Naoko Sugae

University of Tsukuba, Tsukuba, Ibaraki, Japan

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Publications (6)13.84 Total impact

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    ABSTRACT: This study was investigated to characterize the activation mechanism of a mitogen-activated protein (MAP) kinase superfamily in diabetes in aortae and cultured vascular smooth muscle cells (VSMCs) from rats. Male Sprague-Dawley rats were used for this procedure, and diabetes was induced by streptozotocin injection at 50 mg/kg. After 6 weeks, the thoracic aortae from normal and diabetic rats were removed for detection of the MAP kinase superfamily by immunoblot analysis. In aortae, the protein levels of extracellular signal-regulated protein kinase (ERK)-1, c-jun NH2-terminal protein kinase (JNK)-1 and -2, and p38 increased significantly more in diabetic rats than in normal rats. In contrast, phosphorylated protein levels of ERK-1 and -2, JNK-1, and p38 were significantly more elevated in diabetic rats than in normal rats. In VSMCs from normal rats, a high concentration of glucose cultured for three days significantly increased the phosphorylated protein levels of ERKs and p38, but not JNKs, without any change of these protein levels. Serum interleukin (IL)-1beta was significantly higher in diabetic rats than in normal rats. Several types of proinflammatory cytokine dose-dependently phosphorylated the levels of ERKs, JNK-1, and p38, but not JNK-2, in VSMCs from normal rats. In cells from diabetic rats, phosphorylated protein levels of ERKs and p38 were significantly elevated by IL-1beta. In addition, interferon-gamma phosphorylated the levels of ERKs in diabetic cells more than in normal cells. Our results suggest that, under diabetic conditions, the MAP kinase superfamily was activated by different pathways in the vasculature; i.e., ERKs and p38 might be mainly phosphorylated by a complex of high concentrations of glucose and of several types of proinflammatory cytokines, but the phosphorylation of JNK-1 might depend on the concentration of proinflammatory cytokines such as IL-1beta, and/or additional unknown factors, except glucose.
    Journal of atherosclerosis and thrombosis 11/2007; 14(5):235-44. · 2.93 Impact Factor
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    ABSTRACT: We report the differentiation potential of an immortalized non-tumorigenic human liver epithelial cell line, THLE-5b. Under basic culture conditions THLE-5b showed undifferentiated phenotypes. When grown as cell aggregates, THLE-5b exhibited a hepatocyte-like ultrastructure, ammonia metabolic activity and several other indicators that suggest hepatocytic maturation, including up-regulation or induction of liver-specific genes such as albumin and tryptophane 2,3-dioxygenase, and down-regulation of biliary cell markers such as gamma-glutamyl transpeptidase (GGT). Under these conditions, transcriptional factors such as HNF-1 and HNF-4alpha were also up-regulated or induced. In Matrigel culture, expression of GGT was up-regulated. THLE-5b expressed both albumin and alpha 1-antitrypsin, but lost expression of CK19 in severe combined immunodeficient mice. Thus, THLE-5b can be aligned with progenitor cells, which are committed to the hepatocytic or biliary epithelial cell lineage. These results imply that bipotent progenitor cell populations similar to THLE-5b cells may exist in adult human liver.
    Cell Biology International 01/2007; 30(12):992-8. · 1.64 Impact Factor
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    ABSTRACT: We investigated the regulation of p38 mitogen-activated protein kinase (MAPK) by platelet-derived growth factor (PDGF)-BB and its biological effects in cultured normal and diabetic rat vascular smooth muscle cells (VSMCs). VSMC growth from diabetic rats was faster than that from normal rats. The expression of the PDGF beta-receptor in diabetic VSMCs was significantly elevated compared with that in normal cells, and PDGF-BB-induced p38 phosphorylation in diabetic cells was more enhanced via MAPK kinase (MKK) 3/6. The level of PKC activity in diabetic cells increased more than that in normal cells with or without PDGF-BB. Although protein kinase C (PKC)-betaII and PKC-delta were activated by diabetes, PDGF-BB could further enhance the level of PKC-delta alone. PDGF-BB-induced cell migration was more elevated in diabetic VSMCs, and the increase was significantly inhibited by SB-203580, rottlerin, and antisense oligodeoxynucleotides for PKC-delta. PDGF-BB-induced p38 phosphorylation also regulated cell growth, cyclooxygenase-2 levels, and arachidonic acid release, but not apoptosis. These levels were more elevated in diabetic cells, which were inhibited by SB-203580. Our study established that PDGF-BB phosphorylated p38 via PKC-delta and the subsequent MKK 3/6, leading to cell growth regulation and the progression of a chronic inflammatory process in diabetic VSMCs.
    Arteriosclerosis Thrombosis and Vascular Biology 12/2004; 24(11):2095-101. · 6.34 Impact Factor
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    ABSTRACT: The aim of this study was to clarify the mechanism of an inhibitory effect of nipradilol on cultured rat vascular smooth muscle cell (VSMC) growth. After being starved, cultured VSMCs were stimulated by 5% fetal bovine serum with various concentrations of nipradilol. Nipradilol dose-dependently decreased the values of [(3)H]-thymidine incorporation, cell numbers and total cellular protein content, and the levels of phosphorylated extracellular signal-regulated protein kinase 1/2 and p38. It also suppressed the level of proliferative cell nuclear antigen in a dose-dependent manner. In contrast, nipradilol did not change the level of the phosphorylated value of c-jun NH(2)-terminal protein kinase or cytoplasmic histone-associated DNA fragments in VSMCs. These results indicate that nipradilol suppresses cell growth without apoptosis in rat VSMCs, suggesting that it could be effective for preventing the progression of restenosis after angioplasty.
    Journal of atherosclerosis and thrombosis 02/2003; 10(4):226-33. · 2.93 Impact Factor
  • Atherosclerosis Supplements - ATHEROSCLER SUPPL. 01/2003; 4(2):210-210.
  • Atherosclerosis Supplements - ATHEROSCLER SUPPL. 01/2003; 4(2):208-208.