Genomic organization of the genes for human and mouse CC chemokine LEC

Liver-expressed chemokine (LEC) is a CC chemokine that is selectively expre ssed in the liver. We report here the structures of the human and mouse gen es for LEG. The human LEC gene (SCYA16) was isolated from a bacterial artif icial chromosome (BAC) clone that also contained CC chemokine genes for MPI F-1/Ck beta 8, HCC-2/Lkn-1/MIP-5/MIP-1 delta, and HCC-1, The LEC gene is ap proximately 5.0 kb in length and has a three-exon and two-intron structure common to most CC chemokine genes. However, the promoter region is devoid o f a typical TATA box, and transcription initiates at multiple sites. The ge ne for CC chemokine HCC-1, which is most similar to LEG, is located approxi mately 2.2 kb upstream from the 5' end of the LEC gene in a head-to-tail fa shion. The mouse DNA fragment that hybridized with the human LEC cDNA was i solated from a BAC clone that also contained the CC chemokine genes for C10 , MRP-2/CCF18/MIP-1 gamma, and RANTES, Sequence analysis revealed that the isolated gene does not encode a functional chemokine because of deletions, insertions, and base changes. Southern blot analysis revealed that the sequ ence isolated from the BAC clone was the only one hybridizing with human LE C cDNA in the mouse genome, Therefore, mice may have only an LEC pseudogene .