Background: Vascular TRPV channels have emerged as important regulators of vascular tone. TRPV1 and endothelin-1 (ET-1) are independently associated with the pathophysiology of coronary vasospasm but the relationship between their vasomotor functions remains unclear. We characterized the vasomotor function of TRPV1 channels in human arterioles and investigated regulation of their vasomotor function by ET-1. Approach: Arterioles were threaded on two metal wires, equilibrated in a physiological buffer at 37 oC and exposed to increasing concentrations of capsaicin in the absence or presence of SB366791 (TRPV1-selective inhibitor) or GF109203X (PKC-selective inhibitor). Some arterioles were preconstricted with ET-1 or phenylephrine or high K+ buffer. TRPV1 mRNA and protein expression in human arteries were assessed. Results: TRPV1 transcripts and proteins were detected in human resistance arteries. Capsaicin (1 µM) induced concentration-dependent constriction of endothelium-intact (35 ± 8 %) and endothelium-denuded (43 ± 11 %) human adipose arterioles (HAA), which was significantly inhibited by SB366791 (0.2 ± 0.1 %). Preconstriction of HAA with ET-1, but not high potassium buffer or phenylephrine, significantly potentiated capsaicin-induced constriction (33 ± 7 % vs 12 ± 8 %). GF109203X significantly inhibited potentiation of capsaicin-induced constriction by ET-1. Conclusion: TRPV1 channels are expressed in the human vasculature and can influence vascular tone of human arterioles upon activation. Their vasomotor function is modulated by ET-1, mediated in part by PKC.. These findings reveal a novel interplay between ET-1 signaling and TRPV1 channels in human VSMC, adding to our understanding of the ion channel mechanisms that regulate human arteriolar tone and may also contribute to the pathophysiology of coronary vasospasm.
The Popeye Domain Containing Protein 1 (POPDC1), a tight junction-associated transmembrane protein with a unique binding site for cAMP, has been shown to act as a tumour suppressor in cancer cells. Through interaction with many downstream effectors and signalling pathways, POPDC1 promotes cell adhesion and inhibits uncontrolled cell proliferation, epithelial-to-mesenchymal transition, and metastasis. However, POPDC1 expression is downregulated in many types of cancer, thereby reducing its tumour-suppressive actions. This review discusses the role of POPDC1 in the progression of the malignant phenotype and highlights the broad range of benefits POPDC1 stabilisation may achieve therapeutically. Cancer stem cells (CSC) are a key hallmark of malignancies and commonly promote treatment resistance. This article provides a comprehensive overview of CSC signalling mechanisms, many of which have been shown to be regulated by POPDC1 in other cell types, thus suggesting an additional therapeutic benefit for POPDC1-stabilising anticancer drugs.
BACKGROUND AND PURPOSE: The α7 and α4β2* (* denotes possibly assembly with another subunit) nicotinic acetylcholine receptors (nAChR) are the most abundant nAChR in the mammalian brain. These subtypes are also the most commonly targeted nAChR in drug discovery programs for brain disorders. However, the development of subtype-specific agonists remains challenging, mainly due to the high degree of sequence homology coupled to the conservation of function in the nAChR family. Here, we determined the structural underpinning of the selectivity of 10-methylcytisine, a compound with high-affinity for α4β2* nAChR but negligible selectivity for the α7 subtype. EXPERIMENTAL APPROACH: The structural underpinning of the receptor selectivity of 10-methylcytisine was investigated using molecular dynamics simulations combined with mutagenesis and whole-cell and single-channel current recordings. KEY RESULTS: We identify a conserved arginine residue in the β3-strand that exhibits a non-conserved salt-bridge in the nAChR family. In α4β2 nAChR, the arginine forms an inter-subunit salt-bridge with an aspartate residue in loop B that is necessary for functional expression, whereas in the α7 subtype, this residue is not stabilised by electrostatic interactions, making its side chain highly mobile. This produces steric clashes with agonists and affects the dynamics of residues involved in agonist binding or the coupling network. CONCLUSIONS AND IMPLICATIONS: We conclude that the high mobility of the arginine residue in the α7 nAChR subtype affects agonist function by influencing agonist binding and the pathway communicating agonist binding to the ion channel. The findings have implications for the rational design of subtype-selective cholinergic agents.
