Signal transduction by the high-affinity IgE receptor (FcεRI) depends on membrane lipid and protein compartmentalization. Recently published data show that cells treated with 1-heptanol, a cell membrane fluidizer, exhibit changes in membrane properties. However, the functional consequences of 1-heptanol-induced changes on mast cell signaling are unknown. This study shows that short-term exposure to 1-heptanol reduces membrane thermal stability and dysregulates mast cell signaling at multiple levels. Cells treated with 1-heptanol exhibited increased lateral mobility and decreased internalization of the FcεRI. However, this did not affect the initial phosphorylation of the FcεRI-β chain and components of the SYK/LAT1/PLCγ1 signaling pathway after antigen activation. In contrast, 1-heptanol inhibited SAPK/JNK phosphorylation and effector functions such as calcium response, degranulation, and cytokine production. Membrane hyperfluidization induced a heat shock-like response via increased expression of the heat shock protein 70, increased lateral diffusion of ORAI1-mCherry, and unsatisfactory performance of STIM1-ORAI1 coupling, as determined by flow-FRET. Furthermore, 1-heptanol inhibited the antigen-induced production of reactive oxygen species and potentiated stress-induced plasma membrane permeability by interfering with heat shock protein 70 activity. The combined data suggest that 1-heptanol-mediated membrane fluidization does not interfere with the earliest biochemical steps of FcεRI signaling, such as phosphorylation of the FcεRI-β chain and components of the SYK/LAT/PLCγ1 signaling pathway, instead inhibiting the FcεRI internalization and mast cell effector functions, including degranulation and cytokine production.

• Klíčová slova
• FRAP, FcεRI signaling, STIM1-ORAI1 coupling, alkanol, flow-FRET, heat shock response, membrane fluidizer, store-operated calcium entry,
• MeSH
• cholesterol MeSH
• cytokiny MeSH
• heptanol MeSH
• mastocyty * MeSH
• signální transdukce * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cholesterol MeSH
• cytokiny MeSH
• heptanol MeSH

Pentacyclic triterpenoids, including ursolic acid (UA), are bioactive compounds with multiple biological activities involving anti-inflammatory effects. However, the mode of their action on mast cells, key players in the early stages of allergic inflammation, and underlying molecular mechanisms remain enigmatic. To better understand the effect of UA on mast cell signaling, here we examined the consequences of short-term treatment of mouse bone marrow-derived mast cells with UA. Using IgE-sensitized and antigen- or thapsigargin-activated cells, we found that 15 min exposure to UA inhibited high affinity IgE receptor (FcεRI)-mediated degranulation, calcium response, and extracellular calcium uptake. We also found that UA inhibited migration of mouse bone marrow-derived mast cells toward antigen but not toward prostaglandin E2 and stem cell factor. Compared to control antigen-activated cells, UA enhanced the production of tumor necrosis factor-α at the mRNA and protein levels. However, secretion of this cytokine was inhibited. Further analysis showed that UA enhanced tyrosine phosphorylation of the SYK kinase and several other proteins involved in the early stages of FcεRI signaling, even in the absence of antigen activation, but inhibited or reduced their further phosphorylation at later stages. In addition, we show that UA induced changes in the properties of detergent-resistant plasma membrane microdomains and reduced antibody-mediated clustering of the FcεRI and glycosylphosphatidylinositol-anchored protein Thy-1. Finally, UA inhibited mobility of the FcεRI and cholesterol. These combined data suggest that UA exerts its effects, at least in part, via lipid-centric plasma membrane perturbations, hence affecting the functions of the FcεRI signalosome.

