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 chick pineal gland contains histamine and tele-methylhistamine. The levels of both substances are elevated after treatment of chicks with the amino acid precursor of histamine, L-histidine (1 g/kg, ip). In control and L-histidine-loaded animals the pineal levels of histamine and tele-methylhistamine are higher in light-exposed than in dark-adapted animals (measured at the end of the light phase and in the middle of the dark phase of 12 hr light, 12 hr dark illumination cycle, respectively). The chick pineal gland contains histamine-immunofluorescent cells displaying mast cell morphology; they are seen in the vicinity of the capsule and in the parenchyma. Enzymatic studies showed the presence of the activity of histamine synthesizing and inactivating enzyme, i.e., L-histidine decarboxylase (HDC) and histamine-methyltransferase (HMT). The detected enzyme activities were sensitive to specific inhibitors of HDC (alpha-fluoromethylhistidine and alpha-hydrazinohistidine) and HMT (quinacrine and metoprine); inhibitors of aromatic amino acid decarboxylase alpha-methyl-DOPA and NSD-1015 were inactive on HDC. Exogenous histamine added to organ-cultured chick pineals strongly stimulated endogenous cyclic AMP accumulation and moderately increased melatonin secretion. The data, considered collectively, suggest that in avians histamine, probably originating from the pineal mast cell compartment, may function as a regulator of pineal gland activity.
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PMID:Histamine in the chick pineal gland: origin, metabolism, and effects on the pineal function. 906 67

Tryptophan hydroxylase requires Fe2+ for in vitro enzyme activity. In this study, the intracellular activity of tryptophan hydroxylase was assessed by applying 3-hydroxybenzylhydrazine (NSD-1015), an inhibitor of aromatic l-amino acid decarboxylase, to monolayer cultures of RBL2H3 cells, a serotonin producing mast cell line. The effect of manipulating intracellular 'free' iron levels on enzyme activity was analyzed by administration of iron chelators. Desferrioxamine (DFO) suppressed the intracellular enzyme activity. Salicylaldehyde isonicotinoyl hydrazone (SIH) also suppressed enzyme activity, but stimulated it when administered in the Fe-bound form. Hemin also stimulated enzyme activity, which progressively increased over several hours to more than sixfold the initial level. DFO and SIH inhibited the hemin stimulatory effect when administered simultaneously with hemin. Both suppression and stimulation with these chelators took place without a significant decrease or increase in the amount of enzyme. These results indicate that there was an inadequate supply of Fe2+ in the cells to support full activity of tryptophan hydroxylase.
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PMID:Iron dependence of tryptophan hydroxylase activity in RBL2H3 cells and its manipulation by chelators. 1021 90