scholarly journals Exogenous expression of glucagon-like peptide 1 receptor and human insulin in AtT-20 corticotrophs confers cAMP-mediated gene transcription and insulin secretion

2005 ◽  
Vol 187 (3) ◽  
pp. 419-427 ◽  
Author(s):  
K K Sidhu ◽  
R C Fowkes ◽  
R H Skelly ◽  
J M Burrin
Keyword(s):  
Insulin Secretion ◽  
Cell Line ◽  
Gene Transcription ◽  
Expression System ◽  
Fold Increase ◽  
Receptor Expression ◽  
Glycoprotein Hormone ◽  
Α Subunit ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

The insulinotrophic effects of glucagon-like peptide 1 (GLP-1) are mediated by its seven-transmembrane receptor (GLP-1R) in pancreatic β-cells. We have transiently transfected the GLP-1R and a proopiomelanocortin (POMC) promoter-driven human preproinsulin gene vector (pIRES) into the AtT-20 pituitary corticotrophic cell line, to investigate the possibility of creating a regulated, insulin-expressing cell line. Receptor expression was confirmed by RT-PCR and functionality was demonstrated by measuring changes in cAMP levels in response to GLP-1. Rapid (5 min) stimulation of cAMP production was observed with 100 nM GLP-1, 24 h after transfection of 2 μg GLP-1R DNA. AtT-20 cells co-transfected with GLP-1R and human glycoprotein hormone α-subunit or rat POMC promoters revealed GLP-1-stimulated cAMP activation of transcription. Co-transfection of the pIRES vector with the GLP-1R resulted in GLP-1-stimulated activation of POMC promoter-driven preproinsulin gene transcription but insulin secretion was not detected. However, using an adenoviral expression system to infect AtT-20 cells with GLP-1R and the preproinsulin gene (including 120 bp of its own promoter) resulted in a 6.4 ± 0.6-fold increase in cAMP and a 4.9 ± 0.8-fold increase in insulin secretion in response to 100 nM GLP-1. These results demonstrate, for the first time, functional GLP-1R-mediated preproinsulin gene transcription and secretion in a transplantable cell line.

CCR2 knockout exacerbates cerulein-induced chronic pancreatitis with hyperglycemia via decreased GLP-1 receptor expression and insulin secretion

2013 ◽  
Vol 304 (8) ◽  
pp. G700-G707 ◽  
Author(s):  
Yuji Nakamura ◽  
Takanori Kanai ◽  
Keita Saeki ◽  
Miho Takabe ◽  
Junichiro Irie ◽  
...  
Keyword(s):  
Cell Migration ◽  
Insulin Secretion ◽  
Chronic Pancreatitis ◽  
Immune Cells ◽  
Receptor Expression ◽  
Wild Type ◽  
Multiple Series ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
The Relationship

Glucagon-like peptide-1 (GLP-1) promotes insulin release; however, the relationship between the GLP-1 signal and chronic pancreatitis is not well understood. Here we focus on chemokine (C-C motif) ligand 2 (CCL2) and its receptor (CCR2) axis, which regulates various immune cells, including macrophages, to clarify the mechanism of GLP-1-mediated insulin secretion in chronic pancreatitis in mice. One and multiple series of repetitive cerulein administrations were used to induce acute and chronic cerulein pancreatitis, respectively. Acute cerulein-administered CCR2-knockout (KO) mice showed suppressed infiltration of CD11b+Gr-1low macrophages and pancreatic inflammation and significantly upregulated insulin secretion compared with paired wild-type (WT) mice. However, chronic cerulein-administered CCR2-KO mice showed significantly increased infiltration of CD11b+/Gr-1− and CD11b+/Gr-1high cells, but not CD11b+/Gr-1low cells, in pancreas with severe inflammation and significantly decreased insulin secretion compared with their WT counterparts. Furthermore, although serum GLP-1 levels in chronic cerulein-administered WT and CCR2-KO mice were comparably upregulated after cerulein administrations, GLP-1 receptor levels in pancreases of chronic cerulein-administered CCR2-KO mice were significantly lower than in paired WT mice. Nevertheless, a significantly higher hyperglycemia level in chronic cerulein-administered CCR2-KO mice was markedly restored by treatment with a GLP-1 analog to a level comparable to the paired WT mice. Collectively, the CCR2/CCL2 axis-mediated CD11b+-cell migration to the pancreas is critically involved in chronic pancreatitis-mediated hyperglycemia through the modulation of GLP-1 receptor expression and insulin secretion.

