Reduction of stress responses in honey bees by synthetic ligands targeting an allatostatin receptor.

Honey bees are of great economic and ecological importance, but are facing multiple stressors that can jeopardize their pollination efficiency and survival. Therefore, understanding the physiological bases of their stress response may help defining treatments to improve their resilience. We took an original approach to design molecules with this objective.

Upregulated Apelin Signaling in Pancreatic Cancer Activates Oncogenic Signaling Pathways to Promote Tumor Development.

Despite decades of effort in understanding pancreatic ductal adenocarcinoma (PDAC), there is still a lack of innovative targeted therapies for this devastating disease. Herein, we report the expression of apelin and its receptor, APJ, in human pancreatic adenocarcinoma and its protumoral function. Apelin and APJ protein expression in tumor tissues from patients with PDAC and their spatiotemporal pattern of expression in engineered mouse models of PDAC were investigated by immunohistochemistry.

Magneto-mechanical destruction of cancer-associated fibroblasts using ultra-small iron oxide nanoparticles and low frequency rotating magnetic fields.

The destruction of cells using the mechanical activation of magnetic nanoparticles with low-frequency magnetic fields constitutes a recent and interesting approach in cancer therapy. Here, we showed that superparamagnetic iron oxide nanoparticles as small as 6 nm were able to induce the death of pancreatic cancer-associated fibroblasts, chosen as a model. An exhaustive screening of the amplitude, frequency, and type (alternating rotating) of magnetic field demonstrated that the best efficacy was obtained for a rotating low-amplitude low-frequency magnetic field (1 Hz and 40 mT), reaching a 34% ratio in cell death induction; interestingly, the cell death was not maximized for the largest amplitudes of the magnetic field.

GIP receptor: Expression in neuroendocrine tumours, internalization, signalling from endosomes and structure-function relationship studies.

GIP is well known as a peptide regulating metabolic functions. In this review paper, we summarize a series of data on GIP receptor (GIPR). First, expression study of GIPR in human neuroendocrine tumours showed a very high incidence (nearly 100%) and a high density in both functional and non functional pancreatic tumours, ileal tumours, bronchial tumours and medullary thyroid carcinomas.

Understanding Peptide Binding in Class A G Protein-Coupled Receptors.

Many physiologic processes are controlled through the activation of G protein-coupled receptors (GPCRs) by regulatory peptides, making peptide GPCRs particularly useful targets for major human diseases such as diabetes and cancer. Peptide GPCRs are also being evaluated as next-generation targets for the development of novel antiparasite agents and insecticides in veterinary medicine and agriculture. Resolution of crystal structures for several peptide GPCRs has advanced our understanding of peptide-receptor interactions and fueled interest in correlating peptide heterogeneity with receptor-binding properties.

[Internalized receptor for glucose-dependent insulinotropic peptide stimulates adenylyl cyclase on early endosomes].

G-protein coupled receptors represent the largest family of membrane receptors. G-protein dependent signal of GPCR is classically thought to originate exclusively from the plasma membrane and, until very recently, internalized GPCRs were considered silent. At present, experimental proofs exist showing that GPCR can continue to signal via G proteins after internalization.

Combined Treatments of Magnetic Intra-Lysosomal Hyperthermia with Doxorubicin Promotes Synergistic Anti-Tumoral Activity.

Doxorubicin is a cytotoxic drug used for the treatment of many cancer types. However, its significant dose-related adverse effects including cardiotoxicity may hamper its efficiency. Moreover, the multidrug resistance that appears during treatments limits anti-cancer therapies.

Targeted Magnetic Intra-Lysosomal Hyperthermia produces lysosomal reactive oxygen species and causes Caspase-1 dependent cell death.

Therapeutic strategies using drugs which cause Lysosomal Cell Death have been proposed for eradication of resistant cancer cells. In this context, nanotherapy based on Magnetic Intra-Lysosomal Hyperthermia (MILH) generated by magnetic nanoparticles (MNPs) that are grafted with ligands of receptors overexpressed in tumors appears to be a very promising therapeutic option. However, mechanisms whereby MILH induces cell death are still elusive.

Internalized Receptor for Glucose-dependent Insulinotropic Peptide stimulates adenylyl cyclase on early endosomes.

