Collagen stimulates discoidin domain receptor 1-mediated migration of smooth muscle cells through Src
Received 15 September 2009; received in revised form 6 November 2009; accepted 24 December 2009. published online 21 January 2010. Corrected Proof
Abstract
Background
Discoidin domain receptor 1 (DDR1) is a collagen-binding receptor tyrosine kinase which mediates the migration and proliferation of several cell types. DDR1 is expressed in vascular smooth muscle cells (SMCs) during atherosclerosis and following vascular injury, mediating cell migration and contributing to disease pathogenesis. However, very little is known about the signaling pathways activated by the DDR1 in SMCs. Therefore we have studied the involvement of Src and mitogen-activated protein kinase (MAPK) signaling pathways downstream of DDR1 in vascular SMCs.
Methods
Cells harvested from DDR1−/−, DDR1+/+ mice, and DDR1+/+ cells overexpressing human DDR1b (O/hDDR1b) were used for these studies.
Results
Stimulation of O/hDDR1b cells with type I collagen resulted in increased tyrosine phosphorylation of DDR1. The non-receptor kinase Src co-immunoprecipitated with DDR1, and the Src inhibitor PP2 inhibited type I collagen-induced tyrosine phosphorylation of DDR1. Stimulation of DDR1-expressing cells with collagen resulted in the activation of extracellular signal-regulated kinase 1/2 (ERK1/2); however, ERK1/2 was not activated in DDR1-deficient cells. By contrast, p38 MAPK (p38) was activated by collagen stimulation in both DDR1-expressing and DDR1-deficient cells. Treatment with PP2 attenuated DDR1-dependent ERK1/2 activation, but not p38 activation. Finally, treatment of SMCs with PP2, or the MEK inhibitor PD98059, inhibited migration toward type I collagen in a chemotaxis chamber. However, PP2 but not PD98059 had a greater effect in reducing the migration of DDR1+/+ cells compared to DDR1−/− cells, suggesting that Src but not ERK1/2 was important in regulating DDR1-dependent SMC migration.
Conclusions
Type I collagen induces SMC migration through DDR1 and this is mediated via Src signaling.
Department of Laboratory Medicine and Pathobiology and Heart and Stroke Richard Lewar Centre of Excellence in Cardiovascular Research, University of Toronto, Toronto, Ontario, Canada
Corresponding author. Medical Sciences Building, Room 6213, 1 King's College Circle, Toronto, ON, Canada M5S 1A8. Tel.: +1 416 946 7133; fax: +1 416 978 5959.
Financial support: Funded by grants from the CIHR MOP37847 and the HSFO NA6096 and T6734 to M.B. M.B. was a career investigator of the HSFO. K.K.L was supported by a fellowship from the Heart and Stroke Richard Lewar Center at the University of Toronto.
ABSTRACT