Cellular and Molecular Neurobiology

, Volume 33, Issue 1, pp 111–118 | Cite as

Grk2 is an Essential Regulator of CXCR7 Signalling in Astrocytes

Original Research


We previously demonstrated that in astrocytes, SDF-1/CXCL12 exclusively signals through CXCR7 despite the additional presence of the alternate SDF-1/CXCL12 receptor, CXCR4. In addition, we provided evidence that astrocytic CXCR7-signalling involves a G protein-dependent mechanism. This is insofar remarkable as in all other cell types studied to date, CXCR7 either acts as a scavenger chemokine receptor, a modulator of CXCR4, or a non-classical chemokine receptor, signalling through ß-arrestin. To begin to unravel the molecular framework impinging the selective function of CXCR7 on a given cell type, we have now analysed the role of G protein-coupled receptor kinases (Grks) in astrocytic CXCR7 signalling. We demonstrate that Grk2 mediates signalling of SDF-1/CXCL12-bound CXCR7 as suggested by the finding that SDF-1/CXCL12-induced activation of Erk1/2 and Akt is abrogated following RNAi-mediated inhibition of Grk2, but not of Grk3, Grk5, or Grk6. We further unravel that Grk2 additionally controls signalling of SDF-1/CXCL12-bound CXCR7 in astrocytes by mediating internalization and subsequent silencing of CXCR7. Finally, we demonstrate that Grk2 is likewise expressed by microglial cells and Schwann cells, cell types in which CXCR7 does not act as a classical chemokine receptor. In conclusion, our findings establish that Grk2 tightly controls CXCR7 signalling in astrocytes, but does not imprint the cell type-specific function of this chemokine receptor.


SDF-1/CXCL12 RANTES/CCL5 Cell signalling Receptor internalization 



We thank Patrick Küry for providing us with primary Schwann cells. This work was supported by the Deutsche Forschungsgemeinschaft (En 187/5-9).

Supplementary material

10571_2012_9876_MOESM1_ESM.doc (894 kb)
Supplementary material 1 (DOC 894 kb)


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Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  1. 1.Medical Faculty, Institute of AnatomyUniversity of LeipzigLeipzigGermany

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