D-Arg0-Bradykinin-Arg-Arg, a Latent Vasoactive Bradykinin B2 Receptor Agonist Metabolically Activated by Carboxypeptidases

MiR-29b-3p affects growth and biological functions of human extravillous trophoblast cells by regulating bradykinin B2 receptor

INTRODUCTION

This study investigated miR-29b-3p's effects and mechanisms in preeclampsia development.

MATERIAL AND METHODS

In this study, we analysed the pathology and expression of miR-29b-3p and B2R mRNA from normal and preeclampsia placenta tissues using hematoxylin and eosin staining and RT-qPCR assay. For cell experiments, we used transwell assay CCK-8, flow cytometry and wound healing assay to determine the effects and correlation of miR-29b-3p and B2R in HTR-8/SVneo cell proliferation, apoptosis, cell cycle, cell invasion and migration in a preeclampsia cell model. Moreover, the mechanisms were determined using Western blot or immunofluorescence in different groups.

RESULTS

Clinical analysis revealed that miR-29b-3p gene expression dramatically increased with increasing degree of preeclampsia (p < 0.001 or p < 0.05, respectively). The HTR-8/SVneo cell biological activities of the model group were significantly depressed (p < 0.001). However, with miR-29b-3p inhibitor or B2R transfection, the HTR-8/SVneo cell biological activities significantly recovered (p < 0.001). Western blot assay showed that B2R, VEGF-A, CCND-1, MMP-2 and MMP-9 levels were suppressed in the model group, compared with those in the NC groups (p < 0.001, respectively). With miR-29b-3p inhibitor or B2R transfection, the protein expression levels of B2R, VEGF-A, CCND-1, MMP-2 and MMP-9 dramatically increased (p < 0.001, respectively).

CONCLUSIONS

The down-regulation of miR-29b-3p could improve HTR-8/SVneo cell biological activities in a preeclampsia cell model by targeting B2R.

A Robust Bioassay of the Human Bradykinin B2 Receptor that Extends Molecular and Cellular Studies: The Isolated Umbilical Vein

Bradykinin (BK) has various physiological and pathological roles. Medicinal chemistry efforts targeted toward the widely expressed BK B₂ receptor (B₂R), a G-protein-coupled receptor, were primarily aimed at developing antagonists. The only B₂R antagonist in clinical use is the peptide icatibant, approved to abort attacks of hereditary angioedema. However, the anti-inflammatory applications of B₂R antagonists are potentially wider. Furthermore, the B₂R antagonists notoriously exhibit species-specific pharmacological profiles. Classical smooth muscle contractility assays are exploited over a time scale of several hours and support determining potency, competitiveness, residual agonist activity, specificity, and reversibility of pharmacological agents. The contractility assay based on the isolated human umbilical vein, expressing B₂R at physiological density, was introduced when investigating the first non-peptide B₂R antagonist (WIN 64338). Small ligand molecules characterized using the assay include the exquisitely potent competitive antagonist, Pharvaris Compound 3 or the partial agonist Fujisawa Compound 47a. The umbilical vein assay is also useful to verify pharmacologic properties of special peptide B₂R ligands, such as the carboxypeptidase-activated latent agonists and fluorescent probes. Furthermore, the proposed agonist effect of tissue kallikrein on the B₂R has been disproved using the vein. This assay stands in between cellular and molecular pharmacology and in vivo studies.

In Vitro Modeling of Bradykinin-Mediated Angioedema States

Kinins (peptides related to bradykinin, BK) are formed from circulating substrates, the kininogens, by the action of two proteases, the kallikreins. The only clinical application of a BK receptor ligand, the B₂ receptor antagonist icatibant, is the treatment of the rare hereditary angioedema (HAE) caused by the deficiency of C1-esterase inhibitor (C1-INH). Less common forms of HAE (genetic variants of factor XII, plasminogen, kininogen) are presumably mediated by increased BK formation. Acquired forms of BK-mediated angioedema, such as that associated with angiotensin-I converting enzyme (ACE) inhibition, are also known. Antibody-based analytical techniques are briefly reviewed, and support that kinins are extremely short-lived, prominently cleared by ACE. Despite evidence of continuous activation of the kallikrein–kinin system in HAE, patients are not symptomatic most of the time and their blood or plasma obtained during remission does not generate excessive immunoreactive BK (iBK), suggesting effective homeostatic mechanisms. HAE-C1-INH and HAE-FXII plasmas are both hyperresponsive to fibrinolysis activation. On another hand, we suggested a role for the alternate tissue kallikrein–kinin system in patients with a plasminogen mutation. The role of the BK B₁ receptor is still uncertain in angioedema states. iBK profiles under in vitro stimulation provide fresh insight into the physiopathology of angioedema.

