Low density lipoprotein receptor-related protein 1 regulates cardiac hypertrophy induced by pressure overload

Ginsenoside Rg1 treats chronic heart failure by downregulating ERK1/2 protein phosphorylation

In this study, we investigated the potential therapeutic mechanism of ginsenoside Rg1 (GRg1) in chronic heart failure (CHF), focusing on its regulation of ERK1/2 protein phosphorylation. H9c2 cardiomyocytes and SD rats were divided into the control group, CHF (ADR) group, and CHF+ginsenoside Rg1 group using an isolated cardiomyocyte model and an in vivo CHF rat model induced by adriamycin (ADR). Cell viability, proliferation, apoptosis, and the expression of relevant proteins were measured to assess the effects of GRg1. The results showed that treatment with GRg1 increased cell activity and proliferation, while significantly reducing levels of inflammatory and apoptotic factors compared to the CHF (ADR) group. Moreover, the CHF+ginsenoside Rg1 group exhibited higher levels of Bcl-2 mRNA and protein expression, as well as lower levels of Caspase3 and Bax mRNA and protein expression, compared to the CHF (ADR) group. Notably, the CHF+ginsenoside Rg1 group displayed decreased serum NT-proBNP levels and heart weight/body weight (HW/BW) index. Furthermore, the electrocardiogram of rats in the CHF+ginsenoside Rg1 group resembled that of rats in the control group. Overall, our findings suggested that GRg1 alleviated CHF by inhibiting ERK1/2 protein phosphorylation, thereby inhibiting apoptosis, enhancing cell activity and proliferation, and reducing cardiac inflammatory responses.

Cardiomyocyte PAI-1 influences the cardiac transcriptome and limits the extent of cardiac fibrosis in response to left ventricular pressure overload

Plasminogen activator inhibitor-1 (PAI-1) is a specific and rapid-acting inhibitor of endogenous plasminogen activators (uPA and tPA). The global PAI-1 knockout mice (PAI-1KO) develop age-dependent cardiac-selective fibrosis, and young global PAI-1KO mice exhibit augmented susceptibility to developing cardiac fibrosis in response to hypertension. Here, we tested the hypothesis that cardiomyocyte PAI-1 is necessary to provide cardioprotective effects in a left ventricular pressure overload-induced murine model of cardiac hypertrophy and fibrosis using cardiomyocyte-specific PAI-1 knockout (cmPAI-1KO) mice. The results revealed that cmPAI-1KO mice display significantly worse cardiac fibrosis than controls. To investigate the molecular mechanisms responsible for these effects, genome-wide cardiac transcriptome analysis was performed. Loss of cardiomyocyte PAI-1 led to differential expression of 978 genes compared to controls in response to left ventricular pressure overload. Pathway enrichment analysis identified the inflammatory response, cell substrate adhesion, regulation of cytokine production, leukocyte migration, extracellular matrix organization, and cytokine-mediated signaling pathways as being significantly upregulated in cmPAI-1KO hearts. Conversely, specific epigenetic repressors, cation transmembrane transport, muscle system processes, and nitric oxide signaling were significantly downregulated in cmPAI-1KO hearts compared to control hearts in response to left ventricular pressure overload. Collectively, the present study provides strong evidence of the impact of cardiomyocyte PAI-1 in regulation of the transcriptome network involved in the cardiac stress response. In response to stress, the deregulatory impact of cardiomyocyte PAI-1 loss on the cardiac transcriptome may be the underlying cause of cardiac-selective accelerated fibrogenesis in global PAI-1-deficient mice.

LRP5 Regulates HIF-1α Stability via Interaction with PHD2 in Ischemic Myocardium

Low-density lipoprotein receptor-related protein 5 (LRP5) has been studied as a co-receptor for Wnt/β-catenin signaling. However, its role in the ischemic myocardium is largely unknown. Here, we show that LRP5 may act as a negative regulator of ischemic heart injury via its interaction with prolyl hydroxylase 2 (PHD2), resulting in hypoxia-inducible factor-1α (HIF-1α) degradation. Overexpression of LRP5 in cardiomyocytes promoted hypoxia-induced apoptotic cell death, whereas LRP5-silenced cardiomyocytes were protected from hypoxic insult. Gene expression analysis (mRNA-seq) demonstrated that overexpression of LRP5 limited the expression of HIF-1α target genes. LRP5 promoted HIF-1α degradation, as evidenced by the increased hydroxylation and shorter stability of HIF-1α under hypoxic conditions through the interaction between LRP5 and PHD2. Moreover, the specific phosphorylation of LRP5 at T1492 and S1503 is responsible for enhancing the hydroxylation activity of PHD2, resulting in HIF-1α degradation, which is independent of Wnt/β-catenin signaling. Importantly, direct myocardial delivery of adenoviral constructs, silencing LRP5 in vivo, significantly improved cardiac function in infarcted rat hearts, suggesting the potential value of LRP5 as a new target for ischemic injury treatment.