• Klíčová slova
• immunoglobulin E, lipid raft, mast cell, plasma membrane, signal transduction, tumor necrosis factor, tyrosine kinase,
• MeSH
• antigeny metabolismus   MeSH
• degranulace buněk MeSH
• kyselina ursolová MeSH
• lipidy farmakologie   MeSH
• mastocyty metabolismus   MeSH
• myši MeSH
• receptory IgE * metabolismus   MeSH
• triterpeny * farmakologie   metabolismus   MeSH
• vápník metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antigeny MeSH
• lipidy MeSH
• receptory IgE * MeSH
• triterpeny * MeSH
• vápník MeSH

The systemic anaphylactic reaction is a life-threatening allergic response initiated by activated mast cells. Sphingolipids are an essential player in the development and attenuation of this response. De novo synthesis of sphingolipids in mammalian cells is inhibited by the family of three ORMDL proteins (ORMDL1, 2, and 3). However, the cell and tissue-specific functions of ORMDL proteins in mast cell signaling are poorly understood. This study aimed to determine cross-talk of ORMDL2 and ORMDL3 proteins in IgE-mediated responses. To this end, we prepared mice with whole-body knockout (KO) of Ormdl2 and/or Ormdl3 genes and studied their role in mast cell-dependent activation events in vitro and in vivo. We found that the absence of ORMDL3 in bone marrow-derived mast cells (BMMCs) increased the levels of cellular sphingolipids. Such an increase was further raised by simultaneous ORMDL2 deficiency, which alone had no effect on sphingolipid levels. Cells with double ORMDL2 and ORMDL3 KO exhibited increased intracellular levels of sphingosine-1-phosphate (S1P). Furthermore, we found that concurrent ORMDL2 and ORMDL3 deficiency increased IκB-α phosphorylation, degranulation, and production of IL-4, IL-6, and TNF-α cytokines in antigen-activated mast cells. Interestingly, the chemotaxis towards antigen was increased in all mutant cell types analyzed. Experiments in vivo showed that passive cutaneous anaphylaxis (PCA), which is initiated by mast cell activation, was increased only in ORMDL2,3 double KO mice, supporting our in vitro observations with mast cells. On the other hand, ORMDL3 KO and ORMDL2,3 double KO mice showed faster recovery from passive systemic anaphylaxis, which could be mediated by increased levels of blood S1P presented in such mice. Our findings demonstrate that Ormdl2 deficiency potentiates the ORMDL3-dependent changes in mast cell signaling.

• Klíčová slova
• FcϵRI, ORMDL family, mast cells, passive cutaneous anaphylactic reaction, passive systemic anaphylaxis, sphingolipids, sphingosine-1-phosphate,
• MeSH
• anafylaxe etiologie   metabolismus   MeSH
• biologické markery MeSH
• chemotaxe imunologie   MeSH
• cytokiny metabolismus   MeSH
• exprese genu MeSH
• lysofosfolipidy krev   metabolismus   MeSH
• mastocyty imunologie   metabolismus   MeSH
• membránové proteiny chemie   nedostatek   genetika   metabolismus   MeSH
• multigenová rodina MeSH
• myši knockoutované MeSH
• myši MeSH
• náchylnost k nemoci MeSH
• pasivní kožní anafylaxe genetika   imunologie   MeSH
• sekvence aminokyselin MeSH
• sfingolipidy krev   metabolismus   MeSH
• sfingosin analogy a deriváty   krev   metabolismus   MeSH
• signální transdukce * MeSH
• vápník metabolismus   MeSH
• vápníková signalizace MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• biologické markery MeSH
• cytokiny MeSH
• lysofosfolipidy MeSH
• membránové proteiny MeSH
• ORMDL3 protein, mouse MeSH Prohlížeč
• sfingolipidy MeSH
• sfingosin MeSH
• sphingosine 1-phosphate MeSH Prohlížeč
• vápník MeSH

