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在糖尿病小鼠模型中免疫蛋白酶体参与调节心肌大小的证据 |
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Evidence for a role of immunoproteasomes in regulating cardiac muscle mass in diabetic mice |
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Zu L, Bedja D, Fox-Talbot K, Gabrielson KL, Van Kaer L, Becker LC, Cai ZP 2010/7/1 11:56:00 |
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Journal of Molecular and Cellular Cardiology, 2010, Volume 49, Issue 1
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The ubiquitin-proteasome system plays an important role in regulating muscle mass. Inducible immunoproteasome subunits LMP-2 and LMP-7 are constitutively expressed in the heart; however, their regulation and functions are poorly understood. We here investigated the hypothesis that immunoproteasomes regulate cardiac muscle mass in diabetic mice. Type 1 diabetes was induced in wildtype mice by streptozotocin. After hyperglycemia developed, insulin and the proteasome inhibitor epoxomicin were used to treat diabetic mice for 6. weeks. Isolated mouse hearts were perfused with control or high glucose solution. Catalytic proteasome β-subunits and proteolytic activities were analyzed in the heart by immunoblotting and fluorogenic peptide degradation assays, respectively. Insulin and epoxomicin blocked loss of heart weight and improved cardiac function in diabetic mice. LMP-7 and its corresponding chymotryptic-like proteasome activity were increased in diabetic hearts and high glucose-treated hearts. Myosin heavy chain protein was decreased in diabetic hearts, which was largely reversed by epoxomicin. High glucose decreased LMP-2 protein levels in perfused hearts. In diabetic hearts, LMP-2 expression was downregulated whereas expression of the phosphatase and tensin homologue deleted on chromosome ten (PTEN) and the muscle atrophy F-box were upregulated. Moreover, mice with muscle-specific knockout of PTEN gene demonstrated increased cardiac muscle mass, while mice with LMP-2 deficiency demonstrated PTEN accumulation, muscle mass loss, and contractile impairment in the heart. Therefore, we concluded that high glucose regulates immunoproteasome subunits and modifies proteasome activities in the heart, and that dysregulated immunoproteasome subunits may mediate loss of cardiac muscle mass in experimental diabetic mice. © 2010 Elsevier .
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Correspondence Address: Cai, Z.P.; Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, 720 Rutland Avenue, Ross 333, Baltimore, MD 21205, United States; email:czheqin1@jhmi.edu |
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疾病资源中心
王燕燕 王曙
上海交通大学附属瑞金医院内分泌科
患者,女,69岁。2009年1月无明显诱因下出现乏力,当时程度较轻,未予以重视。2009年3月患者乏力症状加重,尿色逐渐加深,大便习惯改变,颜色变淡。4月18日入我院感染科治疗,诉轻度头晕、心慌,体重减轻10kg。无肝区疼痛,无发热,无腹痛、腹泻、腹胀、里急后重,无恶性、呕吐等。入院半月前于外院就诊,查肝功能:ALT 601IU/L,AST 785IU/L,TBIL 97.7umol/L,白蛋白 41g/L,甲状腺功能:游离T3 30.6pmol/L,游离T4 51.9pmol/L,心电图示快速房颤。
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