Cardiovascular Research Advance Access [Accepted Manuscript] published online on October 13, 2008
Cardiovascular Research, doi:10.1093/cvr/cvn278
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MMP-9 and -12 cause N-cadherin Shedding, and thereby β-catenin Signalling and Vascular Smooth Muscle Cell Proliferation
Bristol Heart Institute, University of Bristol, Bristol, BS2 8HW, UK
Author for correspondence Dr Sarah Jane George, Bristol Heart Institute, Level 7, Bristol Royal Infirmary, BRISTOL, BS2 8HW, UK Telephone: 00 44 117 9283154 Fax: 00 44 117 9283581 Email: s.j.george{at}bris.ac.uk
Aims: Vascular smooth muscle cell (VSMC) proliferation contributes to intimal thickening in restenosis and atherosclerosis. Previously we demonstrated that matrix-degrading metalloproteinase (MMP) dependent shedding of the extracellular portion of N-cadherin increased VSMC proliferation via elevation of β-catenin signalling and cyclin D1 expression. In this study we aimed to determine whether MMP-2, -9, -12 or -14 regulate VSMC proliferation via N-cadherin shedding.
Methods and Results: N-cadherin shedding was significantly impaired in proliferating mouse aortic VSMCs deficient in MMP-9 (MMP-9-/-) and MMP-12 (MMP-12-/-) compared to wild-type controls (1.1±0.7 and 1.0±0.1 versus 2.0±0.2 fold). Furthermore, proliferating VSMCs subjected to MMP-9 or -12 siRNA knockdown or deficient in MMP-9 or -12 showed significantly increased cellular levels of N-cadherin compared to controls (1.7±0.2, 2.7±0.6, and 3.5±1.6, 1.7±0.2, fold, respectively). Incubation of VSMCs with active MMP-9 or -12 independently increased N-cadherin cleavage. Additionally, β-catenin signalling was significantly reduced by 52±17% and 81±12% in MMP-9-/- and MMP-12-/- proliferating VSMCs, respectively, and this was corroborated by siRNA knockdown of MMP-9 and -12. Decreased β-catenin signalling coincided with significantly reduced proliferation and cyclin D1 protein levels in MMP-9-/- and MMP-12-/- cells. Little or no additive effect was observed with combined modulation of MMP-9 and -12 in all experiments. In contrast, N-cadherin shedding and VSMC proliferation was not modulated by MMP-2 and -14.
Conclusions: In conclusion we propose that MMP-9 and MMP-12 promote intimal thickening by independent cleavage of N-cadherin, which elevates VSMC proliferation via β-catenin signalling.
Time for primary review: 22 days
* Current address: Paul O'Gorman Lifeline Centre, Southmead Hospital, Bristol, BS10 5NB, UK