Abstract:
OBJECTIVE:Glucagon-like peptide 1 (GLP-1) enhances insulin secretion and protects β-cell mass. Diabetes therapies targeting the GLP-1 receptor (GLP-1R), expressed in numerous tissues, have diminished dose-response in patients with type 2 diabetes compared with healthy human controls. The aim of this study was to determine the mechanistic causes underlying the reduced efficacy of GLP-1R ligands. METHODS:Using primary mouse islets and the β-cell line MIN6, outcomes downstream of the GLP-1R were analyzed: Insulin secretion; phosphorylation of the cAMP-response element binding protein (CREB); cAMP responses. Signaling systems were studied by immunoblotting and qRT-PCR, and PKA activity was assayed. Cell surface localization of the GLP-1R was studied by confocal microscopy using a fluorescein-tagged exendin-4 and GFP-tagged GLP-1R. RESULTS:Rodent β-cells chronically exposed to high glucose had diminished responses to GLP-1R agonists including: diminished insulin secretory response; reduced phosphorylation of (CREB); impaired cAMP response, attributable to chronically increased cAMP levels. GLP-1R signaling systems were affected by hyperglycemia with increased expression of mRNAs encoding the inducible cAMP early repressor (ICER) and adenylyl cyclase 8, reduced PKA activity due to increased expression of the PKA-RIα subunit, reduced GLP-1R mRNA expression and loss of GLP-1R from the cell surface. To specifically examine the loss of GLP-1R from the plasma membrane a GLP-1R-GFP fusion protein was employed to visualize subcellular localization. Under low glucose conditions or when PKA activity was inhibited, GLP-1R-GFP was found at the plasma membrane. Conversely high glucose, expression of a constitutively active PKA subunit, or exposure to exendin-4 or forskolin led to GLP-1R-GFP internalization. Mutation of serine residue 301 of the GLP-1R abolished the glucose-dependent loss of the receptor from the plasma membrane. This was associated with a loss of an interaction between the receptor and the small ubiquitin-related modifier (SUMO), an interaction that was found to be necessary for internalization of the receptor. CONCLUSIONS:These data show that glucose acting, at least in part, via PKA leads to the loss of the GLP-1R from the cell surface and an impairment of GLP-1R signaling, which may underlie the reduced clinical efficacy of GLP-1R based therapies in individuals with poorly controlled hyperglycemia.
journal_name
Mol Metabjournal_title
Molecular metabolismauthors
Rajan S,Dickson LM,Mathew E,Orr CM,Ellenbroek JH,Philipson LH,Wicksteed Bdoi
10.1016/j.molmet.2015.01.010subject
Has Abstractpub_date
2015-02-03 00:00:00pages
265-76issue
4issn
2212-8778pii
S2212-8778(15)00023-Xjournal_volume
4pub_type
杂志文章abstract:OBJECTIVE:In the adult brain, neural stem cells (NSCs) located in the subventricular zone (SVZ) produce both neuronal and glial cells. Thyroid hormones (THs) regulate adult NSC differentiation towards a neuronal phenotype, but also have major roles in mitochondrial metabolism. As NSC metabolism relies mainly on glycoly...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2017.08.003
更新日期:2017-11-01 00:00:00
abstract::Genetic variation in FFAR1 modulates insulin secretion dependent on non-esterified fatty acid (NEFA) concentrations. We previously demonstrated lower insulin secretion in minor allele carriers of PPARG Pro12Ala in high-NEFA environment, but the mode of action could not been revealed. We tested if this effect is mediat...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2014.07.001
更新日期:2014-07-07 00:00:00
abstract::SIRT1 has attracted a lot of interest since it was discovered as a mammalian homolog of Sir2, a protein that influences longevity in yeast. Intensive early research suggested a key role of SIRT1 in mammalian development, metabolic flexibility and oxidative metabolism. However, it is the growing body of transgenic mode...
journal_title:Molecular metabolism
pub_type: 杂志文章,评审
doi:10.1016/j.molmet.2013.10.006
更新日期:2013-10-23 00:00:00
abstract:OBJECTIVE:Appetitive responses to weight loss are mediated by a nutrient-sensing neural network comprised of melanocortin neurons. The role of neural melanocortin-3 receptors (MC3R) in mediating these responses is enigmatic. Mc3r knockout mice exhibit a paradoxical phenotype of obesity and reduced feeding-related behav...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2016.05.002
更新日期:2016-05-12 00:00:00
abstract::Oxyntomodulin (OXM) is a peptide hormone released from the gut in post-prandial state that activates both the glucagon-like peptide-1 receptor (GLP1R) and the glucagon receptor (GCGR) resulting in superior body weight lowering to selective GLP1R agonists. OXM reduces food intake and increases energy expenditure in hum...