Schisandra chinensis polysaccharides prevent cardiac hypertrophy by dissociating thioredoxin-interacting protein/thioredoxin-1 complex and inhibiting oxidative stress

Cardiac hypertrophy is a current, major, global health challenge. Oxidative stress is an important mechanism that contributes to the pathogenesis of cardiac hypertrophy. Schisandra chinensis polysaccharides (SCP), the primary active constituent in Schisandra chinensis, have antioxidative properties. Here, we investigated the role played by SCP in a cardiac hypertrophy model mouse induced by transverse aortic constriction (TAC). We found that SCP treatment improved cardiac function by inhibiting myocardial hypertrophy and oxidative stress. Angiotensin II was used to induce cardiomyocyte hypertrophy and oxidative stress in vitro. We discovered that the antioxidant effects of SCP were mediated through the regulation of the thioredoxin-interacting protein (TXNIP)/Thioredoxin-1 (Trx-1) pathway. Using molecular docking, we found that SCP binds to Arg207, Ser169, Lys166, Lys286 and Ser285 in TXNIP through hydrogen bonds. TXNIP is an endogenous inhibitor of Trx-1, and the binding SCP with TXNIP may restrict or interfere with the binding between TXNIP and Trx-1, resulting in Trx-1 activation. In conclusion, our findings demonstrated that the potential use of SCP as a TXNIP inhibitor to attenuate oxidative stress, suggesting that TXNIP might represent a potential therapeutic target for the treatment of cardiac hypertrophy.

The molecular mechanism of LRP1 in physiological vascular homeostasis and signal transduction pathways

Interactions between vascular smooth muscle cells (VSMCs), endothelial cells (ECs), pericytes (PCs) and macrophages (MФ), the major components of blood vessels, play a crucial role in maintaining vascular structural and functional homeostasis. Low-density lipoprotein (LDL) receptor-related protein-1 (LRP1), a transmembrane receptor protein belonging to the LDL receptor family, plays multifunctional roles in maintaining endocytosis, homeostasis, and signal transduction. Accumulating evidence suggests that LRP1 modulates vascular homeostasis mainly by regulating vasoactive substances and specific intracellular signaling pathways, including the plasminogen activator inhibitor 1 (PAI-1) signaling pathway, platelet-derived growth factor (PDGF) signaling pathway, transforming growth factor-β (TGF-β) signaling pathway and vascular endothelial growth factor (VEGF) signaling pathway. The aim of the present review is to focus on recent advances in the discovery and mechanism of vascular homeostasis regulated by LRP1-dependent signaling pathways. These recent discoveries expand our understanding of the mechanisms controlling LRP1 as a target for studies on vascular complications.

Dual-triggered biomimetic vehicles enable treatment of glioblastoma through a cancer stem cell therapeutic strategy

Glioma stem cells (GSCs) and their complex microenvironment play a crucial role in the high invasion of cancer and therapeutic resistance and are considered to be the most likely cause of cancer relapse. We constructed a biomimetic vehicle (LDL-SAL-Ang) based on a low density lipoprotein triggered by Angiopep-2 peptide and ApoB protein, to improve the transport of an anti-GSC therapeutic agent into the brain. The LDL-SAL-Ang showed significant inhabitation for GSC microsphere formation and induced the highest apoptotic rate in two types of GSCs. LDL-SAL-Ang reduced the number of GSC-derived endothelial tubules at a lower drug concentration and inhibited endothelial cell migration and angiogenesis. The pharmacokinetic analysis showed that the brain tissue uptake rate (% ID g^-1) for LDL-SAL-Ang was significantly enhanced at 0.45. For anti-glioblastoma activity in vivo, the median survival time of LDL-SAL-Ang plus temozolomide group was 47 days, which were significantly increased compared with the control or temozolomide only groups. The endogenous biomimetic nanomedicine that we designed provides a potential approach to improve treatments for intracranial tumors and reduced neurotoxicity of nanomedicine.

ICS II protects against cardiac hypertrophy by regulating metabolic remodelling, not by inhibiting autophagy

Cardiac hypertrophy is characterized by a shift in metabolic substrate utilization. Therefore, the regulation of ketone body uptake and metabolism may have beneficial effects on heart injuries that induce cardiac remodelling. In this study, we investigated whether icariside II (ICS II) protects against cardiac hypertrophy in mice and cardiomyocytes. To create cardiac hypertrophy animal and cell models, mice were subjected to transverse aortic constriction (TAC), and embryonic rat cardiomyocytes (H9C2) were stimulated with angiotensin II, a neurohumoral stressor. Both the in vivo and in vitro results suggest that ICS II treatment ameliorated pressure overload–induced cardiac hypertrophy and preserved heart function. In addition, apoptosis and oxidative stress were reduced in the presence of ICS II. Moreover, ICS II inhibited excess autophagy in TAC‐induced hearts and angiotensin II–stimulated cardiomyocytes. Mechanistically, we found that ICS II administration regulated SIRT3 expression in cardiac remodelling. SIRT3 activation increased ketone body transportation and utilization. Collectively, our data show that ICS II attenuated cardiac hypertrophy by modulating ketone body and fatty acid metabolism, and that this was likely due to the activation of the SIRT3‐AMPK pathway. ICS II treatment may provide a new therapeutic strategy for improving myocardial metabolism in cardiac hypertrophy and heart failure.