Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Expression of receptors for the neuropeptide somatostatin was investigated in vitro in rat and human astrocytes, glioma cell lines, and solid human glial tumors that were all immunopositive for the astrocytic marker glial fibrillary acidic protein. After affinity labelling with a peptide-gold conjugate of known biological activity, somatostatin-binding sites could be visualized at the light-and electron-microscopic level on the surface of glial cells. Glioma cells were generally labeled more strongly than were normal astrocytes and preferentially bound the ligand at their processes and not at their somata as were normal cells. Somatostatin transmembrane receptor (SSTR) subtype expression was probed by reverse transcription-polymerase chain reaction: In rat and human cortical astrocytes and in one glioma cell line (U 118), a pattern of three subtypes (SSTR-1, SSTR-2, and SSTR-4) was detected, whereas, in all other glioma cell lines and in six solid glial tumors investigated, the SSTR-2 subtype was relatively stronger, expressed either alone or in combination with SSTR-1; sometimes SSTR-3 or SSTR-4 was demonstrated in clearly reduced amounts. In astrocytes and gliomas, somatostatin reduced the levels of cyclic AMP elicited by the adenylate cyclase activator forskolin indicating that at least one of the receptor subtypes is negatively linked to adenylate cyclase. In contrast to other cell types, somatostatin did not inhibit the basal or the fetal calf serum-stimulated proliferation of astrocytes, glioma cell lines, or glial tumors in culture. Thus, strong SSTR-2 subtype expression characterizes glial tumors, but somatostatin is ineffective in inhibiting their growth.
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PMID:Expression of somatostatin receptor subtypes in cultured astrocytes and gliomas. 759 83

The effects of somatostatin (SRIF) are mediated through the seven transmembrane receptor family that signals via Gi/Go. To date, five distinct SRIF receptors have been characterized and designated SSTR1-5. We have characterized the SRIF receptor that mediates the increase in [Ca(2+)](i) and insulin secretion in HIT-T15 cells (Simian virus 40-transformed Syrian hamster islets) using high affinity, subtype selective agonists for SSTR1 (L-797,591), SSTR2 (L-779,976), SSTR3 (L-796,778), SSTR4 (L-803,087), SSTR5 (L-817,818) and PRL-2903, a specific SSTR2 antagonist. In the presence of arginine vasopressin (AVP), SRIF increased [Ca(2+)](i) and insulin secretion. Treatment with the SSTR2 agonist L-779,976 resulted in similar responses to SRIF. In addition, L-779,976 increased both [Ca(2+)](i) and insulin secretion in a dose-dependent manner. Treatment with L-779,976 alone did not alter [Ca(2+)](i) or basal insulin secretion. In the presence of AVP, all other SRIF receptor agonists failed to increase [Ca(2+)](i) and insulin secretion. The effects of SRIF and L-779,976 were abolished by the SSTR2 antagonist PRL-2903. Our results suggest that the mechanism underlying SRIF-induced insulin secretion in HIT-T15 cells be mediated through the SSTR2.
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PMID:SSTR2 mediates the somatostatin-induced increase in intracellular Ca(2+) concentration and insulin secretion in the presence of arginine vasopressin in clonal beta-cell HIT-T15. 1208 89

Transcriptional profiling (TP) offers a powerful approach to identify genes activated during memory formation and, by inference, the molecular pathways involved. Trace eyeblink conditioning is well suited for the study of regional gene expression because it requires the hippocampus, whereas the highly parallel task, delay conditioning, does not. First, we determined when gene expression was most regulated during trace conditioning. Rats were exposed to 200 trials per day of paired and unpaired stimuli each day for 4 days. Changes in gene expression were most apparent 24 h after exposure to 200 trials. Therefore, we profiled gene expression in the hippocampus 24 h after 200 trials of trace eyeblink conditioning, on multiple arrays using additional animals. Of 1,186 genes on the filter array, seven genes met the statistical criteria and were also validated by real-time polymerase chain reaction. These genes were growth hormone (GH), c-kit receptor tyrosine kinase (c-kit), glutamate receptor, metabotropic 5 (mGluR5), nerve growth factor-beta (NGF-beta), Jun oncogene (c-Jun), transmembrane receptor Unc5H1 (UNC5H1), and transmembrane receptor Unc5H2 (UNC5H2). All these genes, except for GH, were downregulated in response to trace conditioning. GH was upregulated; therefore, we also validated the downregulation of the GH inhibitor, somatostatin (SST), even though it just failed to meet criteria on the arrays. By during situ hybridization, GH was expressed throughout the cell layers of the hippocampus in response to trace conditioning. None of the genes regulated in trace eyeblink conditioning were similarly affected by delay conditioning, a task that does not require the hippocampus. These findings demonstrate that transcriptional profiling can exhibit a repertoire of genes sensitive to the formation of hippocampal-dependent associative memories.
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PMID:Transcriptional profiling reveals regulated genes in the hippocampus during memory formation. 1254 33

