ORCID Profile
0000-0003-4039-5759
Current Organisations
Monash University
,
Guangdong Medical College - Dongguan Campus
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Publisher: American Diabetes Association
Date: 21-01-2011
DOI: 10.2337/DB10-0403
Abstract: Although Smad3 has been considered as a downstream mediator of transforming growth factor-β (TGF-β) signaling in diabetes complications, the role of Smad7 in diabetes remains largely unclear. The current study tests the hypothesis that Smad7 may play a protective role and has therapeutic potential for diabetic kidney disease. Protective role of Smad7 in diabetic kidney disease was examined in streptozotocin-induced diabetic mice that have Smad7 gene knockout (KO) and in diabetic rats given Smad7 gene transfer using an ultrasound-microbubble-mediated technique. We found that mice deficient for Smad7 developed more severe diabetic kidney injury than wild-type mice as evidenced by a significant increase in microalbuminuria, renal fibrosis (collagen I, IV, and fibronectin), and renal inflammation (interleukin-1β [IL-1β], tumor necrosis factor-α [TNF-α], monocyte chemoattractant protein-1 [MCP-1], intracellular adhesion molecule-1 [ICAM-1], and macrophages). Further studies revealed that enhanced renal fibrosis and inflammation in Smad7 KO mice with diabetes were associated with increased activation of both TGF-β/Smad2/3 and nuclear factor-κB (NF-κB) signaling pathways. To develop a therapeutic potential for diabetic kidney disease, Smad7 gene was transferred into the kidney in diabetic rats by an ultrasound-microbubble-mediated technique. Although overexpression of renal Smad7 had no effect on levels of blood glucose, it significantly attenuated the development of microalbuminuria, TGF-β/Smad3-mediated renal fibrosis such as collagen I and IV and fibronectin accumulation and NF-κB 65-driven renal inflammation including IL-1β, TNF-α, MCP-1, and ICAM-1 expression and macrophage infiltration in diabetic rats. Smad7 plays a protective role in diabetic renal injury. Overexpression of Smad7 may represent a novel therapy for the diabetic kidney complication.
Publisher: Public Library of Science (PLoS)
Date: 09-08-2016
Publisher: Oxford University Press (OUP)
Date: 14-12-2006
DOI: 10.1634/STEMCELLS.2006-0133
Abstract: Recent evidence suggests that bone marrow (BM)-derived cells may integrate into the kidney, giving rise to functional renal cell types, including endothelial and epithelial cells and myofibroblasts. BM-derived cells can contribute to repair of the renal peritubular capillary (PTC) network following acute ischemic injury. However, the cell fate and regulation of BM-derived cells during the progression of chronic renal disease remains unclear. Using chimeric mice transplanted with enhanced green fluorescent protein (EGFP)-expressing BM, we demonstrate that the number of BM-derived myofibroblasts coincided with the development of fibrosis in a mouse adriamycin (ADR)-induced nephrosis model of chronic, progressive renal fibrosis. Four weeks after ADR injection, increased numbers of BM-derived myofibroblasts were observed in the interstitium of ADR-injected mice. Six weeks after ADR injection, more than 30% of renal α-smooth muscle actin (+) (α-SMA+) interstitial myofibroblasts were derived from the BM. In addition, BM-derived cells were observed to express the endothelial cell marker CD31 and the myofibroblast marker α-SMA. Blockade of p38 mitogen-activated protein kinase (MAPK) and transforming growth factor (TGF)-β1/Smad2 signaling was found to protect BM-derived PTC endothelial cells and inhibit the number of BM-derived von Willebrand factor (vWF)(+)/EGFP(+)/α-SMA(+) cells, EGFP(+)/α-SMA(+) cells, and total α-SMA(+) cells in ADR-injected mice. Inhibition of the p38 MAPK and TGF-β1/Smad signaling pathways enhanced PTC repair by decreasing endothelial-myofibroblast transformation, leading to structural and functional renal recovery and the attenuation of renal interstitial fibrosis. Investigation of the signaling pathways that regulate the differentiation and survival of BM-derived cells in a progressive disease setting is vital for the successful development of cell-based therapies for renal repair.
