Epidermal Growth Factor Receptor Transactivation: Mechanisms, Pathophysiology, and Potential Therapies in the Cardiovascular System

The protective mechanism of Tao Hong Si Wu decoction against breast cancer through regulation of EGFR/ERK1/2 signaling

ETHNOPHARMACOLOGICAL RELEVANCE

Tao Hong Si Wu Decoction (THSWD), a traditional Chinese herbal medicine, is widely utilized in clinical settings, either alone or in combination with other medications, for the treatment of breast cancer.

AIM OF THE STUDY

The specific targeting molecule(s) of THSWD and its associated molecular mechanisms remain unclear. This research aims to elucidate the underlying molecular mechanisms of THSWD in the treatment of breast cancer.

MATERIALS AND METHODS

The pharmacological properties of THSWD were investigated in breast cancer cells and tumor tissues using a range of methods including Acridine Orange/Ethidium Bromide (AO/EB) staining, Transwell assay, flow cytometry, immunofluorescence assay, and breast cancer mice models.

RESULTS

Our findings demonstrate that THSWD induces necrosis and/or apoptosis in breast cancer cells, while significantly inhibiting cell migration. Target proteins of THSWD in anticancer activity include EGFR, RAS, and others. THSWD treatment for breast cancer is associated with the EGFR/ERK1/2 signaling pathway.

CONCLUSION

Our findings offer initial insights into the primary mechanism of action of THSWD in breast cancer treatment, indicating its potential as a complementary therapy deserving further investigation.

The BCR::ABL1 tyrosine kinase inhibitors ponatinib and nilotinib differentially affect endothelial angiogenesis and signalling

BCR::ABL1 inhibitors, the treatment of choice for the majority of patients with chronic myeloid leukaemia (CML), can cause vascular side effects that vary between agents. The exact underlying mechanisms are still poorly understood, but the vascular endothelium has been proposed as a site of origin. The present study investigates the effects of three BCR::ABL1 inhibitors, ponatinib, nilotinib and imatinib, on angiogenesis and signalling in human endothelial cells in response to vascular endothelial growth factor (VEGF). The experiments were performed in endothelial cells isolated from human umbilical veins. After exposure to imatinib, ponatinib and nilotinib, the angiogenic capacity of endothelial cells was assessed in spheroid assays. VEGF-induced signalling pathways were examined in Western blotting experiments using different specific antibodies. RNAi technology was used to downregulate proteins of interest. Intracellular cGMP levels were measured by ELISA. Imatinib had no effect on endothelial function. Ponatinib inhibited VEGF-induced sprouting, while nilotinib increased spontaneous and VEGF-stimulated angiogenesis. These effects did not involve wild-type ABL1 or ABL2, as siRNA-mediated knockdown of these kinases did not affect angiogenesis and VEGF signalling. Consistent with their effects on sprouting, ponatinib and nilotinib affected angiogenic pathways in opposite directions. While ponatinib inhibited VEGF-induced signalling and cGMP formation, nilotinib activated angiogenic signalling, in particular phosphorylation of extracellular signal-regulated kinase 1/2 (Erk1/2). The latter occurred in an epidermal growth factor receptor (EGFR)-dependent manner possibly via suppressing Fyn-related kinase (FRK), a negative regulator of EGFR signalling. Both, pharmacological inhibition of Erk1/2 or EGFR suppressed nilotinib-induced angiogenic sprouting. These results support the notion that the vascular endothelium is a site of action of BCR::ABL1 inhibitors from which side effects may arise, and that the different vascular toxicity profiles of BCR::ABL1 inhibitors may be due to their different actions at the molecular level. In addition, the as yet unknown pro-angiogenic effect of nilotinib should be considered in the treatment of patients with comorbidities associated with pathological angiogenesis, such as ocular disease, arthritis or obesity.

Direct GPCR-EGFR interaction enables synergistic membrane-to-nucleus information transfer

We addressed the heteromerization of the epidermal growth factor receptor (EGFR) with G-protein coupled receptors (GPCR) on the basis of angiotensin-II-receptor-subtype-1(AT1R)-EGFR interaction as proof-of-concept and show its functional relevance during synergistic nuclear information transfer, beyond ligand-dependent EGFR transactivation. Following in silico modelling, we generated EGFR-interaction deficient AT1R-mutants and compared them to AT1R-wildtype. Receptor interaction was assessed by co-immunoprecipitation (CoIP), Förster resonance energy transfer (FRET) and fluorescence-lifetime imaging microscopy (FLIM). Changes in cell morphology, ERK1/2-phosphorylation (ppERK1/2), serum response factor (SRF)-activation and cFOS protein expression were determined by digital high content microscopy at the single cell level. FRET, FLIM and CoIP confirmed the physical interaction of AT1R-wildtype with EGFR that was strongly reduced for the AT1R-mutants. Responsiveness of cells transfected with AT1R-WT or -mutants to angiotensin II or EGF was similar regarding changes in cell circularity, ppERK1/2 (direct and by ligand-dependent EGFR-transactivation), cFOS-expression and SRF-activity. By contrast, the EGFR-AT1R-synergism regarding these parameters was completely absent for in the interaction-deficient AT1R mutants. The results show that AT1R-EGFR heteromerisation enables AT1R-EGFR-synergism on downstream gene expression regulation, modulating the intensity and the temporal pattern of nuclear AT1R/EGFR-information transfer. Furthermore, remote EGFR transactivation, via ligand release or cytosolic tyrosine kinases, is not sufficient for the complete synergistic control of gene expression.

Role of iRhom2 in Olfaction: Implications for Odorant Receptor Regulation and Activity-Dependent Adaptation

The cell surface metalloprotease ADAM17 (a disintegrin and metalloprotease 17) and its binding partners iRhom2 and iRhom1 (inactive Rhomboid-like proteins 1 and 2) modulate cell-cell interactions by mediating the release of membrane proteins such as TNFα (Tumor necrosis factor α) and EGFR (Epidermal growth factor receptor) ligands from the cell surface. Most cell types express both iRhoms, though myeloid cells exclusively express iRhom2, and iRhom1 is the main iRhom in the mouse brain. Here, we report that iRhom2 is uniquely expressed in olfactory sensory neurons (OSNs), highly specialized cells expressing one olfactory receptor (OR) from a repertoire of more than a thousand OR genes in mice. iRhom2-/- mice had no evident morphological defects in the olfactory epithelium (OE), yet RNAseq analysis revealed differential expression of a small subset of ORs. Notably, while the majority of ORs remain unaffected in iRhom2-/- OE, OSNs expressing ORs that are enriched in iRhom2-/- OE showed fewer gene expression changes upon odor environmental changes than the majority of OSNs. Moreover, we discovered an inverse correlation between the expression of iRhom2 compared to OSN activity genes and that odor exposure negatively regulates iRhom2 expression. Given that ORs are specialized G-protein coupled receptors (GPCRs) and many GPCRs activate iRhom2/ADAM17, we investigated if ORs could activate iRhom2/ADAM17. Activation of an olfactory receptor that is ectopically expressed in keratinocytes (OR2AT4) by its agonist Sandalore leads to ERK1/2 phosphorylation, likely via an iRhom2/ADAM17-dependent pathway. Taken together, these findings point to a mechanism by which odor stimulation of OSNs activates iRhom2/ADAM17 catalytic activity, resulting in downstream transcriptional changes to the OR repertoire and activity genes, and driving a negative feedback loop to downregulate iRhom2 expression.

Scopoletin alleviates high glucose-induced toxicity in human renal proximal tubular cells via inhibition of oxidative damage, epithelial-mesenchymal transition, and fibrogenesis

BACKGROUND

Recent years of evidence suggest the crucial role of renal tubular cells in developing diabetic kidney disease. Scopoletin (SCOP) is a plant-based coumarin with numerous biological activities. This study aimed to determine the effect of SCOP on renal tubular cells in developing diabetic kidney disease and to elucidate mechanisms.

METHODS AND RESULTS

In this study, SCOP was evaluated in vitro using renal proximal tubular (HK-2) cells under hyperglycemic conditions to understand its mechanism of action. In HK-2 cells, SCOP alleviated the high glucose-generated reactive oxygen species (ROS), restored the levels of reduced glutathione, and decreased lipid peroxidation. High glucose-induced alteration in the mitochondrial membrane potential was markedly restored in the SCOP-treated cells. Moreover, SCOP significantly reduced the high glucose-induced apoptotic cell population in the Annexin V-FITC flow cytometry study. Furthermore, high glucose markedly elevated the mRNA expression of fibrotic and extracellular matrix (ECM) components, namely, transforming growth factor (TGF)-β, alfa-smooth muscle actin (α-SMA), collagen I, and collagen III, in HK-2 cells compared to the untreated cells. SCOP treatment reduced these mRNA expressions compared to the high glucose-treated cells. Collagen I and TGF-β protein levels were also significantly reduced in the SCOP-treated cells. Further findings in HK-2 cells revealed that SCOP interfered with the epithelial-mesenchymal transition (EMT) in the high glucose-treated HK-2 cells by normalizing E-cadherin and downregulating the vimentin and α-SMA proteins.

