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- Title
Chronic mTOR activation induces a degradative smooth muscle cell phenotype.
- Authors
Guangxin Li; Mo Wang; Caulk, Alexander W.; Cilfone, Nicholas A.; Gujja, Sharvari; Lingfeng Qin; Pei-Yu Chen; Zehua Chen; Yousef, Sameh; Yang Jiao; Changshun He; Bo Jiang; Korneva, Arina; Bersi, Matthew R.; Guilin Wang; Xinran Liu; Mehta, Sameet; Geirsson, Arnar; Gulcher, Jeffrey R.; Chittenden, Thomas W.
- Abstract
Smooth muscle cell (SMC) proliferation has been thought to limit the progression of thoracic aortic aneurysm and dissection (TAAD) because loss of medial cells associates with advanced disease. We investigated effects of SMC proliferation in the aortic media by conditional disruption of Tsc1, which hyperactivates mTOR complex 1. Consequent SMC hyperplasia led to progressive medial degeneration and TAAD. In addition to diminished contractile and synthetic functions, fate-mapped SMCs displayed increased proteolysis, endocytosis, phagocytosis, and lysosomal clearance of extracellular matrix and apoptotic cells. SMCs acquired a limited repertoire of macrophage markers and functions via biogenesis of degradative organelles through an mTOR/β-catenin/MITF-dependent pathway, but were distinguishable from conventional macrophages by an absence of hematopoietic lineage markers and certain immune effectors even in the context of hyperlipidemia. Similar mTOR activation and induction of a degradative SMC phenotype in a model of mild TAAD due to Fbn1 mutation greatly worsened disease with near-uniform lethality. The finding of increased lysosomal markers in medial SMCs from clinical TAAD specimens with hyperplasia and matrix degradation further supports the concept that proliferation of degradative SMCs within the media causes aortic disease, thus identifying mTOR-dependent phenotypic modulation as a therapeutic target for combating TAAD.
- Subjects
MUSCLE cells; SMOOTH muscle; THORACIC aneurysms; EXTRACELLULAR matrix; DISSECTING aneurysms; PROTEIN metabolism; PROTEINS; BIOLOGICAL models; RESEARCH; LYSOSOMES; ANIMAL experimentation; RESEARCH methodology; CYTOSKELETAL proteins; EVALUATION research; MEDICAL cooperation; CELLULAR signal transduction; COMPARATIVE studies; CELLS; RESEARCH funding; AORTA; MICE
- Publication
Journal of Clinical Investigation, 2020, Vol 130, Issue 3, p1233
- ISSN
0021-9738
- Publication type
journal article
- DOI
10.1172/JCI131048