The liver is the most essential organ for the metabolism of ammonia, in where most of ammonia is removed by urea and glutamine synthesis. Regulated by leucine, glutamate dehydrogenase(GDH) catalyzes the reversible int...The liver is the most essential organ for the metabolism of ammonia, in where most of ammonia is removed by urea and glutamine synthesis. Regulated by leucine, glutamate dehydrogenase(GDH) catalyzes the reversible inter-conversion of glutamate to ammonia. To determine the mechanism of leucine regulating GDH, pigs weighing 20 ± 1 kg were infused for 80 min with ammonium chloride or alanine in the presence or absence of leucine. Primary pig hepatocytes were incubated with or without leucine. In the in vivo experiments with either ammonium or alanine as the nitrogen source, addition of leucine significantly inhibited ureagenesis and promoted the production of glutamate and glutamine in the perfused pig liver(P < 0.05). Similarly, leucine stimulated GDH activity and inhibited sirtuin4(SIRT4)gene expression(P < 0.01). Leucine could also activate mammalian target of rapamycin complex 1(m TORC1) signaling(P < 0.05), as evidenced by the increased phosphorylation levels of ribosomal protein S6 kinase 1(S6 K1) and ribosomal protein S6(S6). Interestingly, the leucine-induced m TORC1 pathway activation suitably correlated with increased GDH activity and decreased expression of SIRT4.Similar results were observed in primary cultured hepatocytes. Notably, leucine exerted no significant change in GDH activity in SIRT4-deficient hepatocytes(P > 0.05), while m TORC1 signaling was activated.Leucine exerted no significant changes in both GDH activity and SIRT4 gene expression in rapamycin treated hepatocytes(P > 0.05). In conclusion, L-leucine increases GDH activity and stimulates glutamate synthesis from different nitrogen sources by regulating m TORC1/SIRT4 pathway in the liver of pigs.展开更多
目的观察银盏心脉滴丸对大鼠心肌细胞(H9C2)mTORC1/4EBP1信号通路的影响以探讨其对线粒体功能的机制。方法制备银盏心脉滴丸含药血清。将细胞分为对照组、模型组(缺氧/复氧)、空白血清组及银盏心脉滴丸含药血清组。制备缺氧/复氧细胞损...目的观察银盏心脉滴丸对大鼠心肌细胞(H9C2)mTORC1/4EBP1信号通路的影响以探讨其对线粒体功能的机制。方法制备银盏心脉滴丸含药血清。将细胞分为对照组、模型组(缺氧/复氧)、空白血清组及银盏心脉滴丸含药血清组。制备缺氧/复氧细胞损伤模型,利用激光共聚焦检测线粒体膜电位(ΔΨm),利用流式细胞仪检测活性氧(reactive oxygen species, ROS),运用Western Blot技术检测细胞雷帕霉素靶蛋白(mammalian target of rapamycin, mTOR)、真核翻译起始因子4E结合蛋白(eukaryotic translation initiation factor 4E-binding proteins,4E-BP)、mTOR复合体蛋白(regulatory-associated protein of mammalian target of rapamycin,Raptor)蛋白表达,运用q-PCR方法检测mTORC1、4EBP1、Raptor的mRNA含量。结果与对照组相比,模型组细胞内绿色荧光增强,ΔΨm显著高于对照组(P<0.05);而与模型组相比,银盏心脉滴丸组红色荧光增强(P<0.05),说明银盏心脉保护ΔΨm稳定,保护线粒体膜结构;与对照组相比,模型组的ROS合成较对照组升高(P<0.05);而与模型组相比,银盏心脉滴丸组细胞内ROS产生明显降低(P<0.05);与对照组相比,模型组mTOR、Raptor基因mRNA水平下调(P<0.05),4ebp1基因mRNA水平上调,差异有统计学意义(P<0.05)。与模型组比较,银盏心脉滴丸组mTOR、Raptor基因mRNA水平上调(P<0.05),4ebp1基因mRNA水平下调(P<0.05)。结论银盏心脉滴丸改善缺氧复氧损伤的机制可能是通过激活mTORC1/4EBP1信号通路,从而抑制线粒体膜电位,改善活性氧,保护线粒体功能。展开更多
Background: Intramuscular fat(IMF) content is a vital parameter for assessing pork quality. Increasing evidence has shown that microRNAs(miRNAs) play an important role in regulating porcine IMF deposition. Here, a nov...Background: Intramuscular fat(IMF) content is a vital parameter for assessing pork quality. Increasing evidence has shown that microRNAs(miRNAs) play an important role in regulating porcine IMF deposition. Here, a novel miRNA implicated in porcine IMF adipogenesis was found, and its effect and regulatory mechanism were further explored with respect to intramuscular preadipocyte proliferation and differentiation.Results: By porcine adipose tissue miRNA sequencing analysis, we found that miR-146a-5p is a potential regulator of porcine IMF adipogenesis. Further studies showed that miR-146a-5p mimics inhibited porcine intramuscular preadipocyte proliferation and differentiation, while the miR-146a-5p inhibitor promoted cell proliferation and adipogenic differentiation. Mechanistically, miR-146a-5p suppressed cell proliferation by directly targeting SMAD family member 4(SMAD4) to attenuate TGF-β signaling. Moreover, miR-146a-5p inhibited the differentiation of intramuscular preadipocytes by targeting TNF receptor-associated factor 6(TRAF6) to weaken the AKT/mTORC1 signaling downstream of the TRAF6 pathway.Conclusions: MiR-146a-5p targets SMAD4 and TRAF6 to inhibit porcine intramuscular adipogenesis by attenuating TGF-β and AKT/mTORC1 signaling, respectively. These findings provide a novel miRNA biomarker for regulating intramuscular adipogenesis to promote pork quality.展开更多
