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Papers - ITOH Hiroshi

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Prorenin receptor is essential for normal podocyte structure and function

Oshima, Y., Kinouchi, K., Ichihara, A., Sakoda, M., Kurauchi-Mito, A., Bokuda, K., Narita, T., Kurosawa, H., Sun-Wada, G. H., Wada, Y., Yamada, T., Takemoto, M., Saleem, M. A., Quaggin, S. E. and Itoh, H.

J Am Soc Nephrol 22 ( 12 ) 2203 - 12 2011.12

ISSN 1046-6673

The prorenin receptor is an accessory subunit of the vacuolar H(+)-ATPase, suggesting that it has fundamental functions beyond activation of the local renin-angiotensin system. Podocytes express the prorenin receptor, but its function in these cells is unknown. Here, podocyte-specific, conditional, prorenin receptor-knockout mice died of kidney failure and severe proteinuria within 4 weeks of birth. The podocytes of these mice exhibited foot process effacement with reduced and altered localization of the slit-diaphragm proteins nephrin and podocin. Furthermore, the podocytes contained numerous autophagic vacuoles, confirmed by enhanced accumulation of microtubule-associated protein 1 light chain 3-positive intracellular vesicles. Ablation of the prorenin receptor selectively suppressed expression of the V(0) c-subunit of the vacuolar H(+)-ATPase in podocytes, resulting in deacidification of intracellular vesicles. In conclusion, the prorenin receptor is important for the maintenance of normal podocyte structure and function.

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The role of microRNA-145 in human embryonic stem cell differentiation into vascular cells

Yamaguchi, S., Yamahara, K., Homma, K., Suzuki, S., Fujii, S., Morizane, R., Monkawa, T., Matsuzaki, Y., Kangawa, K. and Itoh, H.

Atherosclerosis 219 ( 2 ) 468 - 74 2011.12

ISSN 0021-9150

BACKGROUND: Recent studies have reported that microRNA-145 (miR-145) is a critical mediator in the regulation of proliferation, differentiation, and phenotype expression of smooth muscle cells (SMCs). Previously, we established a system for differentiating human ESCs into vascular cells including endothelial cells (ECs) and vascular smooth muscle cells (SMCs). In the present study, we investigated the role of miR-145 in the differentiation process from human ESCs into ECs and SMCs. METHODS AND RESULTS: Undifferentiated human ESCs were induced to differentiate into vascular lineage according to our established method. Quantitative RT-PCR analysis revealed that human ESC-derived precursor of SMCs (ES-pre-SMCs), similar to human aortic SMCs, expressed a significant amount of miR-145 as well as smooth muscle-specific proteins, compared to undifferentiated human ESCs, adult ECs, or ESC-derived ECs (ES-ECs). However, morphological analysis revealed that human ES-pre-SMCs appeared round and flattened in shape, though human aortic SMCs exhibited the typical spindle-like morphology of SMCs. In addition, Kruppel-like factor 4 and 5 (KLF4 and 5), direct targets of miR-145 and suppressors of smooth muscle differentiation, were upregulated in ES-pre-SMCs compared to aortic SMCs, indicating ES-pre-SMCs were not fully differentiated SMCs. Overexpression of miR-145 in ES-pre-SMCs upregulated the expression of smooth muscle markers, repressed KLF4 and 5 expressions, and changed their morphology into a differentiated spindle-like shape. Furthermore, by introduction of miR-145, ES-pre-SMC proliferation was significantly inhibited and carbachol-stimulated contraction of ES-pre-SMCs was significantly increased. In contrast, downregulation of miR-145 in ES-pre-SMCs upregulated KLF4 and 5 expressions, suppressed the expression of smooth muscle markers, and left unchanged their proliferation and contractility. In ES-ECs, miR-145 overexpression did not induce the synthesis of smooth muscle-related proteins nor suppress the expression of endothelial nitric oxide synthase. CONCLUSION: We showed that miR-145 can regulate the fate and phenotype of human ES-pre-SMCs as they become fully differentiated SMCs. Overexpression of miR-145 on human ES-pre-SMCs is a promising method to obtain functional mature SMCs from human ESCs, which are required for reliable experimental research in the fields of atherosclerosis, hypertension and other vascular diseases.

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A mimic of viral double-stranded RNA triggers fulminant type 1 diabetes-like syndrome in regulatory T cell-deficient autoimmune diabetic mouse

Tada, A., Shimada, A., Yamada, T., Oikawa, Y., Yamada, Y., Okubo, Y., Irie, J., Bluestone, J. A. and Itoh, H.

