title: The adaptor 3BP2 is required for KIT receptor expression and human mast cell survival.
abstract: SH3-binding protein 2 (3BP2) is a cytoplasmic adaptor protein that acts as a positive regulator in mast cell FcεRI-dependent signaling. The KIT receptor whose ligand is the stem cell factor is necessary for mast cell development, proliferation, and survival as well as for optimal IgE-dependent signal. Activating mutations in KIT have been associated with several diseases including mastocytosis. In the present work, we found that 3BP2 silencing impairs KIT signaling pathways, thus affecting phosphoinositide 3-kinase and MAPK pathways in human mast cells (huMCs) from HMC-1, LAD2 (huMC lines), and CD34(+)-derived mast cells. Unexpectedly, silencing of 3BP2 reduces KIT expression in normal huMCs as well as in HMC-1 cells where KIT is mutated, thus increasing cellular apoptosis and caspase-3/7 activity. 3BP2 silencing reduces KIT transcription expression levels. Interestingly, 3BP2 silencing decreased microphthalmia-associated transcription factor (MITF) expression, a transcription factor involved in KIT expression. Reconstitution of 3BP2 in knockdown cells leads to reversal of KIT expression as well as survival phenotype. Accordingly MITF reconstitution enhances KIT expression levels in 3BP2-silenced cells. Moreover, downregulation of KIT expression by miRNA-221 overexpression or the proteasome inhibitor bortezomib also reduced 3BP2 and MITF expression. Furthermore, KIT tyrosine activity inhibition reduced 3BP2 and MITF expression, demonstrating again a tight and reciprocal relationship between these molecules. Taken together, our results show that 3BP2 regulates huMC survival and participates in KIT-mediated signal transduction by directly controlling KIT receptor expression, suggesting its potential as a therapeutic target in mast cell-mediated inflammatory diseases and deregulated KIT disorders.
authors: Biochemistry Unit, Faculty of Medicine, University of Barcelona, 08036 Barcelona, Spain; Laboratori d'Immunoallèrgia Respiratòria Clínica i Experimental, Institut d'Investigacions Biomèdiques August Pi i Sunyer, 08036 Barcelona, Spain;
authors: Erola
authors: E
authors: Ainsua-Enrich
authors: Biochemistry Unit, Faculty of Medicine, University of Barcelona, 08036 Barcelona, Spain; Laboratori d'Immunoallèrgia Respiratòria Clínica i Experimental, Institut d'Investigacions Biomèdiques August Pi i Sunyer, 08036 Barcelona, Spain;
authors: Eva
authors: E
authors: Serrano-Candelas
authors: Biochemistry Unit, Faculty of Medicine, University of Barcelona, 08036 Barcelona, Spain; Laboratori d'Immunoallèrgia Respiratòria Clínica i Experimental, Institut d'Investigacions Biomèdiques August Pi i Sunyer, 08036 Barcelona, Spain;
authors: Damiana
authors: D
authors: Álvarez-Errico
authors: Laboratori d'Immunoallèrgia Respiratòria Clínica i Experimental, Institut d'Investigacions Biomèdiques August Pi i Sunyer, 08036 Barcelona, Spain; Networking Research Center on Respiratory Diseases, Institute of Health Carlos III, 28029 Madrid, Spain;
authors: César
authors: C
authors: Picado
authors: Immunobiology Group, Molecular Biology and Biochemistry Research Center for Nanomedicine, Nanomedicine Program, Vall d'Hebrón Research Institute, Autonomous University of Barcelona, 08035 Barcelona, Spain; Networking Research Center on Bioengineering, Biomaterials and Nanomedicine, Institute of Health Carlos III, 28029 Madrid, Spain; and.
authors: Joan
authors: J
authors: Sayós
authors: Molecular Immunology Section, Laboratory of Molecular Immunogenetics, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892.
authors: Juan
authors: J
authors: Rivera
authors: Biochemistry Unit, Faculty of Medicine, University of Barcelona, 08036 Barcelona, Spain; Laboratori d'Immunoallèrgia Respiratòria Clínica i Experimental, Institut d'Investigacions Biomèdiques August Pi i Sunyer, 08036 Barcelona, Spain; martin_andorra@ub.edu.
authors: Margarita
authors: M
authors: Martín
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D017209:Apoptosis / Q000235:genetics; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000235:genetics; D005786:Gene Expression Regulation; D020868:Gene Silencing; D006801:Humans; D008407:Mast Cells / Q000276:immunology / Q000378:metabolism*; D051739:Microphthalmia-Associated Transcription Factor / Q000378:metabolism; D009154:Mutation; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014158:Transcription, Genetic
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051739:Microphthalmia-Associated Transcription Factor; D012333:RNA, Messenger; C109073:SH3BP2 protein, human; D019009:Proto-Oncogene Proteins c-kit; D053148:Caspase 3; D053179:Caspase 7