Requirement of Gab2 for mast cell development and KitL/c-Kit signaling

Blood ◽  
2002 ◽  
Vol 99 (5) ◽  
pp. 1866-1869 ◽  
Author(s):  
Keigo Nishida ◽  
Lin Wang ◽  
Eiichi Morii ◽  
Sung Joo Park ◽  
Masahiro Narimatsu ◽  
...  

Mast cells are thought to participate in a variety of immune responses, such as parasite resistance and the allergic reaction. Mast cell development depends on stem cell factor (Kit ligand) and its receptor, c-Kit. Gab2 is an adaptor molecule containing a pleckstrin homology domain and potential binding sites for SH2 and SH3 domains. Gab2 is phosphorylated on tyrosine after stimulation with cytokines and growth factors, including KitL. Gab2-deficient mice were created to define the physiological requirement for Gab2 in KitL/c-Kit signaling and mast cell development. In Gab2-deficient mice, the number of mast cells was reduced markedly in the stomach and less severely in the skin. Bone marrow–derived mast cells (BMMCs) from the Gab2-deficient mice grew poorly in response to KitL. KitL-induced ERK MAP kinase and Akt activation were impaired in Gab2-deficient BMMCs. These data indicate that Gab2 is required for mast cell development and KitL/c-Kit signaling.

1992 ◽  
Vol 175 (1) ◽  
pp. 245-255 ◽  
Author(s):  
B K Wershil ◽  
M Tsai ◽  
E N Geissler ◽  
K M Zsebo ◽  
S J Galli

Interactions between products of the mouse W locus, which encodes the c-kit tyrosine kinase receptor, and the Sl locus, which encodes a ligand for c-kit receptor, which we have designated stem cell factor (SCF), have a critical role in the development of mast cells. Mice homozygous for mutations at either locus exhibit several phenotypic abnormalities including a virtual absence of mast cells. Moreover, the c-kit ligand SCF can induce the proliferation and maturation of normal mast cells in vitro or in vivo, and also can result in repair of the mast cell deficiency of Sl/Sld mice in vivo. We now report that administration of SCF intradermally in vivo results in dermal mast cell activation and a mast cell-dependent acute inflammatory response. This effect is c-kit receptor dependent, in that it is not observed when SCF is administered to mice containing dermal mast cells expressing functionally inactive c-kit receptors, is observed with both glycosylated and nonglycosylated forms of SCF, and occurs at doses of SCF at least 10-fold lower on a molar basis than the minimally effective dose of the classical dermal mast cell-activating agent substance P. These findings represent the first demonstration in vivo that a c-kit ligand can result in the functional activation of any cellular lineage expressing the c-kit receptor, and suggest that interactions between the c-kit receptor and its ligand may influence mast cell biology through complex effects on proliferation, maturation, and function.


Blood ◽  
1994 ◽  
Vol 84 (12) ◽  
pp. 4322-4332 ◽  
Author(s):  
P Valent ◽  
E Spanblochl ◽  
HC Bankl ◽  
WR Sperr ◽  
C Marosi ◽  
...  