Publisher: Frontiers Media SA
Date: 04-07-2014
Publisher: Oxford University Press (OUP)
Date: 14-02-2018
DOI: 10.1002/STEM.2794
Abstract: The canonical Wnt/β-catenin pathway is crucial for early embryonic patterning, tissue homeostasis, and regeneration. While canonical Wnt/β-catenin stimulation has been used extensively to modulate pluripotency and differentiation of pluripotent stem cells (PSCs), the mechanism of these two seemingly opposing roles has not been fully characterized and is currently largely attributed to activation of nuclear Wnt target genes. Here, we show that low levels of Wnt stimulation via ectopic expression of Wnt1 or administration of glycogen synthase kinase-3 inhibitor CHIR99021 significantly increases PSC differentiation into neurons, cardiomyocytes and early endodermal intermediates. Our data indicate that enhanced differentiation outcomes are not mediated through activation of traditional Wnt target genes but by β-catenin's secondary role as a binding partner of membrane bound cadherins ultimately leading to the activation of developmental genes. In summary, fine-tuning of Wnt signaling to subthreshold levels for detectable nuclear β-catenin function appears to act as a switch to enhance differentiation of PSCs into multiple lineages. Our observations highlight a mechanism by which Wnt/β-catenin signaling can achieve dosage dependent dual roles in regulating self-renewal and differentiation.
Publisher: American Physiological Society
Date: 04-2016
DOI: 10.1152/AJPRENAL.00497.2015
Abstract: Podocyte depletion plays a major role in the development and progression of glomerulosclerosis. Many kidney diseases are more common in older age and often coexist with hypertension. We hypothesized that podocyte depletion develops in association with older age and is exacerbated by hypertension. Kidneys from 19 adult Caucasian American males without overt renal disease were collected at autopsy in Mississippi. Demographic data were obtained from medical and autopsy records. Subjects were categorized by age and hypertension as potential independent and additive contributors to podocyte depletion. Design-based stereology was used to estimate in idual glomerular volume and total podocyte number per glomerulus, which allowed the calculation of podocyte density (number per volume). Podocyte depletion was defined as a reduction in podocyte number (absolute depletion) or podocyte density (relative depletion). The cortical location of glomeruli (outer or inner cortex) and presence of parietal podocytes were also recorded. Older age was an independent contributor to both absolute and relative podocyte depletion, featuring glomerular hypertrophy, podocyte loss, and thus reduced podocyte density. Hypertension was an independent contributor to relative podocyte depletion by exacerbating glomerular hypertrophy, mostly in glomeruli from the inner cortex. However, hypertension was not associated with podocyte loss. Absolute and relative podocyte depletion were exacerbated by the combination of older age and hypertension. The proportion of glomeruli with parietal podocytes increased with age but not with hypertension alone. These findings demonstrate that older age and hypertension are independent and additive contributors to podocyte depletion in white American men without kidney disease.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2015
Publisher: Public Library of Science (PLoS)
Date: 31-12-2013
Publisher: Wiley
Date: 10-02-2012
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2005
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2009
Publisher: Springer Science and Business Media LLC
Date: 04-11-2015
Publisher: Wiley
Date: 09-03-2012
Publisher: Elsevier BV
Date: 08-2015
DOI: 10.1038/KI.2015.121
Abstract: Signaling by TGF-β/Smad3 plays a key role in renal fibrosis. As obesity is one of the major risk factors of chronic and end-stage renal disease, we studied the role of Smad3 signaling in the pathogenesis of obesity-related renal disease. After switching to a high fat diet, the onset of Smad3 C-terminal phosphorylation, increase in albuminuria, and the early stages of peripheral and renal insulin resistance occurred at 1 day, and 4 and 8 weeks, respectively, in C57BL/6 mice. The loss of synaptopodin, a functional marker of podocytes, and phosphorylation of the Smad3 linker region (T179 and S213) appeared after 4 weeks of the high fat diet. This suggests a temporal pattern of Smad3 signaling activation leading to kidney injury and subsequent insulin resistance in the development of obesity-related renal disease. In vivo, Smad3 knockout attenuated the high fat diet-induced proteinuria, renal fibrosis, overall podocyte injury, and mitochondrial dysfunction in podocytes. In vitro palmitate caused a rapid activation of Smad3 in 30 min, loss of synaptopodin in 2 days, and impaired insulin signaling in 3 days in isolated mouse podocytes. Blockade of either Smad3 phosphorylation by SIS3 (a Smad3 inhibitor) or T179 phosphorylation by flavopiridol (a CDK9 inhibitor) prevented the palmitate-induced loss of synaptopodin and mitochondrial function in podocytes. Thus, Smad3 signaling plays essential roles in obesity-related renal disease and may be a novel therapeutic target.
