Global phosphoproteomics in SCF stimulated human skin mast cells

ABSTRACT: Global phosphoproteomics can reveal signaling cascades in unprecedented detail. The SCF/KIT axis represents a vital hematopoietic receptor tyrosine kinase (RTK) system with gain-of-function mutations prompting the development of mastocytosis and leukemia. Here, we employed a label-free phosphoproteomics profiling strategy to provide the first comprehensive portrayal of SCF-triggered phosphosignaling. Employing untransformed skin-derived mast cells expressing vast amounts of KIT, we uncover around 10,500 class-I-phosphosites following ligand-induced KIT dimerization. Apart from STAT5, the MEK/ERK cascade (including upstream and downstream events) stood out as highly stimulatable by SCF compared to less impacted PI3K/Akt>p38>JNK, a pattern validated by time-resolved immunoblotting. Direct comparison between MEK/ERKÕs and PI3KÕs support of basic programs (anti-apoptosis, cell cycle progression) revealed equipotency with substantial redundancy between the modules. In functional outputs, ERK showed dominance over PI3K regarding cytokine stimulation (TNF-a, IL-8, LIF, OSM) and was the only contributor in the induction of immediate early genes (Fos, JunB, Egr1). Our proteome-wide screen also found Å1,000 phosphosites currently undescribed in databases, pertaining to multiple protein classes. Among candidates, capicua (and components of its network) experienced massive phosphorylation by SCF. Perturbation with capicua by RNA interference unveiled its function as a potent KIT repressor, whose deregulation may contribute to the development of mastocytosis. We demonstrate the utility of an unbiased approach to uncover single protein entities and entire networks activated by RTKs, that can be surveyed experimentally. This rich resource enhances our understanding of RTK-elicited signaling networks and can serve as a benchmark to identify pathological processes, e.g. under circumstances of KIT deregulation.

INSTRUMENT(S): Q Exactive HF-X

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Mast Cell, Skin

SUBMITTER: Marieluise Kirchner  

LAB HEAD: Philipp Mertins

PROVIDER: PXD028245 | Pride | 2022-03-31

REPOSITORIES: Pride