Autonomous, factor-independent growth and differentiation of malignant cells in preleukemic and leukemic disease states is a well-recognized phenomenon and is often associated with a poor prognosis. Mast cells are distinct hematopoietic cells and express a unique profile of antigens. Growth and differentiation of normal mast cells is dependent on mast cell growth factor (MGF), the ligand of the c-kit protooncogene product. In this study, we screened for mast cell-lineage involvement in 52 patients suffering from myeloid leukemias, myelodysplastic syndromes (MDS), systemic mastocytosis, or other diseases by probing for mast cell-related molecules (c-kit, tryptase, histamine, and MGF) and by analyzing kit ligand/MGF-independent growth of mast cells in long-term suspension culture. Of the 52 patients tested, 2 patients with refractory anemia with excess of blast cells in transformation and 1 patient suffering from chronic myeloid leukemia blast crisis (CML-BC) were diagnosed as mastocytic disease. These patients were characterized by complex chromosomal abnormalities, splenomegaly, high percentages of circulating metachromatic cells (5% to 25%), high levels of cellular tryptase (> 10 ng/10(5) peripheral blood mononuclear cells/mL) and a tryptase/histamine (ng:ng) ratio greater than 1. The metachromatic cells expressed the mast-cell-related surface antigen c-kit, but not basophil-related antigens (CD11b, CDw17). Furthermore, in these 3 patients, spontaneous, MGF-independent growth of mast cells along with spontaneous synthesis of tryptase was demonstrable in long-term culture. No autocrine production, paracrine production, or overproduction of MGF was found. The spontaneous growth of mast cells could neither be abbrogated by addition of monoclonal antibodies (MoAbs) to c-kit nor by MoAbs against MGF (< 5% inhibition), whereas factor (MGF)-dependent differentiation of mast cells in these patients could be abbrogated by MoAbs to c-kit or MoAbs to MGF (> 70% inhibition, P < .001). In addition, serum MGF levels in these patients were within the normal range and MGF could not be detected in cell-free culture supernatants. All 3 patients showed rapid progression of disease and had a survival time of less than 1 year. In conclusion, we describe a unique form of transformation in MDS and CML-BC characterized by mast cell lineage involvement and factor-independent differentiation of mast cells. This form of leukemic transformation has to be delineated from chronic myeloid leukemia with basophilia or basophil crisis, from primary mast cell leukemia, and from monocytic leukemias and myelodysplastic disorders associated with basophilia.


2019 ◽  
Vol 54 (4) ◽  
pp. 1900685 ◽  
Author(s):  
Gunnar Pejler

It is now well established that mast cells (MCs) play a crucial role in asthma. This is supported by multiple lines of evidence, including both clinical studies and studies on MC-deficient mice. However, there is still only limited knowledge of the exact effector mechanism(s) by which MCs influence asthma pathology. MCs contain large amounts of secretory granules, which are filled with a variety of bioactive compounds including histamine, cytokines, lysosomal hydrolases, serglycin proteoglycans and a number of MC-restricted proteases. When MCs are activated, e.g. in response to IgE receptor cross-linking, the contents of their granules are released to the exterior and can cause a massive inflammatory reaction. The MC-restricted proteases include tryptases, chymases and carboxypeptidase A3, and these are expressed and stored at remarkably high levels. There is now emerging evidence supporting a prominent role of these enzymes in the pathology of asthma. Interestingly, however, the role of the MC-restricted proteases is multifaceted, encompassing both protective and detrimental activities. Here, the current knowledge of how the MC-restricted proteases impact on asthma is reviewed.


Blood ◽  
2000 ◽  
Vol 95 (9) ◽  
pp. 2821-2828 ◽  
Author(s):  
Tatsuya Kinoshita ◽  
Kenichi Koike ◽  
Hadija Hemed Mwamtemi ◽  
Susumu Ito ◽  
Shuichi Ishida ◽  
...  

We examined the effects of retinoids on the human mast cell development using a serum-deprived culture system. When 10-week cultured mast cells derived from CD34+ cord blood cells were used as target cells, both all-trans retinoic acid (ATRA) and 9-cis RA inhibited the progeny generation under stimulation with stem cell factor (SCF) in a dose-dependent manner (the number of progeny grown by SCF plus RA at 10−7 mol/L was one tenth of the value obtained by SCF alone). The early steps in mast cell development appear to be less sensitive to RA according to the single CD34+c-kit+ cord blood cell culture study. The optimal concentration of RAs also reduced the histamine concentration in the cultured mast cells (3.00 ± 0.47 pg per cell in SCF alone, 1.44 ± 0.18 pg per cell in SCF+ATRA, and 1.41 ± 0.10 pg per cell in SCF+9-cis RA). RT-PCR analyses showed the expression of RAR, RARβ, RXR, and RXRβ messenger ribonucleic acid (mRNA) in 10-week cultured mast cells. The addition of an RAR-selective agonist at 10−10 mol/L to 10−7 mol/L decreased the number of mast cells grown in SCF, whereas an RXR-selective agonist at up to 10−8 mol/L was inactive. Among RAR subtype selective retinoids used at 10−9 mol/L to 10−7 mol/L, only the RAR agonist was equivalent to ATRA at 10−7 mol/L in its ability to inhibit mast cell growth. Conversely, the addition of excess concentrations of a RAR antagonist profoundly counteracted the retinoid-mediated suppressive effects. These results suggest that RA inhibits SCF-dependent differentiation of human mast cell progenitors through a specific receptor.


