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| 通过作用于击垮胰岛素受体底物1的3T3- F442A前脂肪细胞中的SHC和ERK中断生长激素信号 |
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| Interruption of growth hormone signaling via SHC and ERK in 3T3-F442A preadipocytes upon knockdown of insulin receptor substrate-1 |
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| Wang X., Yang N., Deng L., Li X., Jiang J., Gan Y., Frank S.J. 2009/5/29 18:38:56 |
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Molecular Endocrinology, 2009, Volume 23, Issue 4
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| Insulin receptor substrate-1 (IRS-1) is a docking protein tyrosine phosphorylated in response to insulin, IGF-1, GH, and other cytokines. IRS-1 has an N-terminal plekstrin homology domain (which facilitates membrane localization), a phosphotyrosine-binding domain [which associates with tyrosine-phosphorylated insulin receptor or IGF-1 receptor (IGF-1R)], and tyrosine residues that, when phosphorylated, bind signaling molecules. The role of IRS-1 in GH signaling is uncertain. We previously reported that IRS-1 and Janus kinase 2 associate independently of tyrosine phosphorylation via IRS-1's N terminus and that IRS-1 reconstitution greatly enhances GH-induced ERK, but not STAT5, activation. We now use GH-responsive 3T3-F442A preadipocytes to study the influence of IRS-1 on GH action. We stably transfected cells with vector only (Control) or a vector encoding IRS-1 short hairpin RNA [knockdown (KD)] and compared representative clones. Immunoblotting confirmed more than 80% knockdown of IRS-1 in KD cells. GH caused characteristic Janus kinase 2 and STAT5 activation in both Control and KD cells, but ERK activation was dramatically reduced in KD cells in GH time course and dose-response experiments. Notably, GH-induced Src homology collagen (SHC) activation and SHC-Grb2 association in KD cells were also markedly diminished compared with Control cells. Subcellular fractionation revealed that IRS-1 in Control cells was largely cytosolic, but the component isolated with plasma membranes was highly enriched in lipid raft membranes (LR). In KD cells, GH-induced ERK activation in the LR fraction was particularly diminished compared with Control cells. These data suggest that LR-enriched IRS-1 contributes substantiallyto GH-induced ERK activation in LRin3T3-F442A fibroblasts. Furthermore, our results are consistent with IRS-1 residing upstream of SHC in the GH-induced ERK-signaling pathway. (Molecular Endocrinology 23: 486-496, 2009) Copyright © 2009 by The Endocrine Society. |
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| Correspondence Address: Frank, S. J.; University of Alabama at Birmingham, 1530 Third Avenue South, BDB 861, Birmingham, AB 35294-0012; email: sjfrank@uab.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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