions:Serum METTL3 level is reduced in MHD patients with VC. In vivo and in vitro studies demonstrate that METTL3 inhibits VC in CKD by mediating the apoptosis-related protein Bax/Bcl-2.
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Objective:To investigate the role and diagnostic value of miRNA-205 in chronic kidney disease (CKD) patients with vascular calcification.Methods:It was divided into in vitro cell experiment and retrospective cohort study. In vitro experiments were conducted by using rat thoracic aortic smooth muscle cells. Alizarin red staining and calcium content detection were used to detect the calcification of vascular smooth muscle cells (VSMCs). Alkaline phosphatase (ALP) test kit was used to measure ALP activity. Western blotting was used to detect the protein expression levels of osteogenic transcription factors runt-related transcription factor 2 (Runx2), α smooth muscle actin (α-SMA) and smooth muscle-22α (SM-22α) in VSMCs. qRT-PCR was used to detect miRNA-205 and Runx2 expression levels. The double luciferase reporter gene assay was used to verify the targeted relationship between miRNA-205 and Runx2. The non-dialysis patients with CKD 3-5 stage from June 2020 to January 2021 in the Department of Nephrology of Fourth Hospital, Hebei Medical University were selected. According to coronary artery calcium score (CACs), the patients were divided into non-calcification group (CACs=0), mild-moderate calcification group (0<CACs≤400), and severe calcification group (CACs > 400). Spearman correlation analysis was used to analyze the correlation between miRNA-205 and Runx2 and vascular calcification. Logistic regression model and receiver operating characteristic (ROC) curve analysis were used to analyze the ability of miRNA-205 to predict the vascular calcification in patients with CKD. Results:(1)Compared with the control group, calcium nodules were more, and the calcium content, ALP activity and Runx2 protein level were higher, and the expression levels of miRNA-205, α-SMA and SM-22α were significantly lower in high phosphorus group (all P<0.05). Overexpression of miRNA-205 significantly reduced the calcification of VSMCs and Runx2 protein level, and increased the protein levels of α-SMA and SM-22α (all P<0.05). miRNA-205-5p reduced the activity of luciferase in the wild-type Runx2-3'-end non-coding region plasmid. (2) Eighty CKD patients were enrolled, with age of (57.50±14.93) years old and 49 males (61.3%). The results of comparison of miRNA-205 and Runx2 expression levels in non-calcification group ( n=26), mild- moderate calcification group ( n=30) and severe calcification group ( n=24) showed that, the higher degree of calcification, the lower miRNA-205 expression level and the higher Runx2 mRNA expression level (all P<0.05). miRNA-205 was negatively correlated with CACs ( r=-0.50, P<0.01) and Runx2 was positively correlated with CACs ( r=0.55, P<0.01). Multivariate logistic regression analysis results suggested that miRNA-205 ( OR=0.451, 95% CI 0.122-0.873) was an independent influencing factor of vascular calcification in CKD patients. The area under the ROC curve of miRNA-205 and miRNA-205 combined with Runx2 for predicting vascular calcification were 0.796 (95% CI 0.697-0.859) and 0.924 (95% CI 0.866-0.982), respectively. Conclusions:miRNA-205 inhibits vascular calcification by targeting Runx2 to negatively regulate osteogenetic phenotype transformation of VSMCs and is expected to be an early diagnostic marker of vascular calcification in CKD patients.
ABSTRACT
Objective To explore the effect and mechanism of magnesium on calcification induced by hyperphosphate.Methods Vascular smooth muscle cells (VSMCs) were primarily cultured in vitro and induced calcification by β-glycerophosphate (β-GP).VSMCs were randomly divided into control group,high phosphorus group (10 mmol/L β-GP),magnesium intervèntion group(10 mmol/L β-GP + 3 mmol/L MgSO4) and 2-aminoethoxy-diphenylborate (2-APB,an inhibitor of magnesium transporter) intervention group(10 mmol/L β-GP+3 mmol/L MgSO4+ 10-4 mol/L 2-APB).Calcium deposition and alkaline phosphatase (ALP) activity were measured by alizarin red staining,quantification of calcium and euzyme linked immunosorbent assay.RT-PCR and Western blotting were used to observe the expression of core binding factor α-1 (Cbfα-1) mRNA and protein,respectively.In vivo,male Sprague-Dawley rats (n=24) were randomly divided into control group (methylcellulose+high phosphorous diet),vascular calcification group (adenine suspension + high phosphorous diet),high magnesium intervention group(adenine suspension+high phosphorous and magnesium diet).The aortic pulse wave velocity (PWV) was measured,and vascular calcification was determined by von Kossa stain and quantification of calcium.Cbfα-1 in aortic was measured by immunohistochemistry.Results In vitro,compared with high phosphorus group,calcification,ALP activity (P ＜ 0.05) and Cbfα-1expression in VSMCs were significantly decreased in magnesium intervention group after incubation for 14 days,but the addition of 2-APB might inhibit the protective effect of magnesium on VSMCs.Dynamic observation of Cbfα-1 showed that magnesium significantly inhibited the expression of Cbfα-1 (P ＜ 0.05) on the third day and the inhibitory role was obviously increased in a time-dependent manner.Consistent with the findings in vitro,the aortic PWV,calcification were all significantly reduced (P ＜ 0.05) in high magnesium intervention group with high serum magnesium level,when compared with vascular calcification group.Immunohistochemistry showed that hypermagnesemia downregulated obviously the expression of Cbfα-1 induced by hyperphosphatemia(P ＜ 0.05).Conclusion Magnesium protects against vascular calcification by inhibiting osteogenic differentiation of VSMCs.
ABSTRACT
Ballistocardiogram (BCG) signal is a physiological signal, reflecting heart mechanical status. It can be measured without any electrodes touching subject's body surface and can realize physiological monitoring ubiquitously. However, BCG signal is so weak that it would often be interferred by superimposed noises. For measuring BCG signal effectively, we proposed an approach using joint time-frequency distribution and empirical mode decomposition (EMD) for BCG signal denoising. We set up an adaptive optimal kernel for BCG signal and extracted BCG signals components using it. Then we de-noised the BCG signal by combing empirical mode decomposition with it. Simulation results showed that the proposed method overcome the shortcomings of empirical mode decomposition for the signals with identical frequency content at different times, realized the filtering for BCG signal and also reconstructed the characteristics of BCG.