Blood ◽  
2004 ◽  
Vol 103 (3) ◽  
pp. 860-867 ◽  
Author(s):  
Naotomo Kambe ◽  
Hidefumi Hiramatsu ◽  
Mika Shimonaka ◽  
Hisanori Fujino ◽  
Ryuta Nishikomori ◽  
...  

Abstract The transplantation of primitive human cells into sublethally irradiated immune-deficient mice is the well-established in vivo system for the investigation of human hematopoietic stem cell function. Although mast cells are the progeny of hematopoietic stem cells, human mast cell development in mice that underwent human hematopoietic stem cell transplantation has not been reported. Here we report on human mast cell development after xenotransplantation of human hematopoietic stem cells into nonobese diabetic severe combined immunodeficient \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \((\mathrm{NOD{/}SCID}){/}{\gamma}_{\mathrm{c}}^{null}\) \end{document} (NOG) mice with severe combined immunodeficiency and interleukin 2 (IL-2) receptor γ-chain allelic mutation. Supported by the murine environment, human mast cell clusters developed in mouse dermis, but they required more time than other forms of human cell reconstitution. In lung and gastric tract, mucosal-type mast cells containing tryptase but lacking chymase located on gastric mucosa and in alveoli, whereas connective tissue-type mast cells containing both tryptase and chymase located on gastric submucosa and around major airways, as in the human body. Mast cell development was also observed in lymph nodes, spleen, and peritoneal cavity but not in the peripheral blood. Xenotransplantation of human hematopoietic stem cells into NOG mice can be expected to result in a highly effective model for the investigation of human mast cell development and function in vivo.


2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Elín I. Magnúsdóttir ◽  
Mirjana Grujic ◽  
Jessica Bergman ◽  
Gunnar Pejler ◽  
Malin C. Lagerström

Abstract Background Itch is an unpleasant sensation that can be debilitating, especially if it is chronic and of non-histaminergic origin, as treatment options are limited. Endothelin-1 (ET-1) is a potent endogenous vasoconstrictor that also has the ability to induce a burning, non-histaminergic pruritus when exogenously administered, by activating the endothelin A receptor (ETAR) on primary afferents. ET-1 is released endogenously by several cell-types found in the skin, including macrophages and keratinocytes. Mast cells express ETARs and can thereby be degranulated by ET-1, and mast cell proteases chymase and carboxypeptidase A3 (CPA3) are known to either generate or degrade ET-1, respectively, suggesting a role for mast cell proteases in the regulation of ET-1-induced itch. The mouse mast cell proteases (mMCPs) mMCP4 (chymase), mMCP6 (tryptase), and CPA3 are found in connective tissue type mast cells and are the closest functional homologs to human mast cell proteases, but little is known about their role in endothelin-induced itch. Methods In this study, we evaluated the effects of mast cell protease deficiency on scratching behavior induced by ET-1. To investigate this, mMCP knock-out and transgenic mice were injected intradermally with ET-1 and their scratching behavior was recorded and analyzed. Results CPA3-deficient mice and mice lacking all three proteases demonstrated highly elevated levels of scratching behavior compared with wild-type controls. A modest increase in the number of scratching bouts was also seen in mMCP6-deficient mice, while mMCP4-deficiency did not have any effect. Conclusion Altogether, these findings identify a prominent role for the mast cell proteases, in particular CPA3, in the protection against itch induced by ET-1.


1998 ◽  
Vol 187 (8) ◽  
pp. 1235-1247 ◽  
Author(s):  
Daisuke Hata ◽  
Yuko Kawakami ◽  
Naoki Inagaki ◽  
Chris S. Lantz ◽  
Toshio Kitamura ◽  
...  