Background and Purpose: Cancer cachexia and cancer-associated thrombosis are potentially fatal outcomes of advanced cancer. Nevertheless, thrombin expression in NSCLC primary tumor tissues and the association between prognosis of NSCLC patients remain largely unknown. Experimental Approach: Clinical pathological analysis was performed to determine the relationship between thrombin and tumor progression. Effect of r-hirudin and DTIP on cancer progression were evaluated. Western blotting, immunohistochemistry, and immunofluorescence were used to explore the inhibition mechanism of r-hirudin and DTIP. Therapeutic effect of combination of DTIP and chemotherapy was determined. Key Results: We illustrated thrombin expression in NSCLC tissues is closely related to clinicopathological features and the prognosis of patients. Thrombin deficiency inhibited tumor progression. The novel thrombin inhibitors, r-hirudin and DTIP, inhibited cell invasion and metastasis in vitro. They inhibited tumor growth and metastasis in orthotopic lung cancer model; inhibited cells invasion and prolonged survival after injection tumor cells via tail vein; they also inhibited angiogenesis and spontaneous metastases from subcutaneously inoculated tumors. The promotional activity of thrombin in invasion and metastasis was abolished in PAR-1 deficient-NSCLC cells. r-hirudin and DTIP inhibit tumor progression through the thrombin-PAR-1-mediated RhoA and NF-κB signaling cascades via inhibiting the MMP9 and IL6 expression. DTIP potentiated chemotherapy-induced growth and metastatic inhibition and inhibited chemotherapy-induced resistance in mice. Conclusions and Implications: Thrombin makes a substantial contribution, together with PAR-1, to NSCLC malignancy. We concluded the anticoagulants, r-hirudin and DTIP, could be expanded for anti-tumor therap. Combination therapy of DTIP and chemotherapy might achieve a better therapeutic effect.
Background and Purpose: Hypertensive vascular remodeling (VR) is responsible for end-organ damage and is the result of increased extracellular matrix accumulation and excessive vascular smooth muscle cell (VSMC) proliferation. MicroRNA-26a (miR-26a), a non-coding small RNA, is involved in multiple cardiovascular diseases. We aimed to validate the effect and mechanisms of miR-26a in hypertensive VR. Experimental Approach: Spontaneously hypertensive rats (SHRs) were injected intravenously with recombinant adeno-associated virus-miR-26a. In vitro experiments, angiotensin II (AngII)-induced VSMCs were transfected with miR-26a mimic or inhibitor. Key Results: We found miR-26a downregulated in the thoracic aorta and plasma of SHRs. Overexpression of miR-26a inhibited extracellular matrix deposition by targeting connective tissue growth factor (CTGF) and mitigated VSMC proliferation by regulating the enhancer of zeste homolog 2 (EZH2)/p21 pathway both in vitro and in vivo. AngII-mediated Smad3 activation suppressed miR-26a expression, which in turn promoted Smad3 activation via targeted regulation of Smad4, leading to further downregulation of miR-26a. Conclusion and Implications: Our study reveals that AngII stimulates a Smads/miR-26a positive feedback loop, which further reduces miR-26a expression, leading to collagen production and VSMC proliferation and consequently, VR. MiR-26a has an antagonistic effect on hypertensive VR and can be a strategy for treating hypertensive VR.
Hyperexcitability-related diseases include epilepsies, pain syndromes, neuromuscular disorders, and cardiac arrhythmias. Sodium channel inhibitors can be used to treat these conditions, however, their applicability is limited by their nonspecific effect on physiological function. They act by channel block (obstructing ion conduction, since the binding site is within the channel pore), and by modulation (delaying recovery from the non-conducting inactivated state). Channel block inhibits healthy and pathological tissue equally, while modulation can preferentially inhibit pathological activity. Therefore, an ideal sodium channel inhibitor drug would act by modulation alone. Unfortunately, thus far no such drug has been known to exist. Here we present evidence that riluzole acts by this “ideal” mechanism, “non-blocking modulation” (NBM). We propose that, being a relatively small molecule, riluzole is able to stay bound to the binding site, but nonetheless stay off the conduction pathway, by residing in one of the “fenestrations” (cavities connecting the central cavity to the membrane phase). Using precisely timed UV pulses to photolabel specific conformations of the channel, we show that association to the local anesthetic binding site requires prior inactivation. We discuss why kinetics of binding is crucial for selective inhibition of pathological activity, and how the NBM mechanism can be recognized using a special voltage- and drug application-protocol. Our results identify riluzole as the prototype of this new class of sodium channel inhibitors. Drugs of this class are expected to selectively prevent hyperexcitability, while having minimal effect on cells firing at a normal rate from a normal resting potential.
