KLRG1, Cadherins and their Interaction (35.29)

Abstract The killer cell lectin-like receptor G1 (KLRG1) is a unique inhibitory receptor expressed on a phenotypically mature subset of resting NK cells as well as effector memory CD8+ T cells. KLRG1 is a C-type lectin inhibitory receptor that contains an immunoreceptor tyrosine-based inhibitory motif (ITIM) in its cytoplasmic domain. KLRG1 ligands have been recently identified and are members of the broadly expressed cadherin family, N-, R-, and E-cadherin. In this study, we attempt to elucidate the consequences of cadherin engagement by KLRG1 as well as KLRG1 engagement by cadherin. We found that E-cadherin engagement by KLRG1 influences the dynamics of cell adhesion. Along this line, we showed that E-cadherin and KLRG1 interaction regulates the signaling properties of E-cadherin. These data are supported by the fact that recombinant extracellular domain of N-cadherin blocks KLRG1 tetramer binding to cadherin expressing cells. In addition, we show that recombinant extracellular domain of N-cadherin functions to regulate KLRG1 signaling. We also demonstrated ex vivo that KLRG1 engagement by E-cadherin induces a significant inhibition of TCR signaling. Notably, upon analysis of E-cadherin mutants, we discovered that E-cadherin's cytoplasmic domain regulates its cell surface expression. Taken together, our data suggest that immune receptor interaction with cadherin may have an impact not only on immune cells such as NK cells but also on cells expressing cadherin such as epithelial cells. Supported by NIH grant AI 58181.