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)

We have isolated and characterized subpopulations of the rat mucosal mast cell line, RBL-2H3, carrying either high or low density of a glycoprotein, recently established as mast cell function-associated antigen (MAFA, Ortega et al., 1991), on their surface. These populations were investigated in order to better define the involvement of the MAFA in coupling the immunological stimulation of mast cells to mediator release. The MAFA density on the cell surface of the deficient subpopulation was less than or equal to 10-20% that of the parental population and this phenotype was found to be stably maintained for several months. In contrast, the MAFA-enriched cells had maximally twice the number of copies per cell surface than that of the parental population and this phenotype was less stable. Significantly, low copy number of MAFA on the cell's surface was accompanied by a markedly different secretory response, i.e. (i) a considerable decrease in the secretory response to the Fc epsilon RI-mediated stimulus (ii) a marked enhancement of the ionomycin induced secretion. In order to gain insight into the causes for this decrease in cellular response to the Fc epsilon RI-mediated stimulus, we measured the amplitudes of several biochemical processes which are assigned to the stimulus-secretion coupling cascade. The Fc epsilon RI-mediated uptake of 45Ca2+ by the MAFA-deficient cells was considerably lower than that of the parental and MAFA-enriched cells. Similarly, these cell's Fc epsilon RI-induced rise in [Ca2+]i (both the initial transient as well as the sustained elevation), was markedly lower than that of the parental line and the MAFA-enriched cells. Moreover, the low initial transient rise in [Ca2+]i was found to be correlated with the decrease in Fc epsilon RI-mediated IP3 levels. We therefore examined the cell's content of the phosphatidyl-inositides hydrolyzing enzyme, phospholipase C gamma 1. This was found to be similar in the parental line and in its derived subpopulations. However, PLC gamma 1 activation, as measured by the time course of phosphorylation of its tyrosines, showed a marked difference: while PLC gamma 1 tyrosine phosphorylation, in the parental cells, was only transient (detected already 1 min after antigen addition and declined afterwards to basal levels at ca. 10 min), in the MAFA-deficient cells, tyrosine phosphorylated PLC gamma 1 was also observed 1 min after antigen addition, yet showed no decrease with time in its phosphorylation intensity for up to 30 min.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Variants of the mucosal mast cell line (RBL-2H3) deficient in a functional membrane glycoprotein. 145 97

While the current understanding of the stimulus-response coupling networks triggered by the multi-chain immune-recognition receptors (MIRRs) has markedly advanced, knowledge of its control mechanisms is only emerging. Regulation of the secretory response of mast cells to the stimulus provided by the type I Fcepsilon receptor (FcepsilonRI) is our topic of interest. Several mast cell membrane receptors capable of inhibiting both immediate and late responses have so far been identified. However, their ligands and mechanism(s) of operation are only partly known. Moreover, desensitization of mast cells' response to the FcepsilonRI, a well-known and widespread control process of many neural or hormone receptors, is hardly understood in this case. In this brief report we describe results of recent experiments in which we studied both of these aspects of mast cells' response to the FcepsilonRI stimulus by an inhibitory receptor MAFA, as well as those where we have established that these cells are susceptible to physiological modes of FcepsilonRI desensitization caused by prolonged exposure to sub-threshold concentrations of FcepsilonRI clustering agents.
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PMID:Regulation of mast cell secretory response to the type I Fcepsilon receptor: inhibitory elements and desensitization. 1660 29