scholarly journals Ghrelin Octanoylation Is Completely Stabilized in Biological Samples by Alkyl Fluorophosphonates

Endocrinology ◽  
2016 ◽  
Vol 157 (11) ◽  
pp. 4330-4338 ◽  
Author(s):  
Kayleigh R. McGovern-Gooch ◽  
Trevor Rodrigues ◽  
Joseph E. Darling ◽  
Michelle A. Sieburg ◽  
Alfonso Abizaid ◽  
...  
Keyword(s):  
Blood Serum ◽  
Biological Samples ◽  
Energy Homeostasis ◽  
Peptide Hormone ◽  
Microsomal Protein ◽  
Ghrelin Concentration ◽  
Acyltransferase Activity ◽  
Desacyl Ghrelin

Ghrelin is a peptide hormone involved in multiple physiological processes related to energy homeostasis. This hormone features a unique posttranslational serine octanoylation modification catalyzed by the enzyme ghrelin O-acyltransferase, with serine octanoylation essential for ghrelin to bind and activate its cognate receptor. Ghrelin deacylation rapidly occurs in circulation, with both ghrelin and desacyl ghrelin playing important roles in biological signaling. Understanding the regulation and physiological impact of ghrelin signaling requires the ability to rapidly protect ghrelin from deacylation in biological samples such as blood serum or cell lysates to preserve the relative concentrations of ghrelin and desacyl ghrelin. In in vitro ghrelin O-acyltransferase activity assays using insect microsomal protein fractions and mammalian cell lysate and blood serum, we demonstrate that alkyl fluorophosphonate treatment provides rapid, complete, and long-lasting protection of ghrelin acylation against serine ester hydrolysis without interference in enzyme assay or ELISA analysis. Our results support alkyl fluorophosphonate treatment as a general tool for stabilizing ghrelin and improving measurement of ghrelin and desacyl ghrelin concentrations in biochemical and clinical investigations and suggest current estimates for active ghrelin concentration and the ghrelin to desacyl ghrelin ratio in circulation may underestimate in vivo conditions.

Traceable Peptidic Ligands that Target Ghrelin Receptors

2020 ◽  
Vol 21 (10) ◽  
pp. 955-964 ◽  
Author(s):  
Mengjie Liu ◽  
John Wade ◽  
Mohammed Akhter Hossain
Keyword(s):  
In Vivo Imaging ◽  
Peptide Hormone ◽  
Structural Features ◽  
Pharmacological Properties ◽  
Imaging Studies ◽  
Cognate Receptor ◽  
Ghrelin Receptors ◽  
Biochemical Research

: Ghrelin is a 28-amino acid octanoylated peptide hormone that is implicated in many physiological and pathophysiological processes. Specific visualization of ghrelin and its cognate receptor using traceable ligands is crucial in elucidating the localization, functions, and expression pattern of the peptide’s signaling pathway. Here 12 representative radio- and fluorescently-labeled peptide-based ligands are reviewed for in vitro and in vivo imaging studies. In particular, the focus is on their structural features, pharmacological properties, and applications in further biochemical research.

scholarly journals Development of a Topical Insulin Polymeric Nanoformulation for Skin Burn Regeneration: An Experimental Approach

2021 ◽  
Vol 22 (8) ◽  
pp. 4087
Author(s):  
Maria Quitério ◽  
Sandra Simões ◽  
Andreia Ascenso ◽  
Manuela Carvalheiro ◽  
Ana Paula Leandro ◽  
...  
Keyword(s):  
Wound Healing ◽  
Healing Process ◽  
In Vitro Release ◽  
Peptide Hormone ◽  
Plga Nanoparticles ◽  
Wound Healing Process ◽  
Target Area ◽  
Encapsulation Process

Insulin is a peptide hormone with many physiological functions, besides its use in diabetes treatment. An important role of insulin is related to the wound healing process—however, insulin itself is too sensitive to the external environment requiring the protective of a nanocarrier. Polymer-based nanoparticles can protect, deliver, and retain the protein in the target area. This study aims to produce and characterize a topical treatment for wound healing consisting of insulin-loaded poly-DL-lactide/glycolide (PLGA) nanoparticles. Insulin-loaded nanoparticles present a mean size of approximately 500 nm and neutral surface charge. Spherical shaped nanoparticles are observed by scanning electron microscopy and confirmed by atomic force microscopy. SDS-PAGE and circular dichroism analysis demonstrated that insulin preserved its integrity and secondary structure after the encapsulation process. In vitro release studies suggested a controlled release profile. Safety of the formulation was confirmed using cell lines, and cell viability was concentration and time-dependent. Preliminary safety in vivo assays also revealed promising results.