CONCLUSIONS

In conclusion, SCOP modulates the high glucose-generated renal tubular cell oxidative damage and accumulation of ECM components and may be a promising molecule against diabetic nephropathy.

A highly oxidized germacranolide from elephantopus tomentosus inhibits the growth of hepatocellular carcinoma cells by targeting EGFR in vitro and in vivo

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide, with high mortality and poor prognosis. WBDC-1 is a novel highly oxidized germacranolide from the Elephantopus tomentosus in our previous work, which has excellent anti-HCC activity, but the detailed mechanism is still unclear. In this study, we found that WBDC-1 was able to inhibit the proliferation and colony formation of Hep3B and HepG2 cells, as well as the cell migration ability and EMT. In addition, WBDC-1 showed no obvious toxicity to normal liver epithelial cells L-02. The potential targets of WBDC-1 were predicted by network pharmacology, and the following verified experiments showed that WBDC-1 exerted anti-HCC effect by targeting EGFR. Mechanismly, subsequent biological analysis showed that WBDC-1 can inhibit EGFR and its downstream RAS/RAF/MEK/ERK and PI3K/AKT signaling pathways. Overexpression of EGFR reversed the anticancer properties of WBDC-1. Consistent with in vitro experiments, WBDC-1 was able to inhibit tumor growth and was non-toxic in xenograft tumor models. In summary, this study revealed a potential tumor suppressive mechanism of WBDC-1 and provided a novel strategy for HCC treatment. It also laid a foundation for further research on the anti-tumor effect of highly oxidized germacranolides.

EGFR activation differentially affects the inflammatory profiles of female human aortic and coronary artery endothelial cells

Endothelial cells (EC) are key players in vascular function, homeostasis and inflammation. EC show substantial heterogeneity due to inter-individual variability (e.g. sex-differences) and intra-individual differences as they originate from different organs or vessels. This variability may lead to different responsiveness to external stimuli. Here we compared the responsiveness of female human primary EC from the aorta (HAoEC) and coronary arteries (HCAEC) to Epidermal Growth Factor Receptor (EGFR) activation. EGFR is an important signal integration hub for vascular active substances with physiological and pathophysiological relevance. Our transcriptomic analysis suggested that EGFR activation differentially affects the inflammatory profiles of HAoEC and HCAEC, particularly by inducing a HCAEC-driven leukocyte attraction but a downregulation of adhesion molecule and chemoattractant expression in HAoEC. Experimental assessments of selected inflammation markers were performed to validate these predictions and the results confirmed a dual role of EGFR in these cells: its activation initiated an anti-inflammatory response in HAoEC but a pro-inflammatory one in HCAEC. Our study highlights that, although they are both arterial EC, female HAoEC and HCAEC are distinguishable with regard to the role of EGFR and its involvement in inflammation regulation, what may be relevant for vascular maintenance but also the pathogenesis of endothelial dysfunction.

ESCRT-III Component CHMP4C Attenuates Cardiac Hypertrophy by Targeting the Endo-Lysosomal Degradation of EGFR

BACKGROUND

Cardiac hypertrophy and subsequent heart failure impose a considerable burden on public health worldwide. Impaired protein degradation, especially endo-lysosome-mediated degradation of membrane proteins, is associated with cardiac hypertrophy progression. CHMP4C (charged multivesicular body protein 4C), a critical constituent of multivesicular bodies, is involved in cellular trafficking and signaling. However, the specific role of CHMP4C in the progression of cardiac hypertrophy remains largely unknown.

METHODS

Mouse models with CHMP4C knockout or cardiadc-specific overexpression were subjected to transverse aortic constriction surgery for 4 weeks. Cardiac morphology and function were assessed through histological staining and echocardiography. Confocal imaging and coimmunoprecipitation assays were performed to identify the direct target of CHMP4C. An EGFR (epidermal growth factor receptor) inhibitor was administrated to determine whether effects of CHMP4C on cardiac hypertrophy were EGFR dependent.

RESULTS

CHMP4C was significantly upregulated in both pressure-overloaded mice and spontaneously hypertensive rats. Compared with wild-type mice, CHMP4C deficiency exacerbated transverse aortic constriction-induced cardiac hypertrophy, whereas CHMP4C overexpression in cardiomyocytes attenuated cardiac dysfunction. Mechanistically, the effect of CHMP4C on cardiac hypertrophy relied on the EGFR signaling pathway. Fluorescent staining and coimmunoprecipitation assays confirmed that CHMP4C interacts directly with EGFR and promotes lysosome-mediated degradation of activated EGFR, thus attenuating cardiac hypertrophy. Notably, an EGFR inhibitor canertinib counteracted the exacerbation of cardiac hypertrophy induced by CHMP4C knockdown in vitro and in vivo.

CONCLUSIONS

CHMP4C represses cardiac hypertrophy by modulating lysosomal degradation of EGFR and is a potential therapeutic candidate for cardiac hypertrophy.

Exploring the underlying mechanisms of fisetin in the treatment of hepatic insulin resistance via network pharmacology and in vitro validation

OBJECTIVE

To characterize potential mechanisms of fisetin on hepatic insulin resistance (IR) using network pharmacology and in vitro validation.

METHODS

Putative targets of fisetin were retrieved from the Traditional Chinese Medicine Systems Pharmacology database, whereas the potential genes of hepatic IR were obtained from GeneCards database. A protein-protein interaction (PPI) network was constructed according to the intersection targets of fisetin and hepatic IR using the Venn diagram. The biological functions and potential pathways related to genes were determined using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Cell experiments were also conducted to further verify the mechanism of fisetin on hepatic IR.

RESULTS

A total of 118 potential targets from fisetin were associated with hepatic IR. The areas of nodes and corresponding degree values of TP53, AKT1, TNF, IL6, CASP3, CTNNB1, JUN, SRC, epidermal growth factor receptor (EGFR), and HSP90AA1 were larger and could be easily found in the PPI network. Furthermore, GO analysis revealed that these key targets were significantly involved in multiple biological processes that participated in oxidative stress and serine/threonine kinase activity. KEGG enrichment analysis showed that the PI3K/AKT signaling pathway was a significant pathway involved in hepatic IR. Our in vitro results demonstrated that fisetin treatment increased the expressions of EGFR and IRS in HepG2 and L02 cells under normal or IR conditions. Western blot results revealed that p-AKT/AKT levels were significantly up-regulated, suggesting that fisetin was involved in the PI3K/AKT signaling pathway to regulate insulin signaling.

CONCLUSION

We explored the pharmacological actions and the potential molecular mechanism of fisetin in treating hepatic IR from a holistic perspective. Our study lays a theoretical foundation for the development of fisetin for type 2 diabetes.

The role of EGFR in vascular AT1R signaling: From cellular mechanisms to systemic relevance

The epidermal growth factor receptor (EGFR) belongs to the ErbB-family of receptor tyrosine kinases that are of importance in oncology. During the last years, substantial evidence accumulated for a crucial role of EGFR concerning the action of the angiotensin II type 1 receptor (AT1R) in blood vessels, resulting form AT1R-induced EGFR transactivation. This transactivation occurs through the release of membrane-anchored EGFR-ligands, cytosolic tyrosine kinases, heterocomplex formation or enhanced ligand expression. AT1R-EGFR crosstalk amplifies the signaling response and enhances the biological effects of angiotensin II. Downstream signaling cascades include ERK1/2 and p38 MAPK, PLCγ and STAT. AT1R-induced EGFR activation contributes to vascular remodeling and hypertrophy via e.g. smooth muscle cell proliferation, migration and extracellular matrix production. EGFR transactivation results in increased vessel wall thickness and reduced vascular compliance. AT1R and EGFR signaling pathways are also implicated the induction of vascular inflammation. Again, EGFR transactivation exacerbates the effects, leading to endothelial dysfunction that contributes to vascular inflammation, dysfunction and remodeling. Dysregulation of the AT1R-EGFR axis has been implicated in the pathogenesis of various cardiovascular diseases and inhibition or prevention of EGFR signaling can attenuate part of the detrimental impact of enhanced renin-angiotensin-system (RAAS) activity, highlighting the importance of EGFR for the adverse consequences of AT1R activation. In summary, EGFR plays a critical role in vascular AT1R action, enhancing signaling, promoting remodeling, contributing to inflammation, and participating in the pathogenesis of cardiovascular diseases. Understanding the interplay between AT1R and EGFR will foster the development of effective therapeutic strategies of RAAS-induced disorders.

Transcriptome analysis of six tissues obtained post-mortem from sepsis patients

Septic shock is a life-threatening clinical condition characterized by a robust immune inflammatory response to disseminated infection. Little is known about its impact on the transcriptome of distinct human tissues. To address this, we performed RNA sequencing of samples from the prefrontal cortex, hippocampus, heart, lung, kidney and colon of seven individuals who succumbed to sepsis and seven uninfected controls. We identified that the lungs and colon were the most affected organs. While gene activation dominated, strong inhibitory signals were also detected, particularly in the lungs. We found that septic shock is an extremely heterogeneous disease, not only when different individuals are investigated, but also when comparing different tissues of the same patient. However, several pathways, such as respiratory electron transport and other metabolic functions, revealed distinctive alterations, providing evidence that tissue specificity is a hallmark of sepsis. Strikingly, we found evident signals of accelerated ageing in our sepsis population.

