655

BMP7

OBJECTIVE: To examine the relationship between effect of vascular endothelial growth factor (VEGF) on epithelial-myofibroblast transition (EMT) of HK-2 cells and changes in expressions of bone morphogenetic protein-7 (BMP-7) and inhibitor of DNA binding/differentiation (Id) 2, Id3. METHODS: The cultured HK-2 cells were co-treated with transforming growth factor-beta1 (TGF-beta1) (5 ng/ml) and VEGF165 (0.1, 1, 10, 100 ng/ml), or with TGF-beta1 (5 ng/ml) and VEGF receptor-1 neutralized antibody (10 microg/ ml), and were also co-treated with TGF-beta1 (5 ng/ml) and VEGF165 (100 ng/ml) with or without activin receptor-like kinase 6 (Alk6)/Fc Chimera (2 microg/ml, to neutralize endogenous BMP-7) for 48 hours. mRNA and protein expressions of alpha-smooth muscle actin (alpha-SMA), E-cadherin, BMP-7, Id2 and Id3 of HK-2 cells were assessed with double-stain immunocytochemistry, real-time PCR and Western blot respectively. RESULTS: Compared with normal controls, alpha-SMA expression significantly increased, while E-cadherin, BMP-7, Id2, and Id3 mRNA and protein expressions markedly decreased in HK-2 cells treated with TGF-beta1 (5 ng/ml) (P < 0.05). VEGF165 interrupted TGF-beta1 induced alpha-SMA expression in a dose-dependent manner and upregulated BMP-7, Id2 mRNA and protein expressions of the cells (P < 0.05). alpha-SMA expression increased, while E-cadherin, BMP-7, and Id2 expressions decreased further in HK-2 cells co-treated with TGF-beta1 and VEGFR1 antibody compared with normal controls (P < 0.05). When endogenous BMP-7 was neutralized with Alk6/Fc Chimera in the cells co-treated with TGF-beta1 and VEGF165, alpha-SMA expression upregulated (P < 0.05), while Id2 was not changed. CONCLUSIONS: VEGF165 may partially inhibit TGF-beta1-induced EMT of HK-2 cells in vitro. This effect is related to the upregulated expressions of BMP-7 and Id2. Id2 may be upregulated directly by VEGF165, but not related to BMP-7.

Ingestion of aristolochic acid (AA) is associated with the development of aristolochic acid nephropathy (AAN), which is characterized by progressive tubulointerstitial fibrosis, chronic renal failure and urothelial cancer. Our previous study showed that bone morphogenetic protein-7 (BMP-7) could attenuate AA-induced epithelial-to-mesenchymal transition (EMT) in human proximal tubule epithelial cells (PTEC). However, how gremlin (a BMP-7 antagonist) antagonizes the BMP-7 action in PTEC remained unsolved. The aim of the current study was to investigate the role of gremlin in AA-induced EMT in PTEC (HK-2 cells). HK-2 cells were treated with AA (10 mumol/L) for periods up to 72 h. Cell viability was determined by tetrazolium dye (MTT) assay. Morphological changes were assessed by phase-contrast microscopy. Markers of EMT, including E-cadherin and alpha-smooth muscle actin (alpha-SMA) were detected by indirect immunofluorescence stains. The BMP-7 and gremlin mRNA and protein expression in HK-2 cells were analyzed by quantitative real-time PCR (real-time RT-PCR) and western blotting after exposure to AA. The level of phosphorylated Smad1/5/8, a marker of BMP-7 activity, was also determined by western blot analysis. Cells were transfected with gremlin siRNA to determine the effects of gremlin knockdown on markers of EMT following treatment with AA. Our results indicated that AA-induced EMT was associated with acquisition of fibroblast-like cell shape, loss of E-cadherin, and increases of alpha-SMA and collagen type I. Interestingly, exposure of HK-2 cells to 10 mumol/L AA increased the mRNA and protein expression of gremlin in HK-2 cells. This increase was in parallel with a decrease in BMP-7 expression and a down-regulation of phosphorylated Smad1/5/8 protein levels. Moreover, transfection with siRNA to gremlin was able to recover BMP-7 signaling activity, and attenuate EMT-associated phenotypic changes induced by AA. Together, these observations strongly suggest that gremlin plays a critical role in the modulation of reno-protective action of BMP, and that inhibition of gremlin will be a promising means of developmenting novel treatments for AAN.CI - Copyright (c) 2012 Elsevier Ireland Ltd. All rights reserved.

OBJECTIVE: To examine the transfection of Homeobox A13 (HOXA13) on epithelial-mesenchymal transition (EMT) and the expression of bone morphogenetic protein-7 (BMP-7) induced by albumin-overload in human kidney tubular epithelial cells (HKCs). METHODS: The cultured HKCs were treated with 20 mg/mL human serum albumin (HSA) for 48 hours. Protein expression of cytokeratin (CK), vimentin and HOXA13 in the HKCs was assessed by Western blot. Protein expression of CK, vimentin, and BMP-7 was also detected in HKCs transfected with lipofectamine contained HOXA13 DNA. RESULTS: HSA induced EMT in HKCs, presented by decreased CK expression (P<0.01) and increased vimentin expression (P<0.01). The up-regulated expression of HOXA13 transfected by lipofectamine inhibited the level of EMT induced by HSA in HKCs (P<0.05). The decreased rate of BMP-7 protein expression induced by HSA was inhibited by over-expressed HOXA13 in HKCs (P<0.05). CONCLUSIONS: Transfection of HOXA13 in HKCs could inhibit the degree of EMT induced by albumin-overload, possibly by increasing BMP-7 expression.

