Cloning of rat TARC cDNA and analysis of tissue-specific mRNA expression

Abstract

Thymus-and activation-regulated chemokine (TARC) is one that selectively controls the migration of type 2-helper T lymphocytes into inflammatory lesions. TARC is a CC chemokine and plays an essential role in recruiting CC chemokine receptor 4-positive Th2 cells to allergic lesions. We cloned TARC cDNA from rat thymus using RT-PCR. The rat TARC clone contained a full-length open reading frame encoding 93 amino acids that showed 83 and 66% homology with mouse and human homologs, respectively. The expression of TARC mRNA was mainly in the lymphoid organs, for example, the thymus, spleen, and lymph node. The recombinant TARC was expressed in Escherichia coli and purified in an active form. In addition, the purified rat TARC with S-tagged specifically binds to human CCR4 in CD4/CCR4-transfected HOS cells by cell-binding assay using flow cytometry. The TARC cDNA clones obtained in this study will be valuable for future studies on allergic diseases in rats.