1] Center for Food and Nutritional Genomics Research, Department of Food Science and Nutrition, Kyungpook National University, Daegu, Republic of Korea [2] Institute for Innovation in Biology, School of Biological Sciences, University of Auckland, Auckland, New Zealand.
Int J Obes (Lond). 2013 Dec;37(12):1524-31. doi: 10.1038/ijo.2013.52. Epub 2013 Apr 3.
The aim of this study was to establish the time-course of molecular events in intrascapular brown adipose tissue (iBAT) during the development of diet-induced obesity using microarrays and molecular network analysis.
C57BL/6J male inbred mice were fed a high-fat diet (HFD) or normal diet (ND) and killed at multiple time-points over 24 weeks.
Global transcriptional changes in iBAT were determined by time-course microarrays of pooled RNA (n=6, pools per time-point) at 2, 4, 8, 20 and 24 weeks using Illumina MouseWG-6 v2.0 Beadchips. Molecular networks were constructed using the Ingenuity knowledgebase based on differentially expressed genes at each time-point.
Body weight and subcutaneous adipose were progressively increased over 24 weeks, whereas iBAT was significantly increased between 6 and 12 weeks in HFD-fed C57BL/6J mice compared with controls. Blood glucose and insulin levels were increased between 16 and 24 weeks. Time-course microarrays, revealed 155 differentially expressed genes at one or more time-points over 24 weeks in the iBAT of HFD-fed mice compared with controls. Time-course network analysis revealed a network of skeletal muscle development genes that was activated between 2 and 4 weeks, subsequently a network of immune trafficking genes was activated at 8 weeks. After 20 and 24 weeks, multiple lipid metabolism and immune response networks were activated. Several target genes identified by time-course microarrays were independently validated using RT-qPCR. Tnnc1 was upregulated early between 2 and 4 weeks, later Cd68 and Col1a1 were upregulated between 20 and 24 weeks, whereas 11β-hydroxysteroid dehydrogenase (Hsd11b1) was consistently downregulated during the development of diet-induced obesity.
Molecular networks in iBAT are modulated in a time-dependent manner in response to a HFD. A broad range of gene targets exists to alter molecular changes within iBAT during the development of diet-induced obesity.
本研究旨在使用微阵列和分子网络分析，确定在高脂肪饮食诱导肥胖发展过程中肩胛间棕色脂肪组织（iBAT）中分子事件的时程。
C57BL/6J 雄性近交系小鼠喂食高脂肪饮食（HFD）或正常饮食（ND），并在 24 周内的多个时间点处死。
通过 Illumina MouseWG-6 v2.0 Beadchips 对 pooled RNA（n=6，每个时间点的 pool）进行时间过程微阵列分析，确定 iBAT 的全局转录变化，使用 Illumina MouseWG-6 v2.0 Beadchips。根据每个时间点差异表达的基因，使用 Ingenuity 知识库构建分子网络。
在 24 周内，体重和皮下脂肪逐渐增加，而 HFD 喂养的 C57BL/6J 小鼠的 iBAT 在 6 至 12 周时与对照组相比显著增加。血糖和胰岛素水平在 16 至 24 周之间升高。时间过程微阵列分析显示，与对照组相比，HFD 喂养的小鼠 iBAT 在 24 周内的一个或多个时间点有 155 个差异表达基因。时间过程网络分析显示，2 至 4 周时激活了骨骼肌发育基因网络，随后 8 周时激活了免疫运输基因网络。在 20 至 24 周时，多个脂质代谢和免疫反应网络被激活。使用 RT-qPCR 独立验证了时间过程微阵列鉴定的几个靶基因。Tnnc1 在 2 至 4 周之间早期上调，随后在 20 至 24 周之间 Cd68 和 Col1a1 上调，而 11β-羟甾脱氢酶（Hsd11b1）在饮食诱导肥胖的发展过程中一直下调。
HFD 诱导肥胖时，iBAT 中的分子网络以时间依赖的方式调节。在饮食诱导肥胖发展过程中改变 iBAT 内分子变化存在广泛的基因靶标。
