ABSTRACT
Osteoporosis is a kind of systemic metabolic bone diseases ,characterized by bone loss , bone subtle structural dam-age.Leptin is a peptide hormone which secreted by fat cells , that has both positive and negative effects to the bone , and plays a role of regulating on bone metabolism .In vitro, Leptin can regulate proliferation of osteoblast and inhibit reabsorption of osteoblasts depend on osteoclast.In vivo, Leptin can inhibit the synthesis of serotonin in the brain stem and increase the sympathetic nerve signals output by the hypothalamus to the bone , it mainly has a negative effect .But clinical trials about the correlation between Leptin and senile oste-oporosis, the role of Leptin in the central nervous system and peripheral tissue problems are still unclear .In this paper, we will make a comprehensive overview about the latest research progress in the correlation between leptin and senile osteoporosis .
ABSTRACT
This study was aimed to construct eukaryotic expression vectors carrying the small hairpin RNA (shRNA) targeting TRPC6 gene and investigate the effect of TRPC6 knockdown on puromucin aminonucleoside (PAN)-induced podocyte injury. Two DNA sequences containing the small hairpin structure targeting TRPC6 were designed, synthesized and then inserted into the green fluorescence protein (GFP)-contained plasmids (pGC) to establish the plasmids pGCsi-TRPC6A and pGCsi-TRPC6B. Plasmids expressing scrambled shRNA were used as negative control and named pGCsi-NC. These plasmids were transfected into a conditionally immortalized murine podocyte cell line by using liposome. Flow cytometry was used to examine the transfection efficiency. TRPC6 mRNA and protein expression levels were detected by RT-PCR and Western blotting. Cultured podocytes were divided into four groups: control group, PAN treatment group, PAN+TRPC6 shRNA transfected group and PAN+scrambled shRNA transfected group. The paracelluar permeability to BSA was evaluated by Millicell-PCF Inserts and cell viability was measured by the trypan blue assay. Immunofluorescent assay was used to observe the distribution of α-actinin-4 and α-tubulin. The results showed that the transfection efficiency of the shRNA expression vector was about 45%. Expression levels of TRPC6 mRNA and protein were downregulated after transfection with pGCsi-TRPC6A and pGCsi-TRPC6B. Knocking down TRPC6 gene could effectively reverse the PAN-induced increase in the paracelluar permeability to BSA. The distribution of α-actinin-4 and α-tubulin was disrupted after treatment with PAN, which was reversed by knocking down TRPC6 gene. It was concluded that knocking down TRPC6 gene could effectively prevent podocytes from the permeability increase induced by PAN, which may be related to the regulation of podocyte cytoskeleton.
Subject(s)
Animals , Mice , Cell Membrane Permeability , Physiology , Cell Survival , Physiology , Cells, Cultured , Gene Knockdown Techniques , Mice, Knockout , Podocytes , Physiology , Puromycin Aminonucleoside , Pharmacology , TRPC Cation Channels , Genetics , MetabolismABSTRACT
This study was aimed to construct eukaryotic expression vectors carrying the small hairpin RNA (shRNA) targeting TRPC6 gene and investigate the effect of TRPC6 knockdown on puromucin aminonucleoside (PAN)-induced podocyte injury. Two DNA sequences containing the small hairpin structure targeting TRPC6 were designed, synthesized and then inserted into the green fluorescence protein (GFP)-contained plasmids (pGC) to establish the plasmids pGCsi-TRPC6A and pGCsi-TRPC6B. Plasmids expressing scrambled shRNA were used as negative control and named pGCsi-NC. These plasmids were transfected into a conditionally immortalized murine podocyte cell line by using liposome. Flow cytometry was used to examine the transfection efficiency. TRPC6 mRNA and protein expression levels were detected by RT-PCR and Western blotting. Cultured podocytes were divided into four groups: control group, PAN treatment group, PAN+TRPC6 shRNA transfected group and PAN+scrambled shRNA transfected group. The paracelluar permeability to BSA was evaluated by Millicell-PCF Inserts and cell viability was measured by the trypan blue assay. Immunofluorescent assay was used to observe the distribution of α-actinin-4 and α-tubulin. The results showed that the transfection efficiency of the shRNA expression vector was about 45%. Expression levels of TRPC6 mRNA and protein were downregulated after transfection with pGCsi-TRPC6A and pGCsi-TRPC6B. Knocking down TRPC6 gene could effectively reverse the PAN-induced increase in the paracelluar permeability to BSA. The distribution of α-actinin-4 and α-tubulin was disrupted after treatment with PAN, which was reversed by knocking down TRPC6 gene. It was concluded that knocking down TRPC6 gene could effectively prevent podocytes from the permeability increase induced by PAN, which may be related to the regulation of podocyte cytoskeleton.
