scholarly journals Smooth muscle 22 alpha protein inhibits VSMC foam cell formation by supporting normal LXRα signaling, ameliorating atherosclerosis

2021 ◽  
Vol 12 (11) ◽  
Author(s):  
Dan-Dan Zhang ◽  
Yu Song ◽  
Peng Kong ◽  
Xin Xu ◽  
Ya-Kun Gao ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Nuclear Import ◽  
Actin Polymerization ◽  
Foam Cell ◽  
Affinity Purification ◽  
Cell Formation ◽  
Cholesterol Homeostasis ◽  
Foam Cell Formation ◽  
Cholesterol Accumulation ◽  
Importin Α

AbstractVascular smooth muscle cells (VSMCs) are indispensable components in foam cell formation in atherosclerosis. However, the mechanism behind foam cell formation of VSMCs has not been addressed. We found a potential association between deletion of smooth muscle (SM) 22α and deregulated nuclear receptors liver X receptors (LXRs)/retinoid X receptor (RXR) signaling in mice. Here, we investigated the roles of SM22α in LXRα-modulated cholesterol homeostasis, and explore possible mechanisms underlying this process. We identified that the depletion of SM22α was a primary event driving VSMC cholesterol accumulation and the development of atherosclerosis in mice. Proteomic and lipidomic analysis validated that downregulation of SM22α was correlated with reduced expression of LXRα and ATP-binding cassette transporter (ABCA) 1 and increased cholesteryl ester in phenotypically modulated VSMCs induced by platelets-derived growth factor (PDGF)-BB. Notably, LXRα was mainly distributed in the cytoplasm rather than the nucleus in the neointimal and Sm22α−/− VSMCs. Loss of SM22α inhibited the nuclear import of LXRα and reduced ABCA1-mediated cholesterol efflux via promoting depolymerization of actin stress fibers. Affinity purification and mass spectrometry (AP-MS) analysis, co-immunoprecipitation and GST pull-down assays, confocal microscopy, and stochastic optical reconstruction microscopy (STORM) revealed that globular-actin (G-actin), monomeric actin, interacted with and retained LXRα in the cytoplasm in PDGF-BB-treated and Sm22α−/− VSMCs. This interaction blocked LXRα binding to Importin α, a karyopherin that mediates the trafficking of macromolecules across the nuclear envelope, and the resulting reduction of LXRα transcriptional activity. Increasing SM22α expression restored nuclear localization of LXRα and removed cholesterol accumulation via inducing actin polymerization, ameliorating atherosclerosis. Our findings highlight that LXRα is a mechanosensitive nuclear receptor and that the nuclear import of LXRα maintained by the SM22α-actin axis is a potential target for blockade of VSMC foam cell formation and development of anti-atherosclerosis.

Pathways of smooth muscle foam cell formation in atherosclerosis

2019 ◽  
Vol 30 (2) ◽  
pp. 117-124 ◽  
Author(s):  
Collin S. Pryma ◽  
Carleena Ortega ◽  
Joshua A. Dubland ◽  
Gordon A. Francis
Keyword(s):  
Smooth Muscle ◽  
Foam Cell ◽  
Cell Formation ◽  
Foam Cell Formation

Abstract 5523: High Glucose Promotes Intracellular Lipid Accumulation by Impairing the Balance between CD36 and ATP-Binding Cassette Transporter G1 in Vascular Smooth Muscle Cells

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Jia H Xue ◽  
Zu Y Yuan ◽  
Yue Wu ◽  
Yan Zhao ◽  
Wei P Zhang ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
High Glucose ◽  
Cholesterol Efflux ◽  
Foam Cell ◽  
Cell Formation ◽  
Foam Cell Formation ◽  
Intracellular Lipid ◽  
Protein Expressions

Objective: Foam cell formation is a characteristic of atherosclerotic lesions. It’s known that high glucose promotes macrophage-derived foam cell formation involved in increased influx or reduced efflux of lipids. The aim of this study is to investigate the influence of hyperglycemia on foam cell transformation of vascular smooth muscle cells (VSMCs) and possible mechanisms contributing to these effects. Methods and Results: The results showed that high glucose in cultured human aortic SMCs increased the mRNA and protein expressions of CD36, a regulator of lipid influx, and suppressed the mRNA and protein expressions of ATP binding cassette (ABC) transporters ABCG1, a regulator of cholesterol efflux to HDL, in a dose- and time-dependent manner. However, the ability of cholesterol efflux to lipid-free apoAI was not impaired. VSMCs exposed to high glucose were easily developed into lipid-loaded cells as demonstrated by oil red O staining. Meanwhile, it had a maximum 2.3-fold increase in accumulation of esterified cholesterol compared to VSMCs cultured in normal glucose. Additionally, there was no change found in either liver X receptor (LXR)α or LXRβ, suggesting that high glucose-induced down-regulation of ABCG1 was LXR-independent. Down-regulation of ABCG1 induced by high glucose was almost totally reversed by the NF-κB inhibitors BAY 11–7085, tosyl-phenylalanine chloromethyl-ketone (TPCK) and by the antioxidant N-acetyl-L-cysteine(NAC). This reversal was accompanied by reduced intracellular lipid content. Furthermore, we also demonstrated that high glucose enhanced the binding of nuclear proteins extracted from human VSMCs to the NF-κB regulatory elements. This effect was abrogated by NAC and NF-κB inhibitors. Conclusions: These results suggested that hyperglycemia-induced foam cell formation in VSMCs was related to the imbalanced lipid flux by increasing CD36 mediated modified LDL uptake and reducing ABCG1 regulated intracellular cholesterol efflux. Moreover, this effect was associated with activated NF-κB pathway signaling.