ACE2-EGFR-MAPK signaling contributes to SARS-CoV-2 infection

SARS-CoV-2 triggered the most severe pandemic of recent times. To enter into a host cell, SARS-CoV-2 binds to the angiotensin-converting enzyme 2 (ACE2). However, subsequent studies indicated that other cell membrane receptors may act as virus-binding partners. Among these receptors, the epidermal growth factor receptor (EGFR) was hypothesized not only as a spike protein binder, but also to be activated in response to SARS-CoV-2. In our study, we aim at dissecting EGFR activation and its major downstream signaling pathway, the mitogen-activated signaling pathway (MAPK), in SARS-CoV-2 infection. Here, we demonstrate the activation of EGFR-MAPK signaling axis by the SARS-CoV-2 spike protein and we identify a yet unknown cross talk between ACE2 and EGFR that regulated ACE2 abundance and EGFR activation and subcellular localization, respectively. By inhibiting the EGFR-MAPK activation, we observe a reduced infection with either spike-pseudotyped particles or authentic SARS-CoV-2, thus indicating that EGFR serves as a cofactor and the activation of EGFR-MAPK contributes to SARS-CoV-2 infection.

Assessment of the Role of Endothelial and Vascular Smooth Muscle EGFR for Acute Blood Pressure Effects of Angiotensin II and Adrenergic Stimulation in Obese Mice

(1) Background: Obesity is associated with hypertension because of endocrine dysregulation of the adrenergic and the renin-angiotensin-aldosterone systems. The epidermal growth factor receptor (EGFR) is an important signaling hub in the cardiovascular system. In this study, we investigate the role of smooth muscle cell (VSMC) and endothelial cell (EC) EGFRs for blood pressure homeostasis and acute vascular reactivity in vivo. (2) Methods: Mice with deletion of the EGFR in the respective cell type received either a high-fat (HFD) or standard-fat diet (SFD) for 18 weeks. Intravascular blood pressure was measured via a Millar catheter in anesthetized animals upon vehicle load, angiotensin II (AII) and phenylephrine (PE) stimulation. (3) Results: We confirmed that deletion of the EGFR in VSMCs leads to reduced blood pressure and a most probably compensatory heart rate increase. EC-EGFR and VSMC-EGFR had only a minor impact on volume-load-induced blood pressure changes in lean as well as in obese wild-type animals. Regarding vasoactive substances, EC-EGFR seems to have no importance for angiotensin II action and counteracting HFD-induced prolonged blood pressure increase upon PE stimulation. VSMC-EGFR supports the blood pressure response to adrenergic and angiotensin II stimulation in lean animals. The responsiveness to AII and alpha-adrenergic stimulation was similar in lean and obese animals despite the known enhanced activity of the RAAS and the sympathetic nervous system under a high-fat diet. (4) Conclusions: We demonstrate that EGFRs in VSMCs and to a lesser extent in ECs modulate short-term vascular reactivity to AII, catecholamines and volume load in lean and obese animals.

Impact of maternal protein restriction on Hypoxia-Inducible Factor (HIF) expression in male fetal kidney development

BACKGROUND

Kidney developmental studies have demonstrated molecular pathway changes that may be related to decreased nephron numbers in the male 17 gestational days (17GD) low protein (LP) intake offspring compared to normal protein intake (NP) progeny. Here, we evaluated the HIF-1 and components of its pathway in the kidneys of 17-GD LP offspring to elucidate the molecular modulations during nephrogenesis.

METHODS

Pregnant Wistar rats were allocated into two groups: NP (regular protein diet-17%) or LP (Low protein diet-6%). Taking into account miRNA transcriptome sequencing previous study (miRNA-Seq) in 17GD male offspring kidneys investigated predicted target genes and proteins related to the HIF-1 pathway by RT-qPCR and immunohistochemistry.

RESULTS

In the present study, in male 17-GD LP offspring, an increased elF4, HSP90, p53, p300, NFκβ, and AT2 gene encoding compared to the NP progeny. Higher labeling of HIF-1α CAP cells in 17-DG LP offspring was associated with reduced elF4 and phosphorylated elF4 immunoreactivity in LP progeny CAP cells. In 17DG LP, the NFκβ and HSP90 immunoreactivity was enhanced, particularly in the CAP area.

DISCUSSION AND CONCLUSION

The current study supported that the programmed reduced nephron number in the 17-DG LP offspring may be related to changes in the HIF-1α signaling pathway. Factors that facilitate the transposition of HIF-1α to progenitor renal cell nuclei, such as increased NOS, Ep300, and HSP90 expression, may have a crucial role in this regulatory system. Also, HIF-1α changes could be associated with reduced transcription of elF-4 and its respective signaling path.

ADAM10 and ADAM17, Major Regulators of Chronic Kidney Disease Induced Atherosclerosis?

Chronic kidney disease (CKD) is a major health problem, affecting millions of people worldwide, in particular hypertensive and diabetic patients. CKD patients suffer from significantly increased cardiovascular disease (CVD) morbidity and mortality, mainly due to accelerated atherosclerosis development. Indeed, CKD not only affects the kidneys, in which injury and maladaptive repair processes lead to local inflammation and fibrosis, but also causes systemic inflammation and altered mineral bone metabolism leading to vascular dysfunction, calcification, and thus, accelerated atherosclerosis. Although CKD and CVD individually have been extensively studied, relatively little research has studied the link between both diseases. This narrative review focuses on the role of a disintegrin and metalloproteases (ADAM) 10 and ADAM17 in CKD and CVD and will for the first time shed light on their role in CKD-induced CVD. By cleaving cell surface molecules, these enzymes regulate not only cellular sensitivity to their micro-environment (in case of receptor cleavage), but also release soluble ectodomains that can exert agonistic or antagonistic functions, both locally and systemically. Although the cell-specific roles of ADAM10 and ADAM17 in CVD, and to a lesser extent in CKD, have been explored, their impact on CKD-induced CVD is likely, yet remains to be elucidated.

Vascular mechanotransduction

This review aims to survey the current state of mechanotransduction in vascular smooth muscle cells (VSMCs) and endothelial cells (ECs), including their sensing of mechanical stimuli and transduction of mechanical signals that result in the acute functional modulation and longer-term transcriptomic and epigenetic regulation of blood vessels. The mechanosensors discussed include ion channels, plasma membrane-associated structures and receptors, and junction proteins. The mechanosignaling pathways presented include the cytoskeleton, integrins, extracellular matrix, and intracellular signaling molecules. These are followed by discussions on mechanical regulation of transcriptome and epigenetics, relevance of mechanotransduction to health and disease, and interactions between VSMCs and ECs. Throughout this review, we offer suggestions for specific topics that require further understanding. In the closing section on conclusions and perspectives, we summarize what is known and point out the need to treat the vasculature as a system, including not only VSMCs and ECs but also the extracellular matrix and other types of cells such as resident macrophages and pericytes, so that we can fully understand the physiology and pathophysiology of the blood vessel as a whole, thus enhancing the comprehension, diagnosis, treatment, and prevention of vascular diseases.

EGFR inhibition leads to enhanced desmosome assembly and cardiomyocyte cohesion via ROCK activation

Arrhythmogenic cardiomyopathy (AC) is a familial heart disease partly caused by impaired desmosome turnover. Thus, stabilization of desmosome integrity may provide new treatment options. Desmosomes, apart from cellular cohesion, provide the structural framework of a signaling hub. Here, we investigated the role of the epidermal growth factor receptor (EGFR) in cardiomyocyte cohesion. We inhibited EGFR under physiological and pathophysiological conditions using the murine plakoglobin-KO AC model, in which EGFR was upregulated. EGFR inhibition enhanced cardiomyocyte cohesion. Immunoprecipitation showed an interaction of EGFR and desmoglein 2 (DSG2). Immunostaining and atomic force microscopy (AFM) revealed enhanced DSG2 localization and binding at cell borders upon EGFR inhibition. Enhanced area composita length and desmosome assembly were observed upon EGFR inhibition, confirmed by enhanced DSG2 and desmoplakin (DP) recruitment to cell borders. PamGene Kinase assay performed in HL-1 cardiomyocytes treated with erlotinib, an EGFR inhibitor, revealed upregulation of Rho-associated protein kinase (ROCK). Erlotinib-mediated desmosome assembly and cardiomyocyte cohesion were abolished upon ROCK inhibition. Thus, inhibiting EGFR and, thereby, stabilizing desmosome integrity via ROCK might provide treatment options for AC.

