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Background and Purpose: Specific cellular functions mediated by GPCRs are often associated with signalling through a particular G protein or β‐arrestin. Here, we examine signalling through a GPCR, protease‐activated receptor 2 (PAR2), in a high‐grade serous ovarian cancer cell line (OV90). Experimental Approach Human ovarian cancer tissues (n = 1,200) and nine human ovarian cancer cell lines were assessed for PAR2 expression. PAR2 signalling mechanisms leading to cell migration and invasion were dissected using cellular assays, western blots, CRISPR‐Cas9 gene knockouts, pharmacological inhibitors of PAR2 and downstream signalling proteins in OV90 cancer cells. Key Results: PAR2 was significantly overexpressed in clinical ovarian cancer tissues and in OV90 ovarian cancer cells. PAR2 agonists, an endogenous protease (trypsin) and a synthetic peptide (2f‐LIGRL‐NH2), induced migration and invasion of OV90 ovarian cancer cells through activating a combination of Gαq/11, Gα12/13 and β‐arrestin1/2, but not Gαs or Gαi. This novel cooperative rather than parallel signalling resulted in downstream serial activation of Src kinases, then transactivation of epidermal growth factor receptor (EGFR), followed by downstream MEK–ERK1/2–FOS/MYC/STAT3–COX2 signalling. Either a PAR2 antagonist (I‐191), CRISPR‐Cas9 gene knockouts (PAR2 or Gα proteins or β‐arrestin1/2), or inhibitors of each downstream protein attenuated human ovarian cancer cell motility. Conclusion and Implications: This study highlights a novel shared signalling cascade, requiring each of Gαq/11, Gα12/13 and β‐arrestin1/2 for PAR2‐induced ovarian cancer cell migration and invasion. This mechanism controlling a cellular function is unusual in not being linked to a specific individual G protein or β‐arrestin‐mediated signalling pathway. [ABSTRACT FROM AUTHOR]

Background and Purpose Experimental Approach Key Results Conclusion and Implications Most inhibitors of histone deacetylases (HDACs) are not selective and are cytotoxic. Some have anti‐inflammatory activity in disease models, but cytotoxicity prevents long‐term uses in non‐fatal diseases. Inhibitors selective for class IIa HDACs are much less cytotoxic and may have applications in management of chronic inflammatory diseases.LL87 is a novel HDAC inhibitor examined here for HDAC enzyme selectivity. It was also investigated in macrophages for cytotoxicity and for inhibition of lipopolysaccharide (LPS)‐stimulated cytokine secretion. In a rat model of collagen‐induced arthritis, LL87 was investigated for effects on joint inflammation in Dark Agouti rats. Histological, immunohistochemical, micro‐computed tomography and molecular analyses characterise developing arthritis and anti‐inflammatory efficacy.LL87 was significantly more inhibitory against class IIa than class I or IIb HDAC enzymes. In macrophages, LL87 was not cytotoxic and reduced both LPS‐induced secretion of pro‐inflammatory cytokines, and IL6‐induced class IIa HDAC activity. In rats, LL87 attenuated paw swelling and clinical signs of arthritis, reducing collagen loss and histological damage in ankle joints. LL87 decreased immune cell infiltration, especially pro‐inflammatory macrophages and osteoclasts, into synovial joints and significantly reduced expression of pro‐inflammatory cytokines and tissue‐degrading proteases.A novel inhibitor of class IIa HDACs has been shown to have an anti‐inflammatory and anti‐arthritic profile distinct from current therapies. It is efficacious in reducing macrophage infiltration and joint inflammation in a chronic model of rat arthritis. [ABSTRACT FROM AUTHOR]

Aromatic groups are key mediators of protein–membrane association at cell surfaces, contributing to hydrophobic effects and π‐membrane interactions. Here we show electrostatic and hydrophobic influences of aromatic ring substituents on membrane affinity and cell uptake of helical, cyclic and cell penetrating peptides. Hydrophobicity is important, but subtle changes in electrostatic surface potential, dipoles and polarizability also enhance association with phospholipid membranes and cell uptake. A combination of fluorine and sulfur substituents on an aromatic ring induces microdipoles that enhance cell uptake of 12‐residue peptide inhibitors of p53‐HDM2 interaction and of cell‐penetrating cyclic peptides. These aromatic motifs can be readily inserted into peptide sidechains to enhance their cell uptake. [ABSTRACT FROM AUTHOR]