In the cornea, healing of the wounded avascular surface is an intricate process comprising the involvement of epithelial, stromal and neuronal cell interactions. These interactions result to the release of various growth factors that play prominent roles during corneal wound healing response. Bone morphogenetic proteins (BMPs) are unique multi-functional potent growth factors of the transforming growth factor-beta (TGF-β) superfamily. Treatment of corneal epithelial cells with substance P and nerve growth factor resulted to an increase in the expression of BMP7 mRNA. Since BMP7 is known to modulate the process of corneal wound healing, in this present study, we investigated the influence of exogenous rhBMP7 on human corneal epithelial cell and stromal cell (SFs) function. To obtain a high-fidelity expression profiling of activated biomarkers and pathways, transcriptome-wide gene-level expression profiling of epithelial cells in the presence of BMP7 was performed. Gene ontology analysis shows BMP7 stimulation activated TGF-β signaling and cell cycle pathways, whereas biological processes related to cell cycle, microtubule and intermediate filament cytoskeleton organization were significantly impacted in corneal epithelial cells. Scratch wound healing assay showed increased motility and migration of BMP7 treated epithelial cells. BMP7 stimulation studies show activation of MAPK cascade proteins in epithelial cells and SFs. Similarly, a difference in the expression of claudin, Zink finger E-box-binding homeobox 1 was observed along with phosphorylation levels of cofilin in epithelial cells. Stimulation of SFs with BMP7 activated them with increased expression of α-smooth muscle actin. In addition, an elevated phosphorylation of epidermal growth factor receptor following BMP7 stimulation was also observed both in corneal epithelial cells and SFs. Based on our transcriptome analysis data on epithelial cells and the results obtained in SFs, we conclude that BMP7 contributes to epithelial-to-mesenchymal transition-like responses and plays a role equivalent to TGF-β in the course of corneal wound healing.

BACKGROUND/AIMS: Since renal fibrosis always predisposes end-stage renal disease, elucidation of the molecular mechanisms that underlie the progression of renal fibrosis may substantially improve the understanding and treatment for renal failure. Previous studies have highlighted an important counteraction between transforming growth factor beta 1 (TGFbeta1) and bone morphogenic protein 7 (BMP7) in the epithelial-to-mesenchymal transition (EMT) of renal tubular epithelial cells during chronic renal injury. Macrophages are also believed to play a critical role in renal fibrosis. However, the relationship between macrophages and EMT is unknown. METHODS: Here, we used a mouse unilateral ureteral obstruction (UUO) model to address to these questions, and analyzed macrophage and its subpopulations purified by flow cytometry. RESULTS: We found that the recruited macrophages are polarized to a M2 subtype after renal injury. M2 macrophages released high levels TGFbeta1 to suppress BMP7 to enhance EMT-induced renal fibrosis. Depletion of M2 macrophages, but not of M1 macrophages, specifically inhibited EMT, and subsequently the renal fibrosis. Adoptive transplantation of M2 macrophages deteriorated renal fibrosis. CONCLUSION: Thus, our study highlights M2 macrophages as a critical target for treating renal fibrosis.CI - (c) 2015 S. Karger AG, Basel.

This study was designed to show whether rat liver epithelial cells could undergo epithelial-mesenchymal transition (EMT), thereby directly contributing to liver fibrosis. The role of the ratio of transforming growth factor-beta1 (TGF-beta1)/bone morphogenetic protein-7 (BMP-7) was evaluated in the progression of EMT or mesenchymal-epithelial transition. Primary rat liver epithelial cells were stimulated with different ratios of TGF-beta1/BMP-7 and examined for evidence of transition to a mesenchymal or epithelial phenotype. Liver sections were labeled to detect antigens associated with liver epithelial cells [E-cadherin (E-cad)], EMT [fibroblast-specific protein-1 (FSP-1), vimentin], myofibroblasts [alpha-smooth muscle actin (alpha-SMA)], and intracellular signal-transduction mediated by forming liver fibrosis undergo EMT, resulting in the formation of invasive fibroblasts; this process may be driven or impeded by a response to local TGF-beta1 or BMP-7. BMP-7 downregulated alpha-SMA and phosphorylated Smad2/3. Stimulation of cultured cells with TGF-beta1 induced the expression of pSmad2/3, FSP-1, and alpha-SMA. Stimulation of cultured cells with BMP-7 induced the expression of E-cad. We demonstrated that the cells upregulated E-cad release compared with untreated cells, but TGF-beta1 was different. We found that the equilibrium of the ratio of TGF-beta1/BMP-7 was 1/10. In summary, the mechanism for this process was not determined. Demonstration of the contribution of what the ratio of TGF-beta1/BMP-7 induced to EMT to the chronic liver diseases would provide a new basis for understanding pathogenesis and potential treatment.

This study presented the effect of bone morphogenic protein-7 (BMP-7) inhibiting epithelial-mesenchymal transition (EMT) in silicosis model. In vivo, Wistar rats were exposed to silica by intratracheal instillation. Seven days later rats were treated with BMP-7. Rats were sacrificed at 15 and 30days after exposure of silica. The results demonstrated vimentin expression was down-regulated; and E-cadherin was up-regulated after intervention with BMP-7. The TGF-beta expression and phosphorylation-p38 were lower in BMP-7 treated group than in silica group. In vitro, p38 MAPK/Snail signaling pathway was involved in the occurrence of EMT in A549 cells treated by silica. EMT was inhibited by BMP-7. The data showed BMP-7 inhibited EMT induced by silica associated with inhibition of p38 MAPK/Snail pathway.CI - Copyright (c) 2015 Elsevier Inc. All rights reserved.