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Progerin accelerates atherosclerosis by inducing endoplasmic reticulum stress in vascular smooth muscle cells.

ABSTRACT: Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disorder caused by progerin, a mutant lamin A variant. HGPS patients display accelerated aging and die prematurely, typically from atherosclerosis complications. Recently, we demonstrated that progerin-driven vascular smooth muscle cell (VSMC) loss accelerates atherosclerosis leading to premature death in apolipoprotein E-deficient mice. However, the molecular mechanism underlying this process remains unknown. Using a transcriptomic approach, we identify here endoplasmic reticulum stress (ER) and the unfolded protein responses as drivers of VSMC death in two mouse models of HGPS exhibiting ubiquitous and VSMC-specific progerin expression. This stress pathway was also activated in HGPS patient-derived cells. Targeting ER stress response with a chemical chaperone delayed medial VSMC loss and inhibited atherosclerosis in both progeria models, and extended lifespan in the VSMC-specific model. Our results identify a mechanism underlying cardiovascular disease in HGPS that could be targeted in patients. Moreover, these findings may help to understand other vascular diseases associated with VSMC death, and provide insight into aging-dependent vascular damage related to accumulation of unprocessed toxic forms of lamin A.

SUBMITTER: Hamczyk MR

PROVIDER: S-EPMC6460349 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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Progerin accelerates atherosclerosis by inducing endoplasmic reticulum stress in vascular smooth muscle cells.

Hamczyk Magda R MR Villa-Bellosta Ricardo R Quesada Víctor V Gonzalo Pilar P Vidak Sandra S Nevado Rosa M RM Andrés-Manzano María J MJ Misteli Tom T López-Otín Carlos C Andrés Vicente V

EMBO molecular medicine 20190401 4

Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disorder caused by progerin, a mutant lamin A variant. HGPS patients display accelerated aging and die prematurely, typically from atherosclerosis complications. Recently, we demonstrated that progerin-driven vascular smooth muscle cell (VSMC) loss accelerates atherosclerosis leading to premature death in apolipoprotein E-deficient mice. However, the molecular mechanism underlying this process remains unknown. Using a transcriptomic a ...[more]

PMID: 30862662

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Project description:BackgroundTar is the main toxic of cigarettes, and its effect on atherosclerosis progression and the underlying mechanisms remain largely unknown. Vascular smooth muscle cells (VSMCs) play a key role in atherogenesis and plaque vulnerability. The present study sought to investigate the mechanism of atherosclerosis progression through tar-induced VSMC necroptosis, a recently described form of necrosis.MethodsThe effect of tar on atherosclerosis progression and VSMC necroptosis was examined in ApoE-/- mice and cultured VSMCs. The role of necroptosis in tar-induced plaque development was evaluated in RIPK3-deletion mice (ApoE-/-RIPK3-/-). The key proteins of necroptosis in carotid plaques of smokers and non-smokers were also examined. Quantitative proteomics of mice aortas was conducted to further investigate the underlying mechanism. Pharmacological approaches were then applied to modulate the expression of targets to verify the regulatory process of tar-induced necroptosis.ResultsTar administration led to increased atherosclerotic plaque area and reduced collagen and VSMCs in ApoE-/- mice. The expression of RIPK1、RIPK3、and MLKL in VSMCs of plaques were all increased in tar-exposed mice and smokers. RIPK3 deletion protected against VSMC loss and plaque progression stimulated by tar. In mechanistic studies, quantitative proteomics analysis of ApoE-/- mice aortas suggested that tar triggered endoplasmic reticulum (ER) stress. PERK-eIF2α-CHOP axis was activated in tar-treated VSMCs and atherosclerotic plaque. Inhibition of ER stress using 4PBA significantly reduced plaque progression and VSMC necroptosis. Further study revealed that ER stress resulted in calcium (Ca2+) release into mitochondria and cytoplasm. Elevated Ca2+ levels lead to mitochondrial dysfunction and excessive reactive oxygen species (ROS) production, which consequently promote RIPK3-dependent necroptosis. In addition, Ca2+/calmodulin-dependent protein kinase II (CaMKII) activated by cytosolic Ca2+ overload binds to RIPK3, accounting for necroptosis.ConclusionThe findings revealed that cigarette tar promoted atherosclerosis progression by inducing RIPK3-dependent VSMC necroptosis and identified novel avenues of ER stress and Ca2+ overload.

Project description:Accumulation of damaged or misfolded proteins resulted from oxidative protein modification induces endoplasmic reticulum (ER) stress by activating the pathways of unfolded protein response. In pathologic hemolytic conditions, extracellular free hemoglobin is submitted to rapid oxidation causing heme release. Resident cells of atherosclerotic lesions, after intraplaque hemorrhage, are exposed to heme leading to oxidative injury. Therefore, we raised the question whether heme can also provoke ER stress. Smooth muscle cells are one of the key players of atherogenesis; thus, human aortic smooth muscle cells (HAoSMCs) were selected as a model cell to reveal the possible link between heme and ER stress. Using immunoblotting, quantitative polymerase chain reaction and immunocytochemistry, we quantitated the markers of ER stress. These were: phosphorylated eIF2α, Activating transcription factor-4 (ATF4), DNA-damage-inducible transcript 3 (also known as C/EBP homology protein, termed CHOP), X-box binding protein-1 (XBP1), Activating transcription factor-6 (ATF6), GRP78 (glucose-regulated protein, 78kDa) and heme responsive genes heme oxygenase-1 and ferritin. In addition, immunohistochemistry was performed on human carotid artery specimens from patients who had undergone carotid endarterectomy. We demonstrate that heme increases the phosphorylation of eiF2α in HAoSMCs and the expression of ATF4. Heme also enhances the splicing of XBP1 and the proteolytic cleavage of ATF6. Consequently, there is up-regulation of target genes increasing both mRNA and protein levels of CHOP and GRP78. However, TGFβ and collagen type I decreased. When the heme binding proteins, alpha-1-microglobulin (A1M) and hemopexin (Hpx) are present in cell media, the ER stress provoked by heme is inhibited. ER stress pathways are also retarded by the antioxidant N-acetyl cysteine (NAC) indicating that reactive oxygen species are involved in heme-induced ER stress. Consistent with these findings, elevated expression of the ER stress marker GRP78 and CHOP were observed in smooth muscle cells of complicated lesions with hemorrhage compared to either atheromas or healthy arteries. In conclusion, heme triggers ER stress in a time- and dose-dependent manner in HAoSMCs. A1M and Hpx as well as NAC effectively hamper heme-induced ER stress, supporting their use as a potential therapeutic approach to reverse such a deleterious effects of heme toxicity.

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Progerin accelerates atherosclerosis by inducing endoplasmic reticulum stress in vascular smooth muscle cells.

Publications

Progerin accelerates atherosclerosis by inducing endoplasmic reticulum stress in vascular smooth muscle cells.

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