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Plasminogen Activator Inhibitor-1 Regulates the Cytoskeleton and Intrinsic Stiffness of Vascular Smooth Muscle Cells

ABSTRACT: SMCs express plasminogen activator inhibitor-1 (PAI-1), which regulates SMC function and vascular remodeling. However, whether PAI-1 controls SMC cytoskeletal dynamics and stiffness is unknown, and the causal role of PAI-1 in arterial stiffening is undefined. SMCs from human coronary arteries and aortae of wild-type vs. PAI-1-deficient mice were cultured with or without PAI-039, a specific PAI-1 inhibitor, after which cell stiffness was measured by atomic force microscopy, filamentous actin structures were assessed by confocal microscopy, and the activities cofilin, LIM domain kinase 1 (LIMK), slingshot homolog 1 (SSH), and AMP-activated protein kinase (AMPK) were measured. RNA sequencing was performed to determine the effects of PAI-039 on SMC gene expression. Effects of PAI-039 on aortic stiffness were assessed by pulse wave velocity. PAI-039 significantly reduced intrinsic stiffness of human SMCs, which was accompanied by significant decreases in cytoplasmic actin filaments. Similar effects were observed in wild-type, but not in PAI-1-deficient SMCs. Mechanistically, PAI-039 significantly increased the activity of cofilin, an actin depolymerase, in SMCs expressing PAI-1, but not in PAI-1-deficient cells. PAI-039 had no significant effects on LIMK or SSH activity. RNA-sequencing analysis suggested that PAI-039 up-regulates AMPK signaling in SMCs, which was confirmed by western blotting. Inhibition of AMPK prevented activation of cofilin by PAI-039. In mice, PAI-039 significantly decreased aortic stiffness without significantly altering peri-aortic fibrosis. PAI-039 decreases intrinsic SMC stiffness by reducing cytoplasmic stress fiber content. These effects are mediated by AMPK-dependent activation of cofilin. PAI-039 also decreases aortic stiffness in vivo. These findings suggest that PAI-1 is an important regulator of the SMC cytoskeleton and that pharmacologic inhibition of PAI-1 has potential to treat cardiovascular diseases mediated by accelerated arterial stiffening.

ORGANISM(S): Homo sapiens

PROVIDER: GSE225644 | GEO | 2023/02/23

REPOSITORIES: GEO

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Project description:OBJECTIVE: When aortic cells are under stress, such as increased hemodynamic pressure, they adapt to the environment by modifying their functions, allowing the aorta to maintain its strength. To understand the regulation of this adaptive response, we examined the transcriptomic and epigenomic programs in aortic smooth muscle cells (SMCs) during the adaptive response to angiotensin II (AngII) infusion and determined its importance in protecting against aortic aneurysm and dissection. APPROACH AND RESULTS: In wild-type mice, AngII infusion increased medial thickness in the thoracic aorta. Single-cell RNA sequencing analysis revealed an adaptive response in thoracic SMCs characterized by the upregulation of genes with roles in wound healing, elastin and collagen production, proliferation, migration, cytoskeleton organization, cell-matrix focal adhesion, and AKT and TGF-β signaling. Further single-cell sequencing assay for transposase-accessible chromatin (scATAC-seq) analysis showed increased chromatin accessibility at the regulatory regions of adaptive genes and revealed the mechanical sensor YAP/TEADs as a top candidate transcription complex driving the increased abundance of these gene transcripts (e.g., Lox, Col5a2 and Tgfb2). In cultured human aortic SMCs, cyclic stretch activated YAP, which directly bound to the regulatory regions of the adaptive genes (e.g., Lox) and increased the abundance of their transcripts. Finally, SMC-specific Yap deletion in mice compromised this adaptive response in SMCs, leading to an increased incidence of aortic aneurysm and dissection and a trend of increased rupture. CONCLUSIONS: Aortic stress triggers the systemic epigenetic induction of adaptive response (e.g., wound healing, proliferation, and matrix organization) in thoracic aortic SMCs, that depends on functional biomechanical signal transduction (e.g., YAP signaling). Our study highlights the importance of the adaptive response in maintaining aortic homeostasis and preventing aortic disease development in mice.

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Plasminogen Activator Inhibitor-1 Regulates the Cytoskeleton and Intrinsic Stiffness of Vascular Smooth Muscle Cells

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