MAPPING IN VITRO AND IN VIVO DERIVED CYP2C9 AND CYP2C19 ONTOGENY FUNCTIONS: A CRITICAL COMPARISON BETWEEN VARIOUS ONTOGENY MODELS

2015 ◽  
Vol 101 (1) ◽  
pp. e1.38-e1 ◽  
Author(s):  
Farzaneh Salem ◽  
Trevor Johnson ◽  
Amin Rostami-Hodjegan
Keyword(s):  
Literature Review ◽  
Microsomal Protein ◽  
Critical Comparison ◽  
Physiologically Based Pharmacokinetic ◽  
Age Related ◽  
Physiologically Based ◽  
Age Range ◽  
Best Fit

In vivo derived ontogeny profiles for CYP1A2 and CYP3A4, show improved clearance (CL) predictions within a paediatric physiologically based pharmacokinetic (p-PBPK) model1. The aim of this study is to derive ontogeny functions (OF) for CYP2C9 and CYP2C19 based on age related CL data on ibuprofen and pantoprazole & lansoprazole, respectively.A literature review was undertaken to collect age related CL data for these probes, the values were deconvoluted back to intrinsic CL values (per mg of liver microsomal protein) as described previously. The 'best-fit' algorithm for ratio of paediatric to mean adult intrinsic CL with age was determined in Graphpad Prism5 to obtain in vivo OF for CYP2C9 and CYP2C19. These were compared for performance with previously established ‘in vitro' OF in Simcyp Paediatric simulator (v14) using validation datasets.CYP2C9 and CYP2C19 enzyme activities showed an increase with age to values higher than adults by ages 2 and 1 month respectively, maximum values were reached at 1.5 years and 6 months, respectively before declining to typical adult levels by around 25 years.The CYP2C9 in vivo derived OF led to improved predictions of diclofenac and S-Warfarin CL compared to in vitro derived OF across the age range. For CYP2C19 there is a dearth of suitable validation compounds due to lack of clinical data with a possibility of using omeprazole or voriconazole. The reasons for discrepancy between in vitro and in vivo derived OF require further investigation.

Selective amylin inhibition of the glucagon response to arginine is extrinsic to the pancreas

2001 ◽  
Vol 280 (3) ◽  
pp. E443-E449 ◽  
Author(s):  
R. A. Silvestre ◽  
J. Rodrı́guez-Gallardo ◽  
C. Jodka ◽  
D. G. Parkes ◽  
R. A. Pittner ◽  
...  
Keyword(s):  
Glucagon Secretion ◽  
Peptide Hormone ◽  
Β Cells ◽  
Perfused Rat Pancreas ◽  
Anesthetized Rats ◽  
Isolated Pancreas ◽  
Glucagon Suppression ◽  
Insulin Secretion In Vitro

Amylin, a peptide hormone from pancreatic β-cells, is reported to inhibit insulin secretion in vitro and in vivo and to inhibit nutrient-stimulated glucagon secretion in vivo. However, it has been reported not to affect arginine-stimulated glucagon secretion in vitro. To resolve if the latter resulted from inactive peptide (a problem in the early literature), those experiments were repeated here with well-characterized peptide and found to be valid. In isolated perfused rat pancreas preparations, coperfusion with 1 nM amylin had no effect on arginine-, carbachol-, or vasoactive intestinal peptide-stimulated glucagon secretion. Amylin also had no effect on glucagon output stimulated by decreasing glucose concentration from 11 to 3.2 mM or on glucagon suppression caused by increasing glucose from 3.2 to 7 mM. Amylin at 100 nM had no effect in isolated islets in which glucagon secretion was stimulated by exposure to 10 mM arginine, even though glucagon secretion in the same preparation was inhibited by somatostatin. In anesthetized rats, amylin coinfusion had no effect on glucagon secretion stimulated by insulin-induced hypoglycemia. To reconcile reports of glucagon inhibition with the absence of effect in the experiments just described, anesthetized rats coinfused with rat amylin or with saline were exposed sequentially to intravenous l-arginine (during a euglycemic clamp) and then to hypoglycemia. Amylin inhibited arginine-induced, but not hypoglycemia-induced, glucagon secretion in the same animal. In conclusion, we newly identify a selective glucagonostatic effect of amylin that appears to be extrinsic to the isolated pancreas and may be centrally mediated.

scholarly journals Kidney-specific genetic deletion of both AMPK α-subunits causes salt and water wasting

2017 ◽  
Vol 312 (2) ◽  
pp. F352-F365 ◽  
Author(s):  
Yoskaly Lazo-Fernández ◽  
Goretti Baile ◽  
Patricia Meade ◽  
Pilar Torcal ◽  
Laura Martínez ◽  
...  
Keyword(s):  
Energy Homeostasis ◽  
Extracellular Volume ◽  
Atp Synthesis ◽  
Renal Handling ◽  
Salt Wasting ◽  
Cell Energy ◽  
Ampk Activity ◽  
Genetic Deletion

