Anorexigenic Hormones Leptin, Insulin, and α-Melanocyte-Stimulating Hormone Directly Induce Neurotensin (NT) Gene Expression in Novel NT-Expressing Cell Models

Cui, Hong; Cai, Fei; Belsham, Denise D.

doi:10.1523/jneurosci.2269-05.2005

Cited by 53 publications

(57 citation statements)

References 70 publications

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“…Chromatin immunoprecipitation (ChIP) assays were performed using previously described methodology (Cui et al, 2005). Cells were cross-linked with 1% formaldehyde for 10 min at room temperature and then washed with ice-cold PBS.…”

Section: Methodsmentioning

confidence: 99%

Estrogen Facilitates both Phosphatidylinositol 3-Kinase/Akt and ERK1/2 Mitogen-Activated Protein Kinase Membrane Signaling Required for Long-Term Neuropeptide Y Transcriptional Regulation in Clonal, Immortalized Neurons

Titolo¹,

Mayer²,

Dhillon³

et al. 2008

Journal of Neuroscience

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It is established that increases in neuropeptide Y (NPY) expression are associated with hyperphagia and obesity. These effects can be reversed by estrogen, a recognized anorexigen. We found that 17␤-estradiol (E 2 ) regulates biphasic NPY gene expression in a clonal, immortalized hypothalamic cell line, N-38, through estrogen receptor (ER) action at the level of the NPY promoter. However, rapid, nongenomic actions of estrogen, linked to the phosphatidylinositol 3-kinase (PI3-K)/Akt and ERK1/2 mitogen-activated protein kinase (MAPK) pathways, may also play a role. We therefore examined the changes in the phosphorylation status of Akt, ERK1/2, and cAMP response element-binding protein (CREB) after treatment with 10 nM E 2 in the N-38 neurons and found activation of these signaling proteins within 5-30 min. We also demonstrated possible cross talk between the estrogen-activated PI3-K/Akt and MAPK/extracellular signal-regulated kinase pathways using pharmacological inhibitors. We find that only ER␣ is involved in the early signaling events using the ER␣ agonist 4,4Ј,4Љ-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol and the ER␤ agonist 2,3-bis(4-hydroxyphenyl)-propionitrile. Furthermore, we can detect colocalization of ER␣ and caveolin-1, a membrane-associated signaling protein. Remarkably, we find that the membrane-mediated events are critical for the long-term estrogen-mediated repression of NPY gene expression that can be mapped to within Ϫ97 bp of the NPY promoter. To link the early signaling events to downstream effectors, we detected induction of c-fos and inactivation of MSK-1 by estrogen and binding of CREB to this minimal promoter region. These observations suggest that rapid estrogenmediated signaling is mediated by ER␣, and the signal transduction events potentiate the genomic actions of estrogen on NPY gene expression in the N-38 NPY neurons.

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Section: Methodsmentioning

confidence: 99%

Estrogen Facilitates both Phosphatidylinositol 3-Kinase/Akt and ERK1/2 Mitogen-Activated Protein Kinase Membrane Signaling Required for Long-Term Neuropeptide Y Transcriptional Regulation in Clonal, Immortalized Neurons

Titolo¹,

Mayer²,

Dhillon³

et al. 2008

Journal of Neuroscience

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“…Immortalized cell lines were generated as described (Belsham et al 2004, Cui et al 2005. Briefly, hypothalami were harvested and dissected from mice at embryonic day 15 (E15), E17, and E18.…”

Section: Cell Immortalization and Subcloningmentioning

confidence: 99%

“…Cell protein was prepared essentially as described previously (Cui et al 2005). Cell protein was collected in 1!…”

Section: Sds-page and Western Blot Analysismentioning

confidence: 99%

“…These cell models were generated by retroviral transfer of T-antigen into embryonic mouse primary hypothalamic cell cultures, with subsequent subcloning to ensure pure clonal cell lines (Belsham et al 2004). We used these cell lines to determine the effects of peripheral signals on gene expression and secretion (Belsham et al 2004, Cui et al 2005, Titolo et al 2006. Using one of these cell models expressing POMC, we demonstrate the expression of functional glucose-sensing machinery, that these cells specifically respond to glucose, and that glucose itself can regulate neuropeptide gene expression.…”

Section: Introductionmentioning

confidence: 99%

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Glucose regulates AMP-activated protein kinase activity and gene expression in clonal, hypothalamic neurons expressing proopiomelanocortin: additive effects of leptin or insulin

