Pfeiffer Annika, Bandara Geethani, Petersen Jennifer D, Falduto Guido H, Zimmerberg Joshua, Metcalfe Dean D, Olivera Ana
Mast Cell Biology Section Laboratory of Allergic Diseases National Institute of Allergy and Infectious Diseases National Institutes of Health Bethesda Maryland USA.
Section on Integrative Biophysics Division of Basic and Translational Biophysics Eunice Kennedy Shriver National Institute of Child Health and Human Development National Institutes of Health Bethesda Maryland USA.
J Extracell Biol. 2024 Jan 23;3(1):e139. doi: 10.1002/jex2.139. eCollection 2024 Jan.
The receptor tyrosine kinase (RTK) KIT and its ligand stem cell factor (SCF) are essential for human mast cell (huMC) survival and proliferation. HuMCs expressing oncogenic KIT variants secrete large numbers of extracellular vesicles (EVs). The role KIT plays in regulating EV secretion has not been examined. Here, we investigated the effects of stimulation or inhibition of KIT activity on the secretion of small EVs (sEVs). In huMCs expressing constitutively active KIT, the quantity and quality of secreted sEVs positively correlated with the activity status of KIT. SCF-mediated stimulation of KIT in huMCs or murine MCs, or of transiently expressed KIT in HeLa cells, enhanced the release of sEVs expressing exosome markers. In contrast, ligand-mediated stimulation of the RTK EGFR in HeLa cells did not affect sEV secretion. The release of sEVs induced by either constitutively active or ligand-activated KIT was remarkably decreased when cells were treated with KIT inhibitors, concomitant with reduced exosome markers in sEVs. Similarly, inhibition of oncogenic KIT signalling kinases like PI3K, and MAPK significantly reduced the secretion of sEVs. Thus, activation of KIT and its early signalling cascades stimulate the secretion of exosome-like sEVs in a regulated fashion, which may have implications for KIT-driven functions.
受体酪氨酸激酶（RTK）KIT及其配体干细胞因子（SCF）对人肥大细胞（huMC）的存活和增殖至关重要。表达致癌性KIT变体的huMC分泌大量细胞外囊泡（EV）。KIT在调节EV分泌中所起的作用尚未得到研究。在此，我们研究了刺激或抑制KIT活性对小EV（sEV）分泌的影响。在组成型激活KIT的huMC中，分泌的sEV的数量和质量与KIT的活性状态呈正相关。SCF介导的对huMC或小鼠MC中KIT的刺激，或对HeLa细胞中瞬时表达的KIT的刺激，增强了表达外泌体标志物的sEV的释放。相比之下，HeLa细胞中配体介导的RTK表皮生长因子受体（EGFR）刺激不影响sEV分泌。当用KIT抑制剂处理细胞时，组成型激活或配体激活的KIT诱导的sEV释放显著减少，同时sEV中外泌体标志物减少。同样，抑制致癌性KIT信号激酶如PI3K和丝裂原活化蛋白激酶（MAPK）可显著减少sEV的分泌。因此，KIT及其早期信号级联的激活以一种受调控的方式刺激类外泌体sEV的分泌，这可能对KIT驱动的功能有影响。
