Zhang Qian, Koser Stephanie L, Donkin Shawn S
Department of Animal Sciences, Purdue University, West Lafayette 47907.
Department of Animal Sciences, Purdue University, West Lafayette 47907.
J Dairy Sci. 2016 May;99(5):3908-3915. doi: 10.3168/jds.2015-10312.
Hepatocytes monolayers from neonatal calves were used to determine the responses of the cytosolic phosphoenolpyruvate carboxykinase (PCK1) mRNA expression to propionate and direct hormonal cues including cyclic AMP (cAMP), dexamethasone, and insulin. The responses of other key gluconeogenic genes, including mitochondrial phosphoenolpyruvate carboxykinase (PCK2), pyruvate carboxylase (PC), and glucose-6-phosphotase (G6PC), were also measured. Expression of PCK1 was linearly induced with increasing propionate concentrations in media and 2.5 mM propionate increased PCK1 mRNA at 3 and 6h of incubation; however, the induction disappeared at 12 and 24 h. The induction of PCK1 mRNA by propionate was mimicked by 1 mM cAMP, or in combination with 5 µM dexamethasone, but not by dexamethasone alone. The induction of PCK1 mRNA by propionate or cAMP was eliminated by addition of 100 nM insulin. Additionally, expression of PCK2 and PC mRNA was also induced by propionate in a concentration-dependent manner. Consistent with PCK1, propionate-stimulated PCK2 and PC mRNA expression was inhibited by insulin. Expression of G6PC mRNA was neither affected by propionate nor cAMP, dexamethasone, insulin, or their combinations. These findings demonstrate that propionate can directly regulate its own metabolism in bovine calf hepatocytes through upregulation of PCK1, PCK2, and PC mRNA expression.
利用新生小牛的肝细胞单层来确定胞质磷酸烯醇式丙酮酸羧激酶（PCK1）mRNA表达对丙酸以及包括环磷酸腺苷（cAMP）、地塞米松和胰岛素在内的直接激素信号的反应。还测量了其他关键糖异生基因的反应，包括线粒体磷酸烯醇式丙酮酸羧激酶（PCK2）、丙酮酸羧化酶（PC）和葡萄糖-6-磷酸酶（G6PC）。随着培养基中丙酸浓度的增加，PCK1的表达呈线性诱导，2.5 mM丙酸在孵育3小时和6小时时增加了PCK1 mRNA；然而，在12小时和24小时时诱导作用消失。1 mM cAMP或与5 μM地塞米松联合使用可模拟丙酸对PCK1 mRNA的诱导作用，但单独使用地塞米松则不能。添加100 nM胰岛素可消除丙酸或cAMP对PCK1 mRNA的诱导作用。此外，丙酸也以浓度依赖的方式诱导PCK2和PC mRNA的表达。与PCK1一致，胰岛素抑制了丙酸刺激的PCK2和PC mRNA表达。G6PC mRNA的表达既不受丙酸、cAMP、地塞米松、胰岛素的影响，也不受它们组合的影响。这些发现表明，丙酸可通过上调PCK1、PCK2和PC mRNA的表达，直接调节小牛肝细胞自身的代谢。
