Stimulation of Amylase Release by Orexin is Mediated by Orexin 2 Receptor in AR42J Cells

Harris, D. M.; Go, Vay Liang W.; Reeve, Joseph R.; Wu, Sheng-Bing

doi:10.1097/00006676-200211000-00014

Cited by 15 publications

(13 citation statements)

References 16 publications

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“…Indeed, RT-PCR experiments support the presence of OX 2 R in AR42J cells, whereas no transcript for OX 1 R could be detected. This is in line with a previous report on AR42J cells (19). Further pharmacological studies using the few currently available tools for orexin receptors also argue for a specific role of OX 2 R in AR42J cells because the proapoptotic effect of orexin can be mimicked by the specific OX 2 R agonist [Ala 11, d-Leu 15 ]orexin-B (21) but cannot be reversed by the OX 1 R antagonists SB 33487 (22,23) or SB 408124 (24).…”

Section: Discussionsupporting

confidence: 91%

“…Recombinant CHO/OX 1 R and CHO/OX 2 R cell lines (1) stably expressing rat orexin receptor type 1 (OX 1 R) or rat orexin receptor type 2 (OX 2 R) were grown in F12 medium containing l-glutamine, supplemented with 5% fetal calf serum (FCS), 100 g/ml streptomycin, 100 U/ml penicillin, and 0.7 mg/ml geneticin as described (18). The rat pancreatic acinar cell line AR42J (19) was obtained from American Type Culture Collection (CRL 1492; Manassas, VA). AR42J cells were grown in RPMI 1640 (developed at Roswell Park Memorial Institute) containing l-glutamine supplemented with 10% FCS, 100 g/ml streptomycin, and 100 U/ml penicillin.…”

Section: Cell Culturementioning

confidence: 99%

“…After 48 h, apoptotic cell staining was performed according to the manufacturer's instructions using a Guava PCA system. pancreatic acinar AR42J cell line (19), we tested this cell line. As previously discussed, reliable orexin binding assays are still unavailable (18); the nature of orexin receptor subtype(s) expressed in AR42J cells was thus checked by RT-PCR.…”

Section: The Ox 2 R-mediated Antigrowth and Proapoptotic Effects Of Omentioning

confidence: 99%

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Orexin-Induced Apoptosis: The Key Role of the Seven-Transmembrane Domain Orexin Type 2 Receptor

et al. 2006

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3). Orexins were initially characterized in hypothalamic neurons, which project to and excite many brain areas (4, 5). Orexin neurons have functional interactions with hypothalamic feeding pathways and monoaminergic-cholinergic centers to provide a link between energy balance and the brain mechanisms that coordinate sleep/wakefulness states and motivated behavior such as food seeking (6 -10). In this context, the characterization of orexin deficiency in narcoleptic patients (11) and mutation of orexin receptors in canine (12) and murine (13) narcolepsy emphasized the key role of orexins in the regulation of sleep/wakefulness. More recent studies showed that orexins are not restricted to the hypothalamus but are also expressed in peripheral tissues including adrenals, gastrointestinal tract, or endocrine pancreas (for review see Ref.3). Orexins alter endocrine function (14) by increasing glucagon secretion and decreasing glucose-stimulated insulin release from pancreatic islets (15), suppressing GH secretion (16), or regulating corticotropin release (14).Two orexin receptor subtypes OX 1 R and OX 2 R have been cloned (1, 2). They are serpentine G protein-coupled receptors that bind both orexins with poor selectivity and appear to be coupled to calcium mobilization (1). In humans, OX 1 R and OX 2 R show 64% amino acid identity more particularly present in transmembrane domains whereas the N-terminal extracellular domain and C-terminal tail exhibit very weak sequence identity (3). Orexin receptors have been described in the central nervous system as well as peripheral organs (3,17).Recently we discovered a new unexpected aspect of orexins as potent proapoptotic peptides (18). We showed that orexin-A and orexin-B induce a drastic apoptosis in human colon cancer cell lines in culture resulting in massive reduction of cell growth. The effect was extended to human neuroblastoma cells (18). The OX 1 R but not the OX 2 R is expressed in colon cancer and neuroblastoma cells and was shown to be responsible for the proapoptotic effect of orexins. The role of OX 1 R in mediating apoptosis was further demonstrated by transfecting CHO cells with OX 1 R cDNA, which conferred the ability of orexins to promote apoptosis (18). The OX 1 R-mediated apoptosis has been shown to be associated with cytochrome c release into cytosol and activation of caspase-3 and caspase-7 (18).As mentioned above a second orexin receptor OX 2 R has been cloned (1). Like the OX 1 R, it is expressed in both the central nervous system and peripheral organs (3,17). However, its role in orexin-induced apoptosis is still unknown. In the present paper, we explored the role of OX 2 R with respect to apoptosis. We show that transfection of OX 2 R cDNA in