J Immunol 187 ( 10 ) 4947 - 53 2011.11

ISSN 0022-1767

Human fulminant type 1 diabetes (FT1D) is an extremely aggressive disease. The delay of proper diagnosis results in high mortality. However, the pathophysiology of this disease remains unclear. We took advantage of CD28-deficient NOD (CD28(-/-) NOD) mice, which have limited numbers of regulatory T cells and develop aggressive autoimmune diabetes, to create a FT1D model that mimicked the disease in humans. Young CD28(-/-) NOD mice were injected with polyinosinic-polycytidylic acid to activate innate immunity in an effort to induce diabetes onset. In this model, innate immune cell activation precedes the onset of diabetes similar to approximately 70% of FT1D patients. Eighty-three percent of CD28(-/-) NOD mice developed diabetes within 1-6 d after injection of polyinosinic-polycytidylic acid. Moreover, T cells infiltrated the pancreatic exocrine tissue and destroyed alpha cells, an observation characteristic of human FT1D. We conclude that an FT1D-like phenotype can be induced in the background of autoimmune diabetes by a mimic of viral dsRNA, and this model is useful for understanding human FT1D.

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Renal amyloidosis caused by apolipoprotein A-II without a genetic mutation in the coding sequence

Morizane, R., Monkawa, T., Konishi, K., Hashiguchi, A., Ueda, M., Ando, Y., Tokuyama, H., Hayashi, K., Hayashi, M. and Itoh, H.

Clin Exp Nephrol 15 ( 5 ) 774 - 9 2011.10

ISSN 1342-1751

Although the majority of renal amyloidosis is caused by either acquired monoclonal immunoglobulin light-chain amyloidosis or reactive systemic amyloid A, some cases are caused by hereditary amyloidosis. Apolipoprotein A-II (apoAII) amyloidosis is a rare form of hereditary amyloidosis and cannot be diagnosed by a routine examination. Thus, the prevalence and etiology of apoAII amyloidosis are uncertain. In humans, a genetic mutation in the stop codon of apoAII is considered to be a cause of amyloid fibril formation. We report on a 68-year-old man who presented with proteinuria by apoAII amyloidosis without family history. His proteinuria gradually increased to 6 g/day within 1 year. A renal biopsy showed amyloid deposition in the glomeruli, however, acquired monoclonal immunoglobulin light-chain amyloidosis and reactive systemic amyloid A were ruled out. Immunohistochemistry revealed apoAII deposition in the glomeruli, but DNA sequencing did not identify any genetic mutation in the coding sequence of apoAII. Here, we report a case of apoAII amyloidosis without a genetic mutation in the coding sequence and discuss the etiology of apoAII amyloidosis.

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[Obesity: visceral fat]

Mitsuishi, M., Miyashita, K. and Itoh, H.

Nihon Rinsho 69 Suppl 7 568 - 72 2011.09

ISSN 0047-1852

Rho-kinase inhibition ameliorates peritoneal fibrosis and angiogenesis in a rat model of peritoneal sclerosis

Washida, N., Wakino, S., Tonozuka, Y., Homma, K., Tokuyama, H., Hara, Y., Hasegawa, K., Minakuchi, H., Fujimura, K., Hosoya, K., Hayashi, K. and Itoh, H.

Nephrol Dial Transplant 26 ( 9 ) 2770 - 9 2011.09

ISSN 0931-0509

BACKGROUND: 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. METHODS: 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. RESULTS: 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)-beta, fibronectin and alpha-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-beta expression and VEGF secretion, which were blocked by Y-27632. CONCLUSIONS: 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.

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Significance of adrenocorticotropin stimulation test in the diagnosis of an aldosterone-producing adenoma

Sonoyama, T., Sone, M., Miyashita, K., Tamura, N., Yamahara, K., Park, K., Oyamada, N., Taura, D., Inuzuka, M., Kojima, K., Honda, K., Fukunaga, Y., Kanamoto, N., Miura, M., Yasoda, A., Arai, H., Itoh, H. and Nakao, K.

