Obestatin promotes survival of pancreatic β-cells and human islets and induces expression of genes involved in the regulation of β-cell mass and function
Obestatin promotes survival of pancreatic β-cells and human islets and induces expression of genes involved in the regulation of β-cell mass and function
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DOI：
10.2337/db07-1104
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发表时间：
2008-04-01
期刊：
影响因子：
7.7
通讯作者：
Ghigo, Ezio
中科院分区：
文献类型：
--
作者：
Granata, Riccarda;Settanni, Fabio;Ghigo, Ezio
Obestatin是一种新发现的由ghrelin基因编码的多肽，其生物学功能尚不清楚。我们研究了obestatin对β-细胞和人胰岛存活的影响以及潜在的信号传导途径。研究设计和方法-β-细胞和人胰岛用于评估obestatin对细胞增殖、存活、凋亡、细胞内信号传导和基因表达的影响。与胰高血糖素样肽-1受体（GLP-1 R）结合，并识别生长素释放肽结合位点。Obestatin在血清剥夺条件下和干扰素-γ/肿瘤坏死因子-α/白细胞介素-1 β治疗下发挥增殖、存活和抗凋亡作用，特别是在药理学浓度下。生长激素释放肽受体拮抗剂[D-Lys（3）]-生长激素释放肽-6和抗生长激素释放肽抗体阻止了β细胞和人胰岛中肥胖素诱导的存活。β-细胞和胰岛细胞释放肥胖抑制素，并且抗肥胖抑制素抗体的添加降低了它们的活力。Obestatin增加β细胞cAMP并激活细胞外信号相关激酶1/2（ERK 1/2）和磷脂酰肌醇3-激酶（PI 3-kinase）/Akt，其抗凋亡作用可通过抑制腺苷酸环化酶/cAMP/蛋白激酶A（PKA）、PI 3-kinase/Akt和ERK 1/2信号传导而被阻断。此外，obestatin上调GLP-1 R mRNA和胰岛素受体底物-2（IRS-2）的表达和磷酸化。GLP-1 R拮抗剂exendin-（9-39）降低了obestatin对β细胞存活的影响。在人类胰岛中，obestatin，其免疫反应性与ghrelin共定位，促进细胞存活，并通过cAMP增加和参与腺苷酸环化酶/cAMP/PKA信号转导阻断甘氨酸诱导的细胞凋亡。此外，obestatin 1）诱导P13-kinase/Akt、ERK 1/2以及cAMP反应元件结合蛋白磷酸化，2）刺激胰岛素分泌和基因表达;和3）GLP-1 R、IRS-2、胰腺和十二指肠同源框-1上调，结论：这些结果表明，obestatin促进β细胞和人胰岛细胞的存活，并刺激主要的调节β-葡萄糖激酶mRNA的表达。细胞基因，确定这种肽在胰腺内分泌的新作用。
OBJECTIVE - Obestatin is a newly discovered peptide encoded by the ghrelin gene whose biological functions are poorly understood. We investigated obestatin effect on survival of beta-cells and human pancreatic islets and the underlying signaling pathways.RESEARCH DESIGN AND METHODS - beta-Cells and human islets were used to assess obestatin effect on cell proliferation, survival, apoptosis, intracellular signaling, and gene expression.RESULTS - Obestatin showed specific binding on HIT-T15 and INS-IE beta-cells, bound to glucagon-like peptide-1 receptor (GLP-1R), and recognized ghrelin binding sites. Obestatin exerted proliferative, survival, and antiapoptotic effects under serum-deprived conditions and interferon-gamma/tumor necrosis factor-alpha/interleukin-1 beta treatment, particularly at pharmacological concentrations. Ghrelin receptor antagonist [D-Lys(3)]-growth hormone releasing peptide-6 and anti-ghrelin antibody prevented obestatin-induced survival in beta-cells and human islets. beta-Cells and islet cells released obestatin, and addition of anti-obestatin antibody reduced their viability. Obestatin increased beta-cell cAMP and activated extracellular signal-related kinase 1/2 (ERK1/2) and phosphatidylinositol 3-kinase (PI 3-kinase)/Akt,; its antiapoptotic effect was blocked by inhibition of adenylyl cyclase/cAMP/protein kinase A (PKA), PI 3-kinase/Akt, and ERK1/2 signaling. Moreover, obestatin upregulated GLP-1R mRNA and insulin receptor substrate-2 (IRS-2) expression and phosphorylation. The GLP-1R antagonist exendin-(9-39) reduced obestatin effect on beta-cell survival. In human islets, obestatin, whose immunoreactivity colocalized with that of ghrelin, promoted cell survival and blocked cytokine-induced apoptosis through cAMP increase and involvement of adenylyl cyclase/cAMP/PKA signaling. Moreover, obestatin 1) induced Pl 3-kinase/Akt, ERK1/2, and also cAMP response element-binding protein phosphorylation; 2) stimulated insulin secretion and gene expression; and 3) upregulated GLP-1R, IRS-2, pancreatic and duodenal homeobox-1, and glucokinase mRNA.CONCLUSIONS - These results indicate that obestatin promotes beta-cell and human islet cell survival and stimulates the expression of main regulatory beta-cell genes, identifying a new role for this peptide within the endocrine pancreas.