Virág Székely (PhD student), Fellow researcher (1.), First Author
Éva Bakos (PhD), Senior fellow researcher (1.)
Izabel Patik (absolved PhD student), Fellow researcher (1.)
Nóra Kucsma, Fellow researcher (1.)
Csilla Özvegy-Laczka (PhD), Senior fellow researcher, Supervisor (1.)
1.: Membrane Protein Research Group, Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences
Introduction: Liver has central role in the defense of the body against harmful compounds. Detoxification in hepatocytes is a strictly controlled process, in which governed action of membrane transporters involved in the uptake and efflux of potentially dangerous molecules has crucial role. Major drug transporters of the liver belong to the ABC (ATP Binding Cassette) and Organic Anion Transporting Polypeptides (OATPs) protein families. OATP1B1 is one of these drug uptake transporters, exclusively expressed in hepatocytes. It transports bile acids, bilirubin, sex hormones and many clinically used drugs. The removal of toxic molecules from hepatocytes is accomplished by ABC multidrug transporters (ABC-MDR).
Aims: Multipsecific OATP and ABC-MDR transporters have overlapping substrate specificities. Their mutations, polymorphism, and the co-administration of their substrates cause altered pharmacokinetics. Hence, monitoring these proteins during drug development is obligatory. Therefore, reliable and cost effective in vitro assays for ABC-MDR and OATP proteins are of high relevance. The aim of this project was to find common fluorescent substrates of OATP1B1 and ABC-MDR proteins of the liver.
Method: Interaction of the novel fluorescent OATP substrates, identified previously in our laboratory, with ABC-MDR transporters was investigated in inside-out membrane vesicles. Additionally, we established stable cell lines co-expressing OATP and ABC-MDR proteins to characterize transcellular transport of the fluorescent dyes (“transwell method”).
Results: We found that several of the new fluorescent OATP substrates are also recognized by hepatic ABC-MDRs. Based on the transport of these molecules we established fluorescent in vitro assays for simultaneous investigation of OATP and ABC-MDRs.
Conclusion: The fluorescent dye substrates identified in the current work represent a novel tool for studying the activity and drug interactions of OATP and ABC-MDR proteins that is obligatory during drug development.
Funding: This project was supported by research grant of NKFIH (OTKA FK 128751).
Doctoral School: Molecular Medicine
Program: Basis of Human Molecular Genetics and Gene Diagnostics
Supervisor: Csilla Özvegy-Laczka
E-mail address: firstname.lastname@example.org