The antigen-mediated activation of mast cells initiates signaling events leading to their degranulation, to the release of inflammatory mediators, and to the synthesis of cytokines and chemokines. Although rapid and transient microtubule reorganization during activation has been described, the molecular mechanisms that control their rearrangement are largely unknown. Microtubule nucleation is mediated by γ-tubulin complexes. In this study, we report on the regulation of microtubule nucleation in bone marrow-derived mast cells (BMMCs) by Src homology 2 (SH2) domain-containing protein tyrosine phosphatase 1 (SHP-1; Ptpn6). Reciprocal immunoprecipitation experiments and pull-down assays revealed that SHP-1 is present in complexes containing γ-tubulin complex proteins and protein tyrosine kinase Syk. Microtubule regrowth experiments in cells with deleted SHP-1 showed a stimulation of microtubule nucleation, and phenotypic rescue experiments confirmed that SHP-1 represents a negative regulator of microtubule nucleation in BMMCs. Moreover, the inhibition of the SHP-1 activity by inhibitors TPI-1 and NSC87877 also augmented microtubule nucleation. The regulation was due to changes in γ-tubulin accumulation. Further experiments with antigen-activated cells showed that the deletion of SHP-1 stimulated the generation of microtubule protrusions, the activity of Syk kinase, and degranulation. Our data suggest a novel mechanism for the suppression of microtubule formation in the later stages of mast cell activation.

• Klíčová slova
• SHP-1 tyrosine phosphatase, bone marrow-derived mast cells, cell activation, microtubule nucleation, γ-tubulin complexes,
• MeSH
• degranulace buněk MeSH
• HEK293 buňky MeSH
• kinasa Syk metabolismus   MeSH
• lidé MeSH
• mastocyty cytologie   metabolismus   MeSH
• MFC-7 buňky MeSH
• mikrotubuly metabolismus   MeSH
• myši MeSH
• tubulin metabolismus   MeSH
• tyrosinfosfatasa nereceptorového typu 6 antagonisté a inhibitory   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kinasa Syk MeSH
• Ptpn6 protein, mouse MeSH Prohlížeč
• Syk protein, mouse MeSH Prohlížeč
• tubulin MeSH
• tyrosinfosfatasa nereceptorového typu 6 MeSH

Protein 4.1R, a member of the 4.1 family, functions as a bridge between cytoskeletal and plasma membrane proteins. It is expressed in T cells, where it binds to a linker for activation of T cell (LAT) family member 1 and inhibits its phosphorylation and downstream signaling events after T cell receptor triggering. The role of the 4.1R protein in cell activation through other immunoreceptors is not known. In this study, we used 4.1R-deficient (4.1R-KO) and 4.1R wild-type (WT) mice and explored the role of the 4.1R protein in the high-affinity IgE receptor (FcεRI) signaling in mast cells. We found that bone marrow mast cells (BMMCs) derived from 4.1R-KO mice showed normal growth in vitro and expressed FcεRI and c-KIT at levels comparable to WT cells. However, 4.1R-KO cells exhibited reduced antigen-induced degranulation, calcium response, and secretion of tumor necrosis factor-α. Chemotaxis toward antigen and stem cell factor (SCF) and spreading on fibronectin were also reduced in 4.1R-KO BMMCs, whereas prostaglandin E2-mediated chemotaxis was not affected. Antibody-induced aggregation of tetraspanin CD9 inhibited chemotaxis toward antigen in WT but not 4.1R-KO BMMCs, implying a CD9-4.1R protein cross-talk. Further studies documented that in the absence of 4.1R, antigen-mediated phosphorylation of FcεRI β and γ subunits was not affected, but phosphorylation of SYK and subsequent signaling events such as phosphorylation of LAT1, phospholipase Cγ1, phosphatases (SHP1 and SHIP), MAP family kinases (p38, ERK, JNK), STAT5, CBL, and mTOR were reduced. Immunoprecipitation studies showed the presence of both LAT1 and LAT2 (LAT, family member 2) in 4.1R immunocomplexes. The positive regulatory role of 4.1R protein in FcεRI-triggered activation was supported by in vivo experiments in which 4.1R-KO mice showed the normal presence of mast cells in the ears and peritoneum, but exhibited impaired passive cutaneous anaphylaxis. The combined data indicate that the 4.1R protein functions as a positive regulator in the early activation events after FcεRI triggering in mast cells.