Abstract 570: Macrophage Catabolism of Aggregated Lipoproteins Using a Novel Extracellular Compartment Regulates Lipid Accumulation During Atherosclerosis

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Rajesh K Singh ◽  
Abigail S Haka ◽  
Valeria C Barbosa-Lorenzi ◽  
Arky Asmal ◽  
Frederik Lund ◽  
...  
Keyword(s):  
Lipid Accumulation ◽  
Actin Polymerization ◽  
Foam Cell ◽  
Low Density Lipoprotein ◽  
Cell Formation ◽  
Density Lipoprotein ◽  
Foam Cell Formation ◽  
Atherosclerotic Vascular Disease ◽  
Extracellular Compartment

Despite impressive advances in research, prevention, and treatment, atherosclerotic vascular disease remains the leading cause of death in the developed world. Mechanisms of cholesterol accumulation in the arteries have been studied intensively, but the in vivo contributions of different pathways leading to lipid accumulation and foam cell formation are not understood. In the arteries, low-density lipoprotein (LDL) is aggregated and bound to the extracellular matrix. When such aggregated LDL is presented to macrophages, they form a novel acidic, hydrolytic compartment that is topologically extracellular, to which lysosomal enzymes are secreted. Such compartments are observed in vivo in murine atherosclerotic plaque macrophages interacting with cholesterol rich deposits. Using state-of-the-art quantitative and high resolution microscopy techniques, characterization of compartment morphology reveals how macrophages use local actin polymerization to drive plasma membrane remodeling at the interface with aggregated LDL. This leads to sequestration of aggregated LDL into topologically convoluted structures that allow acidification, catabolism and internalization of LDL. We find that a TLR4/MyD88/Syk/PI3 kinase/Akt dependent signaling pathway in macrophages regulates the formation of such catabolic compartments. Consistent with this, deficiency of TLR4 in vivo can protect macrophages from lipid accumulation in murine atherosclerotic plaques. Herein, we provide compelling evidence for a novel form of catabolism that macrophages use to degrade aggregated LDL in vivo during atherosclerosis and this process leads to foam cell formation, cell death and promotes disease progression.

Effect of PCSK9 on Vascular Smooth Muscle Cell Functions: A New Player in Atherosclerosis

2021 ◽  
Vol 28 ◽  
Author(s):  
Qiong Xiang ◽  
WenFeng Liu ◽  
JingLin Zeng ◽  
YiMing Deng ◽  
Juan Peng ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Foam Cell ◽  
Cell Formation ◽  
Atherosclerotic Lesion ◽  
Foam Cell Formation ◽  
Therapeutic Effects ◽  
Pcsk9 Inhibitors ◽  
Cell Functions

: Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secretory serine protease that plays multiple biological functions in the regulation of physiological and pathological processes. PCSK9 inhibitors decrease the circulating LDL-cholesterol level with well-known preventive and therapeutic effects on atherosclerosis (AS), but increasing evidence shows that the direct impact of PCSK9 on the vascular wall also plays an important role in atherosclerotic progression. Compared with other vascular cells, a large proportion of PCSK9 is originated from vascular smooth muscle cells (VSMC). Therefore, defining the effect of VSMC-derived PCSK9 on response changes, such as phenotypic switch, apoptosis, autophagy, inflammation, foam cell formation, and calcification of VSMC, helps us better understand the “pleiotropic” effects of VSMC on the atherosclerotic process. In addition, our understanding of the mechanisms of PCSK9 controlling VSMC functions in vivo is far from enough. This review aims to holistically evaluate and analyze the current state of our knowledge regarding PCSK9 actions affecting on VSMC functions and its mechanism in atherosclerotic lesion development. A mechanistic understanding of PCSK9 effects on VSMC will further underpin the success of a new therapeutic strategy targeting AS.

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