Aromatic groups are key mediators of protein–membrane association at cell surfaces, contributing to hydrophobic effects and π‐membrane interactions. Here we show electrostatic and hydrophobic influences of aromatic ring substituents on membrane affinity and cell uptake of helical, cyclic and cell penetrating peptides. Hydrophobicity is important, but subtle changes in electrostatic surface potential, dipoles and polarizability also enhance association with phospholipid membranes and cell uptake. A combination of fluorine and sulfur substituents on an aromatic ring induces microdipoles that enhance cell uptake of 12‐residue peptide inhibitors of p53‐HDM2 interaction and of cell‐penetrating cyclic peptides. These aromatic motifs can be readily inserted into peptide sidechains to enhance their cell uptake. [ABSTRACT FROM AUTHOR]

[Display omitted] Limacodidae is a family of lepidopteran insects comprising >1500 species. More than half of these species produce pain-inducing defensive venoms in the larval stage, but little is known about their venom toxins. Recently, we characterised proteinaceous toxins from the Australian limacodid caterpillar Doratifera vulnerans , but it is unknown if the venom of this species is typical of other Limacodidae. Here, we use single animal transcriptomics and venom proteomics to investigate the venom of an iconic limacodid, the North American saddleback caterpillar Acharia stimulea. We identified 65 venom polypeptides, grouped into 31 different families. Neurohormones, knottins, and homologues of the immune signaller Diedel make up the majority of A. stimulea venom, indicating strong similarities to D. vulnerans venom, despite the large geographic separation of these caterpillars. One notable difference is the presence of RF-amide peptide toxins in A. stimulea venom. Synthetic versions of one of these RF-amide toxins potently activated the human neuropeptide FF1 receptor, displayed insecticidal activity when injected into Drosophila melanogaster , and moderately inhibited larval development of the parasitic nematode Haemonchus contortus. This study provides insights into the evolution and activity of venom toxins in Limacodidae, and provides a platform for future structure-function characterisation of A. stimulea peptide toxins. [ABSTRACT FROM AUTHOR]

An alpha helical turn can be reproduced in a cyclic pentapeptide if the first and fifth amino acid sidechains are correctly joined. Here structural studies (CD, NMR, in silico) reveal why N-methylation at positions not involved in hydrogen bonds disrupts helicity whereas ester bonds can maintain helicity and promote greater cell uptake. [ABSTRACT FROM AUTHOR]

Activation of protease activated receptor 2 (PAR2) has been implicated in inflammatory and metabolic disorders and its inhibition may yield novel therapeutics. Here, we report a series of PAR2 antagonists based on C-terminal capping of 5-isoxazolyl- l -cyclohexylalanine- l -isoleucine, with benzylamine analogues being effective new PAR2 antagonists. 5-Isoxazolyl- l -cyclohexylalanine- l -isoleucine-2-methoxybenzylamine ( 10 ) inhibited PAR2-, but not PAR1-, induced release of Ca 2+ (IC 50 0.5 μM) in human colon cells, IL-6 and TNFα secretion (IC 50 1–5 μM) from human kidney cells, and was anti-inflammatory in acute rat paw inflammation (ED 50 5 mg/kg sc). These findings show that new benzylamide antagonists of PAR2 have anti-inflammatory activity. [ABSTRACT FROM AUTHOR]

Background and Purpose: Histone deacetylases (HDACs) silence genes by deacetylating lysine residues in histones and other proteins. HDAC inhibitors represent a new class of compounds with anti-inflammatory activity. This study investigated whether treatment with a broad spectrum HDAC inhibitor, suberoylanilide hydroxamic acid (SAHA), would prevent cardiac fibrosis, part of the cardiovascular remodelling in deoxycorticosterone acetate (DOCA)-salt rats.Experimental Approach: Control and DOCA-salt rats were treated with SAHA (25 mg x kg(-1) x day(-1) s.c.) for 32 days. Changes in cardiovascular structure and function were assessed by blood pressure in vivo and in Langendorff perfused hearts, ventricular papillary muscle and in aortic rings in vitro. Left ventricular collagen deposition was assessed by histology.Key Results: Administration of SAHA to DOCA-salt rats attenuated the following parameters: the increased concentration of over 20 pro-inflammatory cytokines in plasma, increased inflammatory cell infiltration and interstitial collagen deposition, increased passive diastolic stiffness in perfused hearts, prolongation of action potential duration at 20% and 90% of repolarization in papillary muscle, development of left ventricular hypertrophy, systolic hypertension and changes in vascular dysfunction.Conclusions and Implications: The HDAC inhibitor, SAHA, attenuated the cardiovascular remodelling associated with DOCA-salt hypertensive rats and improved cardiovascular structure and function, especially fibrosis, in the heart and blood vessels, possibly by suppressing inflammation. Control of cardiac histone or non-histone protein acetylation is a potential therapeutic approach to preventing cardiac remodelling, especially cardiac fibrosis. [ABSTRACT FROM AUTHOR]

