Necessity of extracellular domain of W (c-kit) receptors for attachment of murine cultured mast cells to fibroblasts

Abstract

The receptor encoded by the W (c-kit) locus (W receptor) is expressed on the surface of cultured mast cells (CMC) derived from normal (+/+) mice, whereas its ligand encoded by the Sl locus (Sl ligand) is expressed on the surface of fibroblast cell lines derived from murine embryos. Involvement of W receptors and Sl ligands in attachment of CMC to fibroblasts was investigated. CMC were cocultured with fibroblasts; nonattaching CMC were removed and the remaining CMC were counted. CMC derived from mice of the W/W genotype did not express the extracellular domain of W receptors, and attachment of W/W CMC to +/+ fibroblasts was significantly impaired. Fibroblasts derived from embryos of the Sl/Sl genotype did not express Sl ligands, and the attachment of +/+ CMC to Sl/Sl fibroblasts was also impaired. The Wv and W42 alleles are point mutations at the intracellular tyrosine kinase domain. Attachment of either Wv/Wv, W/Wv, or W/W42 CMC to +/+ fibroblasts was comparable with that of +/+ CMC. Moreover, the addition of monoclonal antibody against the extracellular domain of W receptors inhibited the attachment of +/+ CMC to +/+ fibroblasts. Thus, the extracellular domain of W receptors appeared to be necessary for attachment of CMC to fibroblasts.

Membrane‐bound Kit ligand regulates melanocyte adhesion and survival, providing physical interaction with an intraepithelial niche

“…C-kit-dependent mast cell adhesion to mb-KitL has been observed with wild-type as well as with kinase-dead forms of c-kit (2,48). However, it is not clear whether the c-kit/KitL clusters observed at cell-cell contacts are also present in these cases.…”

“…In contrast, mast cells expressing the kinasedeficient W v allele of c-kit are efficiently recruited (60). Since mast cells expressing either the W v or the completely kinase dead W 42 allele are able to mediate mast cell adhesion to mb-KitL-expressing fibroblasts (2,48), it appears plausible that a c-kit-dependent but kinaseindependent process is responsible for initial mast cell recruitment by endothelial cells. In fact, mb-KitL, but not S-KitL enhances ␣4␤1/VCAM-1 dependent mast cell binding to endothelial cells (67).…”

Stem cell factor expression, mast cells and inflammation in asthma

“…Stem cell factor enables mast cells to adhere to the extracellular matrix [20,21] and itself acts as an adhesion molecule for the mast cells, through the interaction between mSCF and Kit [21][22][23]43]. Murine mast cells from bone marrow, treated with recombinant sSCF, adhere to fibronectin [20,140].…”

“…Murine mast cells from bone marrow adhere to COS-7 cells transfected by mSCF cDNA, but do not adhere to COS-7 transfected with a truncated form of cDNA that encodes only sSCF [43]. Moreover, murine mast cells derived from bone marrow of mutant WBB6F1 ) W/W mice, which do not have a Kit receptor transmembrane domain, do not attach to fibroblasts expressing mSCF; and mast cells derived from the bone marrow of wild-type +/+ mice do not bind to the fibroblasts of WCB6F1 ) Sl/Sl embryos, which do not express mSCF [22]. These studies confirm the involvement of an interaction between mSCF and Kit in cell-cell adhesion.…”

“…SCF improves survival of mast cells by inhibiting their apoptosis [16,17]. It induces their chemotaxis [18,19], plays a role in their adhesion to the extracellular matrix [20,21] and acts as an adhesion molecule for them in its membrane form [21][22][23]. SCF induces mast cell hyperplasia in vivo after subcutaneous injection in humans [24,25].…”