Publisher: Wiley
Date: 06-11-2012
DOI: 10.1002/PATH.4050
Abstract: Resolvin E1 (RvE1) is a naturally occurring lipid-derived mediator generated during the resolution of inflammation. The anti-inflammatory effects of RvE1 have been demonstrated in a variety of disease settings however, it is not known whether RvE1 may also exert direct anti-fibrotic effects. We examined the potential anti-fibrotic actions of RvE1 in the mouse obstructed kidney-a model in which tissue fibrosis is driven by unilateral ureteric obstruction (UUO), an irreversible, non-immune insult. Administration of RvE1 (300 ng/day) to mice significantly reduced accumulation of α-smooth muscle actin (SMA)(+) myofibroblasts and the deposition of collagen IV on day 6 after UUO. This protective effect was associated with a marked reduction of myofibroblast proliferation on days 2, 4 and 6 after UUO. RvE1 treatment also inhibited production of the major fibroblast mitogen, platelet-derived growth factor-BB (PDGF-BB), in the obstructed kidney. Acute resolvin treatment over days 2-4 after UUO also had a profound inhibitory effect upon myofibroblast proliferation without affecting the PDGF expression, suggesting a direct effect upon fibroblast proliferation. In vitro studies established that RvE1 can directly inhibit PDGF-BB-induced proliferation in primary mouse fibroblasts. RvE1 induced transient, but not sustained, activation of the pro-proliferative ERK and AKT signalling pathways. Of note, RvE1 inhibited the sustained activation of ERK and AKT pathways seen in response to PDGF stimulation, thereby preventing up-regulation of molecules required for progression through the cell cycle (c-Myc, cyclin D) and down-regulation of inhibitors of cell cycle progression (p21, cip1). Finally, siRNA-based knock-down studies showed that the RvE1 receptor, ChemR23, is required for the anti-proliferative actions of RvE1 in cultured fibroblasts. In conclusion, this study demonstrates that RvE1 can inhibit fibroblast proliferation in vivo and in vitro, identifying RvE1 as a novel anti-fibrotic therapy.
Publisher: Elsevier BV
Date: 11-2016
Publisher: Wiley
Date: 23-07-2010
DOI: 10.1111/J.1440-1797.2010.01319.X
Abstract: Diabetic nephropathy (DN) is the most common cause of chronic kidney failure and end-stage renal disease in the Western world. Studies from diabetic animal models and clinical trials have shown that inhibition of the renin-angiotensin system delays the progression of advanced DN. However, a recent large-scale clinical trial has revealed that inhibition of renin-angiotensin system in early phases of DN does not slow the decline of renal function or the development of morphological lesions, suggesting that different mechanism(s) may be involved in the different stages of DN. The role of epithelial-mesenchymal transition in renal fibrosis has been intensively investigated. Recently, endothelial-mesenchymal transition, or endothelial-myofibroblast transition (EndoMT) has emerged as another mechanism involved in both developmental and pathological processes. The essential role of EndoMT in cardiac development has been thoroughly studied. EndoMT also exists and contributes to the development and progression of cardiac fibrosis, lung fibrosis, liver fibrosis and corneal fibrosis. EndoMT is a specific form of epithelial-mesenchymal transition. During EndoMT, endothelial cells lose endothelial markers and obtain mesenchymal markers. Recent evidence from our laboratory and others suggests that EndoMT plays an important role in the development of renal fibrosis in several pathological settings, including experimental DN. This review considers the evidence supporting the occurrence of EndoMT in normal development and in pathology, as well as the latest findings suggesting EndoMT contributes to fibrosis in DN. Whether experimental findings of EndoMT will be reproduced in human studies remains to be determined.
