Role of Gs-alpha in pancreatic islet cell growth and function

Gs-α 在胰岛细胞生长和功能中的作用

• 批准号: 8741447
• 负责人: Lee Weinstein
• 金额: $ 7.45万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8741447
• 关键词: Address; Adult; Alpha Cell; Apoptosis; Architecture; Beta Cell; Birth; Body Weight; Cell Line; Cell Proliferation; Cell physiology; Cells; Cyclic AMP; Development; Diabetes Mellitus; Duct (organ) structure; Exocrine pancreas; Exons; Functional disorder; GTP-Binding Protein alpha Subunits, Gs; Genes; Genetic Recombination; Glucagon; Glucose; Glucose Intolerance; Growth; Hyperglycemia; Insulin; Islet Cell; Islets of Langerhans; Lead; Life; Malabsorption Syndromes; Mediating; Mus; Rattus; Regulation; Role; Signal Pathway; Signal Transduction; Site; Structure of alpha Cell of islet; Therapeutic; Transgenic Mice; cell growth; cyclin D2; glucagon-like peptide; human IRS2 protein; impaired glucose tolerance; in vivo; incretin hormone; insulin sensitivity; islet; mouse model; postnatal; promoter; recombinase

We generated mice with Gs-alpha deficiency in beta cells (betaGsKO mice) by repeated matings of rat insulin II promoter-cre recombinase transgenic mice with floxed Gs-alpha mice which have loxP recombination sites surrounding Gs-alpha exon 1. BetaGsKO mice have very poor survival during the first several weeks of life in most cases associated with hyperglycemia and in addition had very poor postnatal growth. Studies in adult mice showed that betaGsKO mice had severe hyperglycemia and glucose intolerance despite having greater than normal insulin sensitivity. Impaired glucose tolerance was due to the fact that these mice were hypoinsulinemic, with reduced islet insulin content and glucose-stimulated insulin release. Although islet architecture was maintained, betaGsKO mice had significantly reduced beta cell mass with reduced beta cell proliferation and increased beta cell apoptosis. Studies on younger mice show that beta cell proliferation is reduced from birth. Although studies have suggested that Gs-cAMP mediates these effects on beta cell growth, survival, and insulin release by stimulating insulin receptor substrate 2 (Irs2) expression, we observed no change in expression of Irs2 or Pdx1, a beta cell growth gene which is induced by Irs2 signaling. Rather, there was a specific reduction in cyclin D2 expression. More recently we have made a second mouse line with beta-cell Gs-alpha deficiency using Pdx1-cre. These mice have Gs-deficiency throughout the endocrine and exocrine pancreas. Results show these mice to also develop severe insulin-deficient diabetes. However these mice have more or less normal survival and there is a greater proportion of pancreatic alpha-cells in the islets with no evidence for reduced proliferation of these cells. Moreover studies in an alpha-cell line showed evidence that Gs-alpha leads to reduced proliferation of these cells, indicating that Gs-alpha may have opposite effects on proliferation of alpha- and beta-cells, respectively. The exocrine pancreas was abnormal with enlarged ducts with large eosinophic cells, which may lead to GI malabsorption. We have most recently generated mice with Gs-alpha deficiency limited to alpha cells using a glucagon-cre transgenic mouse to examine the effects on alpha cells directly. Initial results in these mice show no obvious effects on body weight but there is an increase in glucagon levels and islet size and mass. Effects on pancreatic alpha-cell mass are underway.

我们通过重复的大鼠胰岛素II启动子-CRE-CRE重组酶转基因酶转基因酶转基因酶转基因小鼠的β细胞（betagsko小鼠）中的GS-Alpha缺乏症产生了小鼠，这些小鼠具有Floxed GS-Alpha小鼠，这些小鼠具有LOXP重新组合位点，这些小鼠与GS-Alpha Exon 1。蛋白1.Betagsko小鼠相关的均可及其在第一个数周的生存中，并且在大多数周期内生存了几周的生命。产后生长很差。在成年小鼠中的研究表明，尽管胰岛素敏感性高于正常胰岛素敏感性，但β小鼠尽管患有严重的高血糖和葡萄糖不耐症。葡萄糖耐受性受损是由于这些小鼠是低胰岛素，胰岛素含量降低和葡萄糖刺激的胰岛素释放。尽管保持了胰岛结构，但β小鼠的β细胞量显着降低，β细胞增殖降低并增加了β细胞凋亡。对年轻小鼠的研究表明，β细胞增殖从出生开始减少。尽管研究表明，GS-cAMP通过刺激胰岛素受体底物2（IRS2）表达介导了这些对β细胞生长，存活和胰岛素释放的影响，但我们观察到IRS2或PDX1的表达没有变化，IRS2或PDX1是一种β细胞生长基因，这是由IRS2信号引起的。相反，细胞周期蛋白D2表达的特异性降低。最近，我们使用PDX1-CRE制作了第二个用Beta-Cell GS-Alpha缺乏症的小鼠线。这些小鼠在整个内分泌和外分泌胰腺中具有GS缺乏。结果表明，这些小鼠还会发展出严重的胰岛素缺陷型糖尿病。但是，这些小鼠具有或多或少的正常存活率，胰岛中胰腺细胞的比例较大，没有证据表明这些细胞的增殖降低。此外，在Alpha细胞系中的研究表明，GS-Alpha导致这些细胞的增殖减少，表明GS-Alpha分别对α-和β细胞的增殖有相反的影响。外分泌胰腺异常患有大型嗜酸性细胞的导管，这可能导致胃肠道吸收吸收不良。我们最近使用胰高血糖素CRE转基因小鼠限制了具有GS-Alpha缺乏症的小鼠，限于α细胞，以直接检查对α细胞的影响。这些小鼠的初始结果对体重没有明显的影响，但是胰高血糖素水平和胰岛尺寸和质量也有所增加。 对胰腺α细胞质量的影响正在进行中。