Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The actions of ACTH on the adrenal cortex are known to be 2-fold. In addition to increased steroidogenesis, ACTH also causes marked vasodilation, reflected by an increased rate of blood flow through the gland. Our studies, using the in situ isolated perfused rat adrenal preparation, have shown that zona fasciculata function and corticosterone secretion are closely related to vascular events, with an increase in perfusion medium flow rate causing an increase in corticosterone secretion, in the absence of any known stimulant. These observations give rise to two important questions: how does ACTH stimulate blood flow; and how does increased blood (or perfusion medium) flow stimulate steroidogenesis? Addressing the first question, we have recently identified mast cells in the adrenal capsule, and shown that Compound 48/80, a mast cell degranulator, mimics the actions of ACTH on adrenal blood flow and corticosterone secretion. We have also demonstrated an inhibition of the adrenal vascular response to ACTH in the presence of disodium cromoglycate, which prevents mast cell degranulation. We conclude, therefore, that ACTH stimulates adrenal blood flow by its actions on mast cells in the adrenal capsule. Addressing the second question, we looked at the role of endothelin in the rat adrenal cortex. Endothelin 1, 2 and 3 caused significant stimulation of steroid secretion by collagenase dispersed cells from both the zona glomerulosa and the zona fasciculata. A sensitive response was seen, with significant stimulation at an endothelin concentration of 10(-13) mol/l or lower. Endothelin secretion by the in situ isolated perfused rat adrenal gland was measured using the Amersham assay kit. Administration of ACTH (300 fmol) caused an increase in the rate of immunoreactive endothelin secretion, from an average of 28.7 +/- 2.6 to 52.6 +/- 6 fmol/10 min (P less than 0.01, n = 5). An increase in immunoreactive endothelin secretion was also seen in response to histamine, an adrenal vasodilator, which stimulates corticosterone secretion in the intact gland, but has no effect on collagenase-dispersed cells. From these data we conclude that endothelin may mediate the effects of vasodilation on corticosterone secretion, and this mechanism may explain some of the differences in response characteristics between the intact gland and dispersed cells.
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PMID:The relationship between adrenal vascular events and steroid secretion: the role of mast cells and endothelin. 165 78

Adverse reactions to drugs require that their mechanisms be elucidated, particularly when anaphylaxis is suspected. Early diagnosis can be achieved by plasma histamine measurements. Unfortunately, the short plasma half-life of histamine and the difficulties in handling the sample usually preclude this measurement, although a sensitive radioimmunologic kit is routinely available. It has been recently suggested that mast cell tryptase, a component of the mast cell granules, could provide an alternative to histamine determination. We have measured plasma histamine and tryptase in 19 patients who developed possible anaphylactoid reactions to anesthetic or other drugs. Eight patients had increased values for both histamine and tryptase. In 4 a muscle relaxant drug was proved responsible for the reaction. Six patients had normal levels for both substances. In each case, the clinical signs of anaphylaxis were moderate. Two patients had normal histamine and high tryptase concentrations, due to late sampling (greater than 5 h). In 2 other patients, histamine was high, with normal tryptase: in 1, muscle relaxant allergy was further demonstrated. Tryptase half-life was equal to 90 min in 3 patients. At least 15 min was necessary to reach the peak level when the responsible drug was administered intravenously. The best time for measuring tryptase was 1-2 h after the reaction (not greater than 6 h), whereas for histamine it was 10 min to 1 h. We conclude that measurement of plasma tryptase along with measurement of plasma histamine may aid in diagnosis of anaphylaxis.
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PMID:Biochemical markers of anaphylactoid reactions to drugs. Comparison of plasma histamine and tryptase. 174 15