• Klíčová slova
• 4.1R protein, chemotaxis, degranulation, mast cell, passive cutaneous anaphylaxis,
• MeSH
• chemotaxe imunologie   MeSH
• degranulace buněk imunologie   MeSH
• mastocyty imunologie   metabolismus   MeSH
• mikrofilamentové proteiny imunologie   metabolismus   MeSH
• myši inbrední C57BL MeSH
• myši knockoutované MeSH
• myši MeSH
• pasivní kožní anafylaxe imunologie   MeSH
• receptory IgE imunologie   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• Epb41 protein, mouse MeSH Prohlížeč
• mikrofilamentové proteiny MeSH
• receptory IgE MeSH

C-terminal Src kinase (CSK) is a major negative regulator of Src family tyrosine kinases (SFKs) that play critical roles in immunoreceptor signaling. CSK is brought in contiguity to the plasma membrane-bound SFKs via binding to transmembrane adaptor PAG, also known as CSK-binding protein. The recent finding that PAG can function as a positive regulator of the high-affinity IgE receptor (FcεRI)-mediated mast cell signaling suggested that PAG and CSK have some non-overlapping regulatory functions in mast cell activation. To determine the regulatory roles of CSK in FcεRI signaling, we derived bone marrow-derived mast cells (BMMCs) with reduced or enhanced expression of CSK from wild-type (WT) or PAG knockout (KO) mice and analyzed their FcεRI-mediated activation events. We found that in contrast to PAG-KO cells, antigen-activated BMMCs with CSK knockdown (KD) exhibited significantly higher degranulation, calcium response, and tyrosine phosphorylation of FcεRI, SYK, and phospholipase C. Interestingly, FcεRI-mediated events in BMMCs with PAG-KO were restored upon CSK silencing. BMMCs with CSK-KD/PAG-KO resembled BMMCs with CSK-KD alone. Unexpectedly, cells with CSK-KD showed reduced kinase activity of LYN and decreased phosphorylation of transcription factor STAT5. This was accompanied by impaired production of proinflammatory cytokines and chemokines in antigen-activated cells. In line with this, BMMCs with CSK-KD exhibited enhanced phosphorylation of protein phosphatase SHP-1, which provides a negative feedback loop for regulating phosphorylation of STAT5 and LYN kinase activity. Furthermore, we found that in WT BMMCs SHP-1 forms complexes containing LYN, CSK, and STAT5. Altogether, our data demonstrate that in FcεRI-activated mast cells CSK is a negative regulator of degranulation and chemotaxis, but a positive regulator of adhesion to fibronectin and production of proinflammatory cytokines. Some of these pathways are not dependent on the presence of PAG.

• Klíčová slova
• C-terminal Src kinase, LYN, SHP-1, STAT5, cytokines, degranulation, mast cell, phosphoprotein associated with glycosphingolipid-enriched microdomains,
• MeSH
• analýza rozptylu MeSH
• buňky kostní dřeně fyziologie   MeSH
• C-terminální Src kinasa MeSH
• cytokiny metabolismus   MeSH
• degranulace buněk MeSH
• fibronektiny metabolismus   MeSH
• fosfoproteiny metabolismus   MeSH
• fosforylace MeSH
• genetické vektory MeSH
• HEK293 buňky MeSH
• lidé MeSH
• mastocyty fyziologie   MeSH
• membránové proteiny metabolismus   MeSH
• mezibuněčné signální peptidy a proteiny MeSH
• myši inbrední C57BL MeSH
• myši knockoutované MeSH
• myši MeSH
• receptory IgE metabolismus   MeSH
• signální transdukce imunologie   MeSH
• skupina kinas odvozených od src-genu metabolismus   fyziologie   MeSH
• transkripční faktor STAT5 metabolismus   MeSH
• tyrosin metabolismus   MeSH
• tyrosinfosfatasa nereceptorového typu 6 metabolismus   MeSH
• vápník metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• C-terminální Src kinasa MeSH
• CSK protein, human MeSH Prohlížeč
• cytokiny MeSH
• fibronektiny MeSH
• fosfoproteiny MeSH
• lyn protein-tyrosine kinase MeSH Prohlížeč
• membránové proteiny MeSH
• mezibuněčné signální peptidy a proteiny MeSH
• Pag protein, mouse MeSH Prohlížeč
• Pag1 protein, mouse MeSH Prohlížeč
• Ptpn6 protein, mouse MeSH Prohlížeč
• receptory IgE MeSH
• skupina kinas odvozených od src-genu MeSH
• transkripční faktor STAT5 MeSH
• tyrosin MeSH
• tyrosinfosfatasa nereceptorového typu 6 MeSH
• vápník MeSH

