The human aging process increases the risk of cancer and cardiovascular diseases that together account for the most death in United States. Nuclear lamina, present in most cell nuclei, is implicated in the aging process. Made of type V intermediate filaments called lamin, lamina sits underneath the nuclear envelope, provides structural support, and is involved in chromatin organization and other regulatory pathways. Mutations in lamin, lamin-associated proteins, and other nuclear envelope proteins account for a range of human diseases called laminopathies. Among them is Hutchinson-Gilford progeria syndrome (HGPS), a rare premature aging disorder caused by a point mutation in lamin A/C gene that results in a truncated lamin mutant known as progerin. Progerin is responsible for the characteristics of old age in children with HGPS, who develop atherosclerosis aggressively and usually die from heart attack or stroke in their teens. Interestingly, progerin is also found in normal people, and increases with age. Vasculature of HGPS patients share many similarities with that of old people. Defective nuclear lamina in aged cells resemble nuclei of HGPS cells, with the characteristic distorted nuclear shape. While progerin could be a novel contributor to vascular aging, its role in the mechano-biology of endothelial cells in HGPS patients or older adults is not understood. Our long term goal is to investigate the effect of progerin in human endothelial mechano-biology under shear stress. In this project, we focus on how progerin affects cell alignment and migration in wound recovery under flow. Our overall hypothesis is that progerin-expressing endothelial nuclei have compromised responses to shear stress. Using both computational as well as cell based approaches, this project will evaluate the effects of shear stress on endothelial cell alignment and migration in wound recovery (Aim 1); and begin to develop a hybrid continuum-tensegrity computational model of endothelial cell under flow (Aim 2). Based on previous studies and preliminary data, we hypothesize that progerin-expressing endothelial nuclei have compromised ability to sense shear stress and as a result, cells will fail to align properly under flow and have decreased wound recovery (Aim 1). We also hypothesize that nucleus and MTOC orient under shear stress in a way to minimize internal stress due to fluid flow and that this process is disrupted in cells with progerin. To test this hypothesis, we will develop a computation model of endothelial cell under shear stress using a hybrid approach that integrates continuum and structural models, a cellular fluid-structure interaction model with cytoskeletal elements (Aim 2). Simulation results will be correlated with experimental results to analyze nuclear stress under flow. A complete 3D model will help delineate how shear stress is transduced to the nucleus, especially in diseases that impact nuclear mechanics. This study will foster new insight into how nuclear and cytoskeletal mechanics are involved in mechano-biology processes, and lead to a better understanding of progerin?s role in vascular aging, as well as its potential as a therapeutic target.
Hutchinson-Gilford progeria syndrome (HGPS) is characterized by signs of accelerated aging caused by progerin, a mutant truncated form of nuclear lamin. Progerin could be a novel contributor to vascular aging and endothelial dysfunction which leads to atherosclerosis and other cardiovascular diseases. In this project, we focus on how progerin affects cell alignment and migration in wound recovery under flow using both computation modeling as well as cell based approaches, and results from this research will help clarify the relationship between mechanical force and cell and tissue damage due to aging.
