Differentiating effects of the glucagon-like peptide-1 analogue exendin-4 in a human neuronal cell model

The ubiquitin proteasomal system and autophagic pathway are two main protein degradation systems in eukaryotic cells. Inhibition of the proteasomal system with proteasome inhibitors for cancer treatment can cause neurotoxic side effects. In this study, we investigated neurotoxic side effects of bortezomib (BTZ) and carfilzomib (CFZ) in a human neuronal cell model. Inhibition of proteasome with BTZ upregulated autophagy receptor protein p62 level. BTZ caused reduced mitochondrial mass per cell in a greater extent than CFZ. BTZ caused more clustering of mitochondria than CFZ. In conclusion, mitochondrial toxicity and autophagic upregulation with BTZ may be the reason for more severe neurotoxic profile than CFZ.

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Uncoupling protein 2 negatively regulates glucose-induced glucagon-like peptide 1 secretion

Journal of Molecular Endocrinology ◽

10.1530/jme-11-0114 ◽

2012 ◽

Vol 48 (2) ◽

pp. 151-158 ◽

Cited By ~ 9

Author(s):

Hongjie Zhang ◽

Jing Li ◽

Xiangying Liang ◽

Yun Luo ◽

Ke Zen ◽

...

Keyword(s):

Cell Model ◽

Uncoupling Protein ◽

Uncoupling Protein 2 ◽

Mrna Levels ◽

Incretin Hormone ◽

Mucosal Layer ◽

Glucagon Like Peptide ◽

Glucagon Like Peptide 1 ◽

Deficient Mice

It is known that endogenous levels of the incretin hormone glucagon-like peptide 1 (GLP1) can be enhanced by various secretagogues, but the mechanism underlying GLP1 secretion is still not fully understood. We assessed the possible effect of uncoupling protein 2 (UCP2) on GLP1 secretion in mouse intestinal tract and NCI-H716 cells, a well-characterized human enteroendocrine L cell model. Localization of UCP2 and GLP1 in the gastrointestinal tract was assessed by immunofluorescence staining. Ucp2 mRNA levels in gut were analyzed by quantitative RT-PCR. Human NCI-H716 cells were transiently transfected with siRNAs targeting UCP2. The plasma and ileum tissue levels of GLP1 (7–36) amide were measured using an ELISA kit. UCP2 was primarily expressed in the mucosal layer and colocalized with GLP1 in gastrointestinal mucosa. L cells secreting GLP1 also expressed UCP2. After glucose administration, UCP2-deficient mice showed increased glucose-induced GLP1 secretion compared with wild-type littermates. GLP1 secretion increased after NCI-H716 cells were transfected with siRNAs targeting UCP2. UCP2 was markedly upregulated in ileum tissue from ob/ob mice, and GLP1 secretion decreased compared with normal mice. Furthermore, GLP1 secretion increased after administration of genipin by oral gavage. Taken together, these results reveal an inhibitory role of UCP2 in glucose-induced GLP1 secretion.

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Role of fatty acid transport protein 4 in oleic acid-induced glucagon-like peptide-1 secretion from murine intestinal L cells

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00116.2012 ◽

2012 ◽

Vol 303 (7) ◽

pp. E899-E907 ◽

Cited By ~ 30

Author(s):

M. A. Poreba ◽

C. X. Dong ◽

S. K. Li ◽

A. Stahl ◽

J. H. Miner ◽

...

Keyword(s):

Oleic Acid ◽

Fatty Acid ◽

Cell Model ◽

Fatty Acid Transport ◽

Acid Transport ◽

L Cell ◽

Glucagon Like Peptide ◽

Glucagon Like Peptide 1

The antidiabetic intestinal L cell hormone glucagon-like peptide-1 (GLP-1) enhances glucose-dependent insulin secretion and inhibits gastric emptying. GLP-1 secretion is stimulated by luminal oleic acid (OA), which crosses the cell membrane by an unknown mechanism. We hypothesized that L cell fatty acid transport proteins (FATPs) are essential for OA-induced GLP-1 release. Therefore, the murine GLUTag L cell model was used for immunoblotting, [3H]OA uptake assay, and GLP-1 secretion assay as determined by radioimmunoassay following treatment with OA ± phloretin, sulfo- N-succinimidyl oleate, or siRNA against FATP4. FATP4−/− and cluster-of-differentiation 36 (CD36)−/− mice received intraileal OA, and plasma GLP-1 was measured by sandwich immunoassay. GLUTag cells were found to express CD36, FATP1, FATP3, and FATP4. The cells demonstrated specific 3H[OA] uptake that was dose-dependently inhibited by 500 and 1,000 μM unlabeled OA ( P < 0.001). Cell viability was not altered by treatment with OA. Phloretin and sulfo- N-succinimidyl oleate, inhibitors of protein-mediated transport and CD36, respectively, also decreased [3H]OA uptake, as did knockdown of FATP4 by siRNA transfection ( P < 0.05–0.001). OA dose-dependently increased GLP-1 secretion at 500 and 1,000 μM ( P < 0.001), whereas phloretin, sulfo- N-succinimidyl oleate, and FATP4 knockdown decreased this response ( P < 0.05–0.01). FATP4−/− mice displayed lower plasma GLP-1 at 60 min in response to intraileal OA ( P < 0.05), whereas, unexpectedly, CD36−/− mice displayed higher basal GLP-1 levels ( P < 0.01) but a normal response to intraileal OA. Together, these findings demonstrate a key role for FATP4 in OA-induced GLP-1 secretion from the murine L cell in vitro and in vivo, whereas the precise role of CD36 remains unclear.

