Isolation of cDNA encoding a novel human CC chemokine NCC-4/LEC.

We have determined the entire sequence of human cDNA encoding a novel CC chemokine NCC-4 by 5' and 3' RACE methods. Two types of transcripts, 579 bp and 1503 bp long, respectively, are generated through alternative polyadenylation sites. Both species contain an open reading frame encoding 120 amino acids with 19-38% identity to other human CC chemokines. The short and long transcripts are expressed highly selectively in the liver at nearly equivalent levels. There seems to be one copy of the gene per haploid genome. We now designate NCC-4 as LEC from liver-expressed chemokine.

A novel human CC chemokine PARC that is most homologous to macrophage-inflammatory protein-1 alpha/LD78 alpha and chemotactic for T lymphocytes, but not for monocytes.

By searching the expressed sequence tag (EST) database, we identified partial cDNA sequences encoding a polypeptide with significant sequence identity to the human CC chemokine macrophage-inflammatory protein-1 alpha (MIP-1 alpha)/LD78 alpha. We determined the complete cDNA sequence that contained a reading frame of 89 amino acids with 61% identity to human MIP-1 alpha/LD78 alpha. The mRNA was expressed constitutively at high levels in human lung and at low levels in some lymphoid tissues. Furthermore, the mRNA was strongly induced in several human cell lines, including monocytic U937 cells, by PMA. From these results, we designated this novel CC chemokine as PARC from pulmonary and activation-regulated chemokine. In situ hybridization analyses showed that alveolar macrophages, follicular dendritic cells in the germinal centers of regional lymph nodes, and peripheral blood monocytes stimulated with LPS express PARC mRNA. Using the human CC chemokine yeast artificial chromosome contig that we constructed recently, we mapped the PARC gene (SCYA18) within one of the two subregions of the CC chemokine gene cluster at chromosome 17q11.2. To investigate its biologic activity, the PARC protein was expressed in insect cells. PARC was chemotactic for both activated (CD3+) T cells and nonactivated (CD14-) lymphocytes, but not for monocytes or granulocytes. Binding analysis using PARC fused with alkaline phosphatase-(His)6 showed the presence of a single class of receptors for PARC on lymphocytes with a Kd of 1.9 nM and 590 sites/cell. Thus, PARC is a novel CC chemokine with a close phylogenic relationship with MIP-1 alpha/LD78 alpha, but with a highly selective activity on lymphocytes.