生长激素在脂肪组织中的作用:来自脂肪特异性生长激素受体基因敲除小鼠的启示。
The role of GH in adipose tissue: lessons from adipose-specific GH receptor gene-disrupted mice.
作者信息
List Edward O, Berryman Darlene E, Funk Kevin, Gosney Elahu S, Jara Adam, Kelder Bruce, Wang Xinyue, Kutz Laura, Troike Katie, Lozier Nicholas, Mikula Vincent, Lubbers Ellen R, Zhang Han, Vesel Clare, Junnila Riia K, Frank Stuart J, Masternak Michal M, Bartke Andrzej, Kopchick John J
机构信息
Edison Biotechnology Institute, Athens, OH 45701, USA.
出版信息
Mol Endocrinol. 2013 Mar;27(3):524-35. doi: 10.1210/me.2012-1330. Epub 2013 Jan 24.
GH receptor (GHR) gene-disrupted mice (GHR-/-) have provided countless discoveries as to the numerous actions of GH. Many of these discoveries highlight the importance of GH in adipose tissue. For example GHR-/- mice are insulin sensitive yet obese with preferential enlargement of the sc adipose depot. GHR-/- mice also have elevated levels of leptin, resistin, and adiponectin, compared with controls leading some to suggest that GH may negatively regulate certain adipokines. To help clarify the role that GH exerts specifically on adipose tissue in vivo, we selectively disrupted GHR in adipose tissue to produce Fat GHR Knockout (FaGHRKO) mice. Surprisingly, FaGHRKOs shared only a few characteristics with global GHR-/- mice. Like the GHR-/- mice, FaGHRKO mice are obese with increased total body fat and increased adipocyte size. However, FaGHRKO mice have increases in all adipose depots with no improvements in measures of glucose homeostasis. Furthermore, resistin and adiponectin levels in FaGHRKO mice are similar to controls (or slightly decreased) unlike the increased levels found in GHR-/- mice, suggesting that GH does not regulate these adipokines directly in adipose tissue in vivo. Other features of FaGHRKO mice include decreased levels of adipsin, a near-normal GH/IGF-1 axis, and minimal changes to a large assortment of circulating factors that were measured such as IGF-binding proteins. In conclusion, specific removal of GHR in adipose tissue is sufficient to increase adipose tissue and decrease circulating adipsin. However, removal of GHR in adipose tissue alone is not sufficient to increase levels of resistin or adiponectin and does not alter glucose metabolism.
生长激素受体(GHR)基因敲除小鼠(GHR-/-)为生长激素的众多作用带来了无数发现。其中许多发现突出了生长激素在脂肪组织中的重要性。例如,GHR-/-小鼠对胰岛素敏感,但肥胖,且肩胛下脂肪库优先增大。与对照组相比,GHR-/-小鼠的瘦素、抵抗素和脂联素水平也升高,这使得一些人认为生长激素可能对某些脂肪因子具有负调节作用。为了帮助阐明生长激素在体内对脂肪组织的具体作用,我们选择性地敲除脂肪组织中的GHR,以产生脂肪生长激素受体敲除(FaGHRKO)小鼠。令人惊讶的是,FaGHRKO小鼠与全身性GHR-/-小鼠仅具有一些共同特征。与GHR-/-小鼠一样,FaGHRKO小鼠肥胖,全身脂肪增加,脂肪细胞大小增加。然而,FaGHRKO小鼠所有脂肪库均增大,葡萄糖稳态指标无改善。此外,FaGHRKO小鼠的抵抗素和脂联素水平与对照组相似(或略有下降),这与GHR-/-小鼠中发现的水平升高不同,表明生长激素在体内不会直接调节脂肪组织中的这些脂肪因子。FaGHRKO小鼠的其他特征包括脂肪酶水平降低、生长激素/胰岛素样生长因子-1轴接近正常,以及所检测的大量循环因子(如胰岛素样生长因子结合蛋白)变化极小。总之,特异性去除脂肪组织中的GHR足以增加脂肪组织并降低循环脂肪酶水平。然而,仅去除脂肪组织中的GHR不足以提高抵抗素或脂联素水平,也不会改变葡萄糖代谢。