Aggregation of the high-affinity receptor for IgE (FcεRI) in mast cells initiates activation events that lead to degranulation and release of inflammatory mediators. To better understand the signaling pathways and genes involved in mast cell activation, we developed a high-throughput mast cell degranulation assay suitable for RNA interference experiments using lentivirus-based short hairpin RNA (shRNA) delivery. We tested 432 shRNAs specific for 144 selected genes for effects on FcεRI-mediated mast cell degranulation and identified 15 potential regulators. In further studies, we focused on galectin-3 (Gal3), identified in this study as a negative regulator of mast cell degranulation. FcεRI-activated cells with Gal3 knockdown exhibited upregulated tyrosine phosphorylation of spleen tyrosine kinase and several other signal transduction molecules and enhanced calcium response. We show that Gal3 promotes internalization of IgE-FcεRI complexes; this may be related to our finding that Gal3 is a positive regulator of FcεRI ubiquitination. Furthermore, we found that Gal3 facilitates mast cell adhesion and motility on fibronectin but negatively regulates antigen-induced chemotaxis. The combined data indicate that Gal3 is involved in both positive and negative regulation of FcεRI-mediated signaling events in mast cells.

• MeSH
• aktiny metabolismus   MeSH
• buněčná adheze MeSH
• chemotaxe MeSH
• cytokiny genetika   metabolismus   MeSH
• fosforylace MeSH
• galektin 3 genetika   metabolismus   MeSH
• lyzozomy metabolismus   MeSH
• malá interferující RNA MeSH
• mastocyty cytologie   fyziologie   MeSH
• myši inbrední BALB C MeSH
• prostaglandin D2 metabolismus   MeSH
• receptory IgE genetika   metabolismus   MeSH
• signální transdukce MeSH
• ubikvitinace MeSH
• vápník metabolismus   MeSH
• vysoce účinné nukleotidové sekvenování MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• aktiny MeSH
• cytokiny MeSH
• galektin 3 MeSH
• Lgals3 protein, mouse MeSH Prohlížeč
• malá interferující RNA MeSH
• prostaglandin D2 MeSH
• receptory IgE MeSH
• vápník MeSH

