title: The effect of radixin knockdown on the expression and efflux function of MRP2 in SGC-7901 cells.
abstract: Multidrug resistance-associated protein 2 (MRP2, ABCC2) is the second member of the MRP transporter family and functions physiologically as an organic anion transporter. Earlier studies have confirmed that radixin, which is a member of the ERM (ezrin/radixin/moesin) family, modulates MRP2 localization at the canalicular membrane in hepatocytes. The relationship between radixin and MRP2 - particularly, the effect of radixin on the expression and function of MRP2 in cells or tissues that co-express all three ERM proteins - has not been well studied. To examine the role of radixin in the expression and function of MRP2 and other MRPs, we chose human gastric carcinoma SGC-7901 cells that express all three ERM proteins rather than hepatocytes, which predominantly express radixin. Radixin stable knockdown SGC-7901 cells, which were constructed by RNAi, exhibited no compensatory up-regulation of ezrin or moesin. The mRNA expression profiles of MRPs in the radixin knockdown cells were primarily evaluated by RT-PCR. Real time quantitative RT-PCR and western blot analysis revealed that the radixin deficiency caused the mRNA and protein expression levels of MRP2 to be reduced by about 50%, respectively. Accordingly, efflux and MTT assays showed that the radixin knockdown cells exhibited lower efflux ability with respect to calcein but no significant change in cell viability. In conclusion, among the MRP1-6 family members, radixin selectively modulates the expression and function of MRP2 in a system co-expressing all three ERM proteins.
authors.affiliation: State Key Laboratory of Genetic Engineering, Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai 200433, China. 09210700099@fudan.edu.cn
authors.forename: Xiao-Jie
authors.initials: XJ
authors.lastname: He
authors.forename: Wei-Rong
authors.initials: WR
authors.lastname: Wang
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Qing
authors.initials: Q
authors.lastname: Yang
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002470:Cell Survival; D003598:Cytoskeletal Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D005452:Fluoresceins / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006801:Humans; D008565:Membrane Proteins / Q000172:deficiency* / Q000235:genetics; D008840:Microfilament Proteins / Q000378:metabolism; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism*; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism*; D000099149:Ezrin
chemical_list: D003598:Cytoskeletal Proteins; D005452:Fluoresceins; D005456:Fluorescent Dyes; D008565:Membrane Proteins; D008840:Microfilament Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D012333:RNA, Messenger; D000099149:Ezrin; C000715087:ABCC2 protein, human; C071058:moesin; C071776:radixin; C085925:calcein AM