Publisher: SAGE Publications
Date: 03-2017
Abstract: Spinal cord injury (SCI) causes functional impairment as a result of the initial injury followed by secondary injury mechanism. SCI provokes an inflammatory response that causes secondary tissue damage and neurodegeneration. While the use of neural stem cell (NSC) engraftment to mitigate secondary injury has been of interest to many researchers, it still faces several limitations. As such, we investigated if NSC-conditioned medium (NSC-M) possesses therapeutic potential for the treatment of SCI. It has been proposed that many of the beneficial effects attributed to stem cell therapies are due to secreted factors. Utilizing primary cell culture and murine models of SCI, we determined that systemic treatment with NSC-M was able to significantly improve motor function and lesion healing. In addition, NSC-M demonstrated significant anti-inflammatory potential in vitro and in vivo, reducing inflammatory cytokine expression in both activated macrophages and injured spinal cord tissues. NSC-M was also able to reduce the expression of inducible nitric oxide synthase (iNOS) within the spleen of injured animals, indicating an ability to reduce systemic inflammation. Thus, we believe that NSC-M offers a possible alternative to direct stem cell engraftment for the treatment of SCI.
Publisher: Public Library of Science (PLoS)
Date: 24-01-2013
Publisher: Elsevier BV
Date: 09-2006
Publisher: Mary Ann Liebert Inc
Date: 07-2014
Abstract: The trophoblast (TR) is the first to differentiate during mammalian embryogenesis and play a pivotal role in the development of the placenta. We used a dual inhibitor system (PD0325901 and CHIR99021) with mixed feeders to successfully obtain bovine trophoblast stem-like (bTS) cells, which were similar in phenotype to mouse trophoblast stem cells (TSCs). The bTS cells that were generated using this system continually proliferated, displayed a normal diploid karyotype, and had no signs of altered morphology or differentiation even after 150 passages. These cells exhibited alkaline phosphatase (AP) activity and expressed pluripotency markers, such as OCT4, NANOG, SOX2, SSEA-1, SSEA-4, TRA-1-60, and TRA-1-81, and TR lineage markers such as CDX2, as determined by both immunofluorescence and reverse transcription-polymerase chain reaction (RT-PCR). Additionally, these cells generated dome-like structures, formed teratomas when injected into NOD-SCID mice, and differentiated into placenta TR cells in vitro. The microarray analysis of bTS cells showed high expression levels of many TR markers, such as TEAD4, EOMES, GATA3, ETS2, TFAP2A, ELF5, SMARCA4 (BRG1), CDH3, MASH2, HSD17B1, CYP11A1, PPARG, ID2, GCM1, HAND1, TDK, PAG, IFN-τ, and THAP11. The expression of many pluripotency markers, such as OCT4, SOX2, NANOG, and GDF3, was lower in bTS cells compared with in vitro-produced blastocysts however, compared with bovine fetal fibroblasts, the expression of these pluripotency markers was elevated in bTS cells. The DNA methylation status of the promoter regions of OCT4, NANOG, and SOX2 was investigated, which were significantly higher in bTS cells (OCT4 23.90%, NANOG 74.40%, and SOX2 8.50%) compared with blastocysts (OCT4 8.90%, NANOG 34.4%, and SOX2 3.80%). In contrast, two promoter regions of CDX2 were hypomethylated in bTS cells (13.80% and 3.90%) compared with blastocysts (18.80% and 9.10%). The TSC lines that were established in this study may be used either for basic research that is focused on peri-implantation and placenta development or as donor cells for transgenic animal production.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2006
Publisher: Wiley
Date: 26-06-2020
DOI: 10.1002/AR.24413
Publisher: EMBO
Date: 09-01-2020
Publisher: Wiley
Date: 19-09-2005
DOI: 10.1111/J.1471-4159.2005.03439.X
Abstract: Telomerase is a ribonucleoprotein complex that maintains chromosomal telomere homeostasis and underlies continuous renewal of stem cells and immortalization of neoplastic cells. Telomerase is down-regulated during cell differentiation, but the mechanisms of down-regulation are largely unknown. Here, we examined roles of mitogen-activated protein (MAP) kinase and phosphatidylinositol-3 (PI3) kinase signalling pathways in telomerase down-regulation triggered by nerve growth factor (NGF), and the role of telomerase down-regulation in NGF-induced neural differentiation in PC12 cells. We report that NGF-induced telomerase down-regulation requires MAP kinase signalling. While mutations of all putative Akt phosphorylation sites in telomerase reverse transcriptase (TERT) has no effect on telomerase activity, inhibition of MAP kinase signalling by PD98059 or U0126 abolishes NGF-induced telomerase down-regulation in a concentration-dependent manner. Reversal of NGF-induced telomerase down-regulation by TERT overexpression does not prevent NGF-induced neural differentiation. Down-regulation of telomerase by silencing TERT gene expression does not trigger cell differentiation in the absence of NGF, nor enhances NGF-induced differentiation. Thus, telomerase, withdraws by a mechanism at TERT gene transcription level involving MAP kinase signalling while cells cease proliferation and undergo differentiation. The withdrawal of telomerase is not required to mediate NGF-induced PC12 cell differentiation and re-establishment of telomerase activity at significant levels does not inhibit differentiation.
