Oncogenic Kit signals on endolysosomes and endoplasmic reticulum are essential for neoplastic mast cell proliferation

Obata, Yuichi; Toyoshima, Shota; Wakamatsu, Ei; Suzuki, Shunichi; Ogawa, Seishi; Esumi, Hiroyasu; Ryo, Akihide

doi:10.1038/ncomms6715

Cited by 37 publications

(88 citation statements)

References 70 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These results indicate that in the ER, the Kit-PI3K complex is unable to activate Akt. On the other hand, STAT5 phosphorylation was enhanced by M-COPA treatment (Fig 3A and 3B), supporting our previous finding that Kit mut activates STAT5 on the ER in neoplastic mast cells [29]. Similar results were obtained with RCM cells treated with a well-known ER-to-Golgi trafficking inhibitor brefeldin A (BFA) (S3A–S3C Fig), indicating that through blocking ER export of Kit mut , M-COPA inhibits and enhances the activation of Akt and of STAT5, respectively.…”

Section: Resultssupporting

confidence: 89%

“…Therefore, we investigated the effect of M-COPA on oncogenic Kit signalling in neoplastic mast cells. Immunofluorescence confocal microscopic analysis showed that in RCM and HMC-1.2, Kit co-localized with the endolysosome marker cathepsin D (Fig 2A and S2A Fig), as previously described [29]. M-COPA decreased the endolysosomal localization of Kit in a dose-dependent manner (Fig 2B and S2B Fig).…”

Section: Resultssupporting

confidence: 84%

See 1 more Smart Citation

M-COPA suppresses endolysosomal Kit-Akt oncogenic signalling through inhibiting the secretory pathway in neoplastic mast cells

et al. 2017

Self Cite

View full text Add to dashboard Cite

Gain-of-function mutations in Kit receptor tyrosine kinase result in the development of a variety of cancers, such as mast cell tumours, gastrointestinal stromal tumours (GISTs), acute myeloid leukemia, and melanomas. The drug imatinib, a selective inhibitor of Kit, is used for treatment of mutant Kit-positive cancers. However, mutations in the Kit kinase domain, which are frequently found in neoplastic mast cells, confer an imatinib resistance, and cancers expressing the mutants can proliferate in the presence of imatinib. Recently, we showed that in neoplastic mast cells that endogenously express an imatinib-resistant Kit mutant, Kit causes oncogenic activation of the phosphatidylinositol 3-kinase-Akt (PI3K-Akt) pathway and the signal transducer and activator of transcription 5 (STAT5) but only on endolysosomes and on the endoplasmic reticulum (ER), respectively. Here, we show a strategy for inhibition of the Kit-PI3K-Akt pathway in neoplastic mast cells by M-COPA (2-methylcoprophilinamide), an inhibitor of this secretory pathway. In M-COPA-treated cells, Kit localization in the ER is significantly increased, whereas endolysosomal Kit disappears, indicating that M-COPA blocks the biosynthetic transport of Kit from the ER. The drug greatly inhibits oncogenic Akt activation without affecting the association of Kit with PI3K, indicating that ER-localized Kit-PI3K complex is unable to activate Akt. Importantly, M-COPA but not imatinib suppresses neoplastic mast cell proliferation through inhibiting anti-apoptotic Akt activation. Results of our M-COPA treatment assay show that Kit can activate Erk not only on the ER but also on other compartments. Furthermore, Tyr568/570, Tyr703, Tyr721, and Tyr936 in Kit are phosphorylated on the ER, indicating that these five tyrosine residues are all phosphorylated before mutant Kit reaches the plasma membrane (PM). Our study provides evidence that Kit is tyrosine-phosphorylated soon after synthesis on the ER but is unable to activate Akt and also demonstrates that M-COPA is efficacious for growth suppression of neoplastic mast cells.

show abstract

Section: Resultssupporting

confidence: 89%

Section: Resultssupporting

confidence: 84%

M-COPA suppresses endolysosomal Kit-Akt oncogenic signalling through inhibiting the secretory pathway in neoplastic mast cells

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…Our data suggest that aberrant trafficking of aggregated FcεRI in cells with Gal3 KD is accompanied by enhanced FcεRI-mediated signaling. Consistent with these findings, it has been shown that intracellular-trafficking pathways of plasma membrane receptors can determine the outcome of receptor signaling (62)(63)(64). In this connection it should be noted that we observed enhanced F-actin depolymerization in FcεRI-activated BMMCs with Gal3 KD compared to controls.…”

Section: Discussionsupporting

confidence: 78%

New Regulatory Roles of Galectin-3 in High-Affinity IgE Receptor Signaling

Bambousková

Polakovičová

Hálová

et al. 2016

Molecular and Cellular Biology

View full text Add to dashboard Cite

c Aggregation of the high-affinity receptor for IgE (FcRI) 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 FcRI-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. FcRI-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-FcRI complexes; this may be related to our finding that Gal3 is a positive regulator of FcRI 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 FcRI-mediated signaling events in mast cells. M ast cells are important immune cells involved in multiple biological processes (1, 2). Under pathological conditions, they are responsible for IgE-mediated hyperreactivity and participate in severe diseases, such as allergy and asthma (3). Antigen (Ag)-mediated mast cell activation leads to the release of secretory granules containing a variety of preformed mediators (e.g., histamine and proteases), de novo synthesis of cytokines and chemokines, and enhanced production of arachidonic acid metabolites (4, 5). The principal surface receptor involved in mast cell activation is the high-affinity receptor for IgE (FcεRI), which belongs to the family of multichain immune recognition receptors. FcεRI is a tetrameric complex formed by an IgE-binding ␣ subunit, a signalamplifying ␤ subunit, and a homodimer of disulfide-linked ␥ subunits. Each FcεRI ␤ and ␥ subunit contains one immunoreceptor tyrosine-based activation motif (ITAM), which, after tyrosine phosphorylation, serves as a docking site for other signaling molecules, such as the SRC family kinase LYN or spleen tyrosine kinase (SYK). These two enzymes, together with other kinases, then phosphorylate various adaptor proteins, including linker of activated T cells 1 (LAT1) and LAT2 (also known as non-T cell activation linker [NTAL]). These adaptors are involved in activation of phospholipase C␥ (PLC␥) and subsequent signal transduction events, leading to calcium response and degranulation (6). FcεRI signaling is a complex process that depends on the magnitude of receptor aggregation and a balance between positive and negative signals that determine the extent of the response (7, 8). Although signaling pathways leading to mast cell activation have been extensively...

show abstract

“…The effect of mislocalization of mutant RNF43 in the regulation of Wnt signaling pathways has not been fully elucidated. However, it has recently been reported that an aberrant localization of the receptor protein kit in the ER leads to the activation of oncogenic downstream signaling due to abnormal trafficking originating from its missense mutation, and the mechanism shown in that report may be similar to the mechanism of activation of Wnt/␤-catenin signaling by RNF43 mutants (45).…”

Section: Discussionmentioning

confidence: 80%