Protease-activated receptor-2 (PAR2) has been implicated in multiple pathophysiologies but drug discovery is challenging due to low small molecule tractability and a complex activation mechanism. Here we report the pharmacological profiling of a potent new agonist, suggested by molecular modelling to bind in the putative orthosteric site, and two novel PAR2 antagonists with distinctly different mechanisms of inhibition. We identify coupling between different PAR2 binding sites. One antagonist is a competitive inhibitor that binds to the orthosteric site, while a second antagonist is a negative allosteric modulator that binds at a remote site. The allosteric modulator shows probe dependence, more effectively inhibiting peptide than protease activation of PAR2 signalling. Importantly, both antagonists are active in vivo, inhibiting PAR2 agonist-induced acute paw inflammation in rats and preventing activation of mast cells and neutrophils. These results highlight two distinct mechanisms of inhibition that potentially could be targeted for future development of drugs that modulate PAR2. Kennedy et al. report the pharmacological and in vivo profiling of two small molecule PAR2 inhibitors and an agonist. They conclude that while the small molecule agonist and one of the inhibitors bind to the orthosteric PAR2 binding site, the other inhibitor is a negative allosteric modulator, highlighting two distinct mechanisms of inhibition that could be targeted for future development of drugs that modulate PAR2. [ABSTRACT FROM AUTHOR]

TheG-protein coupled receptor (C3aR) for human inflammatory proteincomplement C3a is an important component of immune, inflammatory,and metabolic diseases. A flexible compound (N2-[(2,2-diphenylethoxy)acetyl]-l-arginine, 4), known as a weak C3aR antagonist(IC50μM), was transformed here into potent agonists(EC50nM) of human macrophages (Ca2+releasein HMDM) by incorporating aromatic heterocycles. Antagonists werealso identified. A linear correlation between binding affinity forC3aR and calculated hydrogen-bond interaction energy of the heteroatomindicated that its hydrogen-bonding capacity influenced ligand affinityand function mediated by C3aR. Hydrogen-bond accepting heterocycles(e.g., imidazole) conferred the highest affinity and agonist potency(e.g., 21, EC5024 nM, Ca2+, HMDM)with comparable efficacy and immunostimulatory activity as that ofC3a in activating human macrophages (Ca2+, IL1β,TNFα, CCL3). These potent and selective modulators of C3aR,inactivated by a C3aR antagonist, are stable C3a surrogates for interrogatingroles for C3aR in physiology and disease. [ABSTRACT FROM AUTHOR]

Obesity, type 2 diabetes, and cardiovascular disease correlate with infiltration to adipose tissue of different immune cells, with uncertain influences on metabolism. Rats were fed a diet high in carbohydrates and saturated fats to develop diet-induced obesity over 16 weeks. This nutritional overload caused overexpression and secretion of phospholipase A(2) group IIA (pla2g2a) from immune cells in adipose tissue rather than adipocytes, whereas expression of adipose-specific phospholipase A(2) (pla2g16) was unchanged. These immune cells produce prostaglandin E(2) (PGE(2)), which influences adipocyte signaling. We found that a selective inhibitor of human pla2g2a (5-(4-benzyloxyphenyl)-(4S)-(phenyl-heptanoylamino)-pentanoic acid [KH064]) attenuated secretion of PGE(2) from human immune cells stimulated with the fatty acid, palmitic acid, or with lipopolysaccharide. Oral administration of KH064 (5 mg/kg/day) to rats fed the high-carbohydrate, high-fat diet prevented the overexpression of pla2g2a and the increased macrophage infiltration and elevated PGE(2) concentrations in adipose tissue. The treatment also attenuated visceral adiposity and reversed most characteristics of metabolic syndrome, producing marked improvements in insulin sensitivity, glucose intolerance, and cardiovascular abnormalities. We suggest that pla2g2a may have a causal relationship with chronic adiposity and metabolic syndrome and that its inhibition in vivo may be a valuable new approach to treat obesity, type 2 diabetes, and metabolic dysfunction in humans. [ABSTRACT FROM AUTHOR]