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  1. Article ; Online: Clorfl86/RHEX Is a Negative Regulator of SCF/KIT Signaling in Human Skin Mast Cells

    Kristin Franke / Gürkan Bal / Zhuoran Li / Torsten Zuberbier / Magda Babina

    Cells, Vol 12, Iss 1306, p

    2023  Volume 1306

    Abstract: Mast cells (MCs) are key effector cells in allergic and inflammatory diseases, and the SCF/KIT axis regulates most aspects of the cells’ biology. Using terminally differentiated skin MCs, we recently reported on proteome-wide phosphorylation changes ... ...

    Abstract Mast cells (MCs) are key effector cells in allergic and inflammatory diseases, and the SCF/KIT axis regulates most aspects of the cells’ biology. Using terminally differentiated skin MCs, we recently reported on proteome-wide phosphorylation changes initiated by KIT dimerization. C1orf186/RHEX was revealed as one of the proteins to become heavily phosphorylated. Its function in MCs is undefined and only some information is available for erythroblasts. Using public databases and our own data, we now report that RHEX exhibits highly restricted expression with a clear dominance in MCs. While expression is most pronounced in mature MCs, RHEX is also abundant in immature/transformed MC cell lines (HMC-1, LAD2), suggesting early expression with further increase during differentiation. Using RHEX-selective RNA interference, we reveal that RHEX unexpectedly acts as a negative regulator of SCF-supported skin MC survival. This finding is substantiated by RHEX’s interference with KIT signal transduction, whereby ERK1/2 and p38 both were more strongly activated when RHEX was attenuated. Comparing RHEX and capicua (a recently identified repressor) revealed that each protein preferentially suppresses other signaling modules elicited by KIT. Induction of immediate-early genes strictly requires ERK1/2 in SCF-triggered MCs; we now demonstrate that RHEX diminution translates to this downstream event, and thereby enhances NR4A2, JUNB, and EGR1 induction. Collectively, our study reveals RHEX as a repressor of KIT signaling and function in MCs. As an abundant and selective lineage marker, RHEX may have various roles in the lineage, and the provided framework will enable future work on its involvement in other crucial processes.
    Keywords mast cell ; RHEX ; C1orf186 ; survival ; apoptosis ; signal transduction ; Biology (General) ; QH301-705.5
    Subject code 910
    Language English
    Publishing date 2023-05-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: MRGPRX2-Mediated Degranulation of Human Skin Mast Cells Requires the Operation of G αi , G αq , Ca++ Channels, ERK1/2 and PI3K—Interconnection between Early and Late Signaling

    Zhao Wang / Kristin Franke / Gürkan Bal / Zhuoran Li / Torsten Zuberbier / Magda Babina

    Cells, Vol 11, Iss 953, p

    2022  Volume 953

    Abstract: The recent discovery of MRGPRX2 explains mast cell (MC)-dependent symptoms independently of FcεRI-activation. Because of its novelty, signaling cascades triggered by MRGPRX2 are rudimentarily understood, especially in cutaneous MCs, by which MRGPRX2 is ... ...

    Abstract The recent discovery of MRGPRX2 explains mast cell (MC)-dependent symptoms independently of FcεRI-activation. Because of its novelty, signaling cascades triggered by MRGPRX2 are rudimentarily understood, especially in cutaneous MCs, by which MRGPRX2 is chiefly expressed. Here, MCs purified from human skin were used following preculture or ex vivo and stimulated by FcεRI-aggregation or MRGPRX2 agonists (compound 48/80, Substance P) in the presence/absence of inhibitors. Degranulation was assessed by β-hexosaminidase or histamine release. Phosphorylation events were studied by immunoblotting. As a G protein-coupled receptor, MRGPRX2 signals by activating G proteins; however, their nature has remained controversial. In skin MCs, G αi and G αq were required for degranulation, but G αi was clearly more relevant. Ca++ channels were likewise crucial. Downstream, PI3K was essential for granule discharge initiated by MRGPRX2 or FcεRI. ERK1/2 and JNK were additional participants, especially in the allergic route. Addressing possible points of intersection between early and later events, pERK1/2 and pAKT were found to depend on G αi , further highlighting its significance. G αq and Ca++ channels made some contributions to the phosphorylation of ERK. Ca++ differentially affected PI3K activation in FcεRI- vis-à-vis MRGPRX2-signaling, as channel inhibition increased pAKT only when triggered via FcεRI. Collectively, our study significantly extends our understanding of the molecular framework behind granule secretion from skin MCs.
    Keywords mast cells ; MRGPRX2 ; FcεRI ; degranulation ; G proteins ; signal transduction ; Biology (General) ; QH301-705.5
    Subject code 571
    Language English
    Publishing date 2022-03-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Transcriptional Profiling of the Hematopoietic Support of Interleukin-Stimulated Human Umbilical Vein Endothelial Cells (HUVECs)

    Gürkan Bal / Julian Kamhieh-Milz / Matthias Futschik / Thomas Häupl / Abdulgabar Salama / Anja Moldenhauer

    Cell Transplantation, Vol

    2012  Volume 21

    Abstract: Endothelial cells can be successfully used to maintain or increase the number of hematopoietic stem cells in vitro. Previously we identified hematopoietic progenitor cell (HPC) expansion or survival benefit induced by IL-1β-, IL-3-, and IL-6-stimulated ... ...