Evaluation of glucagon-like peptide-1 receptor expression in non-diabetic and diabetic atherosclerotic mice using PET tracer 68Ga-NODAGA-exendin-4

2021 ◽  
Author(s):  
Mia Ståhle ◽  
Sanna Hellberg ◽  
Jenni Virta ◽  
Heidi Liljenbäck ◽  
Olli Metsälä ◽  
...  
Keyword(s):  
Vessel Wall ◽  
Vascular Inflammation ◽  
Tracer Uptake ◽  
Receptor Expression ◽  
Atherosclerotic Lesions ◽  
Pet Tracer ◽  
Positron Emission ◽  
Healthy Control ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Activation of glucagon-like peptide-1 receptor (GLP-1R) signaling attenuates development of atherosclerosis and vascular inflammation. However, the expression of GLP-1R in atherosclerotic arteries remains uncertain. We evaluated whether a positron emission tomography (PET) tracer 68Ga-NODAGA-exendin-4 enables detection and imaging of GLP-1R expression in the mouse atherosclerotic aorta. Hypercholesterolemic (LDLR-/-ApoB100/100), hypercholesterolemic and diabetic (IGF-II/LDLR-/-ApoB100/100) as well as healthy control (C57BL/6N) mice were utilized in the study. The uptake of 68Ga-NODAGA-exendin-4 in atherosclerotic lesions was studied by autoradiography of tissue sections followed by immunofluorescence evaluation of inflammatory and vascular cell markers and GLP-1R. A subset of mice was imaged with 68Ga-NODAGA-exendin-4 PET/computed tomography (CT). The aortas of both LDLR-/-ApoB100/100 and IGF-II/LDLR-/-ApoB100/100 mice contained prominent, macrophage-rich atherosclerotic lesions. Diabetic mice demonstrated hyperglycemia and glucose intolerance. We found that by autoradiography, 68Ga-NODAGA-exendin-4 uptake was focally increased in macrophage-rich lesion areas compared with corresponding healthy vessel wall (lesion-to-wall ratio 1.6 ± 0.10, p<0.0001) in both non-diabetic and diabetic hypercholesterolemic mice. Pre-injection of unlabeled exendin-4 peptide significantly reduced cellular uptake of 68Ga-NODAGA-exendin-4. Furthermore, PET/CT imaging showed 68Ga-NODAGA-exendin-4 accumulation in the atherosclerotic aorta. Immunofluorescence stainings demonstrated co-localization of GLP-1R with macrophage-rich areas in atherosclerotic lesions. Tracer uptake was low in the healthy vessel wall of C57BL/6N mice coupled with negative GLP-1R staining. In conclusion, 68Ga-NODAGA-exendin-4 detects GLP-1R expression in atherosclerotic lesions in both non-diabetic and diabetic hypercholesterolemic mice. These results provide evidence that GLP-1R expression is mainly localized in macrophage-rich area in atherosclerotic lesions and may have implications for studies of pharmacological modification of GLP-1R signaling in atherosclerosis.

scholarly journals Glucagon-like peptide-1 receptor expression after myocardial infarction: Imaging study using 68Ga-NODAGA-exendin-4 positron emission tomography

2018 ◽  
Vol 27 (6) ◽  
pp. 2386-2397 ◽  
Author(s):  
Mia Ståhle ◽  
Ville Kytö ◽  
Max Kiugel ◽  
Heidi Liljenbäck ◽  
Olli Metsälä ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Positron Emission Tomography ◽  
Smooth Muscle Actin ◽  
Receptor Expression ◽  
Emission Tomography ◽  
Sham Operation ◽  
Alpha Smooth Muscle Actin ◽  
Positron Emission ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Abstract Background Activation of glucagon-like peptide-1 receptor (GLP-1R) signaling protects against cardiac dysfunction and remodeling after myocardial infarction (MI). The aim of the study was to evaluate 68Ga-NODAGA-exendin-4 positron emission tomography (PET) for assessment of GLP-1R expression after MI in rats. Methods and Results Rats were studied at 3 days, 1 and 12 weeks after permanent coronary ligation or a sham-operation. Rats were injected with 68Ga-NODAGA-exendin-4 and scanned with PET and contrast-enhanced computed tomography (CT) followed by digital autoradiography and histology of left ventricle tissue sections. 68Ga-NODAGA-exendin-4 PET/CT showed focally increased tracer uptake in the infarcted regions peaking at 3 days and continuing at 1 week after MI. Pre-treatment with an unlabeled exendin-4 peptide significantly reduced 68Ga-NODAGA-exendin-4 uptake. By autoradiography, 68Ga-NODAGA-exendin-4 uptake was 8.6-fold higher in the infarcted region and slightly increased also in the remote, non-infarcted myocardium at 1 week and 12 weeks post-MI compared with sham. Uptake of 68Ga-NODAGA-exendin-4 correlated with the amount of CD68-positive macrophages in the infarcted area and alpha-smooth muscle actin staining in the remote myocardium. Conclusions 68Ga-NODAGA-exendin-4 PET detects up-regulation of cardiac GLP-1R expression during healing of MI in rats and may provide information on the activated repair mechanisms after ischemic myocardial injury.

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