Activated fibroblasts in cardiac and cancer fibrosis: An overview of analogies and new potential therapeutic options

Heart disease and cancer are two major causes of morbidity and mortality in the industrialized countries, and their increasingly recognized connections are shifting the focus from single disease studies to an interdisciplinary approach. Fibroblast-mediated intercellular crosstalk is critically involved in the evolution of both pathologies. In healthy myocardium and in non-cancerous conditions, resident fibroblasts are the main cell source for synthesis of the extracellular matrix (ECM) and important sentinels of tissue integrity. In the setting of myocardial disease or cancer, quiescent fibroblasts activate, respectively, into myofibroblasts (myoFbs) and cancer-associated fibroblasts (CAFs), characterized by increased production of contractile proteins, and by a highly proliferative and secretory phenotype. Although the initial activation of myoFbs/CAFs is an adaptive process to repair the damaged tissue, massive deposition of ECM proteins leads to maladaptive cardiac or cancer fibrosis, a recognized marker of adverse outcome. A better understanding of the key mechanisms orchestrating fibroblast hyperactivity may help developing innovative therapeutic options to restrain myocardial or tumor stiffness and improve patient prognosis. Albeit still unappreciated, the dynamic transition of myocardial and tumor fibroblasts into myoFbs and CAFs shares several common triggers and signaling pathways relevant to TGF-β dependent cascade, metabolic reprogramming, mechanotransduction, secretory properties, and epigenetic regulation, which might lay the foundation for future antifibrotic intervention. Therefore, the aim of this review is to highlight emerging analogies in the molecular signature underlying myoFbs and CAFs activation with the purpose of identifying novel prognostic/diagnostic biomarkers, and to elucidate the potential of drug repositioning strategies to mitigate cardiac/cancer fibrosis.

Structural dysregulation of the pulmonary autograft was associated with a greater density of p16INK4A-vascular smooth muscle cells

The present study tested the hypothesis that a senescent phenotype of vascular smooth muscle cells (VSMCs) may represent the seminal event linked to maladaptive pulmonary autograft remodeling of a small number of patients that underwent the Ross procedure. The diameter of the pulmonary autograft (47±4 mm) of three male patients was significantly greater compared to the pulmonary artery (26±1 mm) excised from bicuspid aortic valve (BAV) patients. The pulmonary autograft was associated with a neointimal region and the adjacent medial region was significantly thinner compared to the pulmonary artery of BAV patients. Structural dysregulation was evident as elastin content of the medial region was significantly reduced in the pulmonary autograft compared to the pulmonary artery of BAV patients. By contrast, collagen content of the medial region of the pulmonary autograft and the pulmonary artery of BAV patients was not significantly different. Reduced medial elastin content of the pulmonary autograft was associated with increased protein levels of matrix metalloproteinase-9. The latter phenotype was not attributed to a robust inflammatory response as the percentage of Mac-2⁽⁺⁾-infiltrating monocytes/macrophages was similar between groups. A senescent phenotype was identified as protein levels of the cell cycle inhibitor p27^kip1 were upregulated and the density of p16^INK4A/non-muscle myosin IIB⁽⁺⁾-VSMCs was significantly greater in the pulmonary autograft compared to the pulmonary artery of BAV patients. Thus, senescent VSMCs may represent the predominant cellular source of increased matrix metalloproteinase-9 protein expression translating to maladaptive pulmonary autograft remodeling characterized by elastin degradation, medial thinning and neointimal formation.

Gender differences in GRK2 in cardiovascular diseases and its interactions with estrogen

G protein-coupled receptor kinase 2 (GRK2) is a multifunctional protein involved in regulating G protein-coupled receptor (GPCR) and non-GPCR signaling in the body. In the cardiovascular system, increased expression of GRK2 has been implicated in the occurrence and development of several cardiovascular diseases (CVDs). Recent studies have found gender differences in GRK2 in the cardiovascular system under physiological and pathological conditions, where GRK2's expression and activity are increased in males than in females. The incidence of CVDs in premenopausal women is lower than in men of the same age, which is related to estrogen levels. Given the shared location of GRK2 and estrogen receptors, estrogen may interact with GRK2 by modulating vital molecules such as calmodulin (CaM), caveolin, RhoA, nitrate oxide (NO), and mouse double minute 2 homolog (Mdm2), via signaling pathways mediated by estrogen's genomic (ERα and ERβ), and non-genomic (GPER) receptors, conferring cardiovascular protection in females. Highlighting the gender differences in GRK2 and understanding its interaction with estrogen in the cardiovascular system is pertinent in treating gender-related CVDs. As a result, this article explores the gender differences of GRK2 in the cardiovascular system and its relationship with estrogen during disease conditions. Estrogen's protective and therapeutic effects and its mechanism on GRK2-related cardiovascular diseases have also been discussed.

Molecular Mechanisms in Genetic Aortopathy-Signaling Pathways and Potential Interventions

Thoracic aortic disease affects people of all ages and the majority of those aged <60 years have an underlying genetic cause. There is presently no effective medical therapy for thoracic aneurysm and surgery remains the principal intervention. Unlike abdominal aortic aneurysm, for which the inflammatory/atherosclerotic pathogenesis is well established, the mechanism of thoracic aneurysm is less understood. This paper examines the key cell signaling systems responsible for the growth and development of the aorta, homeostasis of endothelial and vascular smooth muscle cells and interactions between pathways. The evidence supporting a role for individual signaling pathways in pathogenesis of thoracic aortic aneurysm is examined and potential novel therapeutic approaches are reviewed. Several key signaling pathways, notably TGF-β, WNT, NOTCH, PI3K/AKT and ANGII contribute to growth, proliferation, cell phenotype and survival for both vascular smooth muscle and endothelial cells. There is crosstalk between pathways, and between vascular smooth muscle and endothelial cells, with both synergistic and antagonistic interactions. A common feature of the activation of each is response to injury or abnormal cell stress. Considerable experimental evidence supports a contribution of each of these pathways to aneurysm formation. Although human information is less, there is sufficient data to implicate each pathway in the pathogenesis of human thoracic aneurysm. As some pathways i.e., WNT and NOTCH, play key roles in tissue growth and organogenesis in early life, it is possible that dysregulation of these pathways results in an abnormal aortic architecture even in infancy, thereby setting the stage for aneurysm development in later life. Given the fine tuning of these signaling systems, functional polymorphisms in key signaling elements may set up a future risk of thoracic aneurysm. Multiple novel therapeutic agents have been developed, targeting cell signaling pathways, predominantly in cancer medicine. Future investigations addressing cell specific targeting, reduced toxicity and also less intense treatment effects may hold promise for effective new medical treatments of thoracic aortic aneurysm.

Mechanism of Hypoxia-Mediated Smooth Muscle Cell Proliferation Leading to Vascular Remodeling

Vascular remodeling refers to changes in the size, contraction, distribution, and flow rate of blood vessels and even changes in vascular function. Vascular remodeling can cause cardiovascular and cerebrovascular diseases. It can also lead to other systemic diseases, such as pulmonary hypertension, pulmonary atherosclerosis, chronic obstructive pulmonary disease, stroke, and ascites of broilers. Hypoxia is one of the main causes of vascular remodeling. Prolonged hypoxia or intermittent hypoxia can lead to loss of lung ventilation, causing respiratory depression, irregular respiratory rhythms, and central respiratory failure. Animals that are unable to adapt to the highland environment are also prone to sustained constriction of the small pulmonary arteries, increased resistance to pulmonary circulation, and impaired blood circulation, leading to pulmonary hypertension and right heart failure if they live in a highland environment for long periods of time. However, limited studies have been found on the relationship between hypoxia and vascular remodeling. Therefore, this review will explore the relationship between hypoxia and vascular remodeling from the aspects of endoplasmic reticulum stress, mitochondrial dysfunction, abnormal calcium channel, disordered cellular metabolism, abnormal expression of miRNA, and other factors. This will help to understand the detailed mechanism of hypoxia-mediated smooth muscle cell proliferation and vascular remodeling for the better treatment and management of diseases due to vascular remodeling.

Evolution of the ErbB gene family and analysis of regulators of Egfr expression during development of the rat spinal cord

Egfr, a member of the ErbB gene family, plays a critical role in tissue development and homeostasis, wound healing, and disease. However, expression and regulators of Egfr during spinal cord development remain poorly understood. In this study, we investigated ErbB evolution and analyzed co-expression modules, miRNAs, and transcription factors that may regulate Egfr expression in rats. We found that ErbB family members formed via Egfr duplication in the ancient vertebrates but diverged after speciation of gnathostomes. We identified a module that was co-expressed with Egfr, which involved cell proliferation and blood vessel development. We predicted 25 miRNAs and nine transcription factors that may regulate Egfr expression. Dual-luciferase reporter assays showed six out of nine transcription factors significantly affected Egfr promoter reporter activity. Two of these transcription factors (KLF1 and STAT3) inhibited the Egfr promoter reporter, whereas four transcription factors (including FOXA2) activated the Egfr promoter reporter. Real-time PCR and immunofluorescence experiments showed high expression of FOXA2 during the embryonic period and FOXA2 was expressed in the floor plate of the spinal cord, suggesting the importance of FOXA2 during embryonic spinal cord development. Considering the importance of Egfr in embryonic spinal cord development, wound healing, and disease (specifically in cancer), regulatory elements identified in this study may provide candidate targets for nerve regeneration and disease treatment in the future.

