Macrophages are responsible for engulfing lipid deposits, such as oxidized low-density lipoproteins (oxLDL), within the arterial wall resulting in the accumulation of foam cells and atherosclerotic plaque formation, which over time leads to stiffening of the artery. The role of substrate stiffness in influencing foam cell formation is currently poorly understood. In our preliminary work, we show that the stretch activated and Ca2+ permeable ion channel Piezo1 is important in regulating macrophage activation and lipid uptake, and its activity is regulated by stiffness. While increases in intracellular Ca2+ are known to enhance macrophage activation and lipid uptake, there are currently no reported roles for Piezo1 in macrophages. In this project, we propose to test the hypothesis that tissue stiffness regulates macrophage foam cell formation through Piezo1 activity. In AIM 1, we will determine the role of Piezo1-mediated Ca2+ activity in regulating the formation of foam cells. We will utilize a novel transgenic Ca2+ reporter, Salsa6f, and will manipulate Piezo1 activity through Yoda1, a Piezo1 agonist, siRNA, and genetic knock outs to determine the role of this channel in regulating Ca2+ influx in response to oxLDL using confocal and total internal reflectance microscopy. In addition, we will manipulate Piezo1 activity to determine its role in regulating oxLDL uptake, lipid transporter expression, and Ca2+ dependent pathways with known functions in foam cell formation through microscopy, western blots, and qPCRs. In AIM 2, we will evaluate the role of stiffness in influencing Piezo1 activity and foam cell formation. We will fabricate substrates with similar stiffness to those found in plaques and will evaluate Piezo1 activity and its resulting influence on foam cell formation, as described in AIM 1. Finally, in AIM 3 we will investigate the role of Piezo1 in macrophage-mediated plaque formation in vivo using a murine atherosclerotic model. We will utilize LysMCre-Salsa6f-ApoE mice to determine changes in Ca2+ activity in response to plaque formation ex vivo. In addition, we will use LysMCre-Piezo1-ApoE knockout mice to evaluate the role of this channel in regulating atherosclerosis by quantifying plaque size using histology. Mice will be matched by gender and age with littermates used as controls. The proposed work will expand on our current understanding of the development of atherosclerosis and could also lead to the creation of novel therapeutics.
|Program type||Predoctoral Fellowship|
|Effective start/end date||01/01/2020 → 12/31/2021|