ABSTRACT
Glucagon-like peptide 2 (GLP-2) is an intestinotropic peptide that binds to GLP-2 receptor (GLP-2R), a class-B G protein-coupled receptor. The GLP-2R antagonist GLP-2(3-33) has relatively high partial agonistic activity, and there are as yet no ideal known potent GLP-2R antagonists. We therefore prepared several truncated forms of human GLP-2 and characterized them by binding and reporter assays to find antagonists more potent than GLP-2(3-33). We found that GLP-2(11-33) was the most potent orthosteric GLP-2R antagonist, with binding activity almost equal to those of GLP-2 and GLP-2(3-33) and weaker intrinsic agonistic activity than GLP-2(3-33). GLP-2(11-33) retained weak agonistic activity toward human, cynomolgus monkey, dog, and Syrian hamster GLP-2Rs. However, it had no agonistic activity toward rat GLP-2R. GLP-2(11-33) potentiated the agonistic activity of an ago-allosteric modulator of GLP-2R, compound 1 (N-[1-(2,5-dichlorothiophen-3-yl)-2-(phenylsulfanyl)ethylidene]hydroxylamine), synergistically toward human GLP-2R. In the case of rat GLP-2R, GLP-2(11-33) decreased the agonistic activity of compound 1, although GLP-2 and GLP-2(3-33) increased this activity additively. These findings suggest that the binding sites of the ago-allosteric modulator and GLP-2 overlap, at least in rat GLP-2R. GLP-2(11-33) is a novel, useful tool for analyzing the mode of action of agonists and ago-allosteric modulators of GLP-2R.
Subject(s)
Glucagon-Like Peptide 2/chemistry , Peptide Fragments/chemistry , Receptors, Glucagon/agonists , Receptors, Glucagon/antagonists & inhibitors , Alkaline Phosphatase/metabolism , Allosteric Regulation , Animals , Cricetinae , Cyclic AMP/metabolism , Dogs , Glucagon-Like Peptide 2/genetics , Glucagon-Like Peptide 2/pharmacology , Glucagon-Like Peptide-2 Receptor , HEK293 Cells , Humans , Hydroxylamine/chemical synthesis , Hydroxylamine/pharmacology , Kinetics , Macaca fascicularis , Peptide Fragments/genetics , Peptide Fragments/pharmacology , Protein Binding , Rats , Receptors, Glucagon/metabolism , Species Specificity , Thiophenes/chemical synthesis , Thiophenes/pharmacologyABSTRACT
Glucagon-like peptide 2 (GLP-2) is an intestinotropic peptide that binds to GLP-2 receptor (GLP- 2R), a class-B G protein-coupled receptor (GPCR) coupled with Gα(s). Few small-molecule agonists had been reported for class-B GPCRs, but we recently reported the first scaffold compounds of ago-allosteric modulators for human GLP-2R. Methyl 2-{[(2Z)-2-(2,5-dichlorothiophen- 3-yl)-2-(hydroxyimino)ethyl]sulfanyl}benzoate (compound 1) and its de-esterified derivative (compound 2) induced placental alkaline phosphatase (PLAP) activity in HEK293 cells overexpressing human GLP-2R and PLAP driven by cAMP response element. In this study, we observed that rat, Syrian hamster, and dog GLP-2Rs also responded to compounds 1 and 2 in the same reporter system. However, no agonistic activity of the compounds toward mouse GLP-2R was detected. Mutagenesis studies showed that mutant human GLP-2Rs with Pro392Leu substitution of mouse GLP-2R for human GLP-2R amino acid residues nullified the PLAP activity of compound 2, although these mutant receptors responded to GLP-2. This finding suggests that the Pro392 residue of human GLP-2R is essential for the agonistic activity of compound 2.
