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Akira Mima,
Hideharu Abe,
Kojiro Nagai,
Hidenori Arai,
Takeshi Matsubara,
Makoto Araki, Kazuo Torikoshi,
Tatsuya Tominaga,
Noriyuki Iehara,
Atsushi Fukatsu,
Toru Kita,
Toshio Doi
PLoS ONE 01/2012; 7(9). · 4.09 Impact Factor
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Kazuo Torikoshi,
Hideharu Abe,
Takeshi Matsubara,
Takahiro Hirano,
Takayuki Ohshima,
Taichi Murakami,
Makoto Araki,
Akira Mima,
Noriyuki Iehara,
Atsushi Fukatsu,
Toru Kita,
Hidenori Arai,
Toshio Doi
[show abstract]
[hide abstract]
ABSTRACT: Phenotypic transformation of mesangial cells (MCs) is implicated in the development of glomerular disease; however, the mechanisms underlying their altered genetic program is still unclear. α-smooth muscle actin (α-SMA) is known to be a crucial marker for phenotypic transformation of MCs. Recently, E-boxes and the class I basic helix-loop-helix proteins, such as E12 have been shown to regulateα-SMA expression. Therefore, we tried to identify a novel E12 binding protein in MCs and to examine its role in glomerulonephritis. We found that PIASy, one of the protein inhibitors of activated STAT family protein, interacted with E12 by yeast two-hybrid screens and coimmunopreciptation assays. Overexpression of E12 significantly enhanced theα-SMA promoter activity, and the increase was blocked by co-transfection of PIASy, but not by a PIASy RING mutant. In vivo sumoylation assays revealed that PIASy was a SUMO E3 ligase for E12. Furthermore, transforming growth factor-β (TGF-β) treatment induced expression of both PIASy and E12, consistent with α-SMA expression. Moreover, reduced expression of PIASy protein by siRNA specific for PIASy resulted in increased TGF-β-mediated α-SMA expression. In vivo, PIASy and E12 were dramatically upregulated along with α-SMA and TGF-β in the proliferative phase of Thy1 glomerulonephritis. Furthermore, an association between PIASy and E12 proteins was observed at day 6 by IP-western blotting, but not at day 0. These results suggest that TGF-β up-regulates PIASy expression in MCs to down-regulateα-SMA gene transcription by the interaction with E12.
PLoS ONE 01/2012; 7(7):e41186. · 4.09 Impact Factor
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Akira Mima,
Hideharu Abe,
Kojiro Nagai,
Hidenori Arai,
Takeshi Matsubara,
Makoto Araki, Kazuo Torikoshi,
Tatsuya Tominaga,
Noriyuki Iehara,
Atsushi Fukatsu,
Toru Kita,
Toshio Doi
[show abstract]
[hide abstract]
ABSTRACT: Platelet-derived growth factor (PDGF) plays critical roles in mesangial cell (MC) proliferation in mesangial proliferative glomerulonephritis. We showed previously that Smad1 contributes to PDGF-dependent proliferation of MCs, but the mechanism by which Smad1 is activated by PDGF is not precisely known. Here we examined the role of c-Src tyrosine kinase in the proliferative change of MCs. Experimental mesangial proliferative glomerulonephritis (Thy1 GN) was induced by a single intravenous injection of anti-rat Thy-1.1 monoclonal antibody. In Thy1 GN, MC proliferation and type IV collagen (Col4) expression peaked on day 6. Immunohistochemical staining for the expression of phospho-Src (pSrc), phospho-Smad1 (pSmad1), Col4, and smooth muscle α-actin (SMA) revealed that the activation of c-Src and Smad1 signals in glomeruli peaked on day 6, consistent with the peak of mesangial proliferation. When treated with PP2, a Src inhibitor, both mesangial proliferation and sclerosis were significantly reduced. PP2 administration also significantly reduced pSmad1, Col4, and SMA expression. PDGF induced Col4 synthesis in association with increased expression of pSrc and pSmad1 in cultured MCs. In addition, PP2 reduced Col4 synthesis along with decreased pSrc and pSmad1 protein expression in vitro. Moreover, the addition of siRNA against c-Src significantly reduced the phosphorylation of Smad1 and the overproduction of Col4. These results provide new evidence that the activation of Src/Smad1 signaling pathway plays a key role in the development of glomerulosclerosis in experimental glomerulonephritis.
PLoS ONE 01/2011; 6(3):e17929. · 4.09 Impact Factor
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Akira Mima,
Hidenori Arai,
Takeshi Matsubara,
Hideharu Abe,
Kojiro Nagai,
Yukinori Tamura, Kazuo Torikoshi,
Makoto Araki,
Hiroshi Kanamori,
Toshikazu Takahashi,
Tatsuya Tominaga,
Motokazu Matsuura,
Noriyuki Iehara,
Atsushi Fukatsu,
Toru Kita,
Toshio Doi
[show abstract]
[hide abstract]
ABSTRACT: We reported that Smad1 is a key transcriptional factor for mesangial matrix expansion in diabetic nephropathy. In this study, we examined whether urinary Smad1 in an early phase of diabetes can predict later development of glomerulosclerosis in diabetic nephropathy and how an angiotensin II type 1 receptor blocker (ARB) can modulate structural changes and urinary markers.
Smad1 and albumin in the urine were examined 4 weeks after injection of streptozotocin in 48 rats or 6 weeks of diabetes in db/db mice. Their renal pathology was analyzed after 20 weeks in rats or 12 weeks in mice. Among 48 diabetic rats 7 rats were treated with olmesartan for 20 weeks.
Urinary Smad1 of diabetic rats at 4 weeks was nicely correlated with mesangial matrix expansion at 24 weeks (r = 0.70, P < 0.001), while albuminuria showed a weaker association (r = 0.31, P = 0.043). Olmesartan treatment significantly ameliorated glomerulosclerosis and dramatically decreased urinary Smad1 (from 3.9 +/- 2.9 to 0.3 +/- 0.3 ng/mg creatinine, P < 0.05). In db/db mice, urinary Smad1 at 6 weeks was also significantly correlated with mesangial expansion at 18 weeks. In contrast, there was no change in urinary Smad1 in control diabetic rats or mice.
The increase of urinary Smad1 in the early stages of diabetes is correlated with later development of glomerulosclerosis in two rodent models. These data indicate that urinary Smad1 could be a novel predictor for later onset of morphological changes and can be used to monitor the effect of ARBs in diabetic nephropathy.
Diabetes 07/2008; 57(6):1712-22. · 8.29 Impact Factor