J Clin Endocrinol Metab 96 ( 9 ) 2771 - 8 2011.09

ISSN 0021-972

CONTEXT: Adrenal venous sampling is the "gold standard" test in the diagnosis of an aldosterone-producing adenoma (APA) among patients with primary aldosteronism (PA) but is available only in specialized medical centers. Meanwhile, an APA is reported to be generally more sensitive to ACTH than idiopathic hyperaldosteronism. OBJECTIVE: The aim was to evaluate the diagnostic accuracy of the ACTH stimulation test in the diagnosis of an APA among those with suspicion of PA. PATIENTS AND SETTING: Fifty-nine patients admitted to Kyoto University Hospital on suspicion of PA were included in the study. INTERVENTIONS: ACTH stimulation tests with 1-mg dexamethasone suppression were performed. MAIN OUTCOME MEASURE: Plasma aldosterone concentrations (PAC) were examined every 30 min after ACTH stimulation. Receiver-operated characteristics curve analysis was used to evaluate the diagnostic accuracy. RESULTS: PAC after ACTH stimulations were significantly higher in patients with an APA than in patients with idiopathic hyperaldosteronism or non-PA. Receiver-operated characteristics curve analyses showed that the PAC after ACTH stimulation was effective for the diagnosis of an APA among patients suspected of PA. The diagnostic accuracy was highest at 90 min after ACTH injection, with the optimal cutoff value greater than 37.9 ng/dl corresponding with sensitivity and specificity of 91.3 and 80.6% for the diagnosis of an APA. CONCLUSIONS: Our study indicates that the ACTH stimulation test is useful in the diagnosis of an APA among patients suspected of PA. This test can be used to select patients who are highly suspected of an APA and definitely require adrenal venous sampling.

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[Angiotensin receptor vaccines]

Sasamura, H., Azegami, T. and Itoh, H.

Nihon Rinsho 69 ( 9 ) 1633 - 8 2011.09

ISSN 0047-1852

Recent clinical studies have shown that RAS inhibitors are effective not only for the prevention of end-organ damage in hypertensive patients, but also for prevention of new-onset hypertension, diabetes mellitus, and atrial fibrillation. Vaccines against the RAS have been developed since the 1950s, and a recent phase IIa placebo-controlled study has confirmed that an angiotensin vaccine causes a significant decrease in blood pressure in hypertensive patients. The results of animal experiments from our and other laboratories have suggested that vaccination against the angiotensin type 1 (AT1) receptor causes a significant decrease in blood pressure in animal models of hypertension, and also ameliorates hypertensive end-organ damage. The angiotensin receptor may therefore be an important target for the development of vaccines for the prevention of hypertension and related complications.

Human C-reactive protein exacerbates metabolic disorders in association with adipose tissue remodelling

Kaneko, H., Anzai, T., Nagai, T., Anzai, A., Takahashi, T., Mano, Y., Morimoto, K., Maekawa, Y., Itoh, H., Yoshikawa, T., Ogawa, S. and Fukuda, K.

Cardiovasc Res 91 ( 3 ) 546 - 55 2011.08

ISSN 0008-6363

AIMS: C-reactive protein (CRP) expression is increased with metabolic alterations. We sought to clarify the effect of CRP on the development of obesity-induced metabolic disorders using human CRP-overexpressing transgenic mice (CRPTG). METHODS AND RESULTS: CRPTG and their non-transgenic littermates (CON) were fed a standard diet (STD) or a high-fat diet (HFD) from 6 weeks of age. Oral glucose tolerance and intraperitoneal insulin tolerance tests 12 weeks after starting the diets showed deterioration of glucose tolerance and insulin sensitivity in HFD/CRPTG compared with HFD/CON. Hepatocellular ballooning, oil droplets, and peri-sinusoidal fibrosis were more prominent in HFD/CRPTG than in HFD/CON. In HFD/CRPTG, hepatic triglyceride content was higher and serum adiponectin levels lower than in HFD/CON. Epididymal adipose tissue mRNA expression of mucin-like, hormone receptor-like 1, monocyte chemotactic protein-1, and tumour necrosis factor-alpha in HFD/CRPTG was up-regulated compared with that in HFD/CON. Immunohistochemical staining of epididymal adipose tissue showed that the number of Mac-3(+) macrophages was higher in HFD/CRPTG than in HFD/CON. CONCLUSION: Human CRP overexpression facilitated the development of insulin resistance and hepatosteatosis with HFD in association with adiponectin down-regulation and enhancement of macrophage infiltration and expression of pro-inflammatory cytokines in epididymal adipose tissue, suggesting its pathogenic role in the development of obesity-induced metabolic disorders.

