Casein kinase 2α regulates multidrug resistance-associated protein 1 function via phosphorylation of Thr249

Elzbieta I. Stolarczyk, Cassandra J. Reiling, Kerry A. Pickin, Ryan Coppage, Marc R. Knecht, Christian M. Paumi

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


We have shown previously that the function of Ycf1p, yeast ortholog of multidrug resistance-associated protein 1 (MRP1), is regulated by yeast casein kinase 2α (Cka1p) via phosphorylation at Ser251. In this study, we explored whether casein kinase 2α (CK2α), the human homolog of Cka1p, regulates MRP1 by phosphorylation at the semiconserved site Thr249. Knockdown of CK2α in MCF7-derived cells expressing MRP1 [MRP1 CK2α(-)] resulted in increased doxorubicin sensitivity. MRP1-dependent transport of leukotriene C4 and estradiol- 17β-D-glucuronide into vesicles derived from MRP1 CK2β(-) cells was decreased compared with MRP1 vesicles. Moreover, mutation of Thr249 to alanine (MRP1-T249A) also resulted in decreased MRP1-dependent transport, whereas a phosphomimicking mutation (MRP1-T249E) led to dramatic increase in MRP1-dependent transport. Studies in tissue culture confirmed these findings, showing increased intracellular doxorubicin accumulation in MRP1 CK2α(-) and MRP1-T249A cells compared with MRP1 cells. Inhibition of CK2 kinase by 2-dimeth-ylamino- 4,5,6,7-tetrabromo-1H- benzimidazole resulted in increased doxorubicin accumulation in MRP1 cells, but not in MRP1 CK2α(-), MRP1-T249A, or MRP1-T249E cells, suggesting that CK2α regulates MRP1 function via phosphorylation of Thr249. Indeed, CK2α and MRP1 interact physically, and recombinant CK2 phosphorylates MRP1-derived peptide in vitro in a Thr249-dependent manner, whereas knockdown of CK2α results in decreased phosphorylation at MRP1-Thr249. The role of CK2 in regulating MRP1 was confirmed in other cancer cell lines where CK2 inhibition decreased MRP1-mediated efflux of doxorubicin and increased doxorubicin cytotoxicity. This study supports a model in which CK2α potentiates MRP1 function via direct phosphorylation of Thr249.

Original languageEnglish (US)
Pages (from-to)488-499
Number of pages12
JournalMolecular Pharmacology
Issue number3
StatePublished - Sep 2012

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology


Dive into the research topics of 'Casein kinase 2α regulates multidrug resistance-associated protein 1 function via phosphorylation of Thr249'. Together they form a unique fingerprint.

Cite this