Aims: The nephrotoxic side effects of cyclosporine A (CsA) are partly due to induction of the epithelial-to-mesenchymal transition (EMT), possibly through upregulation of connective tissue growth factor (CTGF). Bone morphogenetic protein (BMP-7) has been reported to protect against and reverse renal injury via its renotropic and antifibrotic effects. We therefore designed a method to investigate the mechanism by which BMP-7 inhibits CSA-induced EMT in cultured human renal proximal tubular epithelial (HK-2) cells and whether BMP-7 can antagonize CsA-induced profibrogenic effects. Methods: Cultured HK-2 cells were treated with CsA or a combination of CsA and BMP-7 for 72 h. Morphological changes were assessed by phase-contrast microscopy. The expression of α-smooth muscle actin (α-SMA), E-cadherin, collagen type I and CTGF was analyzed by immunofluorescence, RT-PCR, and Western blot. Additionally, the effect of CTGF silencing on CsA-mediated gene expression was assessed. Results: CsA-induced EMT was associated with decreased expression of E-cadherin, increased expression of α-SMA, collagen type I and CTGF, and loss of epithelial morphology. BMP-7 inhibited these effects in a dose-dependent manner. Using siRNA, CTGF knock-down also attenuated EMT-associated phenotypic changes induced by CsA. Conclusion: These data suggest that BMP-7 can block CsA-induced EMT by downregulating the expression of CTGF, a downstream mediator of EMT.
Periodontal repair is a complex process in which regeneration of alveolar bone is a vital component. The aim of this study was to develop a biodegradable scaffold with good biocompatibility and osteoinductive ability. Two types of composite fibrous scaffolds were produced by electrospinning, ie, type I collagen/poly(ε-caprolactone) (COL/PCL) and type I collagen/poly(ε-caprolactone)/nanoscale hydroxyapatite (COL/PCL/nHA) with an average fiber diameter of about 377 nm. After a simulated body fluid (SBF) immersion test, the COL/PCL/nHA-SBF scaffold developed a rough surface because of the calcium phosphate deposited on the fibers, suggesting that the presence of nHA promoted the mineralization potential of the scaffold. Energy dispersive X-ray spectroscopy clearly showed the calcium and phosphorus content in the COL/PCL/nHA and COL/PCL/nHA-SBF scaffolds, confirming the findings of nHA and calcium phosphate precipitation on scanning electron micrographs. Water contact analysis revealed that nHA could improve the hydrophilic nature of the COL/PCL/nHA-SBF scaffold. The morphology of periodontal ligament cells cultured on COL/PCL-SBF and COL/PCL/nHA-SBF was evaluated by scanning electron microscopy. The results showed that cells adhered to either type of scaffold and were slightly spindle-shaped in the beginning, then extended gradually with stretched filopodia, indicating an ability to fill the fiber pores. A Cell Counting Kit-8 assay showed that both scaffolds supported cell proliferation. However, real-time quantitative polymerase chain reaction analysis showed that expression of the bone-related markers, alkaline phosphatase and osteocalcin, was upregulated only on the COL/PCL/nHA-SBF scaffold, indicating that this scaffold had the ability to induce osteogenic differentiation of periodontal ligament cells. In this study, COL/PCL/nHA-SBF produced by electrospinning followed by biomimetic mineralization had combined electrospun fibers with nHA in it. This scaffold has good biocompatibility and osteoinductive ability as a result of the characteristics of nHA, so could be innovatively applied to periodontal tissue engineering as a potential scaffold.
Inflammatory gene induction, apoptosis and necroptosis are major cellular responses of the cells exposed to tumor necrosis factor (TNF)‐α. Here we systematically investigated inter‐relationships among the key signaling molecules that control these cellular processes to uncover the molecular mechanism underlying the inter‐competetion and conversion among TNF‐α induced signaling complexes that elicit multiple alternative outcomes of TNF‐α in a murine system. By taking advantage of quantitative mass spectrometry, we found that the amount of Receptor interacting protein 1 (Rip1) and Tradd recruited to the TNF receptor 1 (TNFR1) complex is the initial determinant factor that governs the cell's decision to undergo cell death or not. Rip1 in complex I downstream of TNFR1 engagement not only initiates the signaling for inflammatory gene expression but also inhibits Tradd‐dependent recruitment of Fadd and caspase‐8 that can lead to rapid apoptosis. When there is no Rip3 or Mlkl in cells, elimination of the ubiquitination of Rip1 leads to formation of complex II, which triggers slower apoptosis than occurs in the absence of Rip1. Complex II can be converted to the necrosome when there are sufficient Rip3 and Mlkl. Both caspase‐8 and Flip can function in the necrosome to suppress necroptosis. Recruitment of Rsk1 to the necrosome is another layer of security to process necroptosis because Rsk1 inactivates caspase‐8 by phosphorylation. Thus, Rip1 is the central controller for cells to have induction of inflammatory genes and/or cell death; the interplay among Rip3, caspase‐8, Flip and Rsk1 determines whether the cells undergo apoptosis or necroptosis.Support or Funding InformationThis work was supported by the National Basic Research Program of China (973 Program; 2015CB553800), the National Scientific and Technological Major Project (2013ZX10002‐002), the National Natural Science Foundation of China (91429301, 31420103910, 31330047 and 31221065), the Hi‐Tech Research and Development Program of China (863 program; 2012AA02A201), the 111 Project (B12001), the Science and Technology Foundation of Xiamen (No. 3502Z20130027), the National Science Foundation of China for Fostering Talents in Basic Research (Grant No.J1310027) and the Open Research Fund of State Key Laboratory of Cellular Stress Biology, Xiamen University.
We evaluated the efficiency of transfecting adenoviral vectors encoding enhanced green fluorescent protein (AdCMV-EGFP) into rat submandibular gland cells and the effects of gene transfer on cell proliferation and secretory function. Isolated submandibular gland cells were transfected with different titers (or multiplicity of infection, MOI) of AdCMV-EGFP. The transfection efficiency was evaluated by quantifying EGFP-positive cells by inverted fluorescence microscopy, cell proliferation by MTT assay, and cell secretory activity by measuring α-amylase in culture medium. A transfection efficiency of up to 70.8% was achieved in submandibular gland cells. MTT assay showed that increased viral titers resulted in significant inhibition of cell proliferation, which occurs on day 5 post-transfection. Simultaneously, the amylase levels started to reduce with a significant decrease on day 7 after transfection. The results show that AdCMV-EGFP transfection of submandibular gland cells at higher MOI results in cytotoxicity, decreased cell proliferation, and secretory function. However, the lower adenoviral titers (e.g., 200 particles/cell) could be an efficient and safe labeling tool for gene transfer to submandibular gland cells.
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