Inhibition of vascular smooth muscle cell PERK/ATF4 ER stress signaling protects against abdominal aortic aneurysms
Brennan Callow, Xiaobing He, Nicholas Juriga, Kevin D. Mangum, Amrita Joshi, Xianying Xing, Andrea Obi, Abhijnan Chattopadhyay, Dianna M. Milewicz, Mary X. O’Riordan, Johann Gudjonsson, Katherine Gallagher, Frank M. Davis
Brennan Callow, Xiaobing He, Nicholas Juriga, Kevin D. Mangum, Amrita Joshi, Xianying Xing, Andrea Obi, Abhijnan Chattopadhyay, Dianna M. Milewicz, Mary X. O’Riordan, Johann Gudjonsson, Katherine Gallagher, Frank M. Davis
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Research Article Vascular biology

Inhibition of vascular smooth muscle cell PERK/ATF4 ER stress signaling protects against abdominal aortic aneurysms

Abstract

Abdominal aortic aneurysms (AAA) are a life-threatening cardiovascular disease for which there is a lack of effective therapy preventing aortic rupture. During AAA formation, pathological vascular remodeling is driven by vascular smooth muscle cell (VSMC) dysfunction and apoptosis, for which the mechanisms regulating loss of VSMCs within the aortic wall remain poorly defined. Using single-cell RNA-Seq of human AAA tissues, we identified increased activation of the endoplasmic reticulum stress response pathway, PERK/eIF2α/ATF4, in aortic VSMCs resulting in upregulation of an apoptotic cellular response. Mechanistically, we reported that aberrant TNF-α activity within the aortic wall induces VSMC ATF4 activation through the PERK endoplasmic reticulum stress response, resulting in progressive apoptosis. In vivo targeted inhibition of the PERK pathway, with VSMC-specific genetic depletion (Eif2ak3fl/fl Myh11-CreERT2) or pharmacological inhibition in the elastase and angiotensin II–induced AAA model preserved VSMC function, decreased elastin fragmentation, attenuated VSMC apoptosis, and markedly reduced AAA expansion. Together, our findings suggest that cell-specific pharmacologic therapy targeting the PERK/eIF2α/ATF4 pathway in VSMCs may be an effective intervention to prevent AAA expansion.

Authors

Brennan Callow, Xiaobing He, Nicholas Juriga, Kevin D. Mangum, Amrita Joshi, Xianying Xing, Andrea Obi, Abhijnan Chattopadhyay, Dianna M. Milewicz, Mary X. O’Riordan, Johann Gudjonsson, Katherine Gallagher, Frank M. Davis

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Figure 2

TNF-α induces ATF4/CHOP ER stress signaling and apoptosis in vascular smooth muscle cells.

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TNF-α induces ATF4/CHOP ER stress signaling and apoptosis in vascular sm...
(A) MOVAS cells were treated with TNF-α (25 ng/mL) for 12 hours, and eIF2a, Atf4, and Chop mRNA levels, relative to 18S, were determined by qPCR. (B) MOVAS cells were treated with TNF-α (25 ng/mL) for 12 hours and p-EIF2α, EIF2α, ATF4, and CHOP protein abundance were determined by Western blot. Representative Western blotting is shown for treatment conditions and proteins of interest. (C) MOVAS cells were treated with TNF-α (25 ng/mL) and 4-PBA (3mM) for 12 hours, and eIF2a, Atf4, and Chop mRNA levels, relative to 18S, were determined by qPCR. (D) MOVAS cells were treated with TNF-α (25 ng/mL) and 4-PBA (3 mM) for 12 hours, and apoptosis was quantified by flow cytometry with annexin V and Propidium Iodine staining. (E) MOVAS cells were transfected with siControl or siATF4 (30 nM). After 48 hours, cells were serum starved in Opti-MEM for 24 hours. Depletion of Atf4 was confirmed by qPCR analysis. Cells were then stimulated with TNF-α (25 ng/mL) for 12 hours, and Chop mRNA levels, relative to 18S, were determined by qPCR. Bar graphs represent mean values from at least n = 4 independent experiments, with individual data points representing independent experiments. Data are represented as mean ± SEM. 2-way ANOVA with Newman-Keuls multiple-comparison test (C–E). Mann-Whitney U test (A). *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.