Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Leptin exerts its effects by interacting with specific membrane receptors (Ob-R). We studied the exact localization of long intracellular domain form (Ob-Rb) in human brain. In addition, we analyzed the regulatory features of Ob-Rb expression in two neuroblastoma cell lines. The Ob-Rb mRNAs were abundant in putamen, frontal lobe, medulla, cerebral cortex, cerebellum, thalamus, hippocampus, corpus callosum, caudate nucleus, and amygdala, indicating that Ob-Rb transcripts are expressed differently from that of other Ob-R isoforms. In SK-N-MC cells, the expression of Ob-Rb mRNA was induced by increasing doses of insulin, and the maximum amount of mRNA expression was 9.4-fold higher in the presence of insulin (100 nM for 24 h), compared to the absence of insulin. In IMR32 cells, the transcripts were increased 4.0-fold when cells were incubated with 1 nM of insulin for 48 h. In contrast, Ob-Rb expression in IMR32 cells decreased to 18% of control following a 24-h incubation period with 50 ng/mL of leptin, compared to incubation in the absence of leptin. These results indicate that expression of Ob-Rb is differentially regulated by inhibitory signals of energy balance in neuroblastoma cells. The identification of the novel regulatory mechanisms involving the Ob-Rb isoform by insulin and leptin now makes it possible to elucidate the underlying mechanisms involving increased food intake and uncontrolled energy balance associated with leptin resistance in obese individuals.
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PMID:Differential regulation of leptin receptor expression by insulin and leptin in neuroblastoma cells. 1081 26

Neuropeptide Y (NPY) participates in the regulation of reproduction and food intake. The adipose-secreted hormone, leptin, has also been involved in these processes, and has been shown to exert its effects in part by controlling NPY synthesis and release at the hypothalamic level. In the present study, we utilized the SH-SY5Y human neuroblastoma cell line, to study the leptin-NPY interrelationships. SH-SY5Y cells were found to express leptin receptors (RT-PCR and Western blot analyses). A 24-h treatment with leptin at different concentrations did not affect NPY gene expression, but resulted in a stimulation of NPY release. This stimulated secretion was blocked by the combined treatment with leptin and the muscarinic agonist carbachol or the phorbol ester TPA. Leptin and carbachol also caused an increased intracellular content of NPY. In conclusion, the SH-SY5Y human neuroblastoma cell line appears to be a suitable in vitro model for studying the pharmacological effects of leptin on the biosynthesis and secretion of NPY.
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PMID:Control of the expression of human neuropeptide Y by leptin: in vitro studies. 1128 96

Many factors regulate nervous system development, including complex cross-talk between local neuroendocrine systems. The adipocyte-secreted hormone leptin, mainly known for its key roles in nutrition and reproductive balance, may also be involved in neuroanatomical organization, myelination processes, and neuronal/glia maturation. SK-N-SH-SY5Y neuroblastoma cells were employed as an in vitro model of human neuronal cells to determine whether leptin exerts neuroprotective activities. We show that SH-SY5Y cells express leptin, the long and short isoforms of the leptin receptor (ObRl, ObRs). In SH-SY5Y cells, leptin induced signal transducer and activator of transcription (STAT)-3 phosphorylation and suppressor of cytokine signaling-3 mRNA expression. Leptin dose-dependently increased cell number (up to 200% at 1 microm by 48 h, P < 0.01), and at 24-48 h, leptin at 100 nm increased SH-SY5Y cell number by 30-50%, respectively. SH-SY5Y cell viability was reduced in serum-free conditions at 24 h, and addition of leptin at 100 nm significantly reduced apoptosis by approximately 20% (P < 0.001). Leptin's antiapoptotic activity required Janus kinase/STAT, MAPK, and phosphatidylinositol-3-kinase activation because the antiapoptotic effects of leptin were abolished, and caspase-3 immunoreactivity increased in the presence of the specific blockers AG490, U0126, or LY294002. Gene array demonstrated that leptin inhibits apoptosis via potent down-regulation of caspase-10 and TNF-related apoptosis-inducing ligand. Our data thus demonstrate, for the first time, that leptin stimulates, in a time- and dose-dependent manner, neuroblastoma cell proliferation and that the underlying mechanisms involve suppression of apoptosis via the Janus kinase-STAT, phosphatidylinositol-3 kinase, and MAPK pathways that culminate altogether in the down-regulation of the apoptotic factors caspase-10 and TNF-related apoptosis-inducing ligand.
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PMID:Antiapoptotic effects of leptin in human neuroblastoma cells. 1516 21