基金the National Key Research and Development Program(Grant No.2016YFD0500506)the National Natural Science Foundation of China(Grant No.31572409)National Basic Research Program of China(Grant No.2013CB127304)provided the funds necessary for the conduction of this study
文摘The liver is the most essential organ for the metabolism of ammonia, in where most of ammonia is removed by urea and glutamine synthesis. Regulated by leucine, glutamate dehydrogenase(GDH) catalyzes the reversible inter-conversion of glutamate to ammonia. To determine the mechanism of leucine regulating GDH, pigs weighing 20 ± 1 kg were infused for 80 min with ammonium chloride or alanine in the presence or absence of leucine. Primary pig hepatocytes were incubated with or without leucine. In the in vivo experiments with either ammonium or alanine as the nitrogen source, addition of leucine significantly inhibited ureagenesis and promoted the production of glutamate and glutamine in the perfused pig liver(P < 0.05). Similarly, leucine stimulated GDH activity and inhibited sirtuin4(SIRT4)gene expression(P < 0.01). Leucine could also activate mammalian target of rapamycin complex 1(m TORC1) signaling(P < 0.05), as evidenced by the increased phosphorylation levels of ribosomal protein S6 kinase 1(S6 K1) and ribosomal protein S6(S6). Interestingly, the leucine-induced m TORC1 pathway activation suitably correlated with increased GDH activity and decreased expression of SIRT4.Similar results were observed in primary cultured hepatocytes. Notably, leucine exerted no significant change in GDH activity in SIRT4-deficient hepatocytes(P > 0.05), while m TORC1 signaling was activated.Leucine exerted no significant changes in both GDH activity and SIRT4 gene expression in rapamycin treated hepatocytes(P > 0.05). In conclusion, L-leucine increases GDH activity and stimulates glutamate synthesis from different nitrogen sources by regulating m TORC1/SIRT4 pathway in the liver of pigs.
文摘目的观察银盏心脉滴丸对大鼠心肌细胞(H9C2)mTORC1/4EBP1信号通路的影响以探讨其对线粒体功能的机制。方法制备银盏心脉滴丸含药血清。将细胞分为对照组、模型组(缺氧/复氧)、空白血清组及银盏心脉滴丸含药血清组。制备缺氧/复氧细胞损伤模型,利用激光共聚焦检测线粒体膜电位(ΔΨm),利用流式细胞仪检测活性氧(reactive oxygen species, ROS),运用Western Blot技术检测细胞雷帕霉素靶蛋白(mammalian target of rapamycin, mTOR)、真核翻译起始因子4E结合蛋白(eukaryotic translation initiation factor 4E-binding proteins,4E-BP)、mTOR复合体蛋白(regulatory-associated protein of mammalian target of rapamycin,Raptor)蛋白表达,运用q-PCR方法检测mTORC1、4EBP1、Raptor的mRNA含量。结果与对照组相比,模型组细胞内绿色荧光增强,ΔΨm显著高于对照组(P<0.05);而与模型组相比,银盏心脉滴丸组红色荧光增强(P<0.05),说明银盏心脉保护ΔΨm稳定,保护线粒体膜结构;与对照组相比,模型组的ROS合成较对照组升高(P<0.05);而与模型组相比,银盏心脉滴丸组细胞内ROS产生明显降低(P<0.05);与对照组相比,模型组mTOR、Raptor基因mRNA水平下调(P<0.05),4ebp1基因mRNA水平上调,差异有统计学意义(P<0.05)。与模型组比较,银盏心脉滴丸组mTOR、Raptor基因mRNA水平上调(P<0.05),4ebp1基因mRNA水平下调(P<0.05)。结论银盏心脉滴丸改善缺氧复氧损伤的机制可能是通过激活mTORC1/4EBP1信号通路,从而抑制线粒体膜电位,改善活性氧,保护线粒体功能。
基金supported by grants from the National Natural Science Foundation (31872979, 31572366)the National Key Research and Development Program of China (2017YFD0502002)the National Basic Research Programs of China (2015CB943102)。
文摘Background: Intramuscular fat(IMF) content is a vital parameter for assessing pork quality. Increasing evidence has shown that microRNAs(miRNAs) play an important role in regulating porcine IMF deposition. Here, a novel miRNA implicated in porcine IMF adipogenesis was found, and its effect and regulatory mechanism were further explored with respect to intramuscular preadipocyte proliferation and differentiation.Results: By porcine adipose tissue miRNA sequencing analysis, we found that miR-146a-5p is a potential regulator of porcine IMF adipogenesis. Further studies showed that miR-146a-5p mimics inhibited porcine intramuscular preadipocyte proliferation and differentiation, while the miR-146a-5p inhibitor promoted cell proliferation and adipogenic differentiation. Mechanistically, miR-146a-5p suppressed cell proliferation by directly targeting SMAD family member 4(SMAD4) to attenuate TGF-β signaling. Moreover, miR-146a-5p inhibited the differentiation of intramuscular preadipocytes by targeting TNF receptor-associated factor 6(TRAF6) to weaken the AKT/mTORC1 signaling downstream of the TRAF6 pathway.Conclusions: MiR-146a-5p targets SMAD4 and TRAF6 to inhibit porcine intramuscular adipogenesis by attenuating TGF-β and AKT/mTORC1 signaling, respectively. These findings provide a novel miRNA biomarker for regulating intramuscular adipogenesis to promote pork quality.