Until very recently, G-protein dependent signal of GPCRs was thought to originate exclusively from the plasma membrane and internalized GPCRs were considered silent. Here, we demonstrated that, once internalized and located in the membrane of early endosomes, glucose-dependent Insulinotropic receptor (GIPR) continues to trigger production of cAMP and PKA activation. Direct evidence is based on identification of the active form of Gαs in early endosomes containing GIPR using a genetically encoded GFP tagged nanobody, and on detection of a distinct FRET signal accounting for cAMP production at the surface of endosomes containing GIP, compared to endosomes without GIP.

Gut hormone GPCRs: structure, function, drug discovery.

Crystallization and determination of the high resolution three-dimensional structure of the β2-adrenergic receptor in 2007 was followed by structure elucidation of a number of other receptors, including those for neurotensin and glucagon. These major advances foster the understanding of structure-activity relationship of these receptors and structure-based rational design of new ligands having more predictable activity. At present, structure determination of gut hormone receptors in complex with their ligands (natural, synthetic) and interacting signalling proteins, for example, G-proteins, arrestins, represents a challenge which promises to revolutionize gut hormone endocrinonology.

Analysis of the interactions of sulfur-containing amino acids in membrane proteins.

The interactions of Met and Cys with other amino acid side chains have received little attention, in contrast to aromatic-aromatic, aromatic-aliphatic or/and aliphatic-aliphatic interactions. Precisely, these are the only amino acids that contain a sulfur atom, which is highly polarizable and, thus, likely to participate in strong Van der Waals interactions. Analysis of the interactions present in membrane protein crystal structures, together with the characterization of their strength in small-molecule model systems at the ab-initio level, predicts that Met-Met interactions are stronger than Met-Cys ≈ Met-Phe ≈ Cys-Phe interactions, stronger than Phe-Phe ≈ Phe-Leu interactions, stronger than the Met-Leu interaction, and stronger than Leu-Leu ≈ Cys-Leu interactions.

Honey Bee Allatostatins Target Galanin/Somatostatin-Like Receptors and Modulate Learning: A Conserved Function?

Sequencing of the honeybee genome revealed many neuropeptides and putative neuropeptide receptors, yet functional characterization of these peptidic systems is scarce. In this study, we focus on allatostatins, which were first identified as inhibitors of juvenile hormone synthesis, but whose role in the adult honey bee (Apis mellifera) brain remains to be determined. We characterize the bee allatostatin system, represented by two families: allatostatin A (Apime-ASTA) and its receptor (Apime-ASTA-R); and C-type allatostatins (Apime-ASTC and Apime-ASTCC) and their common receptor (Apime-ASTC-R).

Internalization and desensitization of the human glucose-dependent-insulinotropic receptor is affected by N-terminal acetylation of the agonist.

How incretins regulate presence of their receptors at the cell surface and their activity is of paramount importance for the development of therapeutic strategies targeting these receptors. We have studied internalization of the human Glucose-Insulinotropic Polypeptide receptor (GIPR). GIP stimulated rapid robust internalization of the GIPR, the major part being directed to lysosomes.

Functional elements of the gastric inhibitory polypeptide receptor: Comparison between secretin- and rhodopsin-like G protein-coupled receptors.

Innovative crystallographic techniques have resulted in an exponential growth in the number of solved G-protein coupled receptor (GPCR) structures and a better understanding of the mechanisms of class A receptor activation and G protein binding. The recent release of the type 1 receptor for the corticotropin-releasing factor and the glucagon receptor structures, two members of the secretin-like family, gives the opportunity to understand these mechanisms of activation in this family of GPCRs. Here, we addressed the comparison of the functional elements of class A and secretin-like GPCRs, using the glucose-dependent insulinotropic polypeptide receptor (GIPR) as a model receptor.

GPCR structure, function, drug discovery and crystallography: report from Academia-Industry International Conference (UK Royal Society) Chicheley Hall, 1-2 September 2014.

G-protein coupled receptors (GPCRs) are the targets of over half of all prescribed drugs today. The UniProt database has records for about 800 proteins classified as GPCRs, but drugs have only been developed against 50 of these. Thus, there is huge potential in terms of the number of targets for new therapies to be designed.

Real-Time Analysis of Magnetic Hyperthermia Experiments on Living Cells under a Confocal Microscope.