We have shown recently that in human T lymphocytes, leptin stimulates activity and expression of the endocannabinoid-degrading enzyme fatty acid amide hydrolase (FAAH), through STAT3 (signal transducer and activator of transcription 3) and its CRE (cAMP response element)-like transcriptional target in the FAAH promoter [Maccarrone, M., Di Rienzo, M., Finazzi-Agro, A., & Rossi, A. (2003) J. Biol. Chem. 278, 13318-13324]. We have also shown that progesterone, alone or additively with leptin, up-regulates the FAAH gene in human T-cells, through the Ikaros transcription factor [Maccarrone, M., Bari, M., Di Rienzo, M., Finazzi-Agro, A., & Rossi, A. (2003) J. Biol. Chem. 278, 32726-32732]. Here, we extend these observations to immortalized human lymphoma U937 cells, where stimulation of FAAH by leptin (up to approximately 300% of the controls) involves binding to a leptin receptor (Kd = 2.0 +/- 0.1 nm, Bmax = 382 +/- 5 fmol.mg protein(-1), apparent molecular mass of approximately 110 kDa), and stimulation by progesterone involves an intracellular receptor of approximately 120 kDa. Unlike FAAH, the other proteins of the endocannabinoid system are not modulated by the two hormones. Interestingly, human neuroblastoma CHP100 cells also have a leptin receptor (approximately 110 kDa, Kd = 2.2 +/- 0.2 nm, Bmax = 339 +/- 8 fmol.mg protein(-1)), a progesterone receptor (approximately 120 kDa), STAT3 and Ikaros, yet their FAAH is not activated by leptin or progesterone. These data, corroborated by transient expression and electrophoretic mobility-shift assays, demonstrate an unprecedented cell-specific regulation of the FAAH gene, which has important implications for the control of tone and activity of AEA along the neuroimmune axis.
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PMID:Differential regulation of fatty acid amide hydrolase promoter in human immune cells and neuronal cells by leptin and progesterone. 1560 54

Leptin and insulin are major signals to the hypothalamus to regulate energy homoeostasis and body adiposity. IR (insulin receptors) and leptin receptors (long isoform, ObRb) share a number of signalling cascades, such as JAK2/STAT-3 (Janus kinase 2/signal transduction and activator of transcription 3) and PI3K (phosphoinositide 3-kinase); the cross-talk between IR and ObRb have been described previously in non-neuronal cells. Differentiated human neuroblastoma (SH-SY5Y) cells express endogenous ObR and IR, and respond to leptin and insulin with stimulation of STAT-3 and MAPK (mitogen-activated protein kinase) phosphorylation, and PI3K activity. Insulin or leptin pre-treatment of SH-SY5Y cells increased basal STAT-3 phosphorylation, but abolished the acute effect of these hormones, and, interestingly, leptin pre-treatment abolished insulin effect and vice versa. Similar results were obtained for MAPK phosphorylation, but leptin or insulin pre-treatment did not completely abolish the acute effect of insulin or leptin. We have also showed that insulin and leptin are able to activate PI3K through IRS-1 (insulin receptor substrate 1) and IRS-2 respectively. Furthermore, leptin or insulin pre-treatment increased basal PI3K activity and IRS-1 or IRS-2 association with p85 and abolished acute insulin or leptin effect, in addition to the down-regulation of IRS-1 and IRS-2. Finally, insulin pre-treatment reduced leptin binding by approx. 60%, and leptin pre-treatment reduced the expression of insulin receptor by 40% in SH-SY5Y cells, which most likely accounts for the cross down-regulation of leptin and insulin receptors. These results provide evidence to suggest cross down-regulation of leptin and insulin receptors at both receptor and downstream signalling levels. This finding may contribute to the understanding of the complex relationship between leptin resistance and insulin resistance at the neuronal level.
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PMID:Cross down-regulation of leptin and insulin receptor expression and signalling in a human neuronal cell line. 1571 21