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To investigate the protective effects of eplerenone on adriamycin-induced renal injury and the possible mechanisms involved, 36 male Sprague-Dawley rats were randomly divided into control group, adriamycin nephropathy (AN) group and eplerenone-treated group (100 mg·kg(-1)·d(-1) eplerenone). Blood pressure, 24-h urinary protein, serum potassium, sodium and creatinine were measured 28 days after adriamycin injection (a single tail intravenous injection of 6.5 mg/kg adriamycin). The morphological changes of renal tissues were observed by light and electron microscopy. Immunohistochemistry and Western blotting were performed to examine the expression of TGF-β(1) and desmin in renal cortex. The results showed that 28 days after adriamycin injection, there were no significant changes in the level of serum potassium, sodium, creatinine concentrations and blood pressure values in the rats of the three groups. Meanwhile, the 24-h proteinuria excretion in the AN group was significantly higher than that in the control group (P<0.01), but that in the eplerenone-treated group was substantially reduced when compared with that in the AN group (P<0.05). Mild mesangial cell proliferation and matrix expansion, diffuse deformation and confluence of foot processes in podocytes were found in the AN group. By contrast, rats in the eplerenone-treated group exhibited obvious attenuation of these morphological lesions. The protein expression of TGF-β(1) and desmin in the AN group was markedly up-regulated in contrast to that in the control group (P<0.01), whereas that in the eplerenone-treated group was much lower than in the AN group (P<0.05). It was concluded that eplerenone may ameliorate the proteinuria and the development of pathological alteration in adriamycin-induced nephropathy presumably via the inhibition of cytokine release, and restore the morphology of podocytes independent of its blood pressure-lowing effects.
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Objective To access the effects of aldosterone (ALD) and its receptor antagonist- spironolactone (SPI) on the production of reactive oxygen species (ROS) and apoptosis in podocytes and to explore the possible mechanism involved. Methods Conditionally immortalized mouse podocytes were divided into control group, ALD group, SPI group and SPI +ALD group. The level of ROS production and the expression of nephrin protein were assayed by fluorescent spectrophotometry and indirect immunofluorescence technology. The apoptosis rate of podocytes was monitored by flow cytometry. The expression of bax and bcl-2 mRNA and protein was detected by RT-PCR and Western blotting methods. The anti-oxidant N-acetylcysteine (NAC)was applied to determine whether the effects of ALD on podocytes were mediated by ROS pathway.Results Compared with the control group, ALD significantly increased ROS production in podocytes (P＜0.05). SPI completely abolished the above-mentioned effect of ALD (P＜0.05). ALD induced the down-regulation of the expression of nephrin and the up-regulation of podocytes apoptosis (P＜0.05), which was accompanied with the elevated expression of bax mRNA and protein and the reduced expression of bcl-2 mRNA and protein (P＜0.05). SPI or NAC prevented the above-mentioned changes induced by ALD (P＜0.05). Conclusion ALD increases theexpression of pro-apoptotic factor (bax) but decreases the expression of anti-apoptotic factor (bcl-2)to induce podocytes apoptosis through the mineralocorticoid receptor (MR) possibly via the mechanisms involving ROS pathway.
ABSTRACT
Eukaryotic expression vectors carrying the small hairpin RNA (shRNA) for TRPC6 mRNA were constructed, and the effects of knocking-down TRPC6 on puromycin aminonucleoside (PAN)-induced apoptosis of mouse podocytes were observed. Two eukaryotic expression vectors containing small hairpin structure targeting TRPC6 named pGCsi-TRPC6A and pGCsi-TRPC6B were designed and synthesized. The plasmids were transfected into conditionally immortalized murine podocyte cell line by liposome. The changes in the TRPC6 mRNA and protein expression were observed by RT-PCR and Western blot after 48 h. Cultured podocytes were divided into four groups: control group, PAN treatment group, PAN treatment+shRNA transfection group, and PAN treatment+ negative control group. The expression of Bax and Bcl-2 mRNA and proteins was detected by RT-PCR and Western-blot respectively. The apoptotic rate of podocytes was measured by flow cytometry. The results showed that the expression of TRPC6 mRNA and protein was decreased in the podocytes when transfected with pGCsi-TRPC6A, and pGCsi-TRPC6B. The expression of Bax was increased, and that of Bcl-2 was decreased at protein and mRNA levels in the podocytes after treated with PAN for 48 h. These changes was attenuated by knocking-down TRPC6. Knocking-down TRPC6 could effectively decrease the PAN-induced apoptosis of podocytes. It was concluded that TRPC6 may play an important role in the PAN-induced apoptosis of podocytes. Knocking-down TRPC6 gene could effectively prevent the podocytes from apoptosis induced by PAN.
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To investigate the effects of albumin on the production of matrix metalloproteinases-2 (MMP-2) and matrix metalloproteinases-9 (MMP-9) in podocytes. Podocytes were treated with bovine serum albumin (BSA) at the concentration of 0.1, 0.5, 1, 2 g/L, respectively. Conditioned media were harvested 12, 24, 48 and 72 h after the treatment. The expression of MMP-2 and MMP-9 was assayed by gelatin zymography, RT-PCR and Western blotting analysis. Our results showed that in comparison with the control group, BSA increased the expression of MMP-2 and MMP-9 mRNA and protein in a dose- and time-dependent manner (P<0.05). Meanwhile, the enzymatic activities of MMP-2 and MMP-9 in the culture supernatants of podocytes were also increased (P<0.05). It is concluded that albumin up-regulated the expression of MMP-2 and MMP-9 at gene and protein levels in a time- and dose-dependent manner.