AMP-activated kinase (AMPK) controls cell energy homeostasis by modulating ATP synthesis and expenditure. In vitro studies have suggested AMPK may also control key elements of renal epithelial electrolyte transport but in vivo physiological confirmation is still insufficient. We studied sodium renal handling and extracellular volume regulation in mice with genetic deletion of AMPK catalytic subunits. AMPKα1 knockout (KO) mice exhibit normal renal sodium handling and a moderate antidiuretic state. This is accompanied by higher urinary aldosterone excretion rates and reduced blood pressure. Plasma volume, however, was found to be increased compared with wild-type mice. Thus blood volume is preserved despite a significantly lower hematocrit. The lack of a defect in renal function in AMPKα1 KO mice could be explained by a compensatory upregulation in AMPK α2-subunit. Therefore, we used the Cre-loxP system to knock down AMPKα2 expression in renal epithelial cells. Combining this approach with the systemic deletion of AMPKα1 we achieved reduced renal AMPK activity, accompanied by a shift to a moderate water- and salt-wasting phenotype. Thus we confirm the physiologically relevant role of AMPK in the kidney. Furthermore, our results indicate that in vivo AMPK activity stimulates renal sodium and water reabsorption.

scholarly journals Shifted-excitation Raman difference spectroscopy for in vitro and in vivo biological samples analysis

2010 ◽  
Vol 1 (2) ◽  
pp. 617 ◽  
Author(s):  
Mário Augusto da Silva Martins ◽  
Dayana Gonçalves Ribeiro ◽  
Edson Aparecido Pereira dos Santos ◽  
Airton Abrahão Martin ◽  
Adriana Fontes ◽  
...  
Keyword(s):  
Biological Samples ◽  
Difference Spectroscopy

scholarly journals Dissecting the Role of 5′-AMP for Allosteric Stimulation, Activation, and Deactivation of AMP-activated Protein Kinase

2006 ◽  
Vol 281 (43) ◽  
pp. 32207-32216 ◽  
Author(s):  
Marianne Suter ◽  
Uwe Riek ◽  
Roland Tuerk ◽  
Uwe Schlattner ◽  
Theo Wallimann ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Phosphatase ◽  
Energy Homeostasis ◽  
Adenine Nucleotides ◽  
Enzyme Preparations ◽  
Activity Measurements ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

AMP-activated protein kinase (AMPK) is a heterotrimeric protein kinase that is crucial for cellular energy homeostasis of eukaryotic cells and organisms. Here we report on the activation of AMPK α1β1γ1 and α2β2γ1 by their upstream kinases (Ca2+/calmodulin-dependent protein kinase kinase-β and LKB1-MO25α-STRADα), the deactivation by protein phosphatase 2Cα, and on the extent of stimulation of AMPK by its allosteric activator AMP, using purified recombinant enzyme preparations. An accurate high pressure liquid chromatography-based method for AMPK activity measurements was established, which allowed for direct quantitation of the unphosphorylated and phosphorylated artificial peptide substrate, as well as the adenine nucleotides. Our results show a 1000-fold activation of AMPK by the combined effects of upstream kinase and saturating concentrations of AMP. The two AMPK isoforms exhibit similar specific activities (6 μmol/min/mg) and do not differ significantly by their responsiveness to AMP. Due to the inherent instability of ATP and ADP, it proved impossible to assay AMPK activity in the absolute absence of AMP. However, the half-maximal stimulatory effect of AMP is reached below 2 μm. AMP does not appear to augment phosphorylation by upstream kinases in the purified in vitro system, but deactivation by dephosphorylation of AMPK α-subunits at Thr-172 by protein phosphatase 2Cα is attenuated by AMP. Furthermore, it is shown that neither purified NAD+ nor NADH alters the activity of AMPK in a concentration range of 0–300 μm, respectively. Finally, evidence is provided that ZMP, a compound formed in 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside-treated cells to activate AMPK in vivo, allosterically activates purified AMPK in vitro, but compared with AMP, maximal activity is not reached. These data shed new light on physiologically important aspects of AMPK regulation.

scholarly journals Regulation of TRH neurons and energy homeostasis-related signals under stress

2015 ◽  
Vol 224 (3) ◽  
pp. R139-R159 ◽  
Author(s):  
Patricia Joseph-Bravo ◽  
Lorraine Jaimes-Hoy ◽  
Jean-Louis Charli
Keyword(s):  
Energy Homeostasis ◽  
Molecular Mechanisms ◽  
Cell Types ◽  
Cellular Phenotype ◽  
Energy Demands ◽  
Rapid Responses ◽  
Hpt Axis

Energy homeostasis relies on a concerted response of the nervous and endocrine systems to signals evoked by intake, storage, and expenditure of fuels. Glucocorticoids (GCs) and thyroid hormones are involved in meeting immediate energy demands, thus placing the hypothalamo–pituitary–thyroid (HPT) and hypothalamo–pituitary–adrenal axes at a central interface. This review describes the mode of regulation of hypophysiotropic TRHergic neurons and the evidence supporting the concept that they act as metabolic integrators. Emphasis has been be placed on i) the effects of GCs on the modulation of transcription ofTrhin vivoandin vitro, ii) the physiological and molecular mechanisms by which acute or chronic situations of stress and energy demands affect the activity of TRHergic neurons and the HPT axis, and iii) the less explored role of non-hypophysiotropic hypothalamic TRH neurons. The partial evidence gathered so far is indicative of a contrasting involvement of distinct TRH cell types, manifested through variability in cellular phenotype and physiology, including rapid responses to energy demands for thermogenesis or physical activity and nutritional status that may be modified according to stress history.

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