journal_title:Molecular metabolism
pub_type: 杂志文章,评审
doi:10.1016/j.molmet.2013.12.001
更新日期:2013-12-14 00:00:00
abstract:OBJECTIVE:Glucagon is a hormone with metabolic actions that maintains normoglycemia during the fasting state. Strategies enabling either inhibition or activation of glucagon receptor (Gcgr) signaling are being explored for the treatment of diabetes or obesity. However, the cardiovascular consequences of manipulating gl...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2014.11.005
更新日期:2014-11-29 00:00:00
abstract:OBJECTIVE:A sustained high fat diet in mice mimics many features of human obesity. We used male and female Non-Swiss albino mice to investigate the impact of short and long-term high-fat diet-(HFD)-induced obesity on the peripheral neuromuscular junction (NMJ) and whether obesity-related synaptic structural alterations...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2020.100979
更新日期:2020-06-01 00:00:00
abstract:OBJECTIVE:Increasing adaptive thermogenesis by stimulating browning in white adipose tissue is a promising method of improving metabolic health. However, the molecular mechanisms underlying this transition remain elusive. Our study examined the molecular determinants driving the differentiation of precursor cells into ...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2020.101137
更新日期:2020-12-05 00:00:00
abstract:OBJECTIVE:Previous work has suggested that white adipocytes may also show a mammary luminal secretory cell phenotype during lactation. The capacity of brown and beige/brite adipocytes to display a mammary cell phenotype and the levels at which they demonstrate such phenotypes in vivo is currently unknown. METHODS:To i...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2017.07.015
更新日期:2017-10-01 00:00:00
abstract:OBJECTIVE:Nonalcoholic steatohepatitis (NASH) is closely associated with metabolic syndrome and increases the risk for end-stage liver disease, such as cirrhosis and hepatocellular carcinoma. Despite this, the molecular events that influence NASH pathogenesis remain poorly understood. The objectives of the current stud...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2018.12.004
更新日期:2019-02-01 00:00:00
abstract:BACKGROUND:Plasma insulin levels are predominantly the product of the morphological mass of insulin producing beta cells in the pancreatic islets of Langerhans and the functional status of each of these beta cells. Thus, deficiency in either beta cell mass or function, or both, can lead to insufficient levels of insuli...
journal_title:Molecular metabolism
pub_type: 杂志文章,评审
doi:10.1016/j.molmet.2017.06.019
更新日期:2017-07-08 00:00:00
abstract:OBJECTIVE:Glucose-dependent insulinotropic polypeptide (GIP) is secreted from the gut in response to nutrient ingestion and promotes meal-dependent insulin secretion and lipid metabolism. Loss or attenuation of GIP receptor (GIPR) action leads to resistance to diet-induced obesity through incompletely understood mechan...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2019.08.006
更新日期:2019-10-01 00:00:00
abstract:BACKGROUND:GPRC6A, a widely expressed G-protein coupled receptor, is proposed to be a master regulator of complex endocrine networks and metabolic processes. GPRC6A is activated by multiple ligands, including osteocalcin (Ocn), testosterone (T), basic amino acids, and various cations. SCOPE OF REVIEW:We review the con...
journal_title:Molecular metabolism
pub_type: 杂志文章,评审
doi:10.1016/j.molmet.2016.12.006
更新日期:2016-12-21 00:00:00
abstract:OBJECTIVE:Recent reports have implicated the p53 tumor suppressor in the regulation of lipid metabolism. We hypothesized that the pharmacological activation of p53 with low-dose doxorubicin, which is widely used to treat several types of cancer, may have beneficial effects on nonalcoholic fatty liver disease (NAFLD) an...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2017.12.005
更新日期:2018-02-01 00:00:00
abstract:BACKGROUND:The availability of human pancreatic islets with characteristics closely resembling those present in vivo is instrumental for ex vivo studies in diabetes research. SCOPE OF REVIEW:In this review we propose metabolically phenotyped surgical patients as a novel source of pancreatic tissue for islet research. ...
journal_title:Molecular metabolism
pub_type: 杂志文章,评审
doi:10.1016/j.molmet.2019.06.006
更新日期:2019-09-01 00:00:00
abstract::Cytokine signaling has been connected to regulation of metabolism and energy balance. Numerous cytokine gene expression changes are stimulated by accumulation of bile acids in livers of young Foxa2 liver-conditional null mice. We hypothesized that bile acid-induced inflammation in young Foxa2 mutants, once chronic, af...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2013.08.005
更新日期:2013-08-24 00:00:00
abstract:BACKGROUND:Poly-ADP-ribose polymerases (PARPs) are key mediators of cellular stress response. They are intimately linked to cellular metabolism through the consumption of NAD+. PARP1/ARTD1 in the nucleus is the major NAD+ consuming activity and plays a key role in maintaining genomic integrity. SCOPE OF REVIEW:In this...