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objective To assess the effect of aldosterone on the production of matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9)and collagen Ⅳ in culture supematants of podocytes and the possible molecular mechanisms involved in the influence of aldosterone on the synthesis and degradation of extracellular matrix produced by podocytes. Methods Podecytes were treated with aldosterone at the concentration of 10-11, 10-9, 10-7 mol/L respectively. Cultured podocytes were examined at 24, 48 and 72 hours respectively. Spironolactone, a receptor antagonist of aldosterone, was added to observe the blocking effect on aldosterone. An inhibitor of TGF-β1 receptor was used to determine whether the effect of aldosterone on podocytes were mediated through TGF-β1 system. The enzymatic activities of MMP-2 and MMP-9 were assayed by gehtin zymography. Collagen Ⅳ 0.5 chain and TGF-β1 proteins released into culture supematants were assessed by Western blot and ELISA analysis. The adhesion rate of podocytes was monitored by flow cytometry. Results Aldosterone increased the activities of MMP-2 and MMP-9 in a dose- and time-dependent manner (P<0.05). Aldosterone decreased the level of collagen Ⅳ or5 chain protein in culture supernatants (P<0.05). Meanwhile, the expression of TGF-β1 was also increased (P<0.05). Spironolactone completely abolished the above-mentioned changes(P< 0.05). Blockage of TGF-β1 signaling with SB431542 prevented the aldosterone-induced upregulation of MMP-2 and MMP-9 as well as the downregulation of the collagen Ⅳ α5 chain protein and the adhesion rate of podocytes (P<0.05). Conclusions Aldosterone increases the activities of MMP-2 and MMP-9 but decreases the expression of collagen Ⅳ α5 chain and the adhension rate of podocytes possibly via TGF-β1 signaling pathway. Such alterations may contribute to glomerular podocyte injury associated with the GBM abnormality caused by the imbalance between matrix synthesis and degradation.
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Objective To study the effect of overexpression of TRPC6 on Ang Ⅱ-induced apoptosis of mouse podocytes in vitro and to explore the possible mechanisms. Methods Mouse TRPC6 cDNA eukaryotie expression vector pEGFP-NI-mTRPC6 was transfected to conditionally immortalized routine podocyte cell line by liposome. The fluorescent microscopy was used to examine the expression of EGFP after 24 hours. The change of TRPC6 protein expression was observed by Western-blot. Podocytes were treated by different concentrations of Ang Ⅱ. The podocyte intracellular calcium concentration was measured with laser-scanning con_focal microscope. The expression of Bax and Bcl-2 mRNA was assessed by RT-PCR and the expression of Bax and Bcl-2 protein was measured by Western-blot. The apoptotic ratio of podocytes was monitored by flow cytometry and Hoechst staining. Results About 35% of the cells expressed EGFP. An up-regulation of protein expression of TRPC6 was detected in podocytes when transfected with pEGFP-N1-mTRPC6 (P<0.01). The overexpression of TRPC6 promoted the Ang Ⅱ-induced influx of extracellular calcium and elevated the expression of Bax but decreased the expression of Bcl-2 (P<0.01, P<0.05). The apoptotic ratio of podocyte was (2.50±0.72)% when treated by low-dose Ang Ⅱ (10-10 mol/L), and it was increased to (4.33±0.45)% when transfected with pEGFP-N1-mTRPC6 (P <0.05 ). Transfection with pEGFP-NI-mTRPC6 increased apoptosis rate from (15.46± 1.40)% to (18.33±0.87)%(P<0.01) by high-dose Ang Ⅱ (10-6 mol/L). Conclusion TRPC6 plays an important role in the Ang Ⅱ-induced apoptosis of podocytes by promoting the influx of extraeellular calcium, which leads to the apoptosis cascade initiation.
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Objective: Selecting items from item pool for the development of WHOQOL-OLD by six statistical methods. Testing the function of Cronbach ? and test-retest reliability method for item selection.Methods:Collecting data by the means of multistage sampling, two new methods based on Cronbach ? and test-retest reliability were employed to select items in view of internal consistency and stability in addition to the commonly used methods such as methods of dispersion and correlation coefficient. Results: Items selected by different methods were remained to constitute the old module of WHOQOL; items with high internal consistency or high stability were selected by methods based on Cronbach ? and test-retest reliability. Conclusion: The four commonly used methods select items from aspects of representation, independence and discrimination, while methods based on Cronbach ? and test-retest reliability select the items in view of internal consistency and stability. The two new methods are recommended together with the conventional methods in item selection.