This adaptation of a commercially available kit for automated measurement of carboxypeptidase A (CPA; EC 3.4.17.1) activity in serum with the Cobas Bio centrifugal analyzer extends the linear range to an activity concentration of 82 U/L. Results obtained by the described method correlated closely (r = 0.98) with those by the manual kit method. The reference interval for 150 apparently normal individuals was 0.12-0.91 U/L. Total CVs of the method ranged from 4.0% to 13.1%. Bilirubin and glucose decreased the CPA activity in serum by as much as 98% and 26%, respectively. Substantial CPA activity was found in pancreatic tissue, with little activity in intestinal tissue. CPA activity was not as widely distributed in extra-pancreatic tissues as were amylase and lipase activities. Peak activities of CPA, amylase, and lipase in the sera of patients with acute pancreatitis were significantly correlated (r = 0.45 to 0.78, P less than 0.05-0.01). The optimized diagnostic efficiency of CPA for acute pancreatitis was 0.85 at a cutoff value of 5 U/L. Amylase and lipase exhibited similar optimized efficiencies, and parallel testing did not significantly improve diagnostic accuracy. We conclude that automated analysis for CPA activity, even in the absence of interferences, does not add to the diagnostic information provided by the widely available assays for amylase and lipase activity.
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PMID:Measuring carboxypeptidase A activity with a centrifugal analyzer: analytical and clinical considerations. 246 45

Three monoclonal antibodies (MAbs) to the human c-kit receptor tyrosine kinase (P145c-kit), derived in independent laboratories, have been extensively used in studies of c-kit expression and the role of its ligand, steel factor (SLF), in hemopoiesis and mast cell differentiation and function. In this study, the relationship between the epitopes they identify, and their effects on SLF binding, receptor internalization, and signal transduction are compared. Epitope mapping studies carried out on the high P145c-kit-expressing cell line HEL-DR showed that SR-1 identifies an epitope independent of those bound by YB5.B8 and 17F11, while the latter two antibodies bound to distinct but interacting epitopes. SR-1 potently blocked the binding of SLF to P145c-kit on these cells and also on cells of the factor-dependent line MO7e. In contrast, YB5.B8 and 17F11 had minimal effects on ligand binding. Conversely, SLF partially blocked the binding of SR-1 and YB5.B8 to cells, while binding of 17F11 was actually enhanced by SLf on some target cells. Preincubation of HEL-DR and MO7e cells with MAbs prior to exposure to SLF revealed that 17F11 itself brought about partial down-regulation of P145c-kit and did not inhibit SLF-mediated down-regulation. SR-1 caused minimal down-regulation and inhibited SLF-mediated receptor internalization. YB5.B8 had minimal effects on either cell line in this assay. To determine whether the antibodies had any agonist activity, they were compared with SLF for their ability to bring about receptor phosphorylation in intact MO7e cells. All three antibodies induced detectable tyrosine phosphorylation with 17F11 being the most effective, while YB5.B8 was the least effective. Finally, the ability of the antibodies to influence the proliferation of the MO7e cells was examined. As expected, SR-1 potently inhibited the proliferative response to SLF, while 17F11 weakly inhibited and YB5.B8 had negligible effect. In the absence of SLF both 17F11 and YB5.B8 displayed very weak but reproducible agonist activity.
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PMID:Epitope mapping and functional studies with three monoclonal antibodies to the c-kit receptor tyrosine kinase, YB5.B8, 17F11, and SR-1. 751 Feb 97

Exercise-induced urticaria and anaphylaxis have become increasingly recognized during the past 2 decades as more people participate in physical activities. These syndromes can be categorized as cholinergic urticaria or exercise-induced anaphylaxis based on the clinical manifestation. Newer subsets such as food-dependent and familial exercise-induced anaphylaxis have also been recognized. Further studies are needed to characterize the variables involved in mast cell activation and mast cell mediator release in these syndromes. The management strategy for patients who have exercise-induced syndromes with skin manifestations only differs from the management for those with systemic symptoms. Currently, antihistamines, as a single agent or in combination with other agents, may be helpful prophylactically in both groups. Avoidance of precipitating factors, modification of exercise, and use of a self-injectable epinephrine kit are recommended for patients with anaphylaxis.
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PMID:Exercise-induced urticaria and anaphylaxis. 903 47

