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Naoki Washida,
Shu Wakino,
Yukio Tonozuka,
Koichiro Homma,
Hirobumi Tokuyama,
Yoshikazu Hara,
Kazuhiro Hasegawa,
Hitoshi Minakuchi,
Keiko Fujimura,
Kohji Hosoya,
Koichi Hayashi,
Hiroshi Itoh
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ABSTRACT: Peritoneal fibrosis (PF) and angiogenesis are typical morphological changes, leading to loss of peritoneal functions in patients undergoing peritoneal dialysis. The small G protein, Rho, and its downstream effector Rho-kinase have been shown to be involved in the tissue fibrosis process. This study was undertaken to investigate the role of Rho-kinase in the pathogenesis of these alterations.
PF was induced by intraperitoneal administration of chlorhexidine (CHX) in male rats (CHX group). These rats were treated with a Rho-kinase inhibitor, fasudil (Fas group). Human pleural mesothelial cells, MeT-5A cells, were stimulated by glucose with or without another Rho-kinase inhibitor, Y-27632.
Peritoneal damage including peritoneal thickening, fibrous changes, macrophage migration and angiogenesis were evident in the CHX group and were ameliorated in the Fas group. The expression of markers of tissue fibrosis, such as transforming growth factor (TGF)-β, fibronectin and α-smooth muscle cell actin, were increased in the CHX group and were downregulated by fasudil. Similar results were also seen with an inducer of angiogenesis, vascular endothelial growth factor (VEGF). Rho-kinase was activated in the peritoneum of the CHX group, which was inhibited by fasudil. In MeT-5A cells, high glucose increased TGF-β expression and VEGF secretion, which were blocked by Y-27632.
The activation of Rho-kinase is involved in peritoneal damage at multiple stages including tissue fibrosis and angiogenesis. The inhibition of Rho-kinase constitutes a novel strategy for the treatment of PF.
Nephrology Dialysis Transplantation 03/2011; 26(9):2770-9. · 3.40 Impact Factor
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Yoshikazu Hara,
Shu Wakino,
Yoshiyuki Tanabe,
Maki Saito,
Hirobumi Tokuyama, Naoki Washida,
Satoru Tatematsu,
Kyoko Yoshioka,
Koichiro Homma,
Kazuhiro Hasegawa,
Hitoshi Minakuchi,
Keiko Fujimura,
Koji Hosoya,
Koichi Hayashi,
Koichi Nakayama,
Hiroshi Itoh
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ABSTRACT: The development of obesity involves multiple mechanisms. Here, we identify adipocyte signaling through the guanosine triphosphatase Rho and its effector Rho-kinase as one such mechanism. Mice fed a high-fat diet (HFD) showed increased Rho-kinase activity in adipose tissue compared to mice fed a low-fat diet. Treatment with the Rho-kinase inhibitor fasudil attenuated weight gain and insulin resistance in mice on a HFD. Transgenic mice overexpressing an adipocyte-specific, dominant-negative form of RhoA (DN-RhoA TG mice) showed decreased Rho-kinase activity in adipocytes, decreased HFD-induced weight gain, and improved glucose metabolism compared to wild-type littermates. Furthermore, compared to HFD-fed wild-type littermates, DN-RhoA TG mice on a HFD showed decreased adipocyte hypertrophy, reduced macrophage recruitment to adipose tissue, and lower expression of mRNAs encoding various adipocytokines. Lipid accumulation in cultured adipocytes was associated with increased Rho-kinase activity and increased abundance of adipocytokine transcripts, which was reversed by a Rho-kinase inhibitor. Direct application of mechanical stretch to mature adipocytes increased Rho-kinase activity and stress fiber formation. Stress fiber formation, which was also observed in adipocytes from HFD-fed mice, was prevented by Rho-kinase inhibition and in DN-RhoA TG mice. Our findings indicate that lipid accumulation in adipocytes activates Rho to Rho-kinase (Rho-Rho-kinase) signaling at least in part through mechanical stretch and implicate Rho-Rho-kinase signaling in inflammatory changes in adipose tissue in obesity. Thus, inhibition of Rho-Rho-kinase signaling may provide a therapeutic strategy for disrupting a vicious cycle of adipocyte stretch, Rho-Rho-kinase signaling, and inflammation of adipose tissue that contributes to and aggravates obesity.
Science Signaling 01/2011; 4(157):ra3. · 7.50 Impact Factor
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ABSTRACT: Cerebrovascular disease (CVD) is a major determinant of the prognosis in end-stage renal diseases (ESRD). The purpose of this study was to examine whether factors associated with arterial stiffness contributed to the development of CVD in patients with ESRD.
CVD (lacunes and carotid/intracranial artery stenosis) was evaluated with brain magnetic resonance imaging (MRI), and carotid/intracranial artery magnetic resonance angiography (MRA) in 44 pre-dialytic patients. The severity of CVD was evaluated by the number of lacunes and the degree of stenosis, respectively. The association between CVD and atherosclerotic parameters was evaluated.