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Section: Discussionsupporting

confidence: 91%

Section: Cell Culturementioning

confidence: 99%

Section: The Ox 2 R-mediated Antigrowth and Proapoptotic Effects Of Omentioning

confidence: 99%

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Orexin-Induced Apoptosis: The Key Role of the Seven-Transmembrane Domain Orexin Type 2 Receptor

et al. 2006

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“…Orexin A and orexin B induces a phospholipase C (PLC)-mediated release of calcium from intracellular storages in different cell lines over expressing orexin 1 receptor (OX1R) and OX2R [32,34]. The OX1R linked to the influx of Ca 2+ may go through receptor-operated calcium channels and conventional phospholipase C (PLC)-Ca 2+ release-store-operated Ca 2+ channel (SOC) pathways [35] and involves diacylglycerol-activated transient receptor potential canonical (TRPC) channels in neuronal cells [36].…”

Section: Introductionmentioning

confidence: 99%

OX2R activation induces PKC-mediated ERK and CREB phosphorylation

Guo

Feng

2012

Experimental Cell Research

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Deficiencies in brain orexins and components of mitogen activated protein kinase (MAPK) signaling pathway have been reported in either human depression or animal model of depression. Brain administration of orexins affects behaviors toward improvement of depressive symptoms. However, the documentation of endogenous linkage between orexin receptor activation and MAPK signaling pathway remains to be insufficient. In this study, we report the effects of orexin 2 receptor (OX2R) activation on cell signaling in CHO cells over-expressing OX2R and in mouse hypothalamus cell line CLU172. Short-term extracellular signal-regulated kinase (ERK) phosphorylation and long-term cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) phosphorylation were subsequently observed in CHO cells that over-express OX2R while 20 min of ERK phosphorylation was significantly detected in mouse adult hypothalamus neuron cell line CLU172. Orexin A, which can also activate OX2R, mediated ERK phosphorylation was as the same as orexin B in CHO cells. A MAPK inhibitor eliminated ERK phosphorylation but not CREB phosphorylation in CHO cells. Also, ERK and CREB phosphorylation was not mediated by protein kinase A (PKA) or calmodulin kinase (CaMK). However, inhibition of protein kinase C (PKC) by GF 109203X eliminated the phosphorylation of ERK and CREB in CHO cells. A significant decrease in ERK and CREB phosphorylation was observed with 1 μM GF 109203X pre-treatment indicating that the conventional and novel isoforms of PKC are responsible for CREB phosphorylation after OX2R activation. In contrast, ERK phosphorylation induced by orexin B in CLU172 cells cannot be inhibited by 1 μM of protein kinase C inhibitor. From above observation we conclude that OX2R activation by orexin B induces ERK and CREB phosphorylation and orexin A played the same role as orexin B. Several isoforms of PKC may be involved in prolonged CREB phosphorylation. Orexin B induced ERK phosphorylation in mouse hypothalamus neuron cells differs from CHO cell line and cannot be inhibited by PKC inhibitor GF 109203X. And hypothalamus neuron cells may use different downsteam pathway for orexin B induced ERK phosphorylation. This result supports findings that orexins might have anti-depressive roles.

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“…Moreover, it would not be possible to make extracellular recordings from PeH-RVLM neurons. Orexin receptors are expressed both in the central nervous system (CNS) and periphery (50), and we opted for a direct pharmacological approach in the CNS. Interventions that delete the OX 2 -R gene would also affect the receptors located outside the CNS, complicating the interpretation of our results.…”

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confidence: 99%

Activation of Medulla-Projecting Perifornical Neurons Modulates the Adrenal Sympathetic Response to Hypoglycemia: Involvement of Orexin Type 2 (OX2-R) Receptors

2015

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Iatrogenic hypoglycemia in response to insulin treatment is commonly experienced by patients with type 1 diabetes and can be life threatening. The body releases epinephrine in an attempt to counterregulate hypoglycemia, but the neural mechanisms underlying this phenomenon remain to be elucidated. Orexin neurons in the perifornical hypothalamus (PeH) project to the rostral ventrolateral medulla (RVLM) and are likely to be involved in epinephrine secretion during hypoglycemia. In anesthetized rats, we report that hypoglycemia increases the sympathetic preganglionic discharge to the adrenal gland by activating PeH orexin neurons that project to the RVLM (PeH-RVLM). Electrophysiological characterization shows that the majority of identified PeH-RVLM neurons, including a subpopulation of orexin neurons, are activated in response to hypoglycemia or glucoprivation. Furthermore, the excitatory input from the PeH is mediated by orexin type 2 receptors in the RVLM. These results suggest that activation of orexin PeH-RVLM neurons and orexin type 2 receptors in the RVLM facilitates epinephrine release by increasing sympathetic drive to adrenal chromaffin cells during hypoglycemia.

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Stimulation of Amylase Release by Orexin is Mediated by Orexin 2 Receptor in AR42J Cells

Abstract: Our data demonstrate that OX2R mediates Ca -dependent amylase release in AR42J cells, suggesting that Orexins may have secretory functions in pancreatic tumor cells.

Cited by 15 publications

References 16 publications

Orexin-Induced Apoptosis: The Key Role of the Seven-Transmembrane Domain Orexin Type 2 Receptor

Orexin-Induced Apoptosis: The Key Role of the Seven-Transmembrane Domain Orexin Type 2 Receptor

OX2R activation induces PKC-mediated ERK and CREB phosphorylation

Activation of Medulla-Projecting Perifornical Neurons Modulates the Adrenal Sympathetic Response to Hypoglycemia: Involvement of Orexin Type 2 (OX2-R) Receptors

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