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Yohei Maeshima

Publications and source records attributed to Yohei Maeshima.

26 records · Page 2Linked to original sources
PubMed2003

Overexpression of angiotensin type 2 receptor ameliorates glomerular injury in a mouse remnant kidney model.

Angiotensin II mediates the progression of renal disease through the type 1 receptor (AT(1)R). Recent studies have suggested that type 2 receptor (AT(2)R)-mediated signaling inhibits cell proliferation by counteracting the actions of AT(1)R. The aim of the present study was to determine the effect of AT(2)R overexpression on glomerular injury induced by (5/6) nephrectomy ((5/6)Nx). AT(2)R transgenic mice (AT(2)-Tg), overexpressing AT(2)R under the control of alpha-smooth muscle actin (alpha-SMA) promoter, and control wild-type mice (Wild) were subjected to (5/6)Nx. In AT(2)-Tg mice, the glomerular expression of AT(2)R was upregulated after (5/6)Nx. Urinary albumin excretion at 12 wk after (5/6)Nx was decreased by 33.7% in AT(2)-Tg compared with Wild mice. Glomerular size in AT(2)-Tg mice was significantly smaller than in Wild mice after (5/6)Nx (93.1 +/- 3.0 vs. 103.3 +/- 1.8 microm; P < 0.05). Immunohistochemistry revealed significant decreases in glomerular expression of platelet-derived growth factor-BB chain (PDGF-BB) and transforming growth factor-beta(1) (TGF-beta(1)) in AT(2)-Tg with (5/6)Nx compared with Wild mice. Urinary excretion of nitric oxide metabolites was increased 2.5-fold in AT(2)-Tg compared with Wild mice. EMSA showed that activation of early growth response gene-1, which induces the transcription of PDGF-BB and TGF-beta(1), was decreased in AT(2)-Tg mice. These changes in AT(2)-Tg mice at 12 wk after (5/6)Nx were blocked by the AT(2)R antagonist PD-123319. Taken together, our findings suggest that AT(2)R-mediated signaling may protect from glomerular injuries induced by (5/6)Nx and that overexpression of AT(2)R may serve as a potential therapeutic strategy for glomerular disorders.

Actins↗
PubMed2003

Bone morphogenic protein-7 inhibits progression of chronic renal fibrosis associated with two genetic mouse models.

Tubulointerstitial fibrosis is a hallmark feature of chronic renal injury. Specific therapies to control the progression of renal fibrosis toward end-stage renal failure are limited. Previous studies have demonstrated that expression of endogenous bone morphogenic protein-7 (BMP-7) is reduced in the kidneys of several inducible mouse models of acute and chronic renal disease and that administration of exogenous recombinant human BMP-7 (rhBMP-7) has a beneficial effect on kidney function. Here we report that treatment with rhBMP-7 leads to improved renal function, histology, and survival in mice deficient in the alpha3-chain of type IV collagen and MRL/MpJlpr/lpr lupus mice, two genetic models for chronic renal injury and fibrosis. Such therapeutic benefit is also associated with a significant decrease in the expression of profibrotic molecules, such as type I collagen and fibronectin, in renal fibroblasts. Additionally, rhBMP-7 induces expression of active matrix metalloproteinase-2, which is potentially important for removal of fibrotic matrix. Collectively, these studies provide further evidence for rhBMP-7 as an important bone-associated protein with protective function against renal pathology.

Animals↗
PubMed2003

Glomerular cell apoptosis in human lupus nephritis.

Disturbed apoptosis is proposed to be involved in the pathogenesis of systemic lupus erythematosus. However, the role of renal cell apoptosis in the pathogenesis and progression of human lupus nephritis is still controversial. We have investigated glomerular cell apoptosis and the clinicopathological relationship between apoptosis and immunoserological or histological findings in 22 patients with lupus nephritis using electron microscopy and the TdT-mediated dUTP-biotin nick end labeling (TUNEL) method. Resident glomerular cells as well as infiltrating neutrophils undergoing apoptosis were observed in 12 of 20 patients with lupus nephritis using electron microscopy. TUNEL-positive cells were recognized in 93% of patients with diffuse proliferative lupus nephritis (class IV) in contrast to the 20% of patients with class V. The number of TUNEL-positive cells in glomeruli significantly correlated with the level of immunoserological activity of lupus, such as anti-double-stranded DNA autoantibody and consumption of plasma complement. There was a positive correlation between glomerular cell apoptosis and the degree of proliferation in lupus nephritis. These data suggest that apoptosis is increased, but not decreased in glomeruli from patients with lupus nephritis. The signals that could induce glomerular cell apoptosis in lupus nephritis will need to be identified.

Adult↗
PubMed2003

Physiological levels of tumstatin, a fragment of collagen IV alpha3 chain, are generated by MMP-9 proteolysis and suppress angiogenesis via alphaV beta3 integrin.