Cai¹,

Gyulkhandanyan²,

Wheeler³

et al. 2007

Journal of Endocrinology

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The mammalian hypothalamus comprises an array of phenotypically distinct cell types that interpret peripheral signals of energy status and, in turn, elicits an appropriate response to maintain energy homeostasis. We used a clonal representative hypothalamic cell model expressing proopiomelanocortin (POMC; N-43/5) to study changes in AMPactivated protein kinase (AMPK) activity and glucose responsiveness. We have demonstrated the presence of cellular machinery responsible for glucose sensing in the cell line, including glucokinase, glucose transporters, and appropriate ion channels. ATP-sensitive potassium channels were functional and responded to glucose. The N-43/5 POMC neurons may therefore be an appropriate cell model to study glucose-sensing mechanisms in the hypothalamus. In N-43/5 POMC neurons, increasing glucose concentrations decreased phospho-AMPK activity. As a relevant downstream effect, we found that POMC transcription increased with 2 . 8 and 16 . 7 mM glucose. Upon addition of leptin, with either no glucose or with 5 mM glucose, we found that leptin decreased AMPK activity in N-43/5 POMC neurons, but had no significant effect at 25 mM glucose, whereas insulin decreased AMPK activity at only 5 mM glucose. These results demonstrate that individual hypothalamic neuronal cell types, such as the POMC neuron, can have distinct responses to peripheral signals that relay energy status to the brain, and will therefore be activated uniquely to control neuroendocrine function.

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“…2C) we evaluated the effects of insulin on four separate cell lines, the mHypoE-36/1, -38, -39 and mHypoE-46 neurons. [18][19][20] Insulin administration to the cell lines led to an increase in the anorexigenic NT; and a decrease in the orexigenic neuropeptides: NPY, AgRP and preproghrelin. Studies within the anorexigenic NT-expressing mHypoE-36/1 and mHypoE-39 neurons demonstrated an approximate 1.5-fold increase in NT mRNA levels following 10 or 100 nM treatment with insulin and α-MSH, but not NPY (Fig.…”

Section: Insulin Signaling and Downstream Effects On Neuropeptide Mrnmentioning

confidence: 97%

Nutrient sensing and insulin signaling in neuropeptide-expressing immortalized, hypothalamic neurons: A cellular model of insulin resistance

Fick¹,

Belsham²

2010

Cell Cycle

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O besity and type 2 diabetes mellitus represent a significant global health crisis. These two interrelated diseases are typified by perturbed insulin signaling in the hypothalamus. Using novel hypothalamic cell lines, we have begun to elucidate the molecular and intracellular mechanisms involved in the hypothalamic control of energy homeostasis and insulin resistance. In this review, we present evidence of insulin and glucose signaling pathways that lead to changes in neuropeptide gene expression. We have identified some of the molecular mechanisms involved in the control of de novo hypothalamic insulin mRNA expression. And finally, we have defined key mechanisms involved in the etiology of cellular insulin resistance in hypothalamic neurons that may play a fundamental role in cases of high levels of insulin or saturated fatty acids, often linked to the exacerbation of obesity and diabetes.

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Anorexigenic Hormones Leptin, Insulin, and α-Melanocyte-Stimulating Hormone Directly Induce Neurotensin (NT) Gene Expression in Novel NT-Expressing Cell Models

Abstract: Neurotensin (NT) is implicated in the regulation of energy homeostasis, in addition to its many described physiological functions. NT is postulated to mediate, in part, the effects of leptin in the hypothalamus. We generated clonal,

Cited by 53 publications

References 70 publications

Estrogen Facilitates both Phosphatidylinositol 3-Kinase/Akt and ERK1/2 Mitogen-Activated Protein Kinase Membrane Signaling Required for Long-Term Neuropeptide Y Transcriptional Regulation in Clonal, Immortalized Neurons

Estrogen Facilitates both Phosphatidylinositol 3-Kinase/Akt and ERK1/2 Mitogen-Activated Protein Kinase Membrane Signaling Required for Long-Term Neuropeptide Y Transcriptional Regulation in Clonal, Immortalized Neurons

Glucose regulates AMP-activated protein kinase activity and gene expression in clonal, hypothalamic neurons expressing proopiomelanocortin: additive effects of leptin or insulin

Nutrient sensing and insulin signaling in neuropeptide-expressing immortalized, hypothalamic neurons: A cellular model of insulin resistance

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