Human LZIP binds to CCR1 and differentially affects the chemotactic activities of CCR1-dependent chemokines

Abstract

Signaling molecules that bind to chemokine receptors should play key roles in regulation of cell migration induced by chemokines. To characterize the CCR1‐mediated cellular signal transduction mechanism, we used the yeast two‐hybrid system to identify a cellular ligand for CCR1. LZIP, which has been known as a transcription factor in various cell types, was identified as a CCR1 binding protein. Although the ability of LZIP to bind DNA is possibly what allows it to function as a transcription factor, its detailed function and participation in chemotaxis have not been established. We found that LZIP binds to CCR1 based on results of a mammalian two‐ hybrid assay and immunoprecipitation experiments. The 21‐260 residues of LZIP were essential for interaction with CCR1. Results from a chemotaxis assay using LZIP transfected cells showed that LZIP enhanced Lkn‐1‐induced chemotaxis, whereas the chemotactic activities induced by other CC chemokines that bind to CCR1, including MIP‐1α, RANTES, or HCC‐4, were not affected by LZIP overexpression. These data indicate that LZIP binds to CCR1 and that the interaction between CCR1 and LZIP participates in regulation of Lkn‐1‐dependent cell migration without affecting the chemotactic activities of other CC chemokines that bind to CCR1.