ABSTRACT
Aim To explore the effect of Klotho (KL) gene transfection on the apoptosis of MC3T3-E1 osteo-blasts induced by dexamethasone(DEX). Methods MC3T3-E1 osteoblasts were transfected by recombinant adenovirus containing KL gene(Ad-KL) and recombi-nant adenovirus containing green fluorescent protein (GFP) gene(Ad-GFP). The apoptosis model was con-structed. The transfection efficiency of Ad-KL and Ad-GFP in cells were observed using inverted fluorescent microscope, and the level of KL mRNA and protein was detected by qPCR and Western blot,respectively. The cell viability after different concentrations of DEX acting on the cells and the viability of every research group were determined by cell counting kit-8 (CCK-8) assay. The apoptotic rate was evaluated by flow cytom-etry. The level of mRNA and protein was analyzed by qPCR and Western blot, respectively. The level of caspase-9 protein was detected by immunofluorens-cence assay. Results Cells were transfected by Ad-KL and Ad-GFP successfully. KL group and KL +DEX group had higher level of KL mRNA and protein than that in other groups. The optimum concentration of DEX was 2.0 mmol·L-1. When DEX acting on the cells, the cells viability decreased and apoptotic rate increased obviously in DEX group and GFP + DEX group. The level of Bax mRNA and protein presented a upward trend in DEX group and GFP +DEX group, while the level of Bcl-2 mRNA and protein was oppo-site. But after KL transfecting MC3T3-E1 osteoblasts, the markers described above in KL group had more dramatic improvement than in DEX group and KL +DEX group. Conclusions High-dosage DEX can in-duce the apoptosis of MC3T3-E1 osteoblasts, and the pro-apoptosis effect of high-dosage DEX in MC3T3-E1 osteoblasts can be suppressed by up-regulating KL gene expression level, suggesting that the glucocorticoid-in-duced osteoporosis might be improved by up-regulating KL gene expression level, and it may be a new target for the treatment of latrogenic osteoporosis induced by high-dosage glucocorticoid in clinic.
ABSTRACT
<p><b>OBJECTIVE</b>To assess the effect of Klotho gene transduction on the progression of hypertension and heart damage in spontaneous hypertensive rats (SHRs).</p><p><b>METHODS</b>An adeno-associated virus (AAV) carrying full-length mouse Klotho cDNA (rAAV.mKL) was constructed for in vivo expression of Klotho. Three different groups of male SHRs and a control group of sex and age-matched Sprague Dawley (SD) rats (5 rats per group) were used. The experimental groups of SHRs received an IV injection of phosphate buffered saline (PBS), rAAV.mKL and rAAV.EGFP, respectively. The control group only received equal-volume of PBS. The whole study has spanned 12 weeks. Plasma levels of insulin-like growth factor-1 (IGF-1) and insulin were measured with ELISA. The weight of whole heart was measured to calculate the heart weight index (HWI). EGFP expression of heart frozen sections was observed by fluorescence microscopy. Expression of mRNA and protein of Klotho, IGF-1, IGF-1 receptor (IGF-1R) and p-Akt were determined with RT-PCR, immunohistochemical analysis, and Western blotting. Hypertrophic myocardial cell and collagen fiber were observed by histological examination following Haematoxylin-Eosin and Masson staining.</p><p><b>RESULTS</b>Transduction of rAAV.mKL can significantly prevent the increase of blood pressure in SHRs. Compared with the control group, the levels of Klotho mRNA and protein have both increased, and the plasma levels of IGF-1, insulin and glucose were elevated, whereas the expression of phosphor-Akt (also called Protein Kinase B, PKB) was decreased in the rAAV.mKL group. Furthermore, a decrease of hypertrophic myocardial cells and collagen fibers was noticed in the rAAV.mKL group compared with the control group.</p><p><b>CONCLUSION</b>The Klotho gene can attenuate the progression of hypertension and abolishes myocardial hypertrophy and myocardial fibrosis. The protective effect observed in the rAAV.mKL group of SHRs may be attributed to increased Klotho protein and suppression of insulin and IGF-1 signaling pathways through inhibition of Akt phosphorylation.</p>