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Lowering bile acid pool size with a synthetic farnesoid X receptor (FXR) agonist induces obesity and diabetes through reduced energy expenditure

Watanabe, M., Horai, Y., Houten, S. M., Morimoto, K., Sugizaki, T., Arita, E., Mataki, C., Sato, H., Tanigawara, Y., Schoonjans, K., Itoh, H. and Auwerx, J.

J Biol Chem 286 ( 30 ) 26913 - 20 2011.07

ISSN 0021-9258

We evaluated the metabolic impact of farnesoid X receptor (FXR) activation by administering a synthetic FXR agonist (GW4064) to mice in which obesity was induced by a high fat diet. Administration of GW4064 accentuated body weight gain and glucose intolerance induced by the high fat diet and led to a pronounced worsening of the changes in liver and adipose tissue. Mechanistically, treatment with GW4064 decreased bile acid (BA) biosynthesis, BA pool size, and energy expenditure, whereas reconstitution of the BA pool in these GW4064-treated animals by BA administration dose-dependently reverted the metabolic abnormalities. Our data therefore suggest that activation of FXR with synthetic agonists is not useful for long term management of the metabolic syndrome, as it reduces the BA pool size and subsequently decreases energy expenditure, translating as weight gain and insulin resistance. In contrast, expansion of the BA pool size, which can be achieved by BA administration, could be an interesting strategy to manage the metabolic syndrome.

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Functional characterization of (pro)renin receptor in association with V-ATPase

Kinouchi, K., Ichihara, A. and Itoh, H.

Front Biosci (Landmark Ed) 16 3216 - 23 2011.06

ISSN 1093-4715

The (pro)renin receptor ((P)RR) is a unique molecule that binds prorenin and renin in tissues, not only leading to their activation, but also inducing intracellular signaling. As a key player in the local renin-angiotensin system, (P)RR activation plays an important role in the development of cardiac fibrosis and proteinuria in hypertension and diabetes. Intriguingly, the fragment (P)RR is also called ATP6AP2 because it has been shown to be associated with vacuolar-type H(+)-ATPase (V-ATPase). The V-ATPase is a multi-subunit proton pump involved in diverse and fundamental cellular processes, including receptor-mediated endocytosis, processing of proteins and signaling molecules, membrane sorting and trafficking, and activation of lysosomal enzymes. The role of (P)RR in the function of the V-ATPase is implicated in the previous findings and vigorously investigated in the recent studies. Furthermore, the novel function of the (P)RR as an adaptor protein between the Wnt receptor complex and the V-ATPase was discovered. Thus, the (P)RR is a multi-functional molecule that shows the complex structure and behaviour. This review highlights the current insights and the future perspectives in research regarding the (P)RR and mammalian V-ATPase.

Coactivation of SF-1-mediated transcription of steroidogenic enzymes by Ubc9 and PIAS1

Suda, N., Shibata, H., Kurihara, I., Ikeda, Y., Kobayashi, S., Yokota, K., Murai-Takeda, A., Nakagawa, K., Oya, M., Murai, M., Rainey, W. E., Saruta, T. and Itoh, H.

Endocrinology 152 ( 6 ) 2266 - 77 2011.06

ISSN 0013-7227

Steroidogenic factor-1 (SF-1) is a nuclear orphan receptor, which is essential for adrenal development and regulation of steroidogenic enzyme expression. SF-1 is posttranslationally modified by small ubiquitin-related modifier-1 (SUMO-1), thus mostly resulting in attenuation of transcription. We investigated the role of sumoylation enzymes, Ubc9 and protein inhibitors of activated STAT1 (PIAS1), in SF-1-mediated transcription of steroidogenic enzyme genes in the adrenal cortex. Coimmunoprecipitation assays showed that both Ubc9 and PIAS1 interacted with SF-1. Transient transfection assays in adrenocortical H295R cells showed Ubc9 and PIAS1 potentiated SF-1-mediated transactivation of reporter constructs containing human CYP17, CYP11A1, and CYP11B1 but not CYP11B2 promoters. Reduction of endogenous Ubc9 and PIAS1 by introducing corresponding small interfering RNA significantly reduced endogenous CYP17, CYP11A1, and CYP11B1 mRNA levels, indicating that they normally function as coactivators of SF-1. Wild type and sumoylation-inactive mutants of Ubc9 and PIAS1 can similarly enhance the SF-1-mediated transactivation of the CYP17 gene, indicating that the coactivation potency of Ubc9 and PIAS1 is independent of sumoylation activity. Chromatin immunoprecipitation assays demonstrated that SF-1, Ubc9, and PIAS1 were recruited to an endogenous CYP17 gene promoter in the context of chromatin in vivo. Immunohistochemistry and Western blotting showed that SF-1, Ubc9, and PIAS1 were expressed in the nuclei of the human adrenal cortex. In cortisol-producing adenomas, the expression pattern of SF-1 and Ubc9 were markedly increased, whereas that of PIAS1 was decreased compared with adjacent normal adrenals. These results showed the physiological roles of Ubc9 and PIAS1 as SF-1 coactivators beyond sumoylation enzymes in adrenocortical steroidogenesis and suggested their possible pathophysiological roles in human cortisol-producing adenomas.