Opposing Effects of EGF Receptor Signaling on Proliferation and Differentiation Initiated by EGF or TSH/EGF Receptor Transactivation

Regulation of thyroid cells by thyrotropin (TSH) and epidermal growth factor (EGF) has been known but different effects of these regulators on proliferation and differentiation have been reported. We studied these responses in primary cultures of human thyroid cells to determine whether TSH receptor (TSHR) signaling may involve EGF receptor (EGFR) transactivation. We confirm that EGF stimulates proliferation and de-differentiation whereas TSH causes differentiation in the absence of other growth factors. We show that TSH/TSHR transactivates EGFR and characterize it as follows: (1) TSH-induced upregulation of thyroid-specific genes is inhibited by 2 inhibitors of EGFR kinase activity, AG1478 and erlotinib; (2) the mechanism of transactivation is independent of an extracellular EGFR ligand by showing that 2 antibodies, cetuximab and panitumumab, that completely inhibited binding of EGFR ligands to EGFR had no effect on transactivation, and by demonstrating that no EGF was detected in media conditioned by thyrocytes incubated with TSH; (3) TSH/TSHR transactivation of EGFR is different than EGFR activation by EGF by showing that EGF led to rapid phosphorylation of EGFR whereas transactivation occurred in the absence of receptor phosphorylation; (4) EGF caused downregulation of EGFR whereas transactivation had no effect on EGFR level; (5) EGF and TSH stimulation converged on the protein kinase B (AKT) pathway, because TSH, like EGF, stimulated phosphorylation of AKT that was inhibited by EGFR inhibitors; and (6) TSH-induced upregulation of thyroid genes was inhibited by the AKT inhibitor MK2206. Thus, TSH/TSHR causes EGFR transactivation that is independent of extracellular EGFR ligand and in part mediates TSH regulation of thyroid hormone biosynthetic genes.

Involvement of shedding induced by ADAM17 on the nitric oxide pathway in hypertension

A Disintegrin and Metalloprotease 17 (ADAM17), also called tumor necrosis factor-ɑ (TNF-ɑ) convertase (TACE), is a well-known protease involved in the sheddase of growth factors, chemokines and cytokines. ADAM17 is also enrolled in hypertension, especially by shedding of angiotensin converting enzyme type 2 (ACE2) leading to impairment of angiotensin 1–7 [Ang-(1–7)] production and injury in vasodilation, induction of renal damage and cardiac hypertrophy. Activation of Mas receptor (MasR) by binding of Ang-(1–7) induces an increase in the nitric oxide (NO) gaseous molecule, which is an essential factor of vascular homeostasis and blood pressure control. On the other hand, TNF-ɑ has demonstrated to stimulate a decrease in nitric oxide bioavailability, triggering a disrupt in endothelium-dependent vasorelaxation. In spite of the previous studies, little knowledge is available about the involvement of the metalloprotease 17 and the NO pathways. Here we will provide an overview of the role of ADAM17 and Its mechanisms implicated with the NO formation.

Endothelial and Vascular Smooth Muscle Dysfunction in Hypertension

The development of essential hypertension involves several factors. Vascular dysfunction, characterized by endothelial dysfunction, low-grade inflammation and structural remodeling, plays an important role in the initiation and maintenance of essential hypertension. Although the mechanistic pathways by which essential hypertension develops are poorly understood, several pharmacological classes available on the clinical settings improve blood pressure by interfering in the cardiac output and/or vascular function. This review is divided in two major sections. The first section depicts the major molecular pathways as renin angiotensin aldosterone system (RAAS), endothelin, nitric oxide signalling pathway and oxidative stress in the development of vascular dysfunction. The second section describes the role of some pharmacological classes such as i) RAAS inhibitors, ii) dual angiotensin receptor-neprilysin inhibitors, iii) endothelin-1 receptor antagonists, iv) soluble guanylate cyclase modulators, v) phosphodiesterase type 5 inhibitors and vi) sodium-glucose cotransporter 2 inhibitors in the context of hypertension. Some classes are already approved in the treatment of hypertension, but others are not yet approved. However, due to their potential benefits these classes were included.

Compensatory Upregulation of LPA2 and Activation of the PI3K-Akt Pathway Prevent LPA5-Dependent Loss of Intestinal Epithelial Cells in Intestinal Organoids

Renewal of the intestinal epithelium is orchestrated by regenerative epithelial proliferation within crypts. Recent studies have shown that lysophosphatidic acid (LPA) can maintain intestinal epithelial renewal in vitro and conditional deletion of Lpar5 (Lpar5iKO) in mice ablates the intestinal epithelium and increases morbidity. In contrast, constitutive Lpar5 deletion (Lpar5cKO) does not cause a defect in intestinal crypt regeneration. In this study, we investigated whether another LPA receptor (LPAR) compensates for constitutive loss of LPA5 function to allow regeneration of intestinal epithelium. In Lpar5cKO intestinal epithelial cells (IECs), Lpar2 was upregulated and blocking LPA2 function reduced proliferation and increased apoptosis of Lpar5cKO IECs. Similar to Lpar5cKO mice, the absence of Lpar2 (Lpar2-/-) resulted in upregulation of Lpar5 in IECs, indicating that LPA2 and LPA5 reciprocally compensate for the loss of each other. Blocking LPA2 in Lpar5cKO enteroids reduced phosphorylation of Akt, indicating that LPA2 maintains the growth of Lpar5cKO enteroids through activation of the PI3K-Akt pathway. The present study provides evidence that loss of an LPAR can be compensated by another LPAR. This ability to compensate needs to be considered in studies aimed to define receptor functions or test the efficacy of a LPAR-targeting drug using genetically engineered animal models.

The Functional Interaction of EGFR with AT1R or TP in Primary Vascular Smooth Muscle Cells Triggers a Synergistic Regulation of Gene Expression

In vivo, cells are simultaneously exposed to multiple stimuli whose effects are difficult to distinguish. Therefore, they are often investigated in experimental cell culture conditions where stimuli are applied separately. However, it cannot be presumed that their individual effects simply add up. As a proof-of-principle to address the relevance of transcriptional signaling synergy, we investigated the interplay of the Epidermal Growth Factor Receptor (EGFR) with the Angiotensin-II (AT1R) or the Thromboxane-A2 (TP) receptors in murine primary aortic vascular smooth muscle cells. Transcriptome analysis revealed that EGFR-AT1R or EGFR-TP simultaneous activations led to different patterns of regulated genes compared to individual receptor activations (qualitative synergy). Combined EGFR-TP activation also caused a variation of amplitude regulation for a defined set of genes (quantitative synergy), including vascular injury-relevant ones (Klf15 and Spp1). Moreover, Gene Ontology enrichment suggested that EGFR and TP-induced gene expression changes altered processes critical for vascular integrity, such as cell cycle and senescence. These bioinformatics predictions regarding the functional relevance of signaling synergy were experimentally confirmed. Therefore, by showing that the activation of more than one receptor can trigger a synergistic regulation of gene expression, our results epitomize the necessity to perform comprehensive network investigations, as the study of individual receptors may not be sufficient to understand their physiological or pathological impact.

UHPLC-Q-TOF-MS/MS and Network Pharmacology Analysis to Reveal Quality Markers of Xinjiang Cydonia oblonga Mill. for Antiatherosclerosis

Cydonia oblonga Mill. (COM), mature fruit of genus Rosaceae, is consumed as a kind of traditional Chinese medicinal herb. Previous studies have shown that the components in COM extract have antioxidant, anti-inflammatory, blood pressure-lowering, blood lipid-lowering, antithrombotic, and other biological activities. However, the quality markers (Q-markers) of atherosclerosis (AS) have not been elucidated. The Q-marker is based on the five core principles of traceability, transferability, specificity, measurability, validity, and prescription dispensing. In this study, the quality markers of quince were investigated by applying the ultraperformance liquid chromatography-time-of-flight mass spectrometry (UHPLC/Q-TOF-MS/MS) method and network pharmacology method to highlight the three core elements which are, respectively, traceability transmission, measurability, and validity. At the first step, 72 components were identified by applying the ultraperformance liquid chromatography-time-of-flight mass spectrometry (UHPLC/Q-TOF-MS/MS) method. In the next step, 46 candidate components of COM anti-AS were obtained by network pharmacology, and then, 27 active components were filtered with the molecular docking assay. Finally, the 27 active components were intersected with 10 active components obtained by mass transfer and traceable quality markers. Four anti-AS Q-markers of COM were identified, including caffeic acid, chlorogenic acid, ellagic acid, and vanillic acid, which provided a reference for the quality control of quince. The methods and strategies can also be applied to other traditional Chinese medicines and their compound preparations, providing new ideas on the quantitative evaluation and identification of quality markers.

