Vascular Smooth Muscle-Specific Progerin Expression Accelerates Atherosclerosis and Death in a Mouse Model of Hutchinson-Gilford Progeria Syndrome
Background—Progerin, an aberrant protein that accumulates with age, causes the rare genetic disease Hutchinson-Gilford progeria syndrome (HGPS). HGPS patients with ubiquitous progerin expression exhibit accelerated aging and atherosclerosis, and die in their early teens mainly from myocardial infarction or stroke. The mechanisms underlying progerin-induced atherosclerosis remain unexplored, in part due to the lack of appropriate animal models.
Methods—We generated an atherosclerosis-prone model of HGPS by crossing apolipoprotein E-deficient (Apoe-/-) mice with LmnaG609G/G609G mice ubiquitously expressing progerin. To induce progerin expression specifically in macrophages or vascular smooth muscle cells (VSMC), we crossed Apoe-/-LmnaLCS/LCS mice with LysMCre and SM22αCre mice, respectively. Progerin expression was evaluated by PCR and immunofluorescence. Cardiovascular alterations were determined by immunofluorescence and histology in male mice fed normal chow or a high-fat diet (HFD). In vivo low-density lipoprotein (LDL) retention was assessed by intravenous injection of fluorescently-labeled human LDL. Cardiac electrical defects were evaluated by electrocardiography.
Results—Apoe-/-LmnaG609G/G609G mice with ubiquitous progerin expression exhibited a premature aging phenotype that included failure to thrive and shortened survival. In addition, HFD-fed Apoe-/-LmnaG609G/G609G mice developed a severe vascular pathology, including medial VSMC loss and lipid retention, adventitial fibrosis, and accelerated atherosclerosis, thus resembling most aspects of cardiovascular disease observed in HGPS patients. The same vascular alterations were also observed in Apoe-/-LmnaLCS/LCSSM22αCre mice expressing progerin specifically in VSMCs, but not in Apoe-/-LmnaLCS/LCSLysMCre mice with macrophage-specific progerin expression. Moreover, Apoe-/- LmnaLCS/LCSSM22αCre mice had a shortened lifespan despite the lack of any overt aging phenotype. Aortas of ubiquitously and VSMC-specific progerin-expressing mice exhibited increased retention of fluorescently-labeled human LDL, and atheromata in both models showed vulnerable plaque features. Immunohistopathological examination indicated that Apoe-/-LmnaLCS/LCSSM22αCre mice, unlike Apoe-/-LmnaG609G/G609G mice, die of atherosclerosis-related causes.
Conclusions—We have generated the first mouse model of progerin-induced atherosclerosis acceleration, and demonstrate that restricting progerin expression to VSMCs is sufficient to accelerate atherosclerosis, trigger plaque vulnerability and reduce lifespan. Our results identify progerin-induced VSMC death as a major factor triggering atherosclerosis and premature death in HGPS.
- Received August 1, 2017.
- Revision received January 24, 2018.
- Accepted February 15, 2018.