Blood forced through arteries by the pumping action of the heart exerts shear stresses on the endothelial cells (ECs) that line the arteries. ECs respond to shear stress by producing substances that affect blood vessel diameter, blood coagulation, the adhesion of white blood cells to the vessel wall, and the leakiness of the artery wall to water, proteins and cholesterol. Therefore,studies of EC-sensitivity to shear stress will lead to an understanding of how ECs signal the blood vessel to control blood flow, immune responses, and the delivery of nutrients to the tissues. In certain cases, shear stress can cause ECs to become dysfunctional, a situation which leads to hypertension, atherosclerosis and other vascular diseases.
Methodologies used to study EC-sensitivity to shear stress range from studies in animals, tissues, cells, cell components to molecules. Molecules (lipids and proteins)responsible for detecting force reside in specialized structures in the EC-membrane and these structures have unique physical characteristics (their lipid components exist in a liquid-ordered (gel)phase). A molecule's activity is regulated, in part, by the dynamics of molecules around it. Therefore, the proposed research seeks to measure the effects of fluid force on the dynamics of molecules located in these specialized structures.
To measure the dynamics (e.g. rotation rate, lateral diffusion) of single molecules in membrane subdomains, the PI proposes to combine (i) polarized laser light delivered at very short, controlled pulses, (ii) the preference of certain fluorescent lipid-like molecules for specialized domains in the cell membrane, and (iii) the use of optics and fast-response light detection. The PI will combine powerful spectroscopic and microscopy tools to investigate molecular dynamics in subcellular membrane domains in single cells subjected to shear stress.
The PI hypothesizes that shear stress may perturb lipids in membrane microdomains, which, in turn, alters the dynamics of membrane bound proteins important in mechanotransduction. To test this hypothesis the PI proposes to (i) measure the effects of shear stress and membrane modifications on the signaling through three classes of membrane receptors: peripheral membrane proteins (G-proteins), cytoskeleton-linked integral membrane proteins (integrins) and non-cytoskeleton-linked integral membrane proteins (receptor tyrosine kinase, flk-1),(ii)to measure the effects of shear stress and membrane modification on the rotational and lateral dynamics of these molecules using novel fluorescent probes, and (iii)to measure the spatio-temporal aspects of the effects of shear stress on membrane phase sub-domains in endothelial cells. A central feature of this proposal is to integrate these scientific aims with educational aims to incorporate physical, applied, life, and clinical sciences and Bioethics in the education and training of undergraduate and graduate students. As part of a detailed plan to integrate research and education, the PI will act as co-director and educational director in a Penn State Summer Institute (PSSI)for Biomaterials and Bionanotechnology that is jointly funded by NIH and NSF.
|Effective start/end date||2/15/03 → 1/31/09|
- National Science Foundation: $406,000.00