Publisher: Public Library of Science (PLoS)
Date: 18-04-2011
Publisher: Springer Science and Business Media LLC
Date: 04-09-2015
DOI: 10.1007/S00467-015-3195-2
Abstract: Oxidative stress has been reported to play an important role in children with primary nephrotic syndrome (PNS). However, the results of previous studies are controversial. Forty children with steroid-sensitive nephrotic syndrome (SSNS) and 20 age- and sex-matched healthy controls were enrolled. Patients were followed-up for 12-18 months and ided into three subgroups: frequent relapse (n = 10), non-frequent relapse (n = 12), and non-relapse (n = 18). The plasma levels of advanced oxidation protein products (AOPP), malondialdehyde (MDA), and superoxide dismutase (SOD) were tested in controls and patient group at first presentation and after 4 weeks of steroid treatment. Patients had higher AOPP and MDA levels but lower SOD compared with controls. AOPP levels were significantly higher in the frequent relapse subgroup compared with the non-frequent relapse and non-relapse subgroups, respectively. No significant differences were found in the plasma levels of MDA and SOD among the three subgroups. AOPP >87.55 μmol/l before steroid treatment and AOPP >78.5 μmol/l after 4-week steroid treatment were positively correlated with the relapse frequency in patients with SSNS. Children with SSNS have oxidative stress. The plasma levels of AOPP before and after 4-week steroid treatment may predict whether patients with SSNS will relapse frequently.
Publisher: Springer Science and Business Media LLC
Date: 06-05-2016
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 14-03-2016
Abstract: Podocyte depletion is sufficient for the development of numerous glomerular diseases and can be absolute (loss of podocytes) or relative (reduced number of podocytes per volume of glomerulus). Commonly used methods to quantify podocyte depletion introduce bias, whereas gold standard stereologic methodologies are time consuming and impractical. We developed a novel approach for assessing podocyte depletion in whole glomeruli that combines immunofluorescence, optical clearing, confocal microscopy, and three-dimensional analysis. We validated this method in a transgenic mouse model of selective podocyte depletion, in which we determined dose-dependent alterations in several quantitative indices of podocyte depletion. This new approach provides a quantitative tool for the comprehensive and time-efficient analysis of podocyte depletion in whole glomeruli.
Publisher: Elsevier BV
Date: 09-2010
Publisher: Elsevier BV
Date: 04-2014
DOI: 10.1016/J.AJPATH.2013.12.003
Abstract: Transforming growth factor-β (TGF-β) promotes tissue fibrosis via receptor-mediated phosphorylation of the receptor-activated Smad2/3, together with Smad4. Of these, Smad3 plays a major profibrotic role in mouse models of tissue fibrosis. Transcriptional activity of the Smad3 protein is regulated by phosphorylation of residues in the C-terminal domain and the linker region. Herein, we examined the role of a novel phosphorylation site within the MH2 domain (T388) in the regulation of Smad3 activity. Confocal microscopy using an Smad3 phosphorylated T388-specific antibody identified phosphorylation of Smad3 T388 in myofibroblasts and tubular epithelial cells in human focal and segmental glomerulosclerosis and mouse models of unilateral ureteric obstruction and diabetic nephropathy, whereas phosphorylated T388 was largely absent in normal kidney. In vitro, TGF-β1 induced phosphorylation of Smad3 T388 in a biphasic pattern. A point mutation of T388/V in an Smad3 construct demonstrated that phosphorylation of T388 promotes Smad3 binding to Smad4 and CDK8, but was not necessary for nuclear translocation. Furthermore, T388 phosphorylation was required for TGF-β-induced collagen I gene promoter activity and extracellular matrix production in cultured fibroblasts. In conclusion, our study identifies phosphorylation of T388 in the Smad3 MH2 domain as an important mechanism that regulates the profibrotic TGF-β/Smad3 signaling pathway, which has direct relevance to human and experimental fibrotic kidney disease.
