BILE ACIDS AND HEPATOCELLULAR SIGNAL TRANSDUCTION

私人投资基金的拨款建议是基于 肝细胞钙稳态在维持肝功能中的作用。 静息时细胞内钙离子浓度约为100 nM。 肝细胞，血清、胆汁和细胞内细胞器钙 浓度分别为2-3 mm、2-7 mm和2-3 mm。增加了 细胞内钙离子已被证明参与调节 蛋白质和DNA合成、糖原分解和细胞生长。最近， 钙被认为与胆汁酸代谢有关， 包括胆汁酸的摄取和分泌。此外，几种胆汁酸 已被证明可以增加肝细胞胞浆钙离子。的目标是 这项研究计划是为了研究不同胆汁酸所起的作用。 对肝细胞钙稳态的影响及由此产生的影响 不同钙库的钙离子流量对肝细胞的影响 代谢，特别是对钙和胆汁酸的释放，以及 胆汁酸摄取。国际和平研究所提出的第一个目标的目标是 在分离的叙利亚金黄地鼠肝细胞模型中，定义 不同途径参与钙稳态的调节 胆汁酸。更准确地说：1)所示对象的各自效力 胆汁酸对钙动员的影响及其机制 将研究哪些胆汁酸诱导细胞内钙离子流动； 2)钙被动员的胞内位置将是 探讨了，特别强调了 内质网和线粒体；3)胆汁的作用机制 酸诱导钙内流或/和钙外流将被检测； 最后，细胞特异性将通过测试的效果来评估 胆汁酸对培养的人成纤维细胞钙稳态的影响 没有胆汁酸转运蛋白。第二个目标的目标是 在灌流的肝脏中，测定胆汁酸对钙和 胆汁酸通量以及对胆汁流量的影响：1)胆汁酸对 将研究钙释放到胆汁和血液中的情况； 2)胆汁中钙的分泌将与胆汁中的钙相比较。 酸，和胆汁流率。最后一个目标的目标是定义 钙在体外胆汁酸摄取调节中的作用 肝细胞：1)钙动员激素和钙的能力 改变肝细胞胆汁酸摄取的离子载体将得到证实；2) 细胞内和细胞外钙对胆汁的影响 酸摄取将被测定；3)钙对两者的具体影响 将探索钠依赖和钠非依赖胆汁酸摄取； 4)抑制胆汁酸摄取的调节机制(S 将对钙含量进行调查。预计，通过更好的 了解不同胆汁酸对血管紧张素转换酶的影响 肝细胞钙动态平衡，我们将对 基因修饰的代谢后果的机制 胆汁酸引起的肝细胞钙稳态可能与胆汁有关 胃酸分泌和胆结石的形成受到关注。

The grant proposal of the PI is based on the significant role of hepatocellular calcium homeostasis in the maintenance of liver function. The cytosolic calcium concentration is around 100 nM in resting hepatocytes, while the serum, biliary and intracellular organelle calcium concentrations are around 2-3mM, 2-7mM and 2-3mM, respectively. Increased cytosolic calcium has been shown to be involved in the regulation of protein and DNA synthesis, glycogen breakdown and cell growth. Recently, calcium has been proposed to he involved in bile acid metabolism, including bile acid uptake and secretion. In addition, several bile acids have been shown to increase hepatocellular cytosolic calcium. The goal of this research proposal is to study the effects different bile acids exert on hepatocellular calcium homeostasis and the consequent effect that the flux of calcium from the different calcium pools has on hepatocellular metabolism, in particular, on calcium and bile acid release, as well as on bile acid uptake. The goal of the first aim proposed by the PI is to define, in the isolated Golden Syrian hamster hepatocyte model, the different pathways involved in the regulation of calcium homeostasis by bile acids. More precisely: 1) the respective potency of the indicated bile acids on the mobilization of calcium, as well as the mechanism by which bile acids induce intracellular calcium fluxes will be investigated; 2) the intracellular site from which the calcium is mobilized will be explored, with special emphasis given to the role played by the endoplasmic reticulum and the mitochondria; 3) the mechanism by which bile acids induce calcium influx or/and calcium efflux will be examined; finally 4) the cell specificity will be assessed by testing the effect of bile acids on calcium homeostasis in cultured human fibroblasts, which do not possess a bile acid transporter. The goal of the second aim is to determine, in the perfused liver, the effect of bile acids on calcium and bile acid fluxes, as well as on bile flow: 1) the effect of bile acids on the release of calcium into bile and the bloodstream will be investigated; 2) the biliary secretion of calcium will be compared to that of bile acids, and to the bile flow rate. The goal of the last aim is to define the effect of calcium on the regulation of bile acid uptake in isolated hepatocytes: 1) the ability of calcium-mobilizing hormones and calcium ionophores to alter hepatocellular bile acid uptake will be confirmed; 2) the respective effect of intracellular and extracellular calcium on bile acid uptake will be determined; 3) the specific effect of calcium on both sodium-dependent and sodium-independent bile acid uptake will be explored; finally, 4) the mechanism(s) regulating the inhibition of bile acid uptake by calcium will be investigated. It is expected that, through a better understanding of the differential effects of different bile acids on hepatocellular calcium homeostasis, we will gain a clearer perception of the mechanism of the metabolic consequences that the modification of hepatocellular calcium homeostasis by bile acids may have, as far as bile acid secretion and gallstone formation are concerned.