The growth and differentiation of mast cells and melanocytes require stem cell factor (SCF), the ligand for the kit receptor tyrosine kinase. SCF may exist as a membrane-bound or soluble molecule. Abnormalities of the SCF-kit signaling pathway, with increased local concentrations of soluble SCF, have been implicated in the pathogenesis of the human disease cutaneous mastocytosis, but have not yet been shown to play a causal role. To investigate both the potential of SCF to cause mastocytosis and its role in epidermal melanocyte homeostasis, we targeted the expression of SCF to epidermal keratinocytes in mice with two different transgenes controlled by the human keratin 14 promoter. The transgenes contained cDNAs that either produced SCF, which can exist in both membrane-bound and soluble forms, or SCF, which remains essentially membrane bound. Murine epidermal keratinocyte expression of membrane-bound/ soluble SCF reproduced the phenotype of human cutaneous mastocytosis, with dermal mast cell infiltrates and epidermal hyperpigmentation, and caused the maintenance of a population of melanocytes in the interadnexal epidermis, an area where melanocytes and melanin are found in human skin but where they are not typically found in murine skin. Expression of membrane-bound SCF alone resulted in epidermal melanocytosis and melanin production, but did not by itself cause mastocytosis. We conclude, first, that a phenotype matching that of human mastocytosis can be produced in mice by keratinocyte overproduction of soluble SCF, suggesting a potential cause of this disease. Second, we conclude that keratinocyte expression of membrane-bound SCF results in the postnatal maintenance of epidermal melanocytes in mice. Since the resulting animals have skin that more closely approximates human skin than do normal mice, their study may be more relevant to human melanocyte biology than the study of skin of normal mice.
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PMID:Murine cutaneous mastocytosis and epidermal melanocytosis induced by keratinocyte expression of transgenic stem cell factor. 958 35

Mast cells express the receptor tyrosine kinase kit/stem cell factor receptor (SCFR) which is encoded by the proto-oncogene c-kit. Ligation of SCFR induces its dimerization and activation of its intrinsic tyrosine kinase activity leading to activation of Raf-1, phospholipases, phosphatidylinositol 3-kinase, and extracellular signal-regulated kinases. However, little is known about the downstream signals initiated by SCFR ligation except for activation of extracellular signal-regulated kinases. The murine mast cell line, MC/9, synthesizes and secretes TNF-alpha following the aggregation of high affinity Fc receptors for IgE (Fc epsilonRI). Ligation of SCFR or Fc epsilonRI on MC/9 cells resulted in the activation of all three MAP kinase family members, extracellular signal-regulated kinases, c-Jun amino-terminal kinase (JNK), and p38. Stem cell factor (SCF)-induced activation of JNK and p38 was insensitive to wortmannin, cyclosporin A, and FK506 whereas activation of these kinases through Fc epsilonRI was sensitive to these drugs. Coligation of SCFR augmented Fc epsilonRI-mediated activation of MAP kinases, especially JNK activation, and SCF augmented Fc epsilonRI-mediated TNF-alpha production in MC/9 cells, although SCF alone did not induce TNF-alpha production. This augmentation by SCF was regulated at the level of transcription, at least in part, since the promoter activity of TNF-alpha was enhanced following addition of SCF. These results demonstrate that SCF can augment Fc epsilonRI-mediated JNK activation and cytokine gene transcription but via pathways that are regulated differently than the ones activated through Fc epsilonRI.
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PMID:Stem cell factor augments Fc epsilon RI-mediated TNF-alpha production and stimulates MAP kinases via a different pathway in MC/9 mast cells. 975 85