Prostate cancer (PCa) is the second most common malignancy in men, and androgen deprivation therapy (ADT) is the first-line therapy. However, most cases will eventually develop into castration-resistant prostate cancer (CRPC) after ADT treatment. Enzalutamide (Enz) is a second-generation androgen receptor inhibitor approved by the Food and Drug Administration to treat patients with CRPC. Unfortunately, patients receiving Enz treatment will ultimately develop resistance via various complicated mechanisms. In this review, we introduce the emerging information on resistance mechanisms, including androgen receptor-related signalling pathways, glucocorticoid receptor-related pathways, and metabolic mechanisms. Notably, lineage plasticity and phenotype switching, gene polymorphisms, and the relationship between microRNAs and drug resistance are addressed. Furthermore, potential therapeutic strategies for Enz-resistant CRPC treatment are suggested, which can help in the discovery of more effective and specific regimens to overcome Enz resistance.
Background and Purpose Coordinated endothelial control of cardiovascular function is proposed to occur by endothelial cell communication via gap junctions and connexins. To study intercellular communication, the pharmacological agents carbenoxolone (CBX) and 18β glycyrrhetinic acid (18βGA) are used widely as connexin inhibitors and gap junction blockers. Experimental Approach We investigated the effects of CBX and 18βGA on IP3-evoked intercellular Ca2+ waves in the endothelium of intact mesenteric resistance arteries. Key Results Acetylcholine (ACh)-evoked IP3-mediated Ca2+ release and propagated waves were inhibited by CBX (100µM) and 18βGA (40µM). Unexpectedly, the Ca2+ signals were inhibited uniformly in all cells, suggesting that CBX and 18βGA reduced Ca2+ release. Localised photolysis of caged IP3 (cIP3) was used to provide precise spatiotemporal control of site of cell activation. Local cIP3 photolysis generated reproducible Ca2+ increases and Ca2+ waves that propagated across cells distant to the photolysis site. CBX and 18βGA each blocked Ca2+ waves in a time dependent manner by inhibiting the initiating IP3-evoked Ca2+ release event rather than block of gap junctions. This effect was reversed on drug washout, and was unaffected by small or intermediate K+-channel blockers. Furthermore, CBX and 18βGA each rapidly and reversibly collapsed the mitochondrial membrane potential. Conclusion and Implications CBX and 18βGA inhibit IP3-mediated Ca2+ release and depolarise the mitochondrial membrane potential. These results suggest that CBX and 18βGA block cell-cell communication by acting at sites that are unrelated to gap junctions.
COVID-19, the illness caused by SARS-CoV-2, has a wide-ranging clinical spectrum that, in the worst-case scenario, involves a rapid progression to severe acute respiratory syndrome and even death. Epidemiological data show that “diabesity”, the association of obesity and diabetes, is among the main risk factors associated with high morbidity and mortality. The increased susceptibility to SARS-CoV-2 infection documented in diabesity argues for initial defects in defense mechanisms, most likely due to an elevated systemic metabolic inflammation (“metaflammation”). The NLRP3 inflammasome is a master regulator of metaflammation and has a pivotal role in the pathophysiology of diabesity. Here we discuss the most recent findings suggesting contribution of NLRP3 inflammasome to the increase in complications in COVID-19 patients with diabesity. We also review current pharmacological strategies for COVID-19, focusing on treatments whose efficacy could be due, at least in part, to interference with the activation of the NLRP3 inflammasome.
Infertility rates for both females and males have increased continuously in recent years. Currently, effective treatments for male infertility with defined mechanisms or targets are still lacking. G protein-coupled receptors (GPCRs) are the largest class of drug targets, but their functions and the implications on therapeutic development for male infertility largely remain elusive. Nevertheless, recent studies have shown that several members of the GPCR superfamily play crucial roles in the maintenance of ion-water homeostasis of the epididymis, development of the efferent ductules, formation of the blood-epididymal barrier, and maturation of sperm. Knowledge of the functions, genetic variations, and working mechanisms of such GPCRs, along with the drugs and ligands relevant to their specific functions, provide future directions and elicit great arsenal for potential therapy development for treating male infertility.