The heptahelical receptor superfamily constitutes the largest single family of transmembrane-signalling molecules that regulate a wide range of physiological processes. The five somatostatin receptors represent a distinct subgroup of this seven transmembrane receptor superfamily. They range in size from 356 to 391 amino acids with 39-57% protein identity between the subtypes with 100 residues strictly conserved among the somatostatin receptor sequences. A high grade of mRNA homology exists in somatostatin receptor subtypes cloned from different species. Following somatostatin receptor binding and functional activity studies, two alternative models of ligand-binding interaction have been hypothesised. One relies on the presence of a binding pocket within the receptor structure constituted by specific amino acids residues, the other denies the presence of such binding structures and suggests that it is the interaction of agonists with specific extracellular and/or transmembrane domains that determine stable receptor structure conformation. Somatostatin receptors, as, indeed, all G-protein-coupled receptors are able to regulate their responsiveness to agonist exposure. This agonist-specific regulation includes three main events, namely, desensitisation, receptor internalisation and receptor degradation. The cell expression of somatostatin receptor subtypes, at the mRNA level, has been characterised in rodent and in human organs with multiple subtype expression in brain and peripheral tissues.
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PMID:Somatostatin receptor subtypes: basic pharmacology and tissue distribution. 1507 6

The human 7-transmembrane receptor GPR7 has sequence similarity to opioid and somatostatin receptors, and can be activated by the recently discovered neuropeptides NPB and NPW. This receptor is highly expressed in the nervous system, with suggested roles in neuroendocrine events and pain signaling. In this study, we investigated whether the GPR7 receptor is expressed in the peripheral nervous system under normal and pathological conditions. A low level of GPR7 receptor was observed in myelin-forming Schwann cells in both normal human and rat nerve, and in primary rat Schwann cell cultures. Peripheral nerve samples taken from patients exhibiting inflammatory/immune-mediated neuropathies showed a dramatic increase of GPR7 receptor expression restricted to myelin-forming Schwann cells. Complementary animal models of immune-inflammatory and ligation-induced nerve injury and neuropathic pain similarly exhibited an increased myelin-associated expression of GPR7 receptor. These results suggest a relationship between the pathogenesis of inflammatory/immune-mediated neuropathies, GPR7 receptor expression, and pain transmission.
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PMID:Schwann cell overexpression of the GPR7 receptor in inflammatory and painful neuropathies. 1560 41

Menetrier's disease is a rare acquired disorder of the fundus and body of the stomach (ie, oxyntic mucosa) characterized by giant hyperplastic folds, protein-losing gastropathy, hypoalbuminemia, increased mucus secretion, and hypochlorhydria. Recent research implicates overproduction of transforming growth factor-alpha with increased signaling of the epidermal growth factor receptor (EGFR) in the pathogenesis. Activation of the EGFR, a transmembrane receptor with tyrosine kinase activity, triggers a cascade of downstream, intracellular signaling pathways that leads to expansion of the proliferative compartment within the isthmus of the oxyntic gland. The diagnosis of Menetrier's disease is based upon characteristic histologic changes, including foveolar hyperplasia, cystic dilation of pits, and reduced numbers of parietal and chief cells. The best treatment for Menetrier's disease is not clear. It seems reasonable to test and treat for cytomegalovirus and Helicobacter pylori, as 1) in children, evidence exists that the disease may be due to cytomegalovirus infection in up to one third of patients; and 2) in adults, there are anecdotal reports of resolution upon H. pylori eradication. More recently, therapies targeting increased signaling of the EGFR have shown promise, including somatostatin analogues and monoclonal antibodies (eg, cetuximab) directed against the EGFR. In refractory cases, gastrectomy is curative.
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PMID:Menetrier's Disease. 1832 37

Saccoglossus kowalevskii (the acorn worm) is a hemichordate belonging to the superphylum of deuterostome bilateral animals. Hemichordates are sister group to echinoderms, and closely related to chordates. S. kowalevskii has chordate like morphological traits and serves as an important model organism, helping developmental biologists to understand the evolution of the central nervous system (CNS). Despite being such an important model organism, the signalling system repertoire of the largest family of integral transmembrane receptor proteins, G protein-coupled receptors (GPCRs) is largely unknown in S. kowalevskii. Here, we identified 260 unique GPCRs and classified as many as 257 of them into five main mammalian GPCR families; Glutamate (23), Rhodopsin (212), Adhesion (18), Frizzled (3) and Secretin (1). Despite having a diffuse nervous system, the acorn worm contains well conserved orthologues for human Adhesion and Glutamate family members, with a similar N-terminal domain architecture. This is particularly true for genes involved in CNS development and regulation in vertebrates. The average sequence identity between the GPCR orthologues in human and S. kowalevskii is around 47%, and this is same as observed in couple of the closest vertebrate relatives, Ciona intestinalis (41%) and Branchiostoma floridae (~47%). The Rhodopsin family has fewer members than vertebrates and lacks clear homologues for 6 of the 13 subgroups, including olfactory, chemokine, prostaglandin, purine, melanocyte concentrating hormone receptors and MAS-related receptors. However, the peptide and somatostatin binding receptors have expanded locally in the acorn worm. Overall, this study is the first large scale analysis of a major signalling gene superfamily in the hemichordate lineage. The establishment of orthologue relationships with genes involved in neurotransmission and development of the CNS in vertebrates provides a foundation for understanding the evolution of signal transduction and allows for further investigation of the hemichordate neurobiology.
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PMID:Remarkable similarities between the hemichordate (Saccoglossus kowalevskii) and vertebrate GPCR repertoire. 2368 80