We investigated the role of Bruton's tyrosine kinase (Btk) in FcεRI-dependent activation of mouse mast cells, using xid and btk null mutant mice. Unlike B cell development, mast cell development is apparently normal in these btk mutant mice. However, mast cells derived from these mice exhibited significant abnormalities in FcεRI-dependent function. xid mice primed with anti-dinitrophenyl monoclonal IgE antibody exhibited mildly diminished early-phase and severely blunted late-phase anaphylactic reactions in response to antigen challenge in vivo. Consistent with this finding, cultured mast cells derived from the bone marrow cells of xid or btk null mice exhibited mild impairments in degranulation, and more profound defects in the production of several cytokines, upon FcεRI cross-linking. Moreover, the transcriptional activities of these cytokine genes were severely reduced in FcεRI-stimulated btk mutant mast cells. The specificity of these effects of btk mutations was confirmed by the improvement in the ability of btk mutant mast cells to degranulate and to secrete cytokines after the retroviral transfer of wild-type btk cDNA, but not of vector or kinase-dead btk cDNA. Retroviral transfer of Emt (= Itk/Tsk), Btk's closest relative, also partially improved the ability of btk mutant mast cells to secrete mediators. Taken together, these results demonstrate an important role for Btk in the full expression of FcεRI signal transduction in mast cells.


Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 775-775
Author(s):  
Raghuveer Mali ◽  
Holly Rene Martin ◽  
Baskar Ramdas ◽  
Lakshmi Palam ◽  
Valeria Visconte ◽  
...  

Abstract KIT receptor signaling plays an important role in mast cell development. Gain-of-function mutations in KIT receptor have been identified in human diseases including gastrointestinal stromal tumors (GIST), systemic mastocytosis (SM) and acute myeloid leukemia (AML). Although KIT mutations found in GIST are sensitive to imatinib, KIT mutation (KITD816V) found in 90% of SM patients is imatinib-resistant and currently no therapies are available to treat the human diseases associated with this mutation. Our recent studies have identified Ten-Eleven-Translocation 2 (TET2) mutations in ~23% of SM patients and are associated with poor prognosis and overall survival. TET2 is a methylcytosine dioxygenase that plays a vital role in active DNA demethylation. Recent studies suggest that patients with mutations in TET2 and KITD816V develop more aggressive form of mastocytosis with worse prognosis. Although it is known that TET2 and KITD816V cooperate in SM patients, it is not clear how they cooperate with each other and what is the physiologic role of TET2 in normal mast cell development. We show that loss of Tet2 results in impaired maturation of mast cells in vivo and in bone marrow-derived mast cells (BMMC) compared to WT controls, which is associated with reduction in 5-hmc levels compared to WT BMMCs. We also observed reduction in the expression of mast cell-specific genesincluding Mast cell proteinase-5 (MCP-5), Mast cell proteinase-6 (MCP-6) and Carboxypeptidase A (CPA). To determine the mechanism behind altered mast cell differentiation in Tet2-/- BMMCs, we performed RNA-seq analysis in WT and Tet2-/- mast cells and observed altered expression of various genes involved in development of mast cells including Kit, FcεR1, Mitf, Notch, and Myc. We further confirmed altered expression of Mitf, Gata-2, and PU.1 in Tet2-/- BMMCs compared to WT BMMCs by western blotting. Since Tet2 regulates DNA demethylation, we tested whether altered BMMC differentiation in Tet2-/- mice is due to enhanced DNA methylation. We treated WT or Tet2-/- BM cells for 3 weeks with vehicle or 5-azacytidine (hypomethylating agent) and analyzed mast cell differentiation. Treatment with 5-azacytidine completely corrected the defective mast cell differentiation in Tet2-/- cells to WT levels. These results suggest that Tet2 plays a significant role in mast cell differentiation by regulating the expression of critical transcription factors including Mitf, Gata-2 and PU.1. We next analyzed the growth of Tet2-/- BMMCs in response to cytokines. Tet2-deficient BMMCs show enhanced cytokine mediated growth compared to WT BMMCs. Hyper-proliferation of Tet2-/- BMMCs is associated with reduced expression of tumor suppressor, PTEN, whose promoter is hypermethylated and a concomitant increase in the activation of the PI3K/AKT pathway. Since loss of function TET2 mutations have been observed in SM patients in addition to KITD816V mutation, we tested whether loss of Tet2 cooperates with KIT mutation in vitro and in vivo. Tet2-deficiency or knockdown in conjunction with the expression of KIT mutation resulted in significantly enhanced growth compared to cells bearing KIT mutation alone or lacking Tet2 expression. Likewise in human mastocytosis xenograft model, significantly enlarged tumors were observed in NSG mice transplanted with human mastocytosis cell line bearing the KITD816V mutation (HMC1.2) and knockdown of TET2 compared to HMC1.2 cells bearing only the KITD816V mutation. The cooperation between loss of Tet2 and KIT mutation was associated with further increase in PI3K/AKT activation and pharmacologic inhibitor treatment with a PI3K inhibitor GDC-0941 (Pan PI3K), but not TGX221 (p110β-specific) or IC87114 (p110δ-specific), significantly reduced the hyper-proliferation of Tet2-/- BMMCs and cell lines as well as primary BM blasts derived from SM patients bearing the KITD816V mutation. Consistently, combined loss of p110α and p110δ subunits of PI3K resulted in the most profound growth repression in oncogenic KIT bearing BM cells, but did not correct altered differentiation in Tet2-/- BMMCs. Taken together our results suggest that combinational therapy involving 5-azacytidine (which corrects the impaired mast cell differentiation) and PI3K inhibitor (which corrects the excessive proliferation) is a better therapeutic option for treating human mastocytosis patients bearing TET2 and KIT mutations. Disclosures No relevant conflicts of interest to declare.