Patients with severe lacunes (n=18) manifested older age, lower diastolic blood pressure, serum creatinine and albumin, and higher CRP and serum calcium than those with absent-moderate lacunes (n=26). When assessed by multivariate analysis, only baPWV was adopted as an independent risk factor for severe lacunes. Furthermore, baPWV and i-PTH were associated with the severity of carotid/intracranial artery stenosis, both of which were independent of other risk factors, including age and diabetes.
Arterial stiffness may constitute a novel determinant predicting the severity of CVD in pre-dialytic patients besides classical risk factors.
Journal of atherosclerosis and thrombosis 02/2010; 17(2):165-72. · 2.69 Impact Factor
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Kazuhiro Hasegawa,
Shu Wakino,
Kyoko Yoshioka,
Satoru Tatematsu,
Yoshikazu Hara,
Hitoshi Minakuchi,
Keiko Sueyasu, Naoki Washida,
Hirobumi Tokuyama,
Maty Tzukerman,
Karl Skorecki,
Koichi Hayashi,
Hiroshi Itoh
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ABSTRACT: Sirt1, a NAD-dependent protein deacetylase, is reported to regulate intracellular metabolism and attenuate reactive oxidative species (ROS)-induced apoptosis leading to longevity and acute stress resistance. We created transgenic (TG) mice with kidney-specific overexpression of Sirt1 using the promoter sodium-phosphate cotransporter IIa (Npt2) driven specifically in proximal tubules and investigated the kidney-specific role of Sirt1 in the protection against acute kidney injury (AKI). We also elucidated the role of number or function of peroxisome and mitochondria in mediating the mechanisms for renal protective effects of Sirt1 in AKI. Cisplatin-induced AKI decreased the number and function of peroxisomes as well as mitochondria and led to increased local levels of ROS production and renal tubular apoptotic cells. TG mice treated with cisplatin mitigated AKI, local ROS, and renal tubular apoptotic tubular cells. Consistent with these results, TG mice treated with cisplatin also exhibited recovery of peroxisome number and function, as well as rescued mitochondrial function; however, mitochondrial number was not recovered. Immunoelectron microscopic findings consistently demonstrated that the decrease in peroxisome number by cisplatin in wild type mice was restored in transgenic mice. In HK-2 cells, a cultured proximal tubule cell line, overexpression of Sirt1 rescued the cisplatin-induced cell apoptosis through the restoration of peroxisome number, although the mitochondria number was not restored. These results indicate that Sirt1 overexpression in proximal tubules rescues cisplatin-induced AKI by maintaining peroxisomes number and function, concomitant up-regulation of catalase, and elimination of renal ROS levels. Renal Sirt1 can be a potential therapeutic target for the treatment of AKI.
Journal of Biological Chemistry 02/2010; 285(17):13045-56. · 4.77 Impact Factor
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ABSTRACT: NAD(+)-dependent protein deacetylase Sirt1 regulates cellular apoptosis. We examined the role of Sirt1 in renal tubular cell apoptosis by using HK-2 cells, proximal tubular cell lines with or without reactive oxygen species (ROS), H(2)O(2). Without any ROS, Sirt1 inhibitors enhanced apoptosis and the expression of ROS scavenger, catalase, and Sirt1 overexpression downregulated catalase. When apoptosis was induced with H(2)O(2), Sirt1 was upregulated with the concomitant increase in catalase expression. Sirt1 overexpression rescued H(2)O(2)-induced apoptosis through the upregulation of catalase. H(2)O(2) induced the nuclear accumulation of forkhead transcription factor, FoxO3a and the gene silencing of FoxO3a enhanced H(2)O(2)-induced apoptosis. In conclusion, endogenous Sirt1 maintains cell survival by regulating catalase expression and by preventing the depletion of ROS required for cell survival. In contrast, excess ROS upregulates Sirt1, which activates FoxO3a and catalase leading to rescuing apoptosis. Thus, Sirt1 constitutes a determinant of renal tubular cell apoptosis by regulating cellular ROS levels.
Biochemical and Biophysical Research Communications 08/2008; 372(1):51-6. · 2.48 Impact Factor
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ABSTRACT: A 79-year-old woman with progressive systemic sclerosis (PSS) presented with acute pulmonary edema, hypertension and renal failure. Administration of angiotensin-converting enzyme (ACE) inhibitor under suspicion of PSS renal crisis resulted in worsening of the renal function, which necessitated hemodialysis. Magnetic resonance arteriogram (MRA) demonstrated stenosis of the right renal artery, and ischemic nephropathy was diagnosed. Renal function improved after the discontinuation of ACE inhibitor. ACE inhibitor/angiotensin II receptor blocker (ARB), which is recommended for PSS renal crisis, should be avoided in ischemic nephropathy. In elderly PSS patients, careful exclusion of ischemic nephropathy is warranted before the administration of ACE inhibitor/ARB.
Internal Medicine 02/2007; 46(18):1605-7. · 0.94 Impact Factor