Mining Important Herb Combinations of Traditional Chinese Medicine against Hypertension Based on the Symptom-Herb Network Combined with Network Pharmacology

Although data mining methods are extensively used in the rule analysis of famous old traditional Chinese medicine (TCM) experts' prescriptions for the treatment of hypertension, most of them only mine the association between herbs and herbs, ignoring the importance of symptoms in the disease. This study collected 439 cases of hypertension treated by famous old TCM experts from the FangNet platform. Using the structure network algorithm, the symptom-herb network was constructed, which redefined the importance of herb in disease. Based on the network, 21 driver herbs, 76 herb pairs, and 41 symptom-herb associations were mined. Finally, the basic prescription composed of Gouteng (Uncariae Ramulus cum Uncis), Huanglian (Coptidis Rhizoma), Chuanxiong (Chuanxiong Rhizoma), Gegen (Puerariae Lobatae Radix), Danggui (Angelicae Sinensis Radix), and Huangqin (Scutellariae Radix) was found. These herbs are the most significant among all herbs, and they have a potential correlation with each other. To further verify the rationality of the data mining results, we adopted the network pharmacology method. Network pharmacological analysis shows that the five core targets in the basic prescription include IL6, VEGFA, TNF, TP53, and EGF, which link 10 significant active compounds and 7 important KEGG pathways. It was predicted that anti-inflammatory, antioxidant, vascular endothelial protection, emotion regulation, and ion channel intervention might be the main mechanisms of the basic prescription against hypertension. This study reveals the prescription rule of famous old TCM experts for treating hypertension from a new perspective, which provides a new approach to inherit the academic experience of famous old TCM experts and develop new drugs.

Network Pharmacology Prediction and Molecular Docking-Based Strategy to Discover the Potential Pharmacological Mechanism of Wen-Yu-Jin against Pulmonary Fibrosis in a Mouse Model

BACKGROUND

Pulmonary fibrosis (PF) is a devastating lung disease, resulting in gas exchange dysfunction until death. The two drugs approved by the FDA, pirfenidone and nintedanib, have obvious side effects. Wen-yu-jin (WYJ), one of the commonly used herbs in China, can treat respiratory diseases. The potential effects and the underlying mechanism of WYJ against PF are unclear.

PURPOSE

Employing network pharmacology, molecular docking, and in vivo and in vitro experiments to explore the potential effects and underlying mechanisms of WYJ in the treatment of PF.

METHODS

Ultra-high pressure liquid chromatography combined with linear ion trap-orbital tandem mass spectrometry (UHPLC-LTQ-orbital trap) was used to identify compounds of WYJ. We got PF-related targets and WYJ compounds-related targets from public databases and further completed critical targets exploration, network construction, and pathway analysis by network pharmacology. Molecular docking predicted binding activity of WYJ compounds and critical targets. Based on the above results, in vivo and in vitro experiments validated the potential effects and mechanisms of WYJ against PF.

RESULTS

23 major compositions of WYJ were identified based on UHPLC-LTQ-Orbitrap. According to the results of network pharmacology, STAT3, SRC, IL6, MAPK1, AKT1, EGFR, MAPK8, MAPK14, and IL1B are critical therapeutic targets. Molecular docking results showed that most of the compounds have good binding activities with critical targets. The results of in vivo and in vitro experiments showed that WYJ alleviated the process of fibrosis by targeting MAPK and STAT3 pathways.

CONCLUSION

Network pharmacology, molecular docking, and in vivo and in vitro experiments showed the potential effects and mechanisms of WYJ against PF, which provides a theoretical basis for the treatment of WYJ with PF.

Proximity ligation assay to study TSH receptor homodimerization and crosstalk with IGF-1 receptors in human thyroid cells

Proximity ligation assay (PLA) is a methodology that permits detection of protein-protein closeness, that is, proteins that are within 40 nanometers of each other, in cells or tissues at endogenous protein levels or after exogenous overexpression. It detects the protein(s) with high sensitivity and specificity because it employs a DNA hybridization step followed by DNA amplification. PLA has been used successfully with many types of proteins. In this methods paper, we will describe the workings of PLA and provide examples of its use to study TSH/IGF-1 receptor crosstalk in Graves' orbital fibroblasts (GOFs) and TSH receptor homodimerization in primary cultures of human thyrocytes.

Synergy of epidermal growth factor (EGFR) and angiotensin II (AT1R) receptor determines composition and temporal pattern of transcriptome variation

The tyrosine kinase receptor EGFR and the G-protein-coupled receptor AT1R induce essential cellular responses, in part via receptor crosstalk with an unknown role in nuclear information transfer and transcription regulation. We investigated whether this crosstalk results in linear, EGFR-mediated nuclear signalling or in parallel, synergistic information transfer leading to qualitative and temporal variations, relevant for gene expression and environment interaction. AT1R and EGFR synergistically activate SRF via the ERK1/2-TCF and actin-MRTF pathways. Synergism, comprised of switch-like and graded single cell response, converges on the transcription factors AP1 and EGR, resulting in synergistic transcriptome alterations, in qualitative (over-additive number of genes), quantitative (over-additive expression changes of individual genes) and temporal (more late onset and prolonged expressed genes) terms. Gene ontology and IPA^® pathway analysis indicate prolonged cell stress (e.g. hypoxia-like) and dysregulated vascular biology. Synergism occurs during separate but simultaneous activation of both receptors and during AT1R-induced EGFR transactivation. EGFR and AT1R synergistically regulate gene expression in qualitative, quantitative and temporal terms with (patho)physiological relevance, extending the importance of EGFR-AT1R crosstalk beyond cytoplasmic signalling.

Profiling novel pharmacology of receptor complexes using Receptor-HIT

Many receptors are able to undergo heteromerisation, leading to the formation of receptor complexes that may have pharmacological profiles distinct from those of the individual receptors. As a consequence of this, receptor heteromers can be classed as new drug targets, with the potential for achieving greater specificity and selectivity over targeting their constituent receptors. We have developed the Receptor-Heteromer Investigation Technology (Receptor-HIT), which enables the detection of receptor heteromers using a proximity-based reporter system such as bioluminescence resonance energy transfer (BRET). Receptor-HIT detects heteromers in live cells and in real time, by utilising ligand-induced signals that arise from altered interactions with specific biomolecules, such as ligands or proteins. Furthermore, monitoring the interaction between the receptors and the specific biomolecules generates functional information about the heteromer that can be pharmacologically quantified. This review will discuss various applications of Receptor-HIT, including its use with different classes of receptors (e.g. G protein-coupled receptors (GPCRs), receptor tyrosine kinases (RTKs) and others), its use to monitor receptor interactions both intracellularly and extracellularly, and also its use with genome-edited endogenous proteins.

The Role of Epidermal Growth Factor Receptor Family of Receptor Tyrosine Kinases in Mediating Diabetes-Induced Cardiovascular Complications

Diabetes mellitus is a major debilitating disease whose global incidence is progressively increasing with currently over 463 million adult sufferers and this figure will likely reach over 700 million by the year 2045. It is the complications of diabetes such as cardiovascular, renal, neuronal and ocular dysfunction that lead to increased patient morbidity and mortality. Of these, cardiovascular complications that can result in stroke and cardiomyopathies are 2- to 5-fold more likely in diabetes but the underlying mechanisms involved in their development are not fully understood. Emerging research suggests that members of the Epidermal Growth Factor Receptor (EGFR/ErbB/HER) family of tyrosine kinases can have a dual role in that they are beneficially required for normal development and physiological functioning of the cardiovascular system (CVS) as well as in salvage pathways following acute cardiac ischemia/reperfusion injury but their chronic dysregulation may also be intricately involved in mediating diabetes-induced cardiovascular pathologies. Here we review the evidence for EGFR/ErbB/HER receptors in mediating these dual roles in the CVS and also discuss their potential interplay with the Renin-Angiotensin-Aldosterone System heptapeptide, Angiotensin-(1-7), as well the arachidonic acid metabolite, 20-HETE (20-hydroxy-5, 8, 11, 14-eicosatetraenoic acid). A greater understanding of the multi-faceted roles of EGFR/ErbB/HER family of tyrosine kinases and their interplay with other key modulators of cardiovascular function could facilitate the development of novel therapeutic strategies for treating diabetes-induced cardiovascular complications.

Key metalloproteinase-mediated pathways in the kidney

Matrix metalloproteinases (MMPs) and a disintegrin and metalloproteinases (ADAMs) belong to the metzincin family of zinc-containing multidomain molecules, and can act as soluble or membrane-bound proteases. These enzymes inactivate or activate other soluble or membrane-expressed mediator molecules, which enables them to control developmental processes, tissue remodelling, inflammatory responses and proliferative signalling pathways. The dysregulation of MMPs and ADAMs has long been recognized in acute kidney injury and in chronic kidney disease, and genetic targeting of selected MMPs and ADAMs in different mouse models of kidney disease showed that they can have detrimental and protective roles. In particular, MMP-2, MMP-7, MMP-9, ADAM10 and ADAM17 have been shown to have a mainly profibrotic effect and might therefore represent therapeutic targets. Each of these proteases has been associated with a different profibrotic pathway that involves tissue remodelling, Wnt-β-catenin signalling, stem cell factor-c-kit signalling, IL-6 trans-signalling or epidermal growth factor receptor (EGFR) signalling. Broad-spectrum metalloproteinase inhibitors have been used to treat fibrotic kidney diseases experimentally but more targeted approaches have since been developed, including inhibitory antibodies, to avoid the toxic side effects initially observed with broad-spectrum inhibitors. These advances not only provide a solid foundation for additional preclinical studies but also encourage further translation into clinical research.

Myogenic Tone in Peripheral Resistance Arteries and Arterioles: The Pressure Is On!

