eIF2α mediated integrated stress response connects multiple intracellular signaling to reprogram vascular smooth muscle cell fate in carotid plaques

Abstract

Abstract Background As a well-recognized pathological basis of ischemic stroke, the molecular mechanisms of atherosclerotic carotid artery stenosis remain unclear. Vascular smooth muscle cells (VSMCs) play a fundamental role in the initiation and progression of atherosclerosis. The involvement of organelle dynamics has been uncovered in the development of atherosclerosis in the past decade. However, systematic studies still are rare on the relationship between organelle dynamics and the pathogenetic significance of multiple cellular stresses during atherosclerotic progression. Methods Transcriptomics from stable and vulnerable carotid plaques and bioinformatics analysis were performed. Primary VSMCs were isolated from the carotid plaques, followed by histopathological staining to determine the expression profile. The dynamics of endoplasmic reticulum (ER), mitochondria, and lysosomes were observed in primary VSMCs and VSMC cell lines by live-cell imaging. The underlying mechanisms of disordered organelle dynamics were investigated by comprehensive biological approaches. Results ER whorls, a representative structural change of ER stress, was the prominent dynamic reconstruction of VSMCs between vulnerable and stable plaques, followed by the fragmented mitochondria and enlarged lysosomes, which implies mitochondrial stress, and lysosomal defects, respectively. Induction of mitochondrial stress alleviated ER stress levels and autophagy in a dependent manner on eukaryotic translation initiation factor 2α (eIF2α). Furthermore, eIF2α synchronized ER stress, mitochondrial stress and lysosomal defects were validated in clinical samples. Conclusion Morphological and functional changes of VSMCs’ organelles can provide reliable biomarkers to imply the progression of atherosclerosis, especially ER whorls. eIF2α is essential for integrating multiple stress signaling of VSMC’s behavior and fate.