Notch2 and Proteomic Signatures in Mouse Neointimal Lesion Formation

Bergenin alleviates proliferative arterial diseases by modulating glucose metabolism in vascular smooth muscle cells

BACKGROUND

Vascular smooth muscle cell (VSMC) proliferation and phenotypic switching are key mechanisms in the development of proliferative arterial diseases. Notably, reprogramming of the glucose metabolism pattern in VSMCs plays an important role in this process.

PURPOSE

The aim of this study is to investigate the therapeutic potential and the mechanism underlying the effect of bergenin, an active compound found in Bergenia, in proliferative arterial diseases.

METHODS

The effect of bergenin on proliferative arterial disease was evaluated using platelet-derived growth factor (PDGF)-stimulated VSMCs and a mouse model of carotid artery ligation. VSMC proliferation and phenotypic switching were evaluated in vitro using cell counting kit-8, 5-ethynyl-2-deoxyuridine incorporation, scratch, and transwell assays. Carotid artery neointimal hyperplasia was evaluated in vivo using hematoxylin and eosin staining and immunofluorescence. The expression of proliferation and VSMC contractile phenotype markers was evaluated using PCR and western blotting.

RESULTS

Bergenin treatment inhibited PDGF-induced VSMC proliferation and phenotypic switching and reduced neointimal hyperplasia in the carotid artery ligation model. Additionally, bergenin partially reversed the PDGF-induced Warburg-like glucose metabolism pattern in VSMCs. RNA-sequencing data revealed that bergenin treatment significantly upregulated Ndufs2, an essential subunit of mitochondrial complex I. Ndufs2 knockdown attenuated the inhibitory effect of bergenin on PDGF-induced VSMC proliferation and phenotypic switching, and suppressed neointimal hyperplasia in vivo. Conversely, Ndufs2 overexpression enhanced the protective effect of bergenin. Moreover, Ndufs2 knockdown abrogated the effects of bergenin on the regulation of glucose metabolism in VSMCs.

CONCLUSION

These findings suggest that bergenin is effective in alleviating proliferative arterial diseases. The reversal of the Warburg-like glucose metabolism pattern in VSMCs during proliferation and phenotypic switching may underlie this therapeutic mechanism.

N-Glycans on the extracellular domain of the Notch1 receptor control Jagged-1 induced Notch signalling and myogenic differentiation of S100β resident vascular stem cells

Notch signalling, critical for development and postnatal homeostasis of the vascular system, is highly regulated by several mechanisms including glycosylation. While the importance of O-linked glycosylation is widely accepted, the structure and function of N-glycans has yet to be defined. Here, we take advantage of lectin binding assays in combination with pharmacological, molecular, and site-directed mutagenetic approaches to study N-glycosylation of the Notch1 receptor. We find that several key oligosaccharides containing bisecting or core fucosylated structures decorate the receptor, control expression and receptor trafficking, and dictate Jagged-1 activation of Notch target genes and myogenic differentiation of multipotent S100β vascular stem cells. N-glycans at asparagine (N) 1241 and 1587 protect the receptor from accelerated degradation, while the oligosaccharide at N888 directly affects signal transduction. Conversely, N-linked glycans at N959, N1179, N1489 do not impact canonical signalling but inhibit differentiation. Our work highlights a novel functional role for N-glycans in controlling Notch1 signalling and differentiation of vascular stem cells.

Thirty Years with ERH: An mRNA Splicing and Mitosis Factor Only or Rather a Novel Genome Integrity Protector?

ERH is a 100 to about 110 aa nuclear protein with unique primary and three-dimensional structures that are very conserved from simple eukaryotes to humans, albeit some species have lost its gene, with most higher fungi being a noteworthy example. Initially, studies on Drosophila melanogaster implied its function in pyrimidine metabolism. Subsequently, research on Xenopus laevis suggested that it acts as a transcriptional repressor. Finally, studies in humans pointed to a role in pre-mRNA splicing and in mitosis but further research, also in Caenorhabditis elegans and Schizosaccharomyces pombe, demonstrated its much broader activity, namely involvement in the biogenesis of mRNA, and miRNA, piRNA and some other ncRNAs, and in repressive heterochromatin formation. ERH interacts with numerous, mostly taxon-specific proteins, like Mmi1 and Mei2 in S. pombe, PID-3/PICS-1, TOST-1 and PID-1 in C. elegans, and DGCR8, CIZ1, PDIP46/SKAR and SAFB1/2 in humans. There are, however, some common themes in this wide range of processes and partners, such as: (a) ERH homodimerizes to form a scaffold for several complexes involved in the metabolism of nucleic acids, (b) all these RNAs are RNA polymerase II transcripts, (c) pre-mRNAs, whose splicing depends on ERH, are enriched in transcripts of DNA damage response and DNA metabolism genes, and (d) heterochromatin is formed to silence unwanted transcription, e.g., from repetitive elements. Thus, it seems that ERH has been adopted for various pathways that serve to maintain genome integrity.