Resistance arteries and downstream arterioles in the peripheral microcirculation contribute substantially to peripheral vascular resistance, control of blood pressure, the distribution of blood flow to and within tissues, capillary pressure, and microvascular fluid exchange. A hall-mark feature of these vessels is myogenic tone. This pressure-induced, steady-state level of vascular smooth muscle activity maintains arteriolar and resistance artery internal diameter at 50–80% of their maximum passive diameter providing these vessels with the ability to dilate, reducing vascular resistance, and increasing blood flow, or constrict to produce the opposite effect. Despite the central importance of resistance artery and arteriolar myogenic tone in cardiovascular physiology and pathophysiology, our understanding of signaling pathways underlying this key microvascular property remains incomplete. This brief review will present our current understanding of the multiple mechanisms that appear to underlie myogenic tone, including the roles played by G-protein-coupled receptors, a variety of ion channels, and several kinases that have been linked to pressure-induced, steady-state activity of vascular smooth muscle cells (VSMCs) in the wall of resistance arteries and arterioles. Emphasis will be placed on the portions of the signaling pathways underlying myogenic tone for which there is lack of consensus in the literature and areas where our understanding is clearly incomplete.

GPCR-ErbB transactivation pathways and clinical implications

Cell surface receptors including the epidermal growth factor receptor (EGFR) family and G-protein coupled receptors (GPCRs) play quintessential roles in physiology, and in diseases, including cardiovascular diseases. While downstream signaling from these individual receptor families has been well studied, the cross-talk between EGF and GPCR receptor families is still incompletely understood. Including members of both receptor families, the number of receptor and ligand combinations for unique interactions is vast, offering a frontier of pharmacologic targets to explore for preventing and treating disease. This molecular cross-talk, called receptor transactivation, is reviewed here with a focus on the cardiovascular system featuring the well-studied GPCR receptors, but also discussing less-studied receptors from both families for a broad understanding of context of expansile interactions, repertoire of cellular signaling, and disease consequences. Attention is given to cell type, level of chronicity, and disease context given that transactivation and comorbidities, including diabetes, hypertension, coronavirus infection, impact cardiovascular disease and health outcomes.

Angiotensin II receptor type 1 - An update on structure, expression and pathology

The AT₁ receptor, a major effector of the renin-angiotensin system, has been extensively studied in the context of cardiovascular and renal disease. Moreover, angiotensin receptor blockers, sartans, are among the most frequently prescribed drugs for the treatment of hypertension, chronic heart failure and chronic kidney disease. However, precise molecular insights into the structure of this important drug target have not been available until recently. In this context, seminal studies have now revealed exciting new insights into the structure and biased signaling of the receptor and may thus foster the development of novel therapeutic approaches to enhance the efficacy of pharmacological angiotensin receptor antagonism or to enable therapeutic induction of biased receptor activity. In this review, we will therefore highlight these and other seminal publications to summarize the current understanding of the tertiary structure, ligand binding properties and downstream signal transduction of the AT₁ receptor.

Stimulation of the four isoforms of receptor tyrosine kinase ErbB4, but not ErbB1, confers cardiomyocyte hypertrophy

Epidermal growth factor (EGF) receptors (ErbB1-ErbB4) promote cardiac development and growth, although the specific EGF ligands and receptor isoforms involved in growth/repair versus pathology remain undefined. We challenged ventricular cardiomyocytes with EGF-like ligands and observed that selective activation of ErbB4 (the receptor for neuregulin 1 [NRG1]), but not ErbB1 (the receptor for EGF, EGFR), stimulated hypertrophy. This lack of direct ErbB1-mediated hypertrophy occurred despite robust activation of extracellular-regulated kinase 1/2 (ERK) and protein kinase B. Hypertrophic responses to NRG1 were unaffected by the tyrosine kinase inhibitor (AG1478) at concentrations that are selective for ErbB1 over ErbB4. NRG1-induced cardiomyocyte enlargement was suppressed by small interfering RNA (siRNA) knockdown of ErbB4 and ErbB2, whereas ERK phosphorylation was only suppressed by ErbB4 siRNA. Four ErbB4 isoforms exist (JM-a/JM-b and CYT-1/CYT-2), generated by alternative splicing, and their expression declines postnatally and following cardiac hypertrophy. Silencing of all four isoforms in cardiomyocytes, using an ErbB4 siRNA, abrogated NRG1-induced hypertrophic promoter/reporter activity, which was rescued by coexpression of knockdown-resistant versions of the ErbB4 isoforms. Thus, ErbB4 confers cardiomyocyte hypertrophy to NRG1, and all four ErbB4 isoforms possess the capacity to mediate this effect.

The mineralocorticoid receptor leads to increased expression of EGFR and T-type calcium channels that support HL-1 cell hypertrophy

The EGF receptor (EGFR) has been extensively studied in tumor biology and recently a role in cardiovascular pathophysiology was suggested. The mineralocorticoid receptor (MR) is an important effector of the renin-angiotensin-aldosterone-system and elicits pathophysiological effects in the cardiovascular system; however, the underlying molecular mechanisms are unclear. Our aim was to investigate the importance of EGFR for MR-mediated cardiovascular pathophysiology because MR is known to induce EGFR expression. We identified a SNP within the EGFR promoter that modulates MR-induced EGFR expression. In RNA-sequencing and qPCR experiments in heart tissue of EGFR KO and WT mice, changes in EGFR abundance led to differential expression of cardiac ion channels, especially of the T-type calcium channel CACNA1H. Accordingly, CACNA1H expression was increased in WT mice after in vivo MR activation by aldosterone but not in respective EGFR KO mice. Aldosterone- and EGF-responsiveness of CACNA1H expression was confirmed in HL-1 cells by Western blot and by measuring peak current density of T-type calcium channels. Aldosterone-induced CACNA1H protein expression could be abrogated by the EGFR inhibitor AG1478. Furthermore, inhibition of T-type calcium channels with mibefradil or ML218 reduced diameter, volume and BNP levels in HL-1 cells. In conclusion the MR regulates EGFR and CACNA1H expression, which has an effect on HL-1 cell diameter, and the extent of this regulation seems to depend on the SNP-216 (G/T) genotype. This suggests that the EGFR may be an intermediate for MR-mediated cardiovascular changes and that SNP analysis can help identify subgroups of patients that will benefit most from MR antagonists.

Impact of Aldosterone on the Failing Myocardium: Insights from Mitochondria and Adrenergic Receptors Signaling and Function

The mineralocorticoid aldosterone regulates electrolyte and blood volume homeostasis, but it also adversely modulates the structure and function of the chronically failing heart, through its elevated production in chronic human post-myocardial infarction (MI) heart failure (HF). By activating the mineralocorticoid receptor (MR), a ligand-regulated transcription factor, aldosterone promotes inflammation and fibrosis of the heart, while increasing oxidative stress, ultimately induding mitochondrial dysfunction in the failing myocardium. To reduce morbidity and mortality in advanced stage HF, MR antagonist drugs, such as spironolactone and eplerenone, are used. In addition to the MR, aldosterone can bind and stimulate other receptors, such as the plasma membrane-residing G protein-coupled estrogen receptor (GPER), further complicating it signaling properties in the myocardium. Given the salient role that adrenergic receptor (ARs)—particularly βARs—play in cardiac physiology and pathology, unsurprisingly, that part of the impact of aldosterone on the failing heart is mediated by its effects on the signaling and function of these receptors. Aldosterone can significantly precipitate the well-documented derangement of cardiac AR signaling and impairment of AR function, critically underlying chronic human HF. One of the main consequences of HF in mammalian models at the cellular level is the presence of mitochondrial dysfunction. As such, preventing mitochondrial dysfunction could be a valid pharmacological target in this condition. This review summarizes the current experimental evidence for this aldosterone/AR crosstalk in both the healthy and failing heart, and the impact of mitochondrial dysfunction in HF. Recent findings from signaling studies focusing on MR and AR crosstalk via non-conventional signaling of molecules that normally terminate the signaling of ARs in the heart, i.e., the G protein-coupled receptor-kinases (GRKs), are also highlighted.

Breast cancer and the renin-angiotensin system (RAS): Therapeutic approaches and related metabolic diseases

The Renin-Angiotensin System (RAS) is classically recognized for regulating blood pressure and fluid balance. Recently, this role has extended to other areas including inflammation, obesity, diabetes, as well as breast cancer. RAS components are expressed in normal and cancerous breast tissues, and downregulation of RAS inhibits metastasis, proliferation, angiogenesis, and desmoplasia in the tumor microenvironment. Therefore, RAS inhibitors (Angiotensin receptor blockers, ARBs, or angiotensin converting enzyme inhibitors, ACE-I) may be beneficial as preventive adjuvant therapies to thwart breast cancer development and improve outcomes, respectively. Given the beneficial effects of RAS inhibitors in metabolic diseases, which often co-exist in breast cancer patients, combining RAS inhibitors with other breast cancer therapies may enhance the effectiveness of current treatments. This review scrutinizes above associations, to advance our understanding of the role of RAS in breast cancer and its potential for repurposing of RAS inhibitors to improve the therapeutic approach for breast cancer patients.