Intense effort is underway to evaluate potential therapeutic agents for the treatment of COVID-19. In order to respond quickly to the crisis, the repurposing of existing drugs is the primary pharmacological strategy. Despite the urgent clinical need for these therapies, it is imperative to consider potential safety issues. This is important due to the harm-benefit ratios that may be encountered when treating COVID-19, which can depend on the stage of the disease, when therapy is administered and underlying clinical factors in individual patients. Treatments are currently being trialled for a range of scenarios from prophylaxis (where benefit must greatly exceed risk) to severe life-threatening disease (where a degree of potential risk may be tolerated if it is exceeded by the potential benefit). In this perspective, we have reviewed some of the most widely-researched repurposed agents in order to identify potential safety considerations using existing information in the context of COVID-19.
In the search to rapidly identify effective therapies that will mitigate the morbidity and mortality of COVID-19, attention has been directed towards the repurposing of existing drugs. Candidates for repurposing include drugs that target COVID-19 pathobiology, including agents that alter angiotensin signaling. Recent data indicate that key findings in COVID-19 patients include thrombosis and endothelitis Activation of PAR1 (protease activated receptor 1), in particular by the protease thrombin, is a critical element in platelet aggregation and coagulation. PAR1 activation also impacts on the actions of other cell types involved in COVID-19 pathobiology, including endothelial cells, fibroblasts and pulmonary alveolar epithelial cells. Vorapaxar is an approved inhibitor of PAR1, used for treatment of patients with myocardial infarction or peripheral arterial disease. Here, we discuss evidence implying a possible beneficial role for vorapaxar in the treatment of COVID-19 patients and in addition, other as-yet non-approved antagonists of PAR1 and PAR4.
Thrombosis contributes to one in four deaths worldwide and is the cause of a large proportion of mortality and morbidity. A reliable and rapid diagnosis of thrombosis will allow for immediate therapy, thereby providing significant benefits to patients. Molecular imaging is a fast-growing and captivating area of research, in both preclinical and clinical applications. Major advances have been achieved by improvements in three central areas of molecular imaging: 1) Better markers for diseases, with increased sensitivity and selectivity; 2) Optimised contrast agents with improved signal to noise ratio; 3) Progress in scanner technologies with higher sensitivity and resolution. Clinically available imaging modalities used for molecular imaging include, magnetic resonance imaging (MRI), X-ray computed tomography (CT), ultrasound, as well as nuclear imaging, such as positron emission tomography (PET) and single photon emission computed tomography (SPECT). In the preclinical imaging field, optical (fluorescence and bioluminescent) molecular imaging has provided new mechanistic insights in the pathology of thrombembolic diseases. Overall, the advances in molecular imaging, driven by the collaboration of various scientific disciplines, have substantially contributed to an improved understanding of thrombotic disease, and raises the exciting prospect of earlier diagnosis and individualised therapy for cardiovascular diseases. As such, these advances hold significant promise to be translated to clinical practice and ultimately to reduce mortality and morbidity in patients with thromboembolic diseases.
Hydrogen sulfide (H2S) together with polysulfides (H2Sn, n>2) are signaling molecules like nitric oxide (NO) with various physiological roles including regulation of neuronal transmission, vascular tone, inflammation, oxygen sensing etc. H2S and H2Sn diffuse to the target proteins to S-sulfurate their cysteine residues to induce the conformational changes to alter the activity. On the other hand, 3-mercaptopyruvate sulfurtransferase transfers sulfur from a substrate 3-mercaptopyruvate to the cysteine residues of acceptor proteins. A similar mechanism has also been identified in S-nitrosylation. S-sulfuration and S-nitrosylation by enzymes proceed only inside the cell, while reactions induced by H2S, H2Sn and NO even extend to the surrounding cells. Disturbance of signaling by these molecules as well as S-sulfuration and S-nitrosylation causes many neuronal diseases. This review focuses on the signaling by H2S and H2Sn with S-sulfuration compared with those of NO and S-nitrosynation, and discuss on their roles in physiology and pathophysiology.