ERH Interacts With EIF2α and Regulates the EIF2α/ATF4/CHOP Pathway in Bladder Cancer Cells

Background

There is a lack of research on the molecular interaction of the enhancers of rudimentary homolog (ERH) in bladder cancer (BC) cells. This study aimed to determine the interacting proteins of ERH in human T24 cells.

Methods

First, the ERH gene was overexpressed in human T24 cells. Coimmunoprecipitation (co-IP) and shotgun mass spectrometry (MS) analyses were performed to obtain a list of proteins that interact with ERH. Subsequently, bioinformatic analyses with Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and protein–protein interaction (PPI) studies were performed to analyze the ERH-interactive protein list (ERH-IPL). Then, we selected one of the interacting proteins, EIF2α for verification. An immunofluorescence colocalization assay was performed to validate the co-expression of the selected protein, and the binding sites of the two proteins were predicted by ZDOCK technology. Finally, PCR analysis on the downstream molecules of the interacting protein was performed for verification.

Results

ERH protein was successfully overexpressed in human T24 cells. We obtained a list of 205 proteins that might directly or indirectly interact with the ERH protein by mass spectrometric analysis. The bioinformatic analysis showed that ERH-interacting proteins were related to “ribonucleoprotein complex”, “ATPase activity”, “nuclear speck”, and “translation factor activity, RNA binding”. We further identified one of the key genes, EIF2S1, and confirmed that the corresponding protein EIF2α is co-expressed and may bind with ERH in human T24 cells. The mRNA levels of molecules ATF4 and CHOP were found to be upregulated by ERH.

Conclusion

ERH protein affects “ribonucleoprotein complex”, “ATPase activity”, “nuclear speck”, and “translation factor activity, RNA binding”. The ERH protein can interact with EIF2α and regulate the EIF2α-ATF4/CHOP signaling pathway in human T24 cells.

Proteomics of restenosis model in LDLR-deficient hamsters coupled with the proliferative rat vascular smooth muscle cells reveals a new mechanism of vascular remodeling diseases

A major pathological mechanism involved in vascular remodeling diseases is the proliferation and migration of vascular smooth muscle cells. The lipid distribution of golden hamsters is similar to that of humans, which makes them an excellent study model for studying the pathogenesis and molecular characteristics of vascular remodeling diseases. We performed proteomic analysis on Sprague Dawley rat VSMCs (rVSMCs) and restenosis hamsters with low-density lipoprotein receptor (LDLR) deficiency as part of this study. We have also performed the enrichment analysis of differentially modified proteins in regards to Gene Ontology, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and protein domain. 1070 differentially abundant proteins were assessed in rVSMCs before and after platelet-derived growth factor-BB (PDGF-BB) stimulation. Specifically, 1246 proteins displayed significant differences in the restenosis model in LDLR-deficient hamsters. An analysis of crosstalk between LDLR^+/- hamsters artery restenosis and proliferating rVSMCs revealed 130 differentially expressed proteins, including 67 up-regulated proteins and 63 downregulated proteins. Enrichment analysis with KEGG showed differential proteins to be mainly concentrated in metabolic pathways. There are numerous differentially abundant proteins but particularly two proteins (phosphofructokinase 1 of liver type and lactate dehydrogenase A) were found to be up-regulated by PDGF-BB stimulation of rVSMCs and in a restenosis model of hamsters with LDLR^+/- expression. SIGNIFICANCE: Based on bioinformatics, we have found glycolysis pathway plays an important role in both the LDLR^+/- hamsters restenosis model and the proliferation of rVSMCs. Some key glycolysis enzymes may likely be developed either as new biomarkers or drug targets for vascular remodeling diseases.

The Extracellular Matrix Environment of Clear Cell Renal Cell Carcinoma Determines Cancer Associated Fibroblast Growth

Clear cell renal cell carcinoma (ccRCC) is the most common kidney cancer and is often caused by mutations in the oxygen-sensing machinery of kidney epithelial cells. Due to its pseudo-hypoxic state, ccRCC recruits extensive vasculature and other stromal components. Conventional cell culture methods provide poor representation of stromal cell types in primary cultures of ccRCC, and we hypothesized that mimicking the extracellular environment of the tumor would promote growth of both tumor and stromal cells. We employed proteomics to identify the components of ccRCC extracellular matrix (ECM) and found that in contrast to healthy kidney cortex, laminin, collagen IV, and entactin/nidogen are minor contributors. Instead, the ccRCC ECM is composed largely of collagen VI, fibronectin, and tenascin C. Analysis of single cell expression data indicates that cancer-associated fibroblasts are a major source of tumor ECM production. Tumor cells as well as stromal cells bind efficiently to a nine-component ECM blend characteristic of ccRCC. Primary patient-derived tumor cells bind the nine-component blend efficiently, allowing to us to establish mixed primary cultures of tumor cells and stromal cells. These miniature patient-specific replicas are conducive to microscopy and can be used to analyze interactions between cells in a model tumor microenvironment.