journal_title:Molecular metabolism
pub_type: 杂志文章,评审
doi:10.1016/j.molmet.2020.01.014
更新日期:2020-08-01 00:00:00
abstract::Several lines of evidence suggest that novel pharmacological approaches aimed at converting white adipose tissue (WAT) into brown adipose tissue (BAT) may represent an effective therapeutic strategy for obesity and related disorders. ((18))F-fluorodeoxyglucose ((18)F-FDG) is the only positron emission tomography (PET)...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2013.04.002
更新日期:2013-04-21 00:00:00
abstract:OBJECTIVE:α/β-Hydrolase domain-6 (ABHD6) is a newly identified monoacylglycerol (MAG) lipase. We recently reported that it negatively regulates glucose stimulated insulin secretion (GSIS) in the β cells by hydrolyzing lipolysis-derived MAG that acts as a metabolic coupling factor and signaling molecule via exocytotic r...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2015.09.012
更新日期:2015-10-08 00:00:00
abstract:BACKGROUND:The abundance of energy metabolites is intimately interconnected with the activity of chromatin-modifying enzymes in order to guarantee the finely tuned modulation of gene expression in response to cellular energetic status. Metabolism-induced epigenetic gene regulation is a key molecular axis for the mainte...
journal_title:Molecular metabolism
pub_type: 杂志文章,评审
doi:10.1016/j.molmet.2021.101165
更新日期:2021-01-14 00:00:00
abstract:OBJECTIVE:Mice with congenital loss of the glucagon receptor gene (Gcgr-/- mice) remain normoglycemic in insulinopenic conditions, suggesting that unopposed glucagon action is the driving force for hyperglycemia in Type-1 Diabetes Mellitus (T1DM). However, chronic loss of GCGR results in a neomorphic phenotype that inc...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2018.07.012
更新日期:2018-11-01 00:00:00
abstract:OBJECTIVE:Adult obesity risk is influenced by alterations to fetal and neonatal environments. Modifying neonatal gut or neurohormone signaling pathways can have negative metabolic consequences in adulthood. Here we characterize the effect of neonatal activation of glucagon like peptide-1 (GLP-1) receptor (GLP1R) signal...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2017.05.006
更新日期:2017-05-15 00:00:00
abstract:OBJECTIVE:Brown adipose tissue (BAT) thermogenesis depends on the mobilization and oxidation of fatty acids from intracellular lipid droplets (LD) within brown adipocytes (BAs); however, the identity and function of LD proteins that control BAT lipolysis remain incomplete. Proteomic analysis of mouse BAT subcellular fr...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2017.10.014
更新日期:2018-01-01 00:00:00
abstract:OBJECTIVE:Identification of additional regulatory factors involved in the onset of obesity is important to understand the mechanisms underlying this prevailing disease and its associated metabolic disorders and to develop therapeutic strategies. Through isolation and analysis of a mutant, we aimed to uncover the functi...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2017.03.003
更新日期:2017-03-18 00:00:00
abstract:OBJECTIVE:Understanding the mechanisms underlying the remarkable beneficial effects of gastric bypass surgery is important for the development of non-surgical therapies or less invasive surgeries in the fight against obesity and metabolic disease. Although the intestinal L-cell hormones glucagon-like peptide-1 (GLP-1) ...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2019.05.004
更新日期:2019-07-01 00:00:00
abstract::Decreased β-cell mass reflects a shift from quiescence/proliferation into apoptosis, it plays a crucial role in the pathophysiology of diabetes. A major attempt to restore β-cell mass and normoglycemia is to improve β-cell survival. Here we show that switching off the Fas pathway using Fas apoptotic inhibitory protein...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2012.08.006
更新日期:2012-08-17 00:00:00
abstract:OBJECTIVE:Despite the large body of work describing the tumor suppressor functions of Phosphatase and tensin homologue deleted on chromosome ten (PTEN), its roles in adipose homeostasis of adult animals are not yet fully understood. Here, we sought to determine the role of PTEN in whole-body adipose homeostasis. METHO...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2019.09.008
更新日期:2019-12-01 00:00:00
abstract::Metabolic endotoxemia triggers inflammation, targets cells from the stroma-vascular fraction of adipose depots, and metabolic disease. To identify these cells we here infused mice with lipopolysaccharides and showed by FACS analyses and BrdU staining that the number of small subcutaneous adipocytes, preadipocytes and ...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2013.06.005
更新日期:2013-07-04 00:00:00
abstract:OBJECTIVES:Hepatokines are proteins secreted by the liver that impact the functions of the liver and various tissues through autocrine, paracrine, and endocrine signaling. Recently, Tsukushi (TSK) was identified as a new hepatokine that is induced by obesity and cold exposure. It was proposed that TSK controls sympathe...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2019.09.014
更新日期:2019-12-01 00:00:00
abstract:OBJECTIVE:Clear cell renal cell carcinoma (ccRCC) is a subtype of kidney cancer defined by robust lipid accumulation, which prior studies have indicated plays an important role in tumor progression. We hypothesized that the peroxisome proliferator-activated receptor gamma (PPARγ), detected in both ccRCC tumors and cell...
journal_title:Molecular metabolism
pub_type: 杂志文章
doi:10.1016/j.molmet.2018.05.013
更新日期:2018-08-01 00:00:00