Pterostilbene Increases LDL Metabolism in HL-1 Cardiomyocytes by Modulating the PCSK9/HNF1α/SREBP2/LDLR Signaling Cascade, Upregulating Epigenetic hsa-miR-335 and hsa-miR-6825, and LDL Receptor Expression

Abstract

Proprotein convertase subtilisin/kexin type 9 (PCSK9) can promote the degradation of low-density lipoprotein (LDL) receptor (LDLR), leading to hypercholesterolemia and myocardial dysfunction. The intracellular regulatory mechanism by which the natural polyphenol pterostilbene modulates the PCSK9/LDLR signaling pathway in cardiomyocytes has not been evaluated. We conducted Western blotting, flow cytometry, immunofluorescence staining, and mean fluorescence intensity analyses of pterostilbene-treated mouse HL-1 cardiomyocytes. Pterostilbene did not alter cardiomyocyte viability. Compared to the control group, treatment with both 2.5 and 5 μM pterostilbene significantly increased the LDLR protein expression accompanied by increased uptake of LDL. The expression of the mature PCSK9 was significantly suppressed at the protein and mRNA level by the treatment with both 2.5 and 5 μM pterostilbene, respectively, compared to the control. Furthermore, 2.5 and 5 μM pterostilbene treatment resulted in a significant reduction in the protein hepatic nuclear factor 1α (HNF1α)/histone deacetylase 2 (HDAC2) ratio and sterol regulatory element-binding protein-2 (SREBP2)/HDAC2 ratio. The expression of both hypoxia-inducible factor-1 α (HIF1α) and nuclear factor erythroid 2-related factor 2 (Nrf2) at the protein level was also suppressed. Pterostilbene as compared to short hairpin RNA against SREBP2 induced a higher protein expression of LDLR and lower nuclear accumulation of HNF1α and SREBP2. In addition, pterostilbene reduced PCSK9/SREBP2 interaction and mRNA expression by increasing the expression of hsa-miR-335 and hsa-miR-6825, which, in turn, increased LDLR mRNA expression. In cardiomyocytes, pterostilbene dose-dependently decreases and increases the protein and mRNA expression of PCSK9 and LDLR, respectively, by suppressing four transcription factors, HNF1α, SREBP2, HIF1α, and Nrf2, and enhancing the expression of hsa-miR-335 and hsa-miR-6825, which suppress PCSK9/SREBP2 interaction.

Comparative Effect of Bergamot Polyphenolic Fraction and Red Yeast Rice Extract in Rats Fed a Hyperlipidemic Diet: Role of Antioxidant Properties and PCSK9 Expression

“…This is also confirmed by the evidence that newly approved PCSK9 inhibitors reduce LDL receptor degradation and lower LDL-C by >50% [ 32 , 33 , 34 ], thus offering an additional therapeutic option for patients not meeting LDL-C treatment goals with diet and maximally tolerated lipid-lowering therapy. Several recent studies also showed the key role of natural derivatives and the importance of microbiota to inhibit the PCSK9, through its transcriptional and epigenetic regulation and the subsequent up-regulation of low-density lipoprotein receptor expression, thus increasing LDL metabolism [ 35 , 36 , 37 , 38 , 39 , 40 , 41 ]. Interestingly, statin therapy itself increases serum PCSK9 levels [ 42 ], a finding that may in part explain the nonlinear relationship between statin dose and LDL-C reduction and the intra-individual LDL-C response to statin therapy [ 43 , 44 ].…”

Isocoumarins and Benzoquinones with Their Proprotein Convertase Subtilisin/Kexin Type 9 Expression Inhibitory Activities from Dried Roots of Lysimachia vulgaris

“…However, changes in the LDLR protein level were not detected after treatment (Figure ). Previous studies have reported that several natural products with PCSK9 expression downregulatory activities, including stilbene, xanthone, and triterpenoid, increased LDLR protein levels and subsequent LDL uptake, potentially lowering the LDL cholesterol level. ,− In addition, some natural compounds with IDOL expression inhibitory activities, such as platycodin D and xanthohumol, increased the LDLR protein level as well. , …”

Effect of PCSK9 on atherosclerotic cardiovascular diseases and its mechanisms: Focus on immune regulation

“…The expression of PCSK9 is mainly regulated by SREBP2, hepatocyte nuclear factor-1α (HNF-1α), and forkhead box O3 (FoxO3) at the transcriptional level (45)(46)(47)(48). Sequence analysis of the 5′ flanking region from −2,112 to −94 of the PCSK9 gene revealed the presence of the sterol regulatory element (SRE) site (5′-GTGGCGTGAT-3′) in the proximal region of the PCSK9 promoter (49,50).…”