title: RNF2 interacts with the linker region of the human P-glycoprotein.
abstract: The human P-glycoprotein (Pgp) is a drug-efflux pump responsible for innate or acquired multidrug resistance in many cancers. Pgp contains a unique approximately 75 amino acid long linker region in its middle, which is critically important for its drug transport and ATPase functions. To identify cellular proteins that bind to this linker region and modulate Pgp function, a yeast two-hybrid analysis was carried out. This procedure identified RNF2 (RING finger protein 2), an E3 ubiquitin ligase, as a prominent Pgp-interacting protein. Co-expression of RNF2 with Pgp in Sf9 insect cells resulted in decreased ATPase activity and proteolytic protection of the transporter protein. Immunoprecipitation experiments confirmed the physical interaction between these two proteins. Confocal microscopy showed the presence of RNF2 in the cytoplasm of the Pgp-negative, drug-sensitive MCF-7 breast cancer cells. However, it was undetectable in the Pgp-positive and drug-resistant MCF-7 cells. We suggest that RNF2 regulates the cellular abundance of Pgp, and plays a key role in the development of cancer drug resistance through its own down-regulation.
authors.affiliation: The Anticancer Resistance Research Group and the Center for Cancer Biology, Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA.
authors.forename: Prema S
authors.initials: PS
authors.lastname: Rao
authors.forename: Kavita B
authors.initials: KB
authors.lastname: Mallya
authors.forename: Kalkunte S
authors.initials: KS
authors.lastname: Srivenugopal
authors.forename: K C
authors.initials: KC
authors.lastname: Balaji
authors.forename: U Subrahmanyeswara
authors.initials: US
authors.lastname: Rao
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism*; D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D063150:Polycomb Repressive Complex 1; D011485:Protein Binding; D018411:Spodoptera / Q000821:virology; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D015003:Yeasts / Q000235:genetics
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D063150:Polycomb Repressive Complex 1; C489841:RNF2 protein, human; D044767:Ubiquitin-Protein Ligases