Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-7088, USA.
Metab Eng. 2010 Jul;12(4):332-40. doi: 10.1016/j.ymben.2010.04.001. Epub 2010 Apr 20.
Glycerol kinase (GK) is an enzyme with diverse (moonlighting) cellular functions. GK overexpression affects central metabolic fluxes substantially; therefore, to elucidate the mechanism underlying these changes, we employed a systems-level evaluation of GK overexpression in H4IIE rat hepatoma cells. Microarray analysis revealed altered expression of genes in metabolism (central carbon and lipid), which correlated with previous flux analysis, and of genes regulated by the glucocorticoid receptor (GR). Oil Red O staining showed that GK overexpression leads to increased fat storage in H4IIE cells. Network component analysis revealed that activities of peroxisome proliferator-activated receptor alpha, GR, and seven other transcription factors were altered by GK overexpression. The increased activity of GR was experimentally verified by quantitative RT-PCR of GR-responsive genes in the presence and absence of the glucocorticoid agonist, dexamethasone. This systems biology approach further emphasizes GK's essential role in central and lipid metabolism and experimentally verifies GK's alternative (moonlighting) function of affecting GR transcription factor activity.
甘油激酶 (GK) 是一种具有多种（兼职）细胞功能的酶。GK 的过度表达会显著影响中央代谢通量；因此，为了阐明这些变化的机制，我们采用了系统水平的方法来评估 GK 在 H4IIE 大鼠肝癌细胞中的过度表达。微阵列分析显示，代谢（中央碳和脂质）相关基因以及受糖皮质激素受体 (GR) 调节的基因表达发生改变。油红 O 染色显示，GK 的过度表达导致 H4IIE 细胞中脂肪储存增加。网络组件分析显示，过氧化物酶体增殖物激活受体 α、GR 和其他七个转录因子的活性被 GK 的过度表达改变。GR 活性的增加通过定量 RT-PCR 实验在存在和不存在糖皮质激素激动剂地塞米松的情况下验证了 GR 应答基因的变化。这种系统生物学方法进一步强调了 GK 在中央和脂质代谢中的重要作用，并通过实验验证了 GK 影响 GR 转录因子活性的替代（兼职）功能。