Subject(s)
Glucagon-Like Peptide 2/pharmacology , Receptors, Glucagon/agonists , Alkaline Phosphatase/genetics , Alkaline Phosphatase/metabolism , Amino Acid Sequence , Animals , Cell Line , Cricetinae , Dogs , GPI-Linked Proteins/genetics , GPI-Linked Proteins/metabolism , Gene Expression Regulation/drug effects , Genes, Reporter , Glucagon-Like Peptide-2 Receptor , Humans , Isoenzymes/genetics , Isoenzymes/metabolism , Mice , Molecular Sequence Data , Mutation , Rats , Receptors, Glucagon/chemistry , Receptors, Glucagon/genetics , Sequence Alignment , Species SpecificityABSTRACT
Glucagon-like peptide 2 (GLP-2) is an intestinotropic peptide that binds to GLP-2 receptor (GLP-2R), a class-B G protein-coupled receptor (GPCR). Few synthetic agonists have been reported so far for class-B GPCRs. Here, we report the first scaffold compounds of ago-allosteric modulators for human GLP-2R, derived from methyl 2-{[(2Z)-2-(2,5-dichlorothiophen-3-yl)-2-(hydroxyimino)ethyl]sulfanyl}benzoate (compound 1).
Subject(s)
Benzoates/pharmacology , Receptors, Glucagon/agonists , Thiophenes/pharmacology , Benzoates/chemical synthesis , Benzoates/chemistry , Dose-Response Relationship, Drug , Glucagon-Like Peptide-2 Receptor , Humans , Molecular Structure , Structure-Activity Relationship , Thiophenes/chemical synthesis , Thiophenes/chemistryABSTRACT
Even when the daily blood pressure mean is acceptable, too large a circadian amplitude of blood pressure largely increases cardiovascular disease risk. Autogenic training (N = 11), a non-pharmacologic intervention capable of lowering an excessive blood pressure variability, may be well-suited for MESOR-normotensive patients diagnosed with circadian-hyper-amplitude-tension (CHAT). Not all anti-hypertensive drugs affect blood pressure variability. Accordingly, long-acting carteolol (N = 11) and/or atenolol (N = 8) may be preferred to captopril retard (N = 13), nilvadipine (N = 8), or amlodipine (N = 7) for midline-estimating statistic of rhythm (MESOR)-hypertensive patients with CHAT. Prospective outcome studies are needed to assess whether the relative merits of these treatments are in keeping with their effects on blood pressure and blood pressure variability.
Subject(s)
Antihypertensive Agents/therapeutic use , Autogenic Training , Blood Pressure/drug effects , Hypertension/therapy , Blood Pressure Monitoring, Ambulatory , Circadian Rhythm , Humans , Hypertension/drug therapy , PeriodicityABSTRACT
In order to re-examine the extent to which secular circulatory variation can be resolved into possibly accountable, if not yet predictable behavior, the 15-year record of blood pressure and heart rate of an adult male cardiologist (Y.W.) is reanalyzed. Gliding spectral windows with an interval of 4 years progressively displaced throughout the data series examine monthly means from August 1987 to August 2002. A circannual variation is only intermittent and appears to drift for years. A circasemiannual variation is consistent and prominent, yet only for a fraction of the record examined. By contrast to the circadian rhythm in blood pressure and heart rate, which is reliably detectable in most subjects in clinical health, the circannual variation in the human circulation is inconsistent and hence should be monitored, as in this case for its assessment as one goes, a conclusion that also applies to the circasemiannual variation, prominent for years but not detected thereafter. The results prompt the search for interactions between the photic, thermic and societal effects of the seasons that, if solely pertinent, should yield a consistent 1-year spectral component. That non-photic effects may also play an important role may point to modulation by solar cycle stage and solar cycle number, perhaps mediated by the solar wind. This conclusion is extended in proof to the role played by the most recently discovered transannual component in human blood pressure and heart rate, which is a probable further signature of the solar wind. The beating of the transannual and circannual components documented on another data series may contribute to the lack of a consistent 1-year synchronized circannual variation in this case and many others.