Single-nucleotide polymorphism studies have linked the chromosome 17q12-q21 region, where the human orosomucoid-like (ORMDL)3 gene is localized, to the risk of asthma and several other inflammatory diseases. Although mast cells are involved in the development of these diseases, the contribution of ORMDL3 to the mast cell physiology is unknown. In this study, we examined the role of ORMDL3 in antigen-induced activation of murine mast cells with reduced or enhanced ORMDL3 expression. Our data show that in antigen-activated mast cells, reduced expression of the ORMDL3 protein had no effect on degranulation and calcium response, but significantly enhanced phosphorylation of AKT kinase at Ser 473 followed by enhanced phosphorylation and degradation of IκBα and translocation of the NF-κB p65 subunit into the nucleus. These events were associated with an increased expression of proinflammatory cytokines (TNF-α, IL-6, and IL-13), chemokines (CCL3 and CCL4), and cyclooxygenase-2 dependent synthesis of prostaglandin D2. Antigen-mediated chemotaxis was also enhanced in ORMDL3-deficient cells, whereas spreading on fibronectin was decreased. On the other hand, increased expression of ORMDL3 had no significant effect on the studied signaling events, except for reduced antigen-mediated chemotaxis. These data were corroborated by increased IgE-antigen-dependent passive cutaneous anaphylaxis in mice with locally silenced ORMDL3 using short interfering RNAs. Our data also show that antigen triggers suppression of ORMDL3 expression in the mast cells. In summary, we provide evidence that downregulation of ORMDL3 expression in mast cells enhances AKT and NF-κB-directed signaling pathways and chemotaxis and contributes to the development of mast cell-mediated local inflammation in vivo.

• Klíčová slova
• Chemotaxis, Degranulation, Mast cell, ORMDL3 knockdown, Proinflammatory cytokines, Prostaglandin D2, RNA interference,
• MeSH
• chemotaxe * MeSH
• cytokiny genetika   imunologie   MeSH
• degranulace buněk * MeSH
• down regulace MeSH
• kultivované buňky MeSH
• mastocyty cytologie   imunologie   metabolismus   MeSH
• membránové proteiny genetika   imunologie   MeSH
• messenger RNA genetika   MeSH
• myši inbrední BALB C MeSH
• myši MeSH
• receptory IgE imunologie   MeSH
• upregulace MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cytokiny MeSH
• membránové proteiny MeSH
• messenger RNA MeSH
• ORMDL3 protein, mouse MeSH Prohlížeč
• receptory IgE MeSH

Engagement of the Fcepsilon receptor I (FcepsilonRI) on mast cells and basophils initiates signaling pathways leading to degranulation. Early activation events include tyrosine phosphorylation of two transmembrane adaptor proteins, linker for activation of T cells (LAT) and non-T cell activation linker (NTAL; also called LAB; a product of Wbscr5 gene). Previous studies showed that the secretory response was partially inhibited in bone marrow-derived mast cells (BMMCs) from LAT-deficient mice. To clarify the role of NTAL in mast cell degranulation, we compared FcepsilonRI-mediated signaling events in BMMCs from NTAL-deficient and wild-type mice. Although NTAL is structurally similar to LAT, antigen-mediated degranulation responses were unexpectedly increased in NTAL-deficient mast cells. The earliest event affected was enhanced tyrosine phosphorylation of LAT in antigen-activated cells. This was accompanied by enhanced tyrosine phosphorylation and enzymatic activity of phospholipase C gamma1 and phospholipase C gamma2, resulting in elevated levels of inositol 1,4,5-trisphosphate and free intracellular Ca2+. NTAL-deficient BMMCs also exhibited an enhanced activity of phosphatidylinositol 3-OH kinase and Src homology 2 domain-containing protein tyrosine phosphatase-2. Although both LAT and NTAL are considered to be localized in membrane rafts, immunogold electron microscopy on isolated membrane sheets demonstrated their independent clustering. The combined data show that NTAL is functionally and topographically different from LAT.

• MeSH
• adaptorové proteiny signální transdukční fyziologie   MeSH
• adaptorové proteiny vezikulární transportní fyziologie   MeSH
• degranulace buněk MeSH
• fosfatidylinositol-3-kinasy fyziologie   MeSH
• fosfolipasa C gama MeSH
• fosfolipasy typu C metabolismus   MeSH
• fosfoproteiny fyziologie   MeSH
• fosforylace MeSH
• mastocyty fyziologie   MeSH
• membránové proteiny fyziologie   MeSH
• myši MeSH
• proteiny fyziologie   MeSH
• receptory IgE fyziologie   MeSH
• signální transdukce * MeSH
• tyrosin metabolismus   MeSH
• vápník metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adaptorové proteiny signální transdukční MeSH
• adaptorové proteiny vezikulární transportní MeSH
• fosfolipasa C gama MeSH
• fosfolipasy typu C MeSH
• fosfoproteiny MeSH
• LAB protein, mouse MeSH Prohlížeč
• Lat protein, mouse MeSH Prohlížeč
• LAT2 protein, mouse MeSH Prohlížeč
• membránové proteiny MeSH
• proteiny MeSH
• receptory IgE MeSH
• tyrosin MeSH
• vápník MeSH

