Development of novel diagnostic and therapeutic strategies for obesity and insulin resistance by identification of endogenous PPARγ ligands

我们的基因敲除小鼠研究揭示，PPARgamma是脂肪细胞分化所绝对需要的（Mol. Cell. 4：597，1999），并且IRS-1和IRS-2在PPAR γ表达和脂肪细胞分化的上调中起关键作用（Mol. Cell. 21：2521，2001）。噻唑烷二酮（TZD）通过增加小尺寸脂肪细胞的数量和减少肥大脂肪细胞来改善胰岛素抵抗（J.Clin.Invest. 101：1354，1998），其与引起胰岛素抗性的分子减少（J.Biol.Chem. 276：41245，2001）以及胰岛素增敏激素脂联素增加（J.Biol.Chem. 277：25863，2002）有关。脂联素的胰岛素增敏作用似乎是通过AMP激酶（Nature Medicine 8：1288，2002）和PPARα（J.Biol.Chem. 278：2461，2003）的活化而增加脂肪酸氧化，从而降低TG含量（Nature Medicine 7：941，2001）来介导的。出乎意料的是，杂合子CBP基因敲除小鼠的胰岛素分泌增加， 关于我们 n敏感性，尽管脂肪营养不良。杂合CBP敲除小鼠也显示出胰岛素增敏激素如瘦素和脂联素的作用增加，这些可以至少部分地解释杂合CBP敲除小鼠的表型（Nature Genetics 30：221，2002）。Ala等位基因降低PPARgamma活性的受试者与2型糖尿病抵抗相关（BBRC）。271：212，2000）。PPARgamma拮抗剂保护KKA-γ小鼠免于肥胖、胰岛素抗性和2型糖尿病（J.Clin.Invest. 108：1001，2001）。PPARgamma辅激活因子PGC（PPARgamma辅激活因子）-1基因的遗传变异可赋予胰岛素抵抗和对2型糖尿病的易感性（Diabetologja. 45：740，2002）。与较低血浆脂联素水平相关的脂联素SNP具有较高的胰岛素抵抗指数，并且还显著增加了2型糖尿病（Diabetes. 51：536，2002）。最后，我们试图鉴定内源性PPARgamma配体，因为PPARgamma配体可能参与胰岛素敏感性。目前使用HPLC的分级分离研究表明活性为单峰，表明有一种或很少几种组分。该活性的色谱行为表明其不等同于15-脱氧-12，14-PGJ 2。结构测定将揭示这种分子的生物化学性质，并为其生物合成调节的研究打开大门。少

Our knockout mice studies revealed that PPARgamma was absolutely required for adipocyte differentiation (Mol. Cell. 4:597, 1999), and that IRS-1 and IRS-2 played a crucial role in the upregulation of the PPARgamma expression and adipocyte differentiation (Mol. Cell. Biol. 21:2521, 2001). Thiazolidinediones (TZD) ameliorated insulin resistance by increasing the number of small size adipocytes and decreasing hypertrophic adipocytes (J.Clin.Invest. 101:1354, 1998), which was associated with decreased molecules causing insulin resistance (J.Biol.Chem. 276: 41245, 2001) and also increased insulin senisitizing hormone adiponectin (J.Biol.Chem. 277: 25863, 2002). Insulin sensitizing effect of adiponectin appears to be mediated by an increase in fatty acid oxidation via activation of AMP kinase (Nature Medicine 8:1288, 2002) and PPARα (J.Biol.Chem. 278: 2461, 2003), thereby decreasing TG content (Nature Medicine 7:941, 2001). Unexpectedly, heterozygous CBP knockout mice showed increased insuli … More n sensitivity despite lipodystrophy. Heterozygous CBP knockout mice also showed increased effects of insulin sensitizing hormones such as leptin and adiponectin, and these may explain the phenotypes of heterozygous CBP knockout mice at least in part (Nature Genetics 30:221, 2002).We identified a SNP (Pro12Ala) of human PPARgamma gene. Subjects with Ala allele decreasing PPARgamma activity were associated with resistance to type 2 diabetes (BBRC. 271:212, 2000). PPARgamma antagonist protected against obesity, insulin resistance and type 2 diabetes of KKA^y mice (J.Clin.Invest. 108:1001, 2001). A genetic variation in the PPARgamma coactivator PGC (PPARgamma coactivator)-1 gene could confer insulin resistance and susceptibility to Type 2 diabetes (Diabetologja. 45:740, 2002). The adiponectin SNP associated with lower plasma adiponectin levels had a higher insulin resistance index and also a significantly increased risk of type 2 diabetes (Diabetes. 51:536,2002).Finally, we tried to identify the endogenous PPARgamma ligands, because PPARgamma ligands potentially can be involved in insulin sensitivity. Current fractionation studies using HPLC suggest a single peak of activity, indicating one or very few components. The chromatographic behavior of this activity indicates that it is not equivalent to 15-deoxy-12,14-PGJ2. Structural determination will shed light on the biochemical nature of this molecule and open the door to the study of its biosynthetic regulation. Less