Targeted Molecular Imaging of Cardiovascular Diseases by Iron Oxide Nanoparticles

Cardiovascular disease is one of the major contributors to global disease burden. Atherosclerosis is an inflammatory process that involves the accumulation of lipids and fibrous elements in the large arteries, forming an atherosclerotic plaque. Rupture of unstable plaques leads to thrombosis that triggers life-threatening complications such as myocardial infarction. Current diagnostic methods are invasive as they require insertion of a catheter into the coronary artery. Molecular imaging techniques, such as magnetic resonance imaging, have been developed to image atherosclerotic plaques and thrombosis due to its high spatial resolution and safety. The sensitivity of magnetic resonance imaging can be improved with contrast agents, such as iron oxide nanoparticles. This review presents the most recent advances in atherosclerosis, thrombosis, and myocardial infarction molecular imaging using iron oxide-based nanoparticles. While some studies have shown their effectiveness, many are yet to undertake comprehensive testing of biocompatibility. There are still potential hazards to address and complications to diagnosis, therefore strategies for overcoming these challenges are required.

Endothelial Scaffolding Protein ENH (Enigma Homolog Protein) Promotes PHLPP2 (Pleckstrin Homology Domain and Leucine-Rich Repeat Protein Phosphatase 2)-Mediated Dephosphorylation of AKT1 and eNOS (Endothelial NO Synthase) Promoting Vascular Remodeling

OBJECTIVE

A decrease in nitric oxide, leading to vascular smooth muscle cell proliferation, is a common pathological feature of vascular proliferative diseases. Nitric oxide synthesis by eNOS (endothelial nitric oxide synthase) is precisely regulated by protein kinases including AKT1. ENH (enigma homolog protein) is a scaffolding protein for multiple protein kinases, but whether it regulates eNOS activation and vascular remodeling remains unknown. Approach and Results: ENH was upregulated in injured mouse arteries and human atherosclerotic plaques and was associated with coronary artery disease. Neointima formation in carotid arteries, induced by ligation or wire injury, was greatly decreased in endothelium-specific ENH-knockout mice. Vascular ligation reduced AKT and eNOS phosphorylation and nitric oxide production in the endothelium of control but not ENH-knockout mice. ENH was found to interact with AKT1 and its phosphatase PHLPP2 (pleckstrin homology domain and leucine-rich repeat protein phosphatase 2). AKT and eNOS activation were prolonged in VEGF (vascular endothelial growth factor)-induced ENH- or PHLPP2-deficient endothelial cells. Inhibitors of either AKT or eNOS effectively restored ligation-induced neointima formation in ENH-knockout mice. Moreover, endothelium-specific PHLPP2-knockout mice displayed reduced ligation-induced neointima formation. Finally, PHLPP2 was increased in the endothelia of human atherosclerotic plaques and blood cells from patients with coronary artery disease.

CONCLUSIONS

ENH forms a complex with AKT1 and its phosphatase PHLPP2 to negatively regulate AKT1 activation in the artery endothelium. AKT1 deactivation, a decrease in nitric oxide generation, and subsequent neointima formation induced by vascular injury are mediated by ENH and PHLPP2. ENH and PHLPP2 are thus new proatherosclerotic factors that could be therapeutically targeted.

Exploring mechanisms of increased cardiovascular disease risk with antipsychotic medications: Risperidone alters the cardiac proteomic signature in mice

Atypical antipsychotic (AA) medications including risperidone (RIS) and olanzapine (OLAN) are FDA approved for the treatment of psychiatric disorders including schizophrenia, bipolar disorder and depression. Clinical side effects of AA medications include obesity, insulin resistance, dyslipidemia, hypertension and increased cardiovascular disease risk. Despite the known pharmacology of these AA medications, the mechanisms contributing to adverse metabolic side-effects are not well understood. To evaluate drug-associated effects on the heart, we assessed changes in the cardiac proteomic signature in mice administered for 4 weeks with clinically relevant exposure of RIS or OLAN. Using proteomic and gene enrichment analysis, we identified differentially expressed (DE) proteins in both RIS- and OLAN-treated mouse hearts (p < 0.05), including proteins comprising mitochondrial respiratory complex I and pathways involved in mitochondrial function and oxidative phosphorylation. A subset of DE proteins identified were further validated by both western blotting and quantitative real-time PCR. Histological evaluation of hearts indicated that AA-associated aberrant cardiac gene expression occurs prior to the onset of gross pathomorphological changes. Additionally, RIS treatment altered cardiac mitochondrial oxygen consumption and whole body energy expenditure. Our study provides insight into the mechanisms underlying increased patient risk for adverse cardiac outcomes with chronic treatment of AA medications.