ABSTRACT
The HIV viral entry co-receptors CCR5 and CXCR4 function physiologically as typical chemokine receptors. Activation leads to cytosolic signal transduction that results in a variety of cellular responses such as cytoskeletal rearrangement and chemotaxis (CTX). Our aim was to investigate the signalling pathways involved in CC and CXC receptor-mediated cell migration. Inhibition of dynamin I and II GTPase with dynasore completely inhibited CCL3-stimulated CTX in THP-1 cells, whereas the dynasore analogue Dyngo-4a, which is a more potent inhibitor, showed reduced ability to inhibit CC chemokine-induced CTX. In contrast, dynasore was not able to block cell migration via CXCR4. The same activation/inhibition pattern was verified in activated T lymphocytes for different CC and CXC chemokines. Cell migration induced by CC and CXC receptors does not rely on active internalization processes driven by dynamin because the blockade of internalization does not affect migration, but it might rely on dynamin interaction with the cytoskeleton. We identify here a functional difference in how CC and CXC receptor migration is controlled, suggesting that specific signalling networks are being employed for different receptor classes and potentially specific therapeutic targets to prevent receptor migration can be identified.
Subject(s)
Cell Movement , Chemokine CCL3/metabolism , Dynamins/metabolism , Receptors, CCR5/metabolism , Receptors, CXCR4/metabolism , Signal Transduction , Calcium/metabolism , Cell Line, Tumor , Cell Movement/drug effects , Chemotaxis/drug effects , Dynamins/antagonists & inhibitors , Dynamins/chemistry , Humans , Hydrazones/pharmacology , Monocytes/cytology , Monocytes/metabolism , Naphthols/pharmacology , Receptors, CXCR4/antagonists & inhibitors , Signal Transduction/drug effects , T-Lymphocytes/metabolismABSTRACT
CC and CXC chemokine receptor signalling networks are regulated in different ways. Here we show that intracellular calcium release and cell migration occur independent of Gßγ activation in response to CCL3, whereas CXCL11 induced migration of activated T-lymphocytes depends on Gßγ activation. Treatment of a range of cell types with gallein, a pharmacological inhibitor of Gßγ signalling, did not result in a reduction in CCL3 induced cellular migration, but resulted in enhanced calcium mobilisation following chemokine stimulation. Inhibition of PI3 kinase (PI3K) and AKT, which are activated downstream of Gßγ, equally had no effect on calcium release and a minor effect on cell migration. Similarly, inhibition of ERK1/2 did not prevent CCL3 induced migration. Interestingly, Gßγ as well as PI3K activation is necessary for CXCL11 induced migration of activated T-cells. These data not only confirm a role for Gßγ signalling in CXCL11 induced migration, but also demonstrate that targeting Gßγ as a therapeutic target to prevent migration in inflammatory disease may not be beneficial, at least not for CCL3 induced migration. This highlights the distinct differences in the mechanisms on how CC- and CXC-receptors activate cellular migration.