1994 ◽  
Vol 299 (2) ◽  
pp. 507-513 ◽  
Author(s):  
G Pejler ◽  
K Söderström ◽  
A Karlström

Rat peritoneal mast cells were shown to inactivate thrombin rapidly. The thrombin-inactivating activity was purified to homogeneity by a combination of anion-exchange chromatography and h.p.l.c. on a Superdex 75 column. The purified thrombin inactivator had an apparent molecular mass of 29 kDa and an N-terminal amino acid sequence identical to rat mast-cell protease 1 (RMCP-1). After labelling of the mast cells in vivo with 35SO4(2-), RMCP-1 was recovered in a macromolecular complex with [35S]heparin proteoglycans. Dissociation of RMCP-1 from the heparin proteoglycans by Superdex 75 chromatography in the presence of 2 M NaCl resulted in a marked loss of the thrombin-inactivating activity displayed by the enzyme. When RMCP-1 was reconstituted with either endogenous [35S]heparin proteoglycans or standard pig mucosal heparin, the enzyme regained its thrombin-inactivating properties. Affinity chromatography of endogenous [35S]heparin on matrix-linked RMCP-1 demonstrated that all of the heparin molecules contained high-affinity binding sites for the mast-cell protease. In contrast, the endogenous mast-cell heparin showed low affinity for antithrombin, a protease inhibitor involved in the regulation of coagulation enzymes.


1988 ◽  
Vol 36 (8) ◽  
pp. 1053-1060 ◽  
Author(s):  
G H Caughey ◽  
N F Viro ◽  
L D Calonico ◽  
D M McDonald ◽  
S C Lazarus ◽  
...  

Mast cell populations can be distinguished by differences in the content and substrate specificity of their two major cytoplasmic granule proteases, the chymases and the tryptases. To explore the origins of differences in the types of proteases present in mast cells, we used a double cytochemical staining technique to reveal both chymase and tryptase in cells from four lines of dog mast cell tumors containing both enzymes. We expected that if chymase and tryptase were expressed together during cell development the relative staining intensity of chymase compared to tryptase would be constant among different cells of each tumor. Instead, we found substantial variation in the relative intensity of chymase and tryptase staining among cells of a given mastocytoma line, each of which contained cells presumed to be monoclonal in origin but heterogeneous with respect to cell development. The overall staining intensity for chymase or tryptase correlated with the amount of protease activity in extracts of tumor homogenates. Staining specificity was established by use of selective inhibitors and competitive substrates and was tested on various types of dog cells obtained by bronchoalveolar lavage. The results suggest that active chymase and tryptase may be expressed differently during mast cell differentiation and support the possibility of a close developmental relationship between mast cells differing in protease phenotype. Moreover, the success of the staining procedures applied to mastocytoma cells suggests that they may be of general utility in phenotyping of mast cells according to the protease activities present in their granules.


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