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Angiogenic and vasoprotective effects of adrenomedullin on prevention of cognitive decline after chronic cerebral hypoperfusion in mice

Maki, T., Ihara, M., Fujita, Y., Nambu, T., Miyashita, K., Yamada, M., Washida, K., Nishio, K., Ito, H., Harada, H., Yokoi, H., Arai, H., Itoh, H., Nakao, K., Takahashi, R. and Tomimoto, H.

Stroke 42 ( 4 ) 1122 - 8 2011.04

ISSN 0039-2499

BACKGROUND AND PURPOSE: Although subcortical vascular dementia, the major subtype of vascular dementia, is caused by a disruption in white matter integrity after cerebrovascular insufficiency, no therapy has been discovered that will restore cerebral perfusion or functional cerebral vessels. Because adrenomedullin (AM) has been shown to be angiogenic and vasoprotective, the purpose of the study was to investigate whether AM may be used as a putative treatment for subcortical vascular dementia. METHODS: A model of subcortical vascular dementia was reproduced in mice by placing microcoils bilaterally on the common carotid arteries. Using mice overexpressing circulating AM, we assessed the effect of AM on cerebral perfusion, cerebral angioarchitecture, oxidative stress, white matter change, cognitive function, and brain levels of cAMP, vascular endothelial growth factor, and basic fibroblast growth factor. RESULTS: After bilateral common carotid artery stenosis, mice overexpressing circulating AM showed significantly faster cerebral perfusion recovery due to substantial growth of the capillaries, the circle of Willis, and the leptomeningeal anastomoses and reduced oxidative damage in vascular endothelial cells compared with wild-type mice. Vascular changes were preceded by upregulation of cAMP, vascular endothelial growth factor, and basic fibroblast growth factor. White matter damage and working memory deficits induced by bilateral common carotid artery stenosis were subsequently restored in mice overexpressing circulating AM. CONCLUSIONS: These data indicate that AM promotes arteriogenesis and angiogenesis, inhibits oxidative stress, preserves white matter integrity, and prevents cognitive decline after chronic cerebral hypoperfusion. Thus, AM may serve as a strategy to tackle subcortical vascular dementia.

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Involvement of activated prorenin in the pathogenesis of slowly progressive nephropathy in the non-clipped kidney of two kidney, one-clip hypertension

Ryuzaki, M., Ichihara, A., Ohshima, Y., Sakoda, M., Kurauchi-Mito, A., Narita, T., Kinouchi, K., Murohashi-Bokuda, K., Nishiyama, A. and Itoh, H.

Hypertens Res 34 ( 3 ) 301 - 7 2011.03

ISSN 0916-9636

The handle region peptide (HRP), a (pro)renin receptor (P)RR blocker, did not prevent the acute nephropathy occurring 2 weeks after clipping in renovascular hypertensive rats. This study was performed to examine the effects of HRP, its scramble peptide, or a saline vehicle on slowly progressive nephropathy occurring in the kidneys of two-kidney, one-clip Goldblatt hypertensive rats. At 2 weeks after clipping, the renal morphology in the clipped and non-clipped kidneys was similar in the three groups of rats. At 12 weeks after clipping, however, the glomerulosclerosis index (GI) and the tubulointerstitial damage (TD) of the non-clipped kidneys of the HRP-treated rats were significantly lower than those of vehicle-treated rats, although the GI and the TD were similar in the rats treated with scramble peptide and vehicle. The GI and the TD of the clipped kidneys were similar in the three groups of rats at 12 weeks after clipping. In the non-clipped kidneys at 12 weeks after clipping, activated prorenin levels, angiotensin II levels and transforming growth factor (TGF)-beta mRNA levels of HRP-treated rats were significantly lower than those of vehicle-treated rats, although they were similar in the non-clipped kidneys from the rats treated with scramble peptide and vehicle. In the clipped kidneys at 12 weeks after clipping, activated prorenin levels, angiotensin II levels and TGF-beta mRNA levels were similar in the three groups of rats. These results suggest that the ((P)RR)-dependent activation of prorenin contributes to the pathogenesis of slowly progressive nephropathy in the intact kidney in a rat model of renovascular hypertension.

