Studies on the impact of the drug transporter OATP1B3 on the pancreatic effects of CCK-8 and sulfonylurea derivatives

促进细胞摄取的转运蛋白在调节其底物的细胞内功能中起着关键作用。有机阴离子转运多肽是介导细胞摄取的转运蛋白家族之一。特别是，oatp1b亚家族的成员是药理学研究的重点，因为这些蛋白质在临床使用中转运多种药物。在准备这一建议时，我们能够显示摄取转运蛋白OATP1B3在人胰腺胰岛素产生的胰岛细胞中的表达。考虑到先前的研究发现肠内形成的胆囊收缩素-8 （CCK-8）是OATP1B3特异性的内源性底物，并且我们的初步数据和其他人先前的研究结果表明几种磺脲类衍生物与OATP1B3相互作用，因此胰腺中OATP1B3表达的生理和药理学相关性问题上升。为了深入了解OATP1B3在胰岛细胞中的功能，我们将生成一个葡萄糖敏感、产生胰岛素、过表达OATP1B3的细胞系，并对其进行功能表征。转运体对CCK-8和磺酰脲衍生物的细胞效应的影响将是后续体外研究的重点，该研究将评估内源性和外源性底物对转染胰岛细胞胰岛素分泌的影响。此外，还将确定磺脲类衍生物与CCK-8生理功能的潜在相互作用。除了这些细胞效应外，它还旨在证明OATP1B3对磺酰脲衍生物的直接转运。翻译方法的基础是我们之前发现的功能损害，以及经常发生的OATP1B3遗传变异。临床研究的目的是在纳入研究之前对健康志愿者进行OATP1B3变异基因分型，以确定各自的多态性对CCK-8生理功能的影响。为此，将进行一项两手研究。在第一个治疗期，基因变异对肠道形成和分泌的CCK-8的系统配置的影响将在摄入标准化膳食后确定。值得注意的是，OATP1B3在肝细胞中高度表达，因此可能影响CCK-8的生物利用度。在第二个治疗期，将在摄入75 g葡萄糖后评估OATP1B3基因变异对CCK-8胰岛素释放促进作用的影响。除了CCK-8外，胰岛素和其他已知的葡萄糖稳态调节剂的水平也将被确定。该研究已获得当地伦理委员会的批准，并将与Universitätsmedizin Greifswald临床药理学部门合作进行。

Transporters facilitating cellular uptake play a pivotal role in modulating the intracellular functions of their substrates. Organic Anion Transporting Polypeptides are one family of transporters mediating cellular uptake. Particularly, the members of the OATP1B-subfamily were focus of pharmacological studies as these proteins transport a variety of drugs in clinical use.In preparation of this proposal we were able to show expression of the uptake transporter OATP1B3 in the insulin-producing -islet cells of human pancreas. Considering that previous studies revealed choleystokinin-8 (CCK-8), an intestinal formed incretine as an OATP1B3-specific endogenous substrate and that our preliminary data and previous findings by others show interaction of several sulfonylurea derivatives with OATP1B3 the question of the physiological and pharmacological relevance of the pancreatic expression of OATP1B3 rises. In order to obtain insights in the function of OATP1B3 in -islet cells, a glucose-sensitive, insulin-producing, and OATP1B3-overexpressing cell-line will be generated and functionally characterized. The impact of the transporter on the cellular effects of CCK-8 and of sulfonylurea derivatives will be focus of the subsequent in vitro studies assessing the influence of the endogenous and exogenous substrates on the insulin secretion by transfected -islet cells. In addition, the potential interaction of sulfonylurea derivatives with the physiological function of CCK-8 will be determined. In addition to those cellular effects it will be aim to show direct transport of sulfonylurea derivatives by OATP1B3. Basis of a translational approach are our previous findings of function impairing, and frequently occurring genetic variants of OATP1B3. It is aim of the clinical study in healthy volunteers genotyped for OATP1B3 variants prior to study inclusion, to determine the influence of the respective polymorphisms on the physiological function of CCK-8. In order to do so, a two-armed study will be conducted. In the first treatment period the impact of the genetic variants on the systemic disposition of intestinal formed and secreted CCK-8 will be determined after intake of a standardized meal. It seems noteworthy, that OATP1B3 is highly expressed in hepatocytes and might therefore influence bioavailability of CCK-8. In the second treatment period the impact of genetic variants of OATP1B3 on the insulin release promoting effects of CCK-8 will be assessed after intake of 75 g Glucose. In addition to CCK-8, the levels of insulin and other known modulators of glucose homeostasis will be determined. The study has been approved by the local ethic committee and will be conducted in collaboration with the Department of Clinical Pharmacolgy of the Universitätsmedizin Greifswald.