The first step in immunoreceptor signaling is represented by ligand-dependent receptor aggregation, followed by receptor phosphorylation mediated by tyrosine kinases of the Src family. Recently, sphingolipid- and cholesterol-rich plasma membrane microdomains, called lipid rafts, have been identified and proposed to function as platforms where signal transduction molecules may interact with the aggregated immunoreceptors. Here we show that aggregation of the receptors with high affinity for immunoglobulin E (FcepsilonRI) in mast cells is accompanied by a co-redistribution of the Src family kinase Lyn. The co-redistribution requires Lyn dual fatty acylation, Src homology 2 (SH2) and/or SH3 domains, and Lyn kinase activity, in cis or in trans. Palmitoylation site-mutated Lyn, which is anchored to the plasma membrane but exhibits reduced sublocalization into lipid rafts, initiates the tyrosine phosphorylation of FcepsilonRI subunits, Syk protein tyrosine kinase, and the linker for activation of T cells, along with an increase in the concentration of intracellular Ca(2+). However, Lyn mutated in both the palmitoylation and myristoylation sites does not anchor to the plasma membrane and is incapable of initiating FcepsilonRI phosphorylation and early signaling events. These data, together with our finding that a constitutively tyrosine-phosphorylated FcepsilonRI does not exhibit an increased association with lipid rafts, suggest that FcepsilonRI phosphorylation and early activation events can be initiated outside of lipid rafts.

• MeSH
• aktivace enzymů MeSH
• antigeny metabolismus   MeSH
• buněčná membrána metabolismus   MeSH
• časové faktory MeSH
• cholesterol metabolismus   MeSH
• detergenty farmakologie   MeSH
• DNA metabolismus   MeSH
• fosforylace MeSH
• fosfotyrosin metabolismus   MeSH
• fragmentace DNA MeSH
• imunoblotting MeSH
• konfokální mikroskopie MeSH
• konformace proteinů MeSH
• krysa rodu Rattus MeSH
• kyselina myristová metabolismus   MeSH
• kyselina palmitová metabolismus   MeSH
• luminescentní proteiny metabolismus   MeSH
• membránové mikrodomény metabolismus   MeSH
• metabolismus lipidů MeSH
• myši MeSH
• oktoxynol farmakologie   MeSH
• precipitinové testy MeSH
• receptory IgE metabolismus   MeSH
• rekombinantní proteiny metabolismus   MeSH
• sfingolipidy metabolismus   MeSH
• signální transdukce MeSH
• skupina kinas odvozených od src-genu chemie   metabolismus   fyziologie   MeSH
• terciární struktura proteinů MeSH
• transfekce MeSH
• tyrosin metabolismus   MeSH
• vápník metabolismus   MeSH
• vazba proteinů MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zelené fluorescenční proteiny MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antigeny MeSH
• cholesterol MeSH
• detergenty MeSH
• DNA MeSH
• fosfotyrosin MeSH
• kyselina myristová MeSH
• kyselina palmitová MeSH
• luminescentní proteiny MeSH
• lyn protein-tyrosine kinase MeSH Prohlížeč
• oktoxynol MeSH
• receptory IgE MeSH
• rekombinantní proteiny MeSH
• sfingolipidy MeSH
• skupina kinas odvozených od src-genu MeSH
• tyrosin MeSH
• vápník MeSH
• zelené fluorescenční proteiny MeSH