In silico analysis and identification of promising hits against 2019 novel coronavirus 3C-like main protease enzyme

The recent outbreak of the 2019 novel coronavirus disease (COVID-19) has been proved as a global threat. No particular drug or vaccine has not yet been discovered which may act specifically against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and causes COVID-19. For this highly infectious virus, 3CL-like main protease (3CL^pro) plays a key role in the virus life cycle and can be considered as a pivotal drug target. Structure-based virtual screening of DrugBank database resulted in 20 hits against 3CL^pro. Atomistic 100 ns molecular dynamics of five top hits and binding energy calculation analyses were performed for main protease-hit complexes. Among the top five hits, Nafarelin and Icatibant affirmed the binding energy (g_MMPBSA) of -712.94 kJ/mol and -851.74 kJ/mol, respectively. Based on binding energy and stability of protein-ligand complex; the present work reports these two drug-like hits against SARS-CoV-2 main protease.Communicated by Ramaswamy H. Sarma.

Bradykinin receptors: Agonists, antagonists, expression, signaling, and adaptation to sustained stimulation

Bradykinin-related peptides, the kinins, are blood-derived peptides that stimulate 2 G protein-coupled receptors, the B1 and B2 receptors (B1R, B2R). The pharmacologic and molecular identities of these 2 receptor subtypes will be succinctly reviewed herein, with emphasis on drug development, receptor expression, signaling, and adaptation to persistent stimulation. Peptide and non-peptide antagonists and fluorescent ligands have been produced for each receptor. The B2R is widely and constitutively expressed in mammalian tissues, whereas the B1R is mostly inducible under the effect of cytokines during infection and immunopathology. The B2R is temporarily desensitized by a cycle of phosphorylation/endocytosis followed by recycling, whereas the nonphosphorylable B1R is relatively resistant to desensitization and translocated to caveolae on activation. Both receptor subtypes, mainly coupled to protein G Gq, phospholipase C and calcium signaling, mediate the vascular aspects of inflammation (vasodilation, edema formation). On this basis, icatibant, a peptide antagonist of the B2R, is approved in the management of hereditary angioedema attacks. This disease is the therapeutic showcase of the kallikrein-kinin system, with an orally bioavailable B2R antagonist under development, as well as other agents that inhibit the kinin forming protease, plasma kallikrein. Other clinical applications are still elusive despite the maturity of the medicinal chemistry efforts applied to kinin receptors.

Bifunctional ligands of the bradykinin B2 and B1 receptors: An exercise in peptide hormone plasticity

Kinins are the small and fragile hydrophilic peptides related to bradykinin (BK) and derived from circulating kininogens via the action of kallikreins. Kinins bind to the preformed and widely distributed B₂ receptor (B₂R) and to the inducible B₁ receptor (B₁R). B₂Rs and B₁Rs are related G protein coupled receptors that possess natural agonist ligands of nanomolar affinity (BK and Lys BK for B₂Rs, Lys-des-Arg⁹-BK for B₁R). Decades of structure-activity exploration have resulted in the production of peptide analogs that are antagonists, one of which is clinically used (the B₂R antagonist icatibant), and also non-peptide ligands for both receptor subtypes. The modification of kinin receptor ligands has made them resistant to extracellular or endosomal peptidases and/or produced bifunctional ligands, defined as agonist or antagonist peptide ligands conjugated with a chemical fluorophore (emitting in the whole spectrum, from the infrared to the ultraviolet), a drug-like moiety, an epitope, an isotope chelator/carrier, a cleavable sequence (thus forming a pro-drug) and even a fused protein. Dual molecular targets for specific modified peptides may be a source of side effects or of medically exploitable benefits. Biotechnological protein ligands for either receptor subtype have been produced: they are enhanced green fluorescent protein or the engineered peroxidase APEX2 fused to an agonist kinin sequence at their C-terminal terminus. Antibodies endowed with pharmacological actions (agonist, antagonist) at B₂R have been reported, though not monoclonal antibodies. These findings define classes of alternative ligands of the kinin receptor of potential therapeutic and diagnostic value.