Publisher: Oxford University Press (OUP)
Date: 29-12-2009
DOI: 10.1093/NDT/GFP637
Abstract: We have identified that a novel developmental gene and protein, SCUBE1, is expressed in endothelial cells and may play an important role in kidney regeneration. The temporal and spatial expression of SCUBE1 was determined in a mouse model of ischaemia-reperfusion (IR) injury at 3 days and 1, 3 and 6 weeks post-injury by immunofluorescence microscopy. In vitro analysis was used to examine SCUBE1 signalling in endothelial cells under conditions of cell stress using quantitative real-time polymerase chain reaction and immunofluorescence labelling. The media from cultured endothelial cells following SCUBE1 small interfering RNA (siRNA) transfection was used to assess the proliferation capacity of epithelial cells. Immunofluorescence confocal microscopy demonstrated that the SCUBE1 protein was localized to CD31-positive endothelial cells in IR kidneys during the resolution of tissue damage (3 weeks), but not in control animals. The peak expression of SCUBE1 following 3 weeks of IR injury was confirmed by reverse transcription-polymerase chain reaction. SCUBE1 mRNA and protein expression were detected in cultured endothelial cells under hypoxic conditions or serum starving. Furthermore, there was a significant decrease in epithelial cell proliferation following the addition of a supernatant derived from cultured endothelial cells following SCUBE1 siRNA gene silencing compared to control media. Our results indicate that SCUBE1 may be involved in the regulation of tubular cell proliferation and re-epithelialization during the resolution of kidney injury.
Publisher: Springer Science and Business Media LLC
Date: 14-10-2015
Publisher: Elsevier BV
Date: 2014
DOI: 10.1016/J.AANAT.2013.04.007
Abstract: The podocyte depletion hypothesis has emerged as a unifying concept in glomerular pathology. According to this hypothesis podocyte depletion may be absolute (decrease in number of healthy mature podocytes), relative (fewer podocytes per unit of glomerular volume) or involve alterations to the specialized podocyte architecture (such as foot process effacement). To study and understand podocyte depletion it is important to be able to accurately and precisely count these cells. Here we present new design-based stereological methods for estimating podocyte number in in idual glomeruli of known volume, and in average glomeruli. Both methods involve serial histological sectioning, triple label immunohistochemistry, laser confocal microscopy and cell counting with the optical disector/fractionator.
Publisher: Public Library of Science (PLoS)
Date: 28-06-2013
Publisher: American Diabetes Association
Date: 03-08-2010
DOI: 10.2337/DB09-1631
Abstract: A multicenter, controlled trial showed that early blockade of the renin-angiotensin system in patients with type 1 diabetes and normoalbuminuria did not retard the progression of nephropathy, suggesting that other mechanism(s) are involved in the pathogenesis of early diabetic nephropathy (diabetic nephropathy). We have previously demonstrated that endothelial-mesenchymal-transition (EndoMT) contributes to the early development of renal interstitial fibrosis independently of microalbuminuria in mice with streptozotocin (STZ)-induced diabetes. In the present study, we hypothesized that blocking EndoMT reduces the early development of diabetic nephropathy. EndoMT was induced in a mouse pancreatic microvascular endothelial cell line (MMEC) in the presence of advanced glycation end products (AGEs) and in the endothelial lineage–traceble mouse line Tie2-Cre Loxp-EGFP by administration of AGEs, with nonglycated mouse albumin serving as a control. Phosphorylated Smad3 was detected by immunoprecipitation/Western blotting and confocal microscopy. Blocking studies using receptor for AGE siRNA and a specific inhibitor of Smad3 (SIS3) were performed in MMECs and in STZ-induced diabetic nephropathy in Tie2-Cre Loxp-EGFP mice. Confocal microscopy and real-time PCR demonstrated that AGEs induced EndoMT in MMECs and in Tie2-Cre Loxp-EGFP mice. Immunoprecipitation/Western blotting showed that Smad3 was activated by AGEs but was inhibited by SIS3 in MMECs and in STZ-induced diabetic nephropathy. Confocal microscopy and real-time PCR further demonstrated that SIS3 abrogated EndoMT, reduced renal fibrosis, and retarded progression of nephropathy. EndoMT is a novel pathway leading to early development of diabetic nephropathy. Blockade of EndoMT by SIS3 may provide a new strategy to retard the progression of diabetic nephropathy and other diabetes complications.