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[Antihypertensive therapy in the patient with diabetes mellitus or metabolic syndrome]

Miyashita, K. and Itoh, H.

Nihon Naika Gakkai Zasshi 100 ( 2 ) 376 - 84 2011.02

ISSN 0021-5384

Rho and Rho-kinase activity in adipocytes contributes to a vicious cycle in obesity that may involve mechanical stretch

Hara, Y., Wakino, S., Tanabe, Y., Saito, M., Tokuyama, H., Washida, N., Tatematsu, S., Yoshioka, K., Homma, K., Hasegawa, K., Minakuchi, H., Fujimura, K., Hosoya, K., Hayashi, K., Nakayama, K. and Itoh, H.

Sci Signal 4 ( 157 ) ra3 2011.01

ISSN 1945-0877

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.

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[The cutting-edge of medicine; metabolic domino and CKD]

Itoh, H.

Nihon Naika Gakkai Zasshi 100 ( 1 ) 191 - 8 2011.01

ISSN 0021-5384

Podocytes as a target of prorenin in diabetes

Sakoda, M., Itoh, H. and Ichihara, A.

Curr Diabetes Rev 7 ( 1 ) 17 - 21 2011.01

ISSN 1573-3998

High plasma prorenin levels predict the onset of microvascular complications, such as albuminuria/proteinuria,in diabetic patients. In diabetic rats with elevated plasma prorenin levels, treatment with HRP, which competitively inhibits the binding of prorenin to the (pro)renin receptor [(P)RR] as a decoy peptide, significantly prevented the development of albuminuria/proteinuria and glomerulosclerosis, suggesting that (P)RR-bound prorenin plays a significant role in the pathogenesis of diabetic nephropathy. Recently, the presence of (P)RR in podocytes, which represent one of the glomerular filtration barriers, has been reported. Although podocytes are subjected to both high glucose levels and mechanical stretching caused by glomerular hyperfiltration under diabetic conditions, the expression of (P)RR is reportedly regulated by high glucose levels in in vitro mesangial cells and the in vivo kidneys of diabetic rats, whereas mechanical stretching is up-regulated by (P)RR expression in human podocytes. In addition, prorenin treatment not only leads to the generation of intracellular angiotensin (Ang)II, but also activates the phosphorylation of ERK via (P)RR in a manner that acts independently of AngII in human podocytes. Thus, the upregulation of prorenin and (P)RR in podocytes as a result of glomerular hyperfiltration might play an important role in the development of albuminuria/proteinuria via the generation of intracellular AngII and the stimulation of (P)RR-dependent intracellular signals. Further inquiry regarding podocyte (P)RR intracellular signal transduction will be needed to develop a new therapeutic approach targeting podocyte (P)RR in patients with diabetic nephropathy.

[Mitochondrial dysfunction in metabolic syndrome]

Wakino, S. and Itoh, H.

Nihon Rinsho 69 Suppl 1 26 - 31 2011.01

ISSN 0047-1852

[Hypertension and arteriosclerosis]

Sasamura, H. and Itoh, H.

Nihon Rinsho 69 ( 1 ) 125 - 30 2011.01

ISSN 0047-1852

Hypertension is a known risk factor for arteriosclerosis, and causes both atherosclero= sis of medium-large arteries and arteriolosclerosis of the arterioles. Elevated blood pressure causes damage to the endothelium and vascular wall through both mechanical and humoral factors. We and others have shown that inhibition of the renin-angiotensin system at a 'critical period' during the development of hypertension results in a permanent suppression of hypertension in animal models. We have also reported that high-dose renin-angiotensin inhibition results in regression of hypertension, possibly by regression of renal arteriolar hypertrophy. These results suggest that understanding the process of arterial remodeling may play a key role in the development of new strategies for prevention and regression of hypertension and arteriosclerosis.

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