We have recently reported that leptin (L) and progesterone (P) stimulate the activity and the expression of the endocannabinoid-degrading enzyme anandamide hydrolase (fatty acid amide hydrolase, FAAH) in human lymphoma U937 cells, but not in human neuroblastoma CHP100 cells. We have also shown that leptin and progesterone do not affect the proteins of the endocannabinoid system that synthesize and transport AEA. Here, we have summarized these findings, and have extended them by investigating the effect of leptin and progesterone on the endogenous levels of AEA. We show that leptin and progesterone significantly reduce AEA content in U937 cells (down to approximately 20% and approximately 50% of the controls, respectively), whereas they are ineffective on AEA levels in CHP100 cells. In addition, we show that leptin and progesterone prevent the pro-apoptotic activity of AEA in U937 cells, reducing DNA fragmentation by approximately 50% and approximately 35% compared to controls, respectively. Instead, neither hormone affects apoptosis induced by AEA in CHP100 cells. Since the anti-apoptotic activity of leptin and progesterone parallels their effect on FAAH, it can be suggested that enhanced degradation of AEA is the means to protect U937 cells against the toxicity of this compound. Altogether, these data suggest that a cell-specific regulation of FAAH gene might modulate the apoptotic potential of endocannabinoids along the neuroimmune axis. These findings might be relevant for the development of cell-selective drugs targeted towards FAAH.
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PMID:Further insights into the regulation of human FAAH by progesterone and leptin implications for endogenous levels of anandamide and apoptosis of immune and neuronal cells. 1615 99

Human peripheral gammadelta-T-cells are able to induce cytolysis of neuroblastoma (Nb) tumor cells. Besides innate effector functions against infected cells and tumors, gammadelta-T-cells are involved in T-helper 1/T-helper 2 (TH1/TH2) differentiation of alphabeta-T-cells. However, as different gammadelta-T-cell subsets vary considerably in their functional properties, the aim of the present study was to define repertoires of cytokines, chemokines, and angiogenic factors of in vitro expanded Vdelta1+ and Vdelta2+ T cells in response to Nb. After short-term culture, both subsets released TH1 [interleukin (IL)-2, interferon (IFN)-gamma, IL-12, tumor necrosis factor (TNF)-alpha, TNF-beta)] and TH2 cytokines (IL-4, -5, -6, -10, -13, Vdelta1 also transforming growth factor (TGF)-beta, chemokines (I-309, monocyte chemotactic protein (MCP)-1-3, regulated upon activation, normal T-cell expressed and secreted), ILs (IL-1, -8, -15), cytokines (leptin) as well as angiogenic growth factors [angiogenin (ANG), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), Insulin-like growth factor (IGF)-I]. These molecules were expressed at higher levels in Vdelta2+ than Vdelta1+ T cells. Nb challenge changed protein expression. TH2 cytokine and IFN-gamma release was blocked in both gammadelta-T-cell subsets. In Vdelta2 gammadelta-T-cells, TH1 cytokines were down-regulated and tumor growth-promoting factors (ANG, VEGF, EGF, and IGF-I) were strongly up-regulated. In contrast, Vdelta1+ gammadelta-T-cells stopped the release of tumor-supportive factors and tolerogenic TGF-beta, and strongly up-regulated TNF-alpha, TNF-beta, MCP-1 and -2 and maintained their IL-2 production. In summary, our data show that after being challenged with Nb cells, propagated Vdelta1+ rather than Vdelta2+ T cells support antitumor responses by secretion of proinflammatory cytokines. Furthermore, in contrast to other cell types, Vdelta1+ T cells do not sustain a growth-promoting or tolerogenic microenvironment. These data make Vdelta1+ T cells an ideal candidate for upcoming immunotherapy trials in Nb.
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PMID:Immune response of human propagated gammadelta-T-cells to neuroblastoma recommend the Vdelta1+ subset for gammadelta-T-cell-based immunotherapy. 1883 98