Combining high-frequency alternating magnetic fields (AMF) and magnetic nanoparticles (MNPs) is an efficient way to induce biological responses through several approaches: magnetic hyperthermia, drug release, controls of gene expression and neurons, or activation of chemical reactions. So far, these experiments cannot be analyzed in real-time during the AMF application. A miniaturized electromagnet fitting under a confocal microscope is built, which produces an AMF of frequency and amplitude similar to the ones used in magnetic hyperthermia.

The glucose-dependent insulinotropic polypeptide receptor: a novel target for neuroendocrine tumor imaging—first preclinical studies.

Unlabelled: A new family of peptide receptors, the incretin receptor family, overexpressed on many neuroendocrine tumors (NETs) is of great importance because it may enable the in vivo peptide-based receptor targeting of a category of NETs that does not express the somatostatin receptor. Impressive in vivo diagnostic data were published for glucagonlike peptide 1 receptor-targeting radiopeptides. Recently, promising in vitro data have appeared for the second member of the incretin family, the glucose-dependent insulinotropic polypeptide (GIP) receptor.

Targeting a G-protein-coupled receptor overexpressed in endocrine tumors by magnetic nanoparticles to induce cell death.

Nanotherapy using targeted magnetic nanoparticles grafted with peptidic ligands of receptors overexpressed in cancers is a promising therapeutic strategy. However, nanoconjugation of peptides can dramatically affect their properties with respect to receptor recognition, mechanism of internalization, intracellular trafficking, and fate. Furthermore, investigations are needed to better understand the mechanism whereby application of an alternating magnetic field to cells containing targeted nanoparticles induces cell death.

Acting on Hormone Receptors with Minimal Side Effect on Cell Proliferation: A Timely Challenge Illustrated with GLP-1R and GPER.

G protein-coupled receptors (GPCRs) constitute a large family of receptors that sense molecules outside the cell and activate inside signal transduction pathways and cellular responses. GPCR are involved in a wide variety of physiological processes, including in the neuroendocrine system. GPCR are also involved in many diseases and are the target of 30% of marketed medicinal drugs.

Sulfur-containing amino acids in 7TMRs: molecular gears for pharmacology and function.

Seven-transmembrane receptors (7TMRs) mediate the majority of physiological responses to hormones and neurotransmitters in higher organisms. Tertiary structure stability and activation of these versatile membrane proteins require formation or disruption of complex networks of well-recognized interactions (such as H-bonds, ionic, or aromatic-aromatic) but also of other type of interactions which have been less studied. In this review, we compile evidence from crystal structure, biophysical, and site-directed mutagenesis data that indicate or support the importance of interactions involving Met and Cys in 7TMRs in terms of pharmacology and function.

Distinct CCK-2 receptor conformations associated with β-arrestin-2 recruitment or phospholipase-C activation revealed by a biased antagonist.

Seven-transmembrane receptors (7TMRs), also termed G protein-coupled receptors (GPCRs), form the largest class of cell surface membrane receptors, involving several hundred members in the human genome. Nearly 30% of marketed pharmacological agents target 7TMRs. 7TMRs adopt multiple conformations upon agonist binding.

A switch of G protein-coupled receptor binding preference from phosphoinositide 3-kinase (PI3K)-p85 to filamin A negatively controls the PI3K pathway.

Frequent oncogenic alterations occur in the phosphoinositide 3-kinase (PI3K) pathway, urging identification of novel negative controls. We previously reported an original mechanism for restraining PI3K activity, controlled by the somatostatin G protein-coupled receptor (GPCR) sst2 and involving a ligand-regulated interaction between sst2 with the PI3K regulatory p85 subunit. We here identify the scaffolding protein filamin A (FLNA) as a critical player regulating the dynamic of this complex.

Glucose-dependent insulinotropic polypeptide receptors in most gastroenteropancreatic and bronchial neuroendocrine tumors.

Context: Gastrointestinal peptide hormone receptors overexpressed in neuroendocrine tumors (NET), such as somatostatin or glucagon-like peptide-1 (GLP-1) receptors, are used for in vivo tumor targeting. Unfortunately, not all NET express these receptors sufficiently.

Objective: Our aim was to evaluate in vitro the expression of another incretin receptor, glucose-dependent insulinotropic polypeptide (GIP) receptor, in human tumors and compare it with that in adjacent nonneoplastic tissues and also with somatostatin and GLP-1 receptor expression.