Thromb Haemost 2017; 117(01): 105-115
DOI: 10.1160/TH16-01-0045
Cellular Haemostasis and Platelets
Schattauer GmbH

Several adaptor proteins promote intracellular localisation of the transporter MRP4/ABCC4 in platelets and haematopoietic cells

Yvonne Schaletzki
1   Department of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
,
Marie-Luise Kromrey
1   Department of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
,
Susanne Bröderdorf
1   Department of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
,
Elke Hammer
2   Department of Functional Genomics, Interfaculty Institute of Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
,
Markus Grube
1   Department of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
,
Paul Hagen
1   Department of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
,
Sonja Sucic
3   Department of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
,
Michael Freissmuth
3   Department of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
,
Uwe Völker
2   Department of Functional Genomics, Interfaculty Institute of Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
,
Andreas Greinacher
4   Department of Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
,
Bernhard H. Rauch
1   Department of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
,
Heyo K. Kroemer*
1   Department of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
,
Gabriele Jedlitschky
1   Department of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
› Author Affiliations

Financial support: The work was supported by the Deutsche Forschungsgemeinschaft (DFG) through grant JE 234/4–1 to GJ and by the European Union through grant EU-FP7-REGPOT-2010–1 (“EnVision”, grant agreement no. 264143).
Further Information

Publication History

Received: 18 January 2016

Accepted after major revision: 20 September 2016

Publication Date:
01 December 2017 (online)

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Summary

The multidrug resistance protein 4 (MRP4/ABCC4) has been identified as an important transporter for signalling molecules including cyclic nucleotides and several lipid mediators in platelets and may thus represent a novel target to interfere with platelet function. Besides its localisation in the plasma membrane, MRP4 has been also detected in the membrane of dense granules in resting platelets. In polarised cells it is localised at the basolateral or apical plasma membrane. To date, the mechanism of MRP4 trafficking has not been elucidated; protein interactions may regulate both the localisation and function of this transporter. We approached this issue by searching for interacting proteins by in vitro binding assays, followed by immunoblotting and mass spectrometry, and by visualising their co-localisation in platelets and haematopoietic cells. We identified the PDZ domain containing scaffold proteins ezrin-binding protein 50 (EBP50/NHERF1), postsynaptic density protein 95 (PSD95), and sorting nexin 27 (SNX27), but also the adaptor protein complex 3 subunit β3A (AP3B1) and the heat shock protein HSP90 as putative interaction partners of MRP4. The knockdown of SNX27, PSD95, and AP3B1 by siRNA in megakaryoblastic leuk aemia cells led to a redistribution of MRP4 from intracellular structures to the plasma membrane. Inhibition of HSP90 led to a diminished expression and retention of MRP4 in the endoplasmic reticulum. These results indicate that MRP4 localisation and function are regulated by multiple protein interactions. Changes in the adaptor proteins can hence lead to altered localisation and function of the transporter.

Supplementary Material to this article is available at www.thrombosis-online.com.

* Present address: University Medicine Göttingen, Göttingen, Germany.