| Research Abstract |
Chemokine family is a group of cytokines involved in inflammation, lymphocyte homing and cell growth. There are now well over 40 chemokines including those cloned by our group. In order to reveal the generation mechanism of chemokine gene clusters, we investigated organizations of chemokine gene clusters. We localized several human CC chemokines and observed a strong correlation between the target cell types of chemokines and the chromosomal locations of the chemokine genes. In addition, we found various gene rearrangements including duplications, a gene fusion, gene conversions and a retroposon insertion in the CC chemokine gene clusters. For example, we found that the human CC chemokine PARC gene has been generated by fusion of two MIP-1α-like sequences and that there is no mouse counterpart of the human PARC gene. These results suggest that a number of duplications have occurred in the clusters after diversification of primates and rodents and therefore orthologs of some chemokine genes do not exist in the human or mouse genome. In the course of these studies, we also identified and cloned two novel CC chemokines, ILC and eotaxin-3, in the genomic sequences deposited in GenBank.
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