Recombinant Human TSLPR Fc Chimera Protein, CF

TSLPR, also named Delta (1) and CRLM-2 (2) (cytokine receptor-like module-2), was originally cloned as a novel type 1 cytokine receptor with similarity to the common gamma chain. It was subsequently identified to be a subunit of the cellular receptor for the IL-7-like cytokine TSLP and termed TSLPR (3). The human TSLPR cDNA encodes a 371 amino acid (aa) residue type 1 membrane protein with a 22 aa residue signal peptide, a 210 aa residue extracellular domain, a 20 aa residue transmembrane domain, and a 119 aa residue cytoplasmic domain (4, 5). The extracellular region contains two fibronectin type III-like domains and a WSXWS-like motif. The cytoplasmic domain contains a membrane-proximal box 1 motif that is known to be important for association with JAKs (4). Human TSLPR displays 39% identity to mouse TSLPR and 24% identity to the common gamma receptor (4). An alternatively spliced mRNA variant encoding a soluble TSLPR has also been reported in mouse (2). TSLPR expression is ubiquitous in the immune and hematopoietic cells, but is up-regulated in Th2-skewed cells. Cells expressing TSLPR alone bind TSLP with low affinity. Co-expression of TSLPR and IL-7 R alpha is required for high-affinity TSLP binding and signal transduction (3-6). The TSLPR and IL-7 R alpha are co-expressed primarily on monocytes and dendritic cells and at lower levels in lymphoid cells. TSLP has been shown to induce the release of T cell-attracting chemokines from monocytes and enhance the maturation of CD11c⁺ dendritic cells (5).