Metabolic pathways have emerged as cornerstones in carcinogenic deregulation providing new therapeutic strategies for cancer management. This is illustrated by the recent discovery of a cholesterol metabolic branch involving the biochemical transformation of 5,6-epoxycholesterol (5,6-ECs). 5,6-ECs have been shown to be differentially metabolized in breast cancers (BC) compared to normal breast tissue. 5,6-ECs are metabolized into the tumour promoter oncosterone in BC, while they are transformed into the tumour suppressor metabolite dendrogenin A (DDA) in normal breast tissue. Blocking oncosterone’s mitogenic and invasive potential will represent new opportunities for BC treatment. The reactivation of DDA biosynthesis, or its use as a drug, represents promising therapeutic approaches such as DDA-deficiency complementation, activation of BC cell re-differentiation and BC chemoprevention. This review presents current knowledge as to the 5,6-EC metabolic pathway in BC focusing on the 5,6-EC metabolic enzymes ChEH and HSD11B2, and on 5,6-EC metabolite targets LXRβ and GR.
Many Western countries have been affected by the outbreak of COVID-19. Italy has been particularly hit at the beginning of the pandemic, immediately after China. In Italy and elsewhere women seem to be less affected then men by severe/fatal COVID-19 infection, regardless of their age. Despite the evidence that women and men are different fort this infection, very few studies consider different therapeutic approaches for the two sexes. Undoubtedly, understanding the mechanisms at the bases of these differences may help to find appropriate and sex specific therapies. Here we consider that other mechanisms but estrogen protection are involved. Several X-linked genes (such as ACE2) and Y-linked genes (SRY, SOX9) may explain sex differences. Cardiovascular comorbidities are among the major enhancers of virus lethality. In addition, the number of sex-independent non-genetic factors that can change susceptibility and mortality is enormous, and many other factors are likely to be considered, including gender and cultural habits in different countries.
COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has overwhelmed Healthcare Systems requiring the rapid development of treatments, at least, to reduce COVID-19 severity. Drug repurposing offers a fast track. Here, we discuss the potential beneficial effects of statins in COVID-19 patients based on evidence that they may target virus receptors, replication, degradation and downstream responses in infected cells, addressing both basic research and epidemiological information. Briefly, statins could act modulating virus entry, acting on the SARS-CoV-2 receptors, ACE2 and CD147, and/or lipid rafts engagement. Statins, by inducing autophagy activation, could regulate virus replication or degradation, exerting protective effects. The well-known anti-inflammatory properties of statins, by blocking several molecular mechanisms, including NF-κB and NLRP3 inflammasome, could limit the “cytokine storm” in severe COVID-19 patients which is linked to fatal outcome. Finally, statin moderation of coagulation response activation may also contribute to improve COVID-19 outcomes.
Background and Purpose: Although human blood flows are redistributed into the mesenteric circulation after meals, it is not well understood how postprandial nutrients induces vasorelaxation of mesenteric micro-arterioles and whether this process is involved in the pathogenesis of colitis. Experimental Approach: We used an auto dual wire myograph system, fluorescence imaging system and DSS-induced colitis mouse model to investigate the roles and mechanisms of nutrient-induced mesenteric relaxation in health and disease. Key Results: We found that acute application of glucose and sodium induced endothelium-dependent relaxation of human and mouse mesenteric micro-arterioles via a hyperosmotic action, which also stimulated Ca2+ influx through endothelial TRPV1 channels. The nutrient-induced vasorelaxation was almost abolished by selective blockers for TRPV1, IKCa and SKCa channels, but marginally altered by inhibition of nitric oxide production. The nutrient-induced hyperosmosis also activated functional activities of Na+/K+-ATPase and Na+/Ca2+-exchanger to further reduce [Ca2+]i in vascular smooth muscle cells. Moreover, hyperosmosis-induced endothelium-dependent hyperpolarization was significantly impaired in colitis mouse model. Conclusion and Implications: Our study provides the first evidence that nutrient-induced hyperosmosis stimulates endothelial TRPV1/Ca2+/EDH signaling pathway to eventually evoke vasorelaxation of mesenteric micro-arterioles, which may contribute to the pathogenesis of colitis as well.