We demonstrate a physiological role for tumstatin, a cleavage fragment of the alpha3 chain of type IV collagen (Col IValpha3), which is present in the circulation. Mice with a genetic deletion of Col IValpha3 show accelerated tumor growth associated with enhanced pathological angiogenesis, while angiogenesis associated with development and tissue repair are unaffected. Supplementing Col IValpha3-deficient mice with recombinant tumstatin to a normal physiological concentration abolishes the increased rate of tumor growth. The suppressive effects of tumstatin require alphaVbeta3 integrin expressed on pathological, but not on physiological, angiogenic blood vessels. Mice deficient in matrix metalloproteinase-9, which cleaves tumstatin efficiently from Col IValpha3, have decreased circulating tumstatin and accelerated growth of tumor. These results indicate that MMP-generated fragments of basement membrane collagen can have endogenous function as integrin-mediated suppressors of pathologic angiogenesis and tumor growth.

Animals↗
PubMed2003

Transforming growth factor-beta 1 induces vascular endothelial growth factor expression in murine proximal tubular epithelial cells.

Vascular endothelial growth factor (VEGF) is a potent endothelial cell mitogen that promotes angiogenesis, vasculogenesis, and increases vascular permeability. VEGF is expressed in renal tubular epithelial cells and urinary VEGF excretion is increased in various glomerular disorders. However, the mechanisms underlying expression of VEGF in renal tubular epithelial cells have not been fully elucidated. In the present study, we attempted to define a predominant regulator of VEGF expression using a cultured murine renal proximal tubular epithelial cell line (mProx24). VEGF protein concentration in the culture supernatant was measured by sandwich enzyme-linked immunosorbent assay. mProx24 constitutively produced VEGF at low level. Major isoforms expressed in this cell line were VEGF164 and VEGF120 determined by reverse transcription-polymerase chain reaction method. Among various stimuli including angiotensin II, transforming growth factor-beta1 (TGF-beta1), lipopolysaccharides, interleukin-1beta, interleukin-10 and interferon-gamma, only TGF-beta1 significantly increased the level of VEGF protein at 24 h in a dose-dependent manner. The steady-state mRNA level of VEGF was dose dependently increased by TGF-beta1 detected by Northern blotting. Treatment with neutralizing anti-TGF-beta1 antibody abolished TGF-beta1-induced VEGF expression by 70%. Inhibitors of protein kinase C (PKC), Ro-31-8220 and staurosporin, significantly suppressed TGF-beta1-induced VEGF protein expression. These results demonstrate the role of TGF-beta1 on the expression of VEGF in proximal tubular epithelial cells mediated potentially via PKC pathway. This regulatory mechanism may be associated with the progression of tubulointerstitial lesions in renal disorders.

Animals↗
PubMed2002

Tumstatin, an endothelial cell-specific inhibitor of protein synthesis.

Tumstatin is a 28-kilodalton fragment of type IV collagen that displays both anti-angiogenic and proapoptotic activity. Here we show that tumstatin functions as an endothelial cell-specific inhibitor of protein synthesis. Through a requisite interaction with alphaVbeta3 integrin, tumstatin inhibits activation of focal adhesion kinase (FAK), phosphatidylinositol 3-kinase (PI3-kinase), protein kinase B (PKB/Akt), and mammalian target of rapamycin (mTOR), and it prevents the dissociation of eukaryotic initiation factor 4E protein (eIF4E) from 4E-binding protein 1. These results establish a role for integrins in mediating cell-specific inhibition of cap-dependent protein synthesis and suggest a potential mechanism for tumstatin's selective effects on endothelial cells.

Adaptor Proteins, Signal Transducing↗
PubMed2002

Renal fibrosis. Extracellular matrix microenvironment regulates migratory behavior of activated tubular epithelial cells.

During progression of chronic renal disease, qualitative and quantitative changes in the composition of tubular basement membranes (TBMs) and interstitial matrix occur. Transforming growth factor (TGF)-beta(1)-mediated activation of tubular epithelial cells (TECs) is speculated to be a key contributor to the progression of tubulointerstitial fibrosis. To further understand the pathogenesis associated with renal fibrosis, we developed an in vitro Boyden chamber system using renal basement membranes that partially mimics in vivo conditions of TECs during health and disease. Direct stimulation of TECs with TGF-beta(1)/epithelial growth factor results in an increased migratory capacity across bovine TBM preparations. This is associated with increased matrix metalloproteinase (MMP) production, namely MMP-2 and MMP-9. Indirect chemotactic stimulation by TGF-beta(1)/EGF or collagen type I was insufficient in inducing migration of untreated TECs across bovine TBM preparation, suggesting that basement membrane integrity and composition play an important role in protecting TECs from interstitial fibrotic stimuli. Additionally, neutralization of MMPs by COL-3 inhibitor dramatically decreases the capacity of TGF-beta(1)-stimulated TECs to migrate through bovine TBM preparation. Collectively, these results demonstrate that basement membrane structure, integrity, and composition play an important role in determining interstitial influences on TECs and subsequent impact on potential aberrant cell-matrix interactions.

Adult↗