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A Novel Human Neuronal Cell Model to Study Iron Accumulation in Parkinson’s Disease

Journal of Alzheimer’s Disease & Parkinsonism ◽

10.4172/2161-0460.1000461 ◽

2019 ◽

Vol 09 (01) ◽

Cited By ~ 1

Author(s):

Kosha J Mehta ◽

Bushra Y Ahmed ◽

Sebastien JC Farnaud

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Cell Model ◽

Neuronal Cell ◽

Iron Accumulation ◽

Human Neuronal Cell

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Glucagon-Like Peptide-1 Receptor Agonist, Exendin-4, Regulates Feeding-Associated Neuropeptides in Hypothalamic Neurons in Vivo and in Vitro

Endocrinology ◽

10.1210/en.2011-1795 ◽

2012 ◽

Vol 153 (5) ◽

pp. 2208-2222 ◽

Cited By ~ 42

Author(s):

Prasad S. Dalvi ◽

Anaies Nazarians-Armavil ◽

Matthew J. Purser ◽

Denise D. Belsham

Keyword(s):

Neuropeptide Y ◽

Paraventricular Nucleus ◽

Arcuate Nucleus ◽

Neuronal Cell ◽

Reduce Food Intake ◽

Hypothalamic Neurons ◽

Melanocyte Stimulating Hormone ◽

Glucagon Like Peptide ◽

Glucagon Like Peptide 1 ◽

Stimulating Hormone

Exendin-4, a long-acting glucagon-like peptide-1 receptor (GLP-1R) agonist, is a potential regulator of feeding behavior through its ability to inhibit gastric emptying, reduce food intake, and induce satiety. GLP-1R activation by exendin-4 induces anorexia; however, the specific populations of neuropeptidergic neurons activated by exendin-4 within the hypothalamus, the central regulator of energy homeostasis, remain unclear. This study determines whether exendin-4 regulates hypothalamic neuropeptide expression and explores the signaling mechanisms involved. The distribution and quantity of exendin-4-induced c-Fos immunoreactivity were evaluated to determine activation of α-melanocyte-stimulating hormone/proopiomelanocortin, neuropeptide Y, neurotensin (NT), and ghrelin neurons in hypothalamic nuclei during exendin-4-induced anorexia in mice. Additionally, exendin-4 action on NT and ghrelin transcript regulation was examined in immortalized hypothalamic neurons. With anorexia induced by intracerebroventricular exendin-4, α-melanocyte-stimulating hormone/proopiomelanocortin and neuropeptide Y neurons were activated in the arcuate nucleus, with simultaneous activation of NT-expressing neurons in the paraventricular nucleus, and ghrelin-expressing neurons in the arcuate nucleus, paraventricular nucleus, and periventricular hypothalamus, suggesting that neurons in one or more of these areas mediate the anorexic action of exendin-4. In the hypothalamic neuronal cell models, exendin-4 increased cAMP, cAMP response element-binding protein/activating transcription factor-1 and c-Fos activation, and via a protein kinase A-dependent mechanism regulated NT and ghrelin mRNA expression, indicating that these neuropeptides may serve as downstream mediators of exendin-4 action. These findings provide a previously unrecognized link between central GLP-1R activation by exendin-4 and the regulation of hypothalamic NT and ghrelin. Further understanding of this central GLP-1R activation may lead to safe and effective therapeutics for the treatment of metabolic disorders.

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Short-term sleep deprivation with nocturnal light exposure alters time-dependent glucagon-like peptide-1 and insulin secretion in male volunteers

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00298.2015 ◽

2016 ◽

Vol 310 (1) ◽

pp. E41-E50 ◽

Cited By ~ 39

Author(s):

Manuel Gil-Lozano ◽

Paola M. Hunter ◽

Lucy-Ann Behan ◽

Bojana Gladanac ◽

Robert F. Casper ◽

...

Keyword(s):

Sleep Deprivation ◽

Cell Model ◽

Light Exposure ◽

Time Dependent ◽

Mrna Levels ◽

Short Term ◽

Male Volunteers ◽

L Cell ◽

Glucagon Like Peptide ◽

Glucagon Like Peptide 1

The intestinal L cell is the principal source of glucagon-like peptide-1 (GLP-1), a major determinant of insulin release. Because GLP-1 secretion is regulated in a circadian manner in rodents, we investigated whether the activity of the human L cell is also time sensitive. Rhythmic fluctuations in the mRNA levels of canonical clock genes were found in the human NCI-H716 L cell model, which also showed a time-dependent pattern in their response to well-established secretagogues. A diurnal variation in GLP-1 responses to identical meals (850 kcal), served 12 h apart in the normal dark (2300) and light (1100) periods, was also observed in male volunteers maintained under standard sleep and light conditions. These findings suggest the existence of a daily pattern of activity in the human L cell. Moreover, we separately tested the short-term effects of sleep deprivation and nocturnal light exposure on basal and postprandial GLP-1, insulin, and glucose levels in the same volunteers. Sleep deprivation with nocturnal light exposure disrupted the melatonin and cortisol profiles and increased insulin resistance. Moreover, it also induced profound derangements in GLP-1 and insulin responses such that postprandial GLP-1 and insulin levels were markedly elevated and the normal variation in GLP-1 responses was abrogated. These alterations were not observed in sleep-deprived participants maintained under dark conditions, indicating a direct effect of light on the mechanisms that regulate glucose homeostasis. Accordingly, the metabolic abnormalities known to occur in shift workers may be related to the effects of irregular light-dark cycles on these glucoregulatory pathways.

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