Browsing by Subject "P-glycoprotein"

P-glycoprotein (ABCB1, MDR1) is an efflux transporter expressed widely through the body, but mainly focused on tissues that have protective or excretive function, such as liver and blood-brain-barrier. Many clinically used drugs from variety of therapeutic groups are substrates of P-glycoprotein, and changes in the function of P-glycoprotein may have impact on the drugs pharmacokinetics and -dynamics. The impact of genetic polymorphism on P-glycoprotein activity have been investigated for several years, but due to contradictory results no consensus has been made. The aim of this Master’s thesis was to investigate the effect of five different P-glycoprotein single nucleotide polymorphisms (SNPs) on transport activity. The study was performed by Spodoptera frugiperda (Sf9) membrane vesicles expressing P-glycoprotein variants. Baculovirus-derived expression system was used to introduce the ABCB1 gene to the cells. Vesicle assay was performed with N-methylquinidine (NMQ), and ATP-dependent transport of P-glycoprotein variants was compared to the reference gene. Amino acid change Cys717Tyr led to no transport activity compared to reference gene, and Arg669Cys associated with higher transport activity of NMQ. Arg588Cys, Ser795Cys and Ile836Val indicated no effect on the transport activity. Other aim for this Master’s thesis was to create a new in-house protocol to study P-glycoprotein polymorphism in vitro. Substrate accumulation assay for Rhodamine-123 in Sf9 cells analysed with flow cytometry was established, as flow cytometry is widely used method in other laboratories to study P-glycoprotein polymorphism. The baseline for flow cytometry assay was created successfully by optimizing substrate concentration and incubation time. According to the results, SNPs can impair P-glycoprotein function. New method to study P-glycoprotein function was created, and this method can be used to further study the effects of genetic polymorphism of P-glycoprotein and to compare the result between studies. The results gained from these in vitro studies can be utilized to understand in vivo pharmacogenetic findings.