OPALS: A New Osimertinib Adjunctive Treatment of Lung Adenocarcinoma or Glioblastoma Using Five Repurposed Drugs

Background: Pharmacological targeting aberrant activation of epidermal growth factor receptor tyrosine kinase signaling is an established approach to treating lung adenocarcinoma. Osimertinib is a tyrosine kinase approved and effective in treating lung adenocarcinomas that have one of several common activating mutations in epidermal growth factor receptor. The emergence of resistance to osimertinib after a year or two is the rule. We developed a five-drug adjuvant regimen designed to increase osimertinib’s growth inhibition and thereby delay the development of resistance. Areas of Uncertainty: Although the assembled preclinical data is strong, preclinical data and the following clinical trial results can be discrepant. The safety of OPALS drugs when used individually is excellent. We have no data from humans on their tolerability when used as an ensemble. That there is no data from the individual drugs to suspect problematic interaction does not exclude the possibility. Data Sources: All relevant PubMed.org articles on the OPALS drugs and corresponding pathophysiology of lung adenocarcinoma and glioblastoma were reviewed. Therapeutic Opinion: The five drugs of OPALS are in wide use in general medicine for non-oncology indications. OPALS uses the anti-protozoal drug pyrimethamine, the antihistamine cyproheptadine, the antibiotic azithromycin, the antihistamine loratadine, and the potassium sparing diuretic spironolactone. We show how these inexpensive and generically available drugs intersect with and inhibit lung adenocarcinoma growth drive. We also review data showing that both OPALS adjuvant drugs and osimertinib have data showing they may be active in suppressing glioblastoma growth.

Contribution of ADAM17 and related ADAMs in cardiovascular diseases

A disintegrin and metalloproteases (ADAMs) are key mediators of cell signaling by ectodomain shedding of various growth factors, cytokines, receptors and adhesion molecules at the cellular membrane. ADAMs regulate cell proliferation, cell growth, inflammation, and other regular cellular processes. ADAM17, the most extensively studied ADAM family member, is also known as tumor necrosis factor (TNF)-α converting enzyme (TACE). ADAMs-mediated shedding of cytokines such as TNF-α orchestrates immune system or inflammatory cascades and ADAMs-mediated shedding of growth factors causes cell growth or proliferation by transactivation of the growth factor receptors including epidermal growth factor receptor. Therefore, increased ADAMs-mediated shedding can induce inflammation, tissue remodeling and dysfunction associated with various cardiovascular diseases such as hypertension and atherosclerosis, and ADAMs can be a potential therapeutic target in these diseases. In this review, we focus on the role of ADAMs in cardiovascular pathophysiology and cardiovascular diseases. The main aim of this review is to stimulate new interest in this area by highlighting remarkable evidence.

Neuroprotective effects of Ginkgolide B in focal cerebral ischemia through selective activation of prostaglandin E2 receptor EP4 and the downstream transactivation of epidermal growth factor receptor

The present study was undertaken to identify whether prostaglandin E2 receptor is the potential receptor/binding site for Ginkgolide A, Ginkgolide B, Ginkgolide K, and Bilobalide, the four main ingredients of the Ginkgo biloba L., leaves. Using functional assays, we identified EP4, coupled with Gs protein, as a target of Ginkgolide B. In human neuroblastoma SH-SY5Y cells suffered from oxygen-glucose deprivation/reperfusion, Ginkgolide B-activated PKA, Akt, and ERK1/2 as well as Src-mediated transactivation of epidermal growth factor receptor. These resulted in downstream signaling pathways, which enhanced cell survival and inhibited apoptosis. Knockdown of EP4 prevented Ginkgolide B-mediated Src, epidermal growth factor receptor (EGFR), Akt, and ERK1/2 phosphorylation and neuroprotective effects. Moreover, Src inhibitor prevented Ginkgolide B-mediated EGFR transactivation and the downstream Akt and ERK1/2 activation, while the phosphorylation of PKA induced by Ginkgolide B was not affected, indicating Ginkgolide B might transactivate EGFR in a ligand-independent manner. EP4 knockdown in a rat middle cerebral artery occlusion (MCAO) model prevented Ginkgolide B-mediated infarct size reduction and neurological assessment improvement. At the same time, the increased expressions of p-Akt, p-ERK1/2, p-PKA, p-Src, and p-EGFR and the deceased expression of cleaved capases-3 induced by Ginkgolide B in cerebral cortex were blocked due to EP4 knockdown. In conclusion, Ginkgolide B exerts neuroprotective effects in rat MCAO model through the activation of EP4 and the downstream transactivation of EGFR.

The Impact of microRNAs in Renin-Angiotensin-System-Induced Cardiac Remodelling

Current knowledge on the renin-angiotensin system (RAS) indicates its central role in the pathogenesis of cardiovascular remodelling via both hemodynamic alterations and direct growth and the proliferation effects of angiotensin II or aldosterone resulting in the hypertrophy of cardiomyocytes, the proliferation of fibroblasts, and inflammatory immune cell activation. The noncoding regulatory microRNAs has recently emerged as a completely novel approach to the study of the RAS. A growing number of microRNAs serve as mediators and/or regulators of RAS-induced cardiac remodelling by directly targeting RAS enzymes, receptors, signalling molecules, or inhibitors of signalling pathways. Specifically, microRNAs that directly modulate pro-hypertrophic, pro-fibrotic and pro-inflammatory signalling initiated by angiotensin II receptor type 1 (AT1R) stimulation are of particular relevance in mediating the cardiovascular effects of the RAS. The aim of this review is to summarize the current knowledge in the field that is still in the early stage of preclinical investigation with occasionally conflicting reports. Understanding the big picture of microRNAs not only aids in the improved understanding of cardiac response to injury but also leads to better therapeutic strategies utilizing microRNAs as biomarkers, therapeutic agents and pharmacological targets.

Endothelial epidermal growth factor receptor is of minor importance for vascular and renal function and obesity-induced dysfunction in mice

Vascular EGF receptors (EGFR) influence function and structure of arterial vessels. In genetic mouse models we described the role of vascular smooth muscle (VSMC) EGFR for proper physiological function and structure as well as for pathophysiological alterations by obesity or angiotensin II. As the importance of endothelial (EC) EGFR in vivo is unknown, we analyzed the impact of EC-EGFR knockout in a conditional mouse model on vascular and renal function under control condition as well as in obesity and in comparison to VSMC-KO. Heart and lung weight, blood pressure and aortic transcriptome (determined by RNA-seq) were not affected by EC-EGFR-KO. Aortic reactivity to α1-adrenergic stimulation was not affected by EC-EGFR-KO contrary to VSMC-EGFR-KO. Endothelial-induced relaxation was reduced in abdominal aorta of EC-EGFR-KO animals, whereas it was enhanced in VSMC-EGFR-KO animals. Mesenteric arteries of EC-EGFR-KO animals showed enhanced sensitivity to α1-adrenergic stimulation, whereas endothelial-induced relaxation and vessel morphology were not affected. Renal weight, histomorphology, function (albumin excretion, serum creatinine, fractional water excretion) or transcriptome were not affected by EC-EGFR-KO, likewise in VSMC-EGFR-KO. High fat diet (HFD) over 18 weeks induced arterial wall thickening, renal weight increase, creatininemia, renal and aortic transcriptome alterations with a similar pattern in EC-EGFR-WT and EC-EGFR-KO animals by contrast to the previously reported impact of VSMC-EGFR-KO. HFD induced endothelial dysfunction in abdominal aortae of EC-EGFR-WT, which was not additive to the EC-EGFR-KO-induced endothelial dysfunction. As shown before, VSMC-EGFR-KO prevented HFD-induced endothelial dysfunction. HFD-induced albuminuria was less pronounced in EC-EGFR-KO animals and abrogated in VSMC-EGFR-KO animals. Our results indicate that EC-EGFR, in comparison to VSMC-EGFR, is of minor and opposite importance for basal renovascular function as well as for high fat diet-induced vascular remodeling and renal end organ damage.

Signalling mechanisms in the cardiovascular protective effects of estrogen: With a focus on rapid/membrane signalling

In modern society, cardiovascular disease remains the biggest single threat to life, being responsible for approximately one third of worldwide deaths. Male prevalence is significantly higher than that of women until after menopause, when the prevalence of CVD increases in females until it eventually exceeds that of men. Because of the coincidence of CVD prevalence increasing after menopause, the role of estrogen in the cardiovascular system has been intensively researched during the past two decades in vitro, in vivo and in observational studies. Most of these studies suggested that endogenous estrogen confers cardiovascular protective and anti-inflammatory effects. However, clinical studies of the cardioprotective effects of hormone replacement therapies (HRT) not only failed to produce proof of protective effects, but also revealed the potential harm estrogen could cause. The "critical window of hormone therapy" hypothesis affirms that the moment of its administration is essential for positive treatment outcomes, pre-menopause (3-5 years before menopause) and immediately post menopause being thought to be the most appropriate time for intervention. Since many of the cardioprotective effects of estrogen signaling are mediated by effects on the vasculature, this review aims to discuss the effects of estrogen on vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) with a focus on the role of estrogen receptors (ERα, ERβ and GPER) in triggering the more recently discovered rapid, or membrane delimited (non-genomic), signaling cascades that are vital for regulating vascular tone, preventing hypertension and other cardiovascular diseases.