Substrate Stiffness Regulates PDGF-Induced Circular Dorsal Ruffle Formation Through MLCK
As atherosclerosis progresses, vascular smooth muscle cells (VSMCs) invade from the medial layer into the intimal layer and proliferate, contributing to atherosclerotic plaque formation. This migration is stimulated in part by platelet-derived growth factor (PDGF), which is released by endothelial cells and inflammatory cells, and vessel stiffening, which occurs with age and atherosclerosis progression. PDGF induces the formation of circular dorsal ruffles (CDRs), actin-based structures associated with increased cell motility. Here we show that mechanical changes in matrix stiffness enhance the formation of CDRs in VSMCs in response to PDGF stimulation. Our data indicate that matrix stiffness increases cellular contractility, and that intracellular pre-stress is necessary for robust CDR formation. When treated with agonists that promote contractility, cells increase CDR formation, whereas agonists that inhibit contractility lead to decreased CDR formation. Substrate stiffness promotes CDR formation in response to PDGF by upregulating Src activity through myosin light chain kinase. Together, these data indicate that vessel stiffening accompanying atherogenesis may exacerbate VSMC response to PDGF leading to CDR formation.
KeywordsCell migration Traction force Actin Vascular smooth muscle cells Cell contractility
The study was supported in part by the Affinito-Stewart Grant from the President’s Council of Cornell Women and grants from the American Federation for Aging Research and the NIH (HL097296) to CAR.
- 5.Ballestrem, C., B. Wehrle-Haller, and B. A. Imhof. Actin dynamics in living mammalian cells. J. Cell Sci. 111(Pt 12):1649–1658, 1998.Google Scholar
- 14.Evanko, S. P., E. W. Raines, R. Ross, L. I. Gold, and T. N. Wight. Proteoglycan distribution in lesions of atherosclerosis depends on lesion severity, structural characteristics, and the proximity of platelet-derived growth factor and transforming growth factor-beta. Am. J. Pathol. 152(2):533–546, 1998.Google Scholar
- 24.Krishnan, R., D. D. Klumpers, C. Y. Park, K. Rajendran, X. Trepat, J. van Bezu, V. W. van Hinsbergh, C. V. Carman, J. D. Brain, J. J. Fredberg, J. P. Butler, and G. P. van Nieuw Amerongen. Substrate stiffening promotes endothelial monolayer disruption through enhanced physical forces. Am. J. Physiol. Cell Physiol. 300(1):C146–C154, 2011.CrossRefGoogle Scholar
- 30.Mattace-Raso, F. U., T. J. van der Cammen, A. Hofman, N. M. van Popele, M. L. Bos, M. A. Schalekamp, R. Asmar, R. S. Reneman, A. P. Hoeks, M. M. Breteler, and J. C. Witteman. Arterial stiffness and risk of coronary heart disease and stroke: the Rotterdam Study. Circulation 113(5):657–663, 2006.CrossRefGoogle Scholar
- 48.Sutton-Tyrrell, K., S. S. Najjar, R. M. Boudreau, L. Venkitachalam, V. Kupelian, E. M. Simonsick, R. Havlik, E. G. Lakatta, H. Spurgeon, S. Kritchevsky, M. Pahor, D. Bauer, and A. Newman. Elevated aortic pulse wave velocity, a marker of arterial stiffness, predicts cardiovascular events in well-functioning older adults. Circulation 111(25):3384–3390, 2005.CrossRefGoogle Scholar
- 49.Totsukawa, G., Y. Yamakita, S. Yamashiro, D. J. Hartshorne, Y. Sasaki, and F. Matsumura. Distinct roles of ROCK (Rho-kinase) and MLCK in spatial regulation of MLC phosphorylation for assembly of stress fibers and focal adhesions in 3T3 fibroblasts. J. Cell Biol. 150(4):797–806, 2000.CrossRefGoogle Scholar
- 56.Zieman, S. J., V. Melenovsky, L. Clattenburg, M. C. Corretti, A. Capriotti, G. Gerstenblith, and D. A. Kass. Advanced glycation endproduct crosslink breaker (alagebrium) improves endothelial function in patients with isolated systolic hypertension. J. Hypertens. 25(3):577–583, 2007.CrossRefGoogle Scholar