scholarly journals Role of the signal peptide in the synthesis and processing of the glucagon-like peptide-1 receptor

2009 ◽  
Vol 159 (1) ◽  
pp. 237-251 ◽  
Author(s):  
Y Huang ◽  
GF Wilkinson ◽  
GB Willars
Keyword(s):  
Signal Peptide ◽  
Synthesis And Processing ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

scholarly journals The putative signal peptide of glucagon-like peptide-1 receptor is not required for receptor synthesis but promotes receptor expression

2014 ◽  
Vol 34 (6) ◽  
Author(s):  
Yunjun Ge ◽  
Dehua Yang ◽  
Antao Dai ◽  
Caihong Zhou ◽  
Yue Zhu ◽  
...  
Keyword(s):  
Signal Peptide ◽  
Receptor Expression ◽  
Hek293 Cells ◽  
Putative Signal Peptide ◽  
293 Cells ◽  
Class B ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
G Protein Coupled

GLP-1R (glucagon-like peptide-1 receptor) mediates the ‘incretin effect’ and many other anti-diabetic actions of its cognate ligand, GLP-1 (glucagon-like peptide-1). It belongs to the class B family of GPCRs (G protein-coupled receptors) and possesses an N-terminal putative SP (signal peptide). It has been reported that this sequence is required for the synthesis of GLP-1R and is cleaved after receptor synthesis. In the present study, we conducted an in-depth exploration towards the role of the putative SP in GLP-1R synthesis. A mutant GLP-1R without this sequence was expressed in HEK293 cells (human embryonic kidney 293 cells) and displayed normal functionality with respect to ligand binding and activation of adenylate cyclase. Thus the putative SP does not seem to be required for receptor synthesis. Immunoblotting analysis shows that the amount of GLP-1R synthesized in HEK293 cells is low when the putative SP is absent. This indicates that the role of the sequence is to promote the expression of GLP-1R. Furthermore, epitopes tagged at the N-terminal of GLP-1R are detectable by immunofluorescence and immunoblotting in our experiments. In conclusion, the present study points to different roles of SP in GLP-1R expression which broadens our understanding of the functionality of this putative SP of GLP-1R and possibly other Class B GPCRs.

scholarly journals Ileal short-chain fatty acids inhibit gastric motility by a humoral pathway

2000 ◽  
Vol 279 (5) ◽  
pp. G925-G930 ◽  
Author(s):  
G. Cuche ◽  
J. C. Cuber ◽  
C. H. Malbert
Keyword(s):  
Gastric Motility ◽  
Short Chain Fatty Acid ◽  
Peptide Yy ◽  
Short Chain Fatty Acids ◽  
Short Chain ◽  
Maximal Amplitude ◽  
Inhibiting Factor ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

The aim of this study was to evaluate the nervous and humoral pathways involved in short-chain fatty acid (SCFA)-induced ileal brake in conscious pigs. The role of extrinsic ileal innervation was evaluated after SCFA infusion in innervated and denervated Babkin's ileal loops, and gastric motility was measured with strain gauges. Peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) concentrations were evaluated in both situations. The possible involvement of absorbed SCFA was tested by using intravenous infusion of acetate. Ileal SCFA infusion in the intact terminal ileum decreased the amplitude of distal and terminal antral contractions (33 ± 1.2 vs. 49 ± 1.2% of the maximal amplitude recorded before infusion) and increased their frequency (1.5 ± 0.11 vs. 1.3 ± 0.10/min). Similar effects were observed during SCFA infusion in ileal innervated and denervated loops (amplitude, 35 ± 1.0 and 34 ± 0.8 vs. 47 ± 1.3 and 43 ± 1.2%; frequency, 1.4 ± 0.07 and 1.6 ± 0.06 vs. 1.1 ± 0.14 and 1.0 ± 0.12/min). Intravenous acetate did not modify the amplitude and frequency of antral contractions. PYY but not GLP-1 concentrations were increased during SCFA infusion in innervated and denervated loops. In conclusion, ileal SCFA inhibit distal gastric motility by a humoral pathway involving the release of an inhibiting factor, which is likely PYY.

Abstract 13483: Pathological Decline in Incretin Hormone Glucagon-like Peptide-1 Causes Cardiac Apoptosis and Dysfunction in Pressure-overloaded Heart Failure Through Cyclic AMP-dependent Mechanisms. -Distinct Role of Protein Kinase a and EPAC

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Morihiko Aoyama ◽  
Yasuko K Bando ◽  
Haruya Kawase ◽  
Akio Monji ◽  
Toko Mitsui ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cyclic Amp ◽  
Left Ventricular ◽  
Ample Evidence ◽  
Incretin Hormone ◽  
Myocardial Apoptosis ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
Distinct Role

Introduction: Ample evidence demonstrates cardiovascular protection by incretin hormone glucagon-like peptide-1 (GLP-1) through the cyclic AMP axis. GLP-1 is known for its inotropic effect on heart, however, the role of GLP-1 in heart failure remains uncertain. Hypothesis: To explore the pathophysiological role of GLP-1 in heart failure Methods: Pressure overload-induced heart failure model was generated by transverse aortic constriction in mice (TAC). Results: At 4 week after the operation, TAC exhibited systolic left-ventricular dysfunction, myocardial hypertrophy and augmented apoptosis. Unexpectedly, circulating GLP-1 concentration was markedly decreased in TAC (in pM; 0.86±0.10 for TAC versus 2.13±0.54 for sham) with concomitant reduction of myocardial cyclic AMP concentration (in pmole/mg protein; 33.0±1.4 for TAC versus 42.2±1.5). TAC exhibited pathological changes in signaling molecules of myocardial contractility [SERCA, phospho-phospholamban(Serine16; pPL), β-myosin heavy chain (MYH7)], remodeling (Akt/mTOR/S6K), and cell death markers (procaspase-3/Bcl2 for apoptosis and PINK/PARKIN complex for mitophagy detecting damaged mitochondria). All of these changes observed in TAC heart were reversed selectively by treatment with GLP-1 analog exendin-4 (Ex4; 24nmole/kg/day for 4 weeks) and indirect supplement of GLP-1 by a DPP4 inhibitor alogliptin (ALO; 10mg/kg/day for 4 weeks). In vitro TUNEL assay using cultured cardiomyocytes revealed that Ex-4 reduced myocardial apoptosis in a cAMP/EPAC1-dependent but PKA-independent manner (Figure). Conclusions: Pressure-overloaded heart failure exhibits decline in GLP-1, leading to cAMP/EPAC1-dependent impairment in myocardial apoptosis, and cAMP/PKA/pPL/SERCA-dependent myocardial contractile dysfunction. Our data suggest the distinct role of PKA and EPAC in pathophysiology underlying heart failure.

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