Mastocytosis represents a mast cell proliferative disease that generally runs a benign clinical course, with spontaneous remissions mostly by puberty in childhood-onset disease, although rare forms, particularly in adult-onset disease, can be associated with (pre)malignant hematologic disorders and very rarely present as mast cell leukemia or malignant mastocytosis. Reasons for this divergent clinical behavior of childhood- versus adult-onset disease are unknown. Recently, two activating mutations in the intracellular domain of the proto-oncogene c-kit, which encodes a tyrosine kinase receptor for the mast cell growth factor stem cell factor, have been detected in the human leukemic mast cell line HMC-1. We have therefore studied lesional skin biopsies from patients with adult- and childhood-onset indolent mastocytosis for the presence of these codon 560 and 816 mutations. C-kit coding DNA sequences were amplified and analyzed by mutation-specific restriction analyses, and mutated polymerase chain reaction products were additionally cloned and sequenced. The codon 816 mutation was found in all six samples from adult patients, but not in any of the 11 specimens from children. In addition, the codon 560 mutation could be demonstrated for the first time in indolent mastocytosis, namely in two of four specimens from adult patients, but not in those from two children. These data thus provide a possible explanation for the divergent clinical behavior of adult- versus childhood-onset indolent mastocytosis, with the first being associated with an activating mutation, possibly as part of a neoplastic process, and the latter representing most likely a reactive process of an as yet unknown pathogenesis.
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PMID:Identification of activating c-kit mutations in adult-, but not in childhood-onset indolent mastocytosis: a possible explanation for divergent clinical behavior. 985 47

Spontaneous mast cell tumors (MCT) are the most common malignant neoplasm in the dog, representing between 7% and 21% of all canine tumors, an incidence much higher than that found in humans. These tumors often behave in an aggressive manner, metastasizing to local lymph nodes, liver, spleen, and bone marrow. The proto-oncogene c-kit is known to play a critical role in the development and function of mast cells. Point mutations in the kinase domain of c-kit leading to tyrosine phosphorylation in the absence of ligand binding have been identified in three mastocytoma lines, (P815, RBL, and HMC-1), and some human patients with various forms of mastocytosis. We now demonstrate that although c-kit derived from canine MCT did not contain the previously described activating point mutations, 5 of the 11 tumors analyzed possessed novel mutations consisting of tandem duplications involving exons 11 and 12. We also show that one such duplication, detected in a canine mastocytoma cell line, was associated with constitutive phosphorylation of c-kit protein (KIT), suggesting that these mutations may contribute to the development or progression of canine MCT.
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PMID:Spontaneous canine mast cell tumors express tandem duplications in the proto-oncogene c-kit. 1021 Mar 27

The c-kit protooncogene encodes a receptor tyrosine kinase that is known to play a critical role in hemopoiesis and is essential for mast cell growth, differentiation, and cytokine production. Studies have shown that the Th2 cytokine IL-4 can down-regulate Kit expression on human and murine mast cells, but the mechanism of this down-regulation has remained unresolved. Using mouse bone marrow-derived mast cells, we demonstrate that IL-4-mediated Kit down-regulation requires STAT6 expression and phosphotidylinositide-3'-kinase activation. We also find that the Th2 cytokine IL-10 potently down-regulates Kit expression. IL-4 enhances IL-10-mediated inhibition in a manner that is STAT6 independent and phosphotidylinositide-3'-kinase dependent. Both IL-4- and IL-10-mediated Kit down-regulation were coupled with little or no change in c-kit mRNA levels, no significant change in Kit protein stability, but decreased total Kit protein expression. Inhibition of Kit expression by IL-4 and IL-10 resulted in a loss of Kit-mediated signaling, as evidenced by reduced IL-13 and TNF-alpha mRNA induction after stem cell factor stimulation. These data offer a role for STAT6 and phosphotidylinositide-3'-kinase in IL-4-mediated Kit down-regulation, coupled with the novel observation that IL-10 is a potent inhibitor of Kit expression and function. Regulating Kit expression and signaling may be essential to controlling mast cell-mediated inflammatory responses.
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PMID:Inhibition of Kit expression by IL-4 and IL-10 in murine mast cells: role of STAT6 and phosphatidylinositol 3'-kinase. 1045 90


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