Publisher: American Society for Microbiology
Date: 09-2013
DOI: 10.1128/AAC.02587-12
Abstract: The nephrotoxicity of polymyxins is a major dose-limiting factor for treatment of infections caused by multidrug-resistant Gram-negative pathogens. The mechanism(s) of polymyxin-induced nephrotoxicity is not clear. This study aimed to investigate polymyxin B-induced apoptosis in kidney proximal tubular cells. Polymyxin B-induced apoptosis in NRK-52E cells was examined by caspase activation, DNA breakage, and translocation of membrane phosphatidylserine using Red-VAD-FMK [Val-Ala-Asp(O-Me) fluoromethyl ketone] staining, a terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) assay, and double staining with annexin V-propidium iodide (PI). The concentration dependence (50% effective concentration [EC 50 ]) and time course for polymyxin B-induced apoptosis were measured in NRK-52E and HK-2 cells by fluorescence-activated cell sorting (FACS) with annexin V and PI. Polymyxin B-induced apoptosis in NRK-52E cells was confirmed by positive labeling from Red-VAD-FMK staining, TUNEL assay, and annexin V-PI double staining. The EC 50 (95% confidence interval [CI]) of polymyxin B for the NRK-52E cells was 1.05 (0.91 to 1.22) mM and was 0.35 (0.29 to 0.42) mM for HK-2 cells. At lower concentrations of polymyxin B, minimal apoptosis was observed, followed by a sharp rise in the apoptotic index at higher concentrations in both cell lines. After treatment of NRK-52E cells with 2.0 mM polymyxin B, the percentage of apoptotic cells (mean ± standard deviation [SD]) was 10.9% ± 4.69% at 6 h and reached plateau ( %) at 24 h, whereas treatment with 0.5 mM polymyxin B for 24 h led to 93.6% ± 5.57% of HK-2 cells in apoptosis. Understanding the mechanism of polymyxin B-induced apoptosis will provide important information for discovering less nephrotoxic polymyxin-like lipopeptides.
Publisher: Elsevier BV
Date: 11-2006
DOI: 10.2353/AJPATH.2006.060169
Abstract: Inflammation and fibrogenesis are the two determinants of the progression of renal fibrosis, the common pathway leading to end-stage renal disease. The p38 mitogen-activated protein kinase (MAPK) and transforming growth factor (TGF)-beta1/Smad signaling pathways play critical roles in inflammation and fibrogenesis, respectively. The present study examined the beneficial renoprotective effect of combination therapy using the p38 MAPK pathway inhibitor (SB203580) and a TGF-beta receptor I (ALK5) inhibitor (ALK5I) in a mouse model of adriamycin (ADR) nephrosis. The p38 MAPK and TGF-beta1/Smad2 signaling pathways were activated in ADR-induced nephropathy in a sequential time course manner. Two weeks after ADR injection, the combined administration of SB203580 (1 mg/kg/24 hours) and ALK5I (1 mg/kg/24 hours) markedly reduced p38 MAPK and Smad2 activities. Moreover, the co-administration of SB203580 and ALK5I to ADR-injected mice resulted in a down-regulation of total and active TGF-beta1 production, reduced myofibroblast accumulation, and decreased expression of collagen type IV and fibronectin. In these mice, retardation in the development of glomerulosclerosis and interstitial fibrosis was observed. In conclusion, although p38 MAPK and TGF-beta1/Smad signaling pathways are distinct they coordinate the progression of renal fibrosis in ADR nephrosis. The co-administration of a p38 MAPK inhibitor and an ALK5 inhibitor may have potential applications in the treatment of renal fibrosis.
Publisher: Elsevier BV
Date: 12-2015
DOI: 10.1038/KI.2015.235
Abstract: Transforming growth factor-β1 (TGF-β1)/Smad signaling has a central role in the pathogenesis of renal fibrosis. Smad3 and Smad4 are pro-fibrotic, while Smad2 is anti-fibrotic. However, these Smads form heterogeneous complexes, the functions of which are poorly understood. Here we studied Smad complex function in renal fibrosis using the mouse model of unilateral ureteric obstruction. Mice heterozygous for Smad3/4 (Smad3/4
No related grants have been discovered for Jinhua Li.