Individual smooth muscle cells of the vessel wall are encased by a basement membrane (BM), and are interconnected by a layer of interstitial matrix of fibrillar collagens. Vascular remodelling has been shown to be associated with changes in the fibrillar collagens. In addition, in SmArt we showed that changes in the smooth muscle BM components leads to expansion of fibrillar collagens and increased wall thickness in resistance arteries, which correlates with reduced contractility in response to increasing luminal pressure.
Hypothesis: Smooth muscle interaction with laminin α5 in the smooth muscle BM is required for smooth muscle homeostasis, and disruption of this interaction compromises smooth muscle contractility.
Objectives: To define molecular mechanisms of laminin α5 mediated interactions in smooth muscle and the signal transduction pathways induced and their role in vascular remodelling in response to hypertension.
Training: Indirect evidence suggests that laminin α5 in the smooth muscle BM interacts with integrin α7β11 and RGD- binding integrins2 on the smooth muscle cells. This will be further analysed using isolated vascular smooth muscle cells (established in SmArt) in in vitro adhesion assays. Signal transduction pathways and expression of mechanosensitive genes induced when cells are plated on laminin α5 containing isoforms will be investigated. With AU and DMT we will study whether calcium signalling is induced by laminin α5 in vascular smooth muscle. Whole vessel explants from WT and smooth muscle specific laminin α5 KO mice will be analysed using atomic force microscope for biophysical parameters of vessel compliance, in collaboration with AMC. Actin dynamics will be studied using smooth muscle cells isolated from mice carrying GFP-tagged actin3 and plated on laminin 511 versus other laminin isoforms or other ECM molecules. In addition, smooth muscle cells will be isolated from smooth muscle cell specific KO mice and will be transfected with GFP-actin constructs to follow actin dynamics in response to stretch. In collaboration with LU we will investigate whether microRNAs important for smooth muscle contractility are altered in laminin α5 smooth muscle specific KO mice. Whole animal imaging of vascular smooth muscle remodelling will be investigated using the myocardial ischemia-reperfusion models, where both vascular smooth muscle and cardiac muscle undergo remodelling, in the smooth muscle specific laminin α5 KO mice using SPECT and PET, paving the way for translation to medical imaging of patients.
1 Wilson (2007) Circ Res. 101, 672-81; 2 Martinez-Lemus et al., (2005). Am J Physiol. 289, 322-9. 3 Riedl et al., 2010. Nat Methods 7, 168-9.
Wegner, J., Loser, K., Aspite, G., Nischt, R., Eckes, B., Krieg, T., Werner. S., and Sorokin, L. (2016). Laminin α5 in the keratinocyte basement membrane is required for epidermal-dermal intercommunication. Matrix Biol, 56, 24-41. doi: 10.1016/j.matbio.2016.05.001.
Di Russo, J., Hannocks, M.J., Luik, A.L., Song, J., Zhang, X., Yousif, L., Aspite, G., Hallmann, R., and Sorokin, L. (2016). Vascular laminins in physiology and pathology. Matrix Biol., doi: 10.1016/j.matbio.2016.06.008.
Ph.D student / post-doc
Prof. Lydia Sorokin