    Abstract Endothelial cells can be successfully used to maintain or increase the number of hematopoietic stem cells in vitro. Previously we identified hematopoietic progenitor cell (HPC) expansion or survival benefit induced by IL-1β-, IL-3-, and IL-6-stimulated human umbilical vein endothelial cell (HUVEC) supernatants. In order to identify molecular mechanisms that support hematopoiesis, we examined the time-dependent expression profiles of IL-1β-, IL-3-, and IL-6-stimulated HUVECs via microarray. Here, we present 24 common upregulated elements and three common downregulated elements of IL-1β- and IL-3-stimulated HUVECs, with these factors exhibiting great potential for the observed HPC expansion. Furthermore, metabolic pathway analysis resulted in the identification of nonproteinogenic factors such as prostaglandin E 2 (PGE 2 ) and nitric oxide (NO) and determined their HPC expansion potential via delta, methylcellulose, and cobblestone assays. We confirmed PGE 2 and spermine as hematopoietic expansion factors. Furthermore, we identified several factors such as SSAT, extracellular matrix components, microRNA21, and a microvesicle-mediated cross-talk between the endothelium and HPCs that may play a crucial role in determining stem cell fate. Our results suggest that microarray in combination with functional annotations is a convenient method to identify novel factors with great impact on HPC proliferation and differentiation.
    Keywords Medicine ; R
    Subject code 570
    Language English
    Publishing date 2012-02-01T00:00:00Z
    Publisher SAGE Publishing
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Differentially Expressed MicroRNAs in Maternal Plasma for the Noninvasive Prenatal Diagnosis of Down Syndrome (Trisomy 21)

    Julian Kamhieh-Milz / Reham Fadl Hassan Moftah / Gürkan Bal / Matthias Futschik / Viktor Sterzer / Omid Khorramshahi / Martin Burow / Gundula Thiel / Annegret Stuke-Sontheimer / Rabih Chaoui / Sundrela Kamhieh-Milz / Abdulgabar Salama

    BioMed Research International, Vol

    2014  Volume 2014

    Abstract: Objectives. Most developmental processes are under the control of small regulatory RNAs called microRNAs (miRNAs). We hypothesize that different fetal developmental processes might be reflected by extracellular miRNAs in maternal plasma and may be ... ...

    Abstract Objectives. Most developmental processes are under the control of small regulatory RNAs called microRNAs (miRNAs). We hypothesize that different fetal developmental processes might be reflected by extracellular miRNAs in maternal plasma and may be utilized as biomarkers for the noninvasive prenatal diagnosis of chromosomal aneuploidies. In this proof-of-concept study, we report on the identification of extracellular miRNAs in maternal plasma of Down syndrome (DS) pregnancies. Methods. Using high-throughput quantitative PCR (HT-qPCR), 1043 miRNAs were investigated in maternal plasma via comparison of seven DS pregnancies with age and fetal sex matched controls. Results. Six hundred and ninety-five miRNAs were identified. Thirty-six significantly differentially expressed mature miRNAs were identified as potential biomarkers. Hierarchical cluster analysis of these miRNAs resulted in the clear discrimination of DS from euploid pregnancies. Gene targets of the differentially expressed miRNAs were enriched in signaling pathways such as mucin type-O-glycans, ECM-receptor interactions, TGF-beta, and endocytosis, which have been previously associated with DS. Conclusions. miRNAs are promising and stable biomarkers for a broad range of diseases and may allow a reliable, cost-efficient diagnostic tool for the noninvasive prenatal diagnosis of DS.
    Keywords Medicine ; R
    Subject code 500 ; 610
    Language English
    Publishing date 2014-01-01T00:00:00Z
    Publisher Hindawi Limited
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Proteomic Profiling of Secreted Proteins for the Hematopoietic Support of Interleukin-Stimulated Human Umbilical Vein Endothelial Cells

    Gürkan Bal / Julian Kamhieh-Milz / Viktor Sterzer / Muhammad Al-Samman / Janusz Debski / Oliver Klein / Sundrela Kamhieh-Milz / Sucharit Bhakdi / Abdulgabar Salama

    Cell Transplantation, Vol

    2013  Volume 22

    Abstract: Human umbilical cord vein endothelial cells (HUVECs) secrete a number of factors that greatly impact the proliferation and differentiation of hematopoietic stem and progenitor cells (HSPCs). These factors remain largely unknown. Here, we report on the ... ...

    Abstract Human umbilical cord vein endothelial cells (HUVECs) secrete a number of factors that greatly impact the proliferation and differentiation of hematopoietic stem and progenitor cells (HSPCs). These factors remain largely unknown. Here, we report on the most comprehensive proteomic profiling of the HUVEC secretome and identified 827 different secreted proteins. Two hundred and thirty-one proteins were found in all conditions, whereas 369 proteins were identified only under proinflammatory conditions following IL-1β, IL-3, and IL-6 stimulation. Thirteen proteins including complement factor b (CFb) were identified only under IL-1β and IL-3 conditions and may potentially represent HSPC proliferation factors. The combination of bioinformatics and gene ontology annotations indicates the role of the complement system and its activation. Furthermore, CFb was found to be transcriptionally strongly upregulated. Addition of complement component 5b-9 (C5b-9) monoclonal antibody to the stem cell expansion assay was capable of significantly reducing their proliferation. This study suggests a complement-mediated cross-talk between endothelial cells and HSPCs under proinflammatory conditions.
    Keywords Medicine ; R
    Subject code 610
    Language English
    Publishing date 2013-07-01T00:00:00Z
    Publisher SAGE Publishing
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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