Leucine Affects α-Amylase Synthesis through PI3K/Akt-mTOR Signaling Pathways in Pancreatic Acinar Cells of Dairy Calves
Leucine Affects α-Amylase Synthesis through PI3K/Akt-mTOR Signaling Pathways in Pancreatic Acinar Cells of Dairy Calves
复制标题
亮氨酸通过 PI3K/Akt-mTOR 信号通路影响奶牛胰腺腺泡细胞中 α-淀粉酶的合成
DOI：
10.1021/acs.jafc.8b01111
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发表时间：
2018-05-23
影响因子：
6.1
通讯作者：
Yao, Junhu
中科院分区：
文献类型：
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作者：
Guo, Long;Liang, Ziqi;Yao, Junhu
由于α -淀粉酶的缺乏，奶牛小肠的消化可能会限制饲粮营养物质的利用，尤其是淀粉的利用。亮氨酸是mTOR信号通路中有效的信号分子，调控一系列生物过程，尤其是蛋白质合成。有报道称亮氨酸可影响反刍动物胰腺α -淀粉酶的合成和分泌，但其作用机制尚未阐明。本研究以胰腺腺泡细胞（PA）为模型，测定亮氨酸对α -淀粉酶合成的影响。从新生荷斯坦奶牛犊牛中分离PA细胞，在含有4种亮氨酸处理（分别为0、0.23、0.45和0.90 mM）的Dulbecco改良Eagle培养基/营养混合物F12液体培养基中培养，检测α -淀粉酶活性、酶原颗粒和信号通路因子表达。雷帕霉素，mTOR的特异性抑制剂，也应用于PA细胞。结果表明，亮氨酸增加了α -淀粉酶的合成（p < 0.05）以及PI3K、Akt、mTOR和S6K1的磷酸化（p < 0.05），降低了GCN2的表达（p < 0.05）。抑制mTOR信号可以下调α -淀粉酶的合成。此外，细胞外亮氨酸剂量显著影响异亮氨酸细胞内代谢（p < 0.05）。总体而言，亮氨酸通过促进犊牛PA细胞中PI3K/Akt-mTOR通路和降低GCN2通路调节α -淀粉酶合成。这些途径形成了控制蛋白质合成和代谢的信号网络。探索亮氨酸在反刍动物营养中的作用是今后研究的热点。
Dietary nutrient utilization, particularly starch, is potentially limited by digestion in dairy cow small intestine because of shortage of alpha-amylase. Leucine acts as an effective signal molecular in the mTOR signaling pathway, which regulates a series of biological processes, especially protein synthesis. It has been reported that leucine could affect alpha-amylase synthesis and secretion in ruminant pancreas, but mechanisms have not been elaborated. In this study, pancreatic acinar (PA) cells were used as a model to determine the cellular signal of leucine influence on alpha-amylase synthesis. PA cells were isolated from newborn Holstein dairy bull calves and cultured in Dulbecco's modifed Eagle's medium/nutrient mixture F12 liquid media containing four leucine treatments (0, 0.23, 0.45, and 0.90 mM, respectively), following alpha-amylase activity, zymogen granule, and signal pathway factor expression detection. Rapamycin, a specific inhibitor of mTOR, was also applied to PA cells. Results showed that leucine increased (p < 0.05) synthesis of alpha-amylase as well as phosphorylation of PI3K, Akt, mTOR, and S6K1 while reduced (p < 0.05) GCN2 expression. Inhibition of mTOR signaling downregulated the alpha-amylase synthesis. In addition, the extracellular leucine dosage significantly influenced intracellular metabolism of isoleucine (p < 0.05). Overall, leucine regulates alpha-amylase synthesis through promoting the PI3K/Akt-mTOR pathway and reducing the GCN2 pathway in PA cells of dairy calves. These pathways form the signaling network that controls the protein synthesis and metabolism. It would be of great interest in future studies to explore the function of leucine in ruminant nutrition.