Salidroside-Mediated Autophagic Targeting of Active Src and Caveolin-1 Suppresses Low-Density Lipoprotein Transcytosis across Endothelial Cells

Abstract

Subendothelial retention of apolipoprotein B100-containing lipoprotein, such as low-density lipoprotein (LDL), is the initial step of atherogenesis. Activation of autophagy exhibits beneficial effects for the treatment of atherosclerosis. In our previous study, we demonstrated that hyperglycemia suppressed autophagic degradation of caveolin-1, which in turn resulted in acceleration of caveolae-mediated LDL transcytosis across endothelial cells and lipid retention. Therefore, targeting the crossed pathway in autophagy activation and LDL transcytosis interruption may be a promising antiatherosclerotic strategy. In metabolic diseases, including atherosclerosis, salidroside, a phenylpropanoid glycoside compound (3,5-dimethoxyphenyl) methyl-β-glucopyranoside), is the most important compound responsible for the therapeutic activities of Rhodiola. However, whether salidroside suppresses LDL transcytosis to alleviate atherosclerosis has not yet been elucidated. In the present study, we demonstrated that salidroside significantly decreased LDL transcytosis across endothelial cells. Salidroside-induced effects were dramatically blocked by AMPK (adenosine monophosphate-activated protein kinase) inhibitor (compound c, AMPKα siRNA) and by overexpression of exogenous tyrosine-phosphorylated caveolin-1 using transfected cells with phosphomimicking caveolin-1 on tyrosine 14 mutant plasmids (Y14D). Furthermore, we observed that salidroside promoted autophagosome formation via activating AMPK. Meanwhile, the interaction between caveolin-1 and LC3B-II, as well as the interaction between active Src (indicated by the phosphorylation of Src on tyrosine 416) and LC3B-II, was significantly increased, upon stimulation with salidroside. In addition, both bafilomycin A1 (a lysosome inhibitor) and an AMPK inhibitor (compound c) markedly prevented salidroside-induced autophagic degradation of p-Src and caveolin-1. Moreover, the phosphorylation of caveolin-1 on tyrosine 14 was disrupted due to the downregulation of p-Src and caveolin-1, thereby directly decreasing LDL transcytosis by attenuating the number of caveolae on the cell membrane and by preventing caveolae-mediated LDL endocytosis released from the cell membrane. In ApoE-/- mice, salidroside significantly delayed the formation of atherosclerotic lesions. Meanwhile, a significant increase in LC3B, accompanied by attenuated accumulation of the autophagy substrate SQSTM1, was observed in aortic endothelium of ApoE-/- mice. Taken together, our findings demonstrated that salidroside protected against atherosclerosis by inhibiting LDL transcytosis through enhancing the autophagic degradation of active Src and caveolin-1.

Salidroside Ameliorated Intermittent Hypoxia-Aggravated Endothelial Barrier Disruption and Atherosclerosis via the cAMP/PKA/RhoA Signaling Pathway

“…Therefore, potential drugs for OSA-related atherosclerotic cardiovascular diseases remain to be further investigated. Salidroside can improve atherosclerosis in high fat diet-fed ApoE -/- mice ( Bai et al, 2020 ; Song et al, 2021 ). However, the effect of salidroside on CIH-related atherosclerosis has not been reported.…”

“…Salidroside exhibited activity similar to that of Rhodiola extract. Salidroside improved CIH-mediated myocardial cell apoptosis ( Zhong et al, 2010 ; Lai et al, 2014 ), chronic persistent hypoxia-induced pulmonary hypertension ( Chen et al, 2016 ) and high fat diet-related atherosclerosis ( Xing et al, 2015 ; Bai et al, 2020 ; Song et al, 2021 ) in animal models. Moreover, salidroside suppresses oxidative stress-induced HUVECs cell injury ( Zhao et al, 2013 ; Zhu et al, 2016 ).…”

Deacetylation of Caveolin-1 by Sirt6 induces autophagy and retards high glucose-stimulated LDL transcytosis and atherosclerosis formation

“…2C, E). LDL uptake by ECs is not only an intermediate step of LDL transcytosis, but is also crucial to atherogenesis [36]. Therefore, the concentration of LDL in the ECs is an indicator of LDL transcytosis.…”

Salidroside regulates mitochondrial homeostasis after polarization of RAW264.7 macrophages

“…4,5 Studies have shown that SAL has antiatherosclerotic effects, 6,7 and the mechanisms involved include various pathways such as oxidative stress, inflammation, mitochondrial dysfunction, autophagy, and AMP-activated protein kinase signal transduction. 8–11…”

“…4,5 Studies have shown that SAL has antiatherosclerotic effects, 6,7 and the mechanisms involved include various pathways such as oxidative stress, inflammation, mitochondrial dysfunction, autophagy, and AMP-activated protein kinase signal transduction. [8][9][10][11] In fact, as a chronic inflammatory disease, a large part of the treatment of atherosclerosis benefits from its inhibition of inflammatory signaling. Liu et al showed that SAL reduced atherosclerotic plaque formation by inhibiting NOD-like receptor protein 3 (NLRP3)-associated endothelial cell pyroptosis.…”