Growing evidences suggest that obesity is associated with hypothalamic leptin resistance, leading to the alteration of food intake control. Alternative treatment using ciliary neurotrophic factor (CNTF) has been suggested because CNTF exerts a leptin-like effect, even in leptin-resistant states, but the mechanisms by which CNTF maintains this effect are not yet understood. Both leptin and CNTF act in the hypothalamus through similar signaling pathways including janus kinase-2/signal transducer and activator of transcription (STAT)-3 pathway. To explore the differences and interactions between leptin and CNTF signaling pathways, differentiated human neuroblastoma cells (SH-SY5Y) were exposed to either leptin or CNTF and then challenged for each cytokine. Leptin pretreatment completely abolished leptin-dependent STAT-3 and ERK 1/2 phosphorylations without affecting CNTF action. The lack of cross-desensitization between leptin and CNTF signaling pathways occurred despite the induction of suppressor of cytokine signaling-3 in response to both cytokines. Interestingly, leptin as well as insulin induced the expression of phosphotyrosine phosphatase (PTP)-1B, whereas CNTF treatment did not affect its expression. In addition, acute leptin treatment but not CNTF induced PTP-1B expression in mouse hypothalamic arcuate nucleus. Furthermore, the overexpression of human PTP-1B in SH-SY5Y cells completely abolished leptin- and insulin-dependent janus kinase-2, STAT-3, and ERK 1/2 phosphorylations, but CNTF action was not altered. Collectively, our results suggest that PTP-1B constitutes a key divergent element between leptin/insulin and CNTF signaling pathways at the neuronal level, which may constitute a possible mechanism that explains the efficacy of CNTF in leptin-resistant states.
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PMID:Leptin but not ciliary neurotrophic factor (CNTF) induces phosphotyrosine phosphatase-1B expression in human neuronal cells (SH-SY5Y): putative explanation of CNTF efficacy in leptin-resistant state. 1900 9

The adipocyte-derived hormone leptin plays a critical role in a variety of physiological and pathological actions. As such the determination of leptin signal transduction pathways are important both for understanding the molecular mechanisms of leptin action and for identifying sites for possible therapeutic intervention. Since the hypothalamus is the primary site of leptin action, we sought to identify a neuronal-derived human cell line containing the long form of the leptin receptor (OBRb). To this end, we screened several neuroblastoma cell lines and isolated a sub-line of SH-SY5Y cells, which we designated as SH-OBRb, for further studies. We characterized the transduction pathways induced by leptin in SH-OBRb cells and demonstrated that OBRb mediates tyrosine phosphorylation of STAT3, phosphorylation of ERK1/2, but not SAPK/JNK and p38 MAPK, in a dose and time dependent fashion. In addition, Akt appears to be phosphorylated in the basal state and to be insensitive to further activation by leptin. In summary, we have isolated a unique cell line that can be utilized as a model for use in the study of leptin action and molecular mechanisms.
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PMID:Identification and characterization of a leptin-responsive neuroblastoma cell line. 1912 99

The first intron of FTO contains common single nucleotide polymorphisms associated with body weight and adiposity in humans. In an effort to identify the molecular basis for this association, we discovered that FTO and RPGRIP1L (a ciliary gene located in close proximity to the transcriptional start site of FTO) are regulated by isoforms P200 and P110 of the transcription factor, CUX1. This regulation occurs via a single AATAAATA regulatory site (conserved in the mouse) within the FTO intronic region associated with adiposity in humans. Single nucleotide polymorphism rs8050136 (located in this regulatory site) affects binding affinities of P200 and P110. Promoter-probe analysis revealed that binding of P200 to this site represses FTO, whereas binding of P110 increases transcriptional activity from the FTO as well as RPGRIP1L minimal promoters. Reduced expression of Fto or Rpgrip1l affects leptin receptor isoform b trafficking and leptin signaling in N41 mouse hypothalamic or N2a neuroblastoma cells in vitro. Leptin receptor clusters in the vicinity of the cilium of arcuate hypothalamic neurons in C57BL/6J mice treated with leptin, but not in fasted mice, suggesting a potentially important role of the cilium in leptin signaling that is, in part, regulated by FTO and RPGRIP1L. Decreased Fto/Rpgrip1l expression in the arcuate hypothalamus coincides with decreased nuclear enzymatic activity of a protease (cathepsin L) that has been shown to cleave full-length CUX1 (P200) to P110. P200 disrupts (whereas P110 promotes) leptin receptor isoform b clustering in the vicinity of the cilium in vitro. Clustering of the receptor coincides with increased leptin signaling as reflected in protein levels of phosphorylated Stat3 (p-Stat3). Association of the FTO locus with adiposity in humans may reflect functional consequences of A/C alleles at rs8050136. The obesity-risk (A) allele shows reduced affinity for the FTO and RPGRIP1L transcriptional activator P110, leading to the following: 1) decreased FTO and RPGRIP1L mRNA levels; 2) reduced LEPR trafficking to the cilium; and, as a consequence, 3) a diminished cellular response to leptin.
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PMID:Cut-like homeobox 1 (CUX1) regulates expression of the fat mass and obesity-associated and retinitis pigmentosa GTPase regulator-interacting protein-1-like (RPGRIP1L) genes and coordinates leptin receptor signaling. 2103 23


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