Gene structure, cDNA cloning, and expression of the rat cytokine-induced neutrophil chemoattractant-2 (CINC-2) gene.

Cytokine-induced neutrophil chemoattractant-2 (CINC-2) belongs to the CXC chemokine family and consists of two isoforms, CINC-2 alpha and CINC-2 beta. We have studied the genomic organization and expression of the CINC-2 gene. The gene spans approximately 14 kb and is composed of three common exons, one CINC-2 alpha-specific exon and two CINC-2 beta specific exons. This finding suggests that two isoforms of CINC-2 are encoded by mRNAs produced by alternative splicing. Each isoform is encoded in four exons, and exon-intron boundaries are placed identically within the aligned sequences of CXC chemokines. The CINC-2 alpha-specific exon encodes an extra C-terminal serine residue, in addition to three amino acid residues (DKS) which were determined from amino acid sequence analysis of CINC-2 alpha previously. The 5' flanking region of the gene contains a TATA box and putative binding sites for NF-kappa B and AP-1. Northern blot analyses showed that the mRNA level for CINC-2 was very low in rat peritoneal macrophages without stimulation and increased up to 4 h after lipopolysaccharide stimulation, similar to that for CINC-1 or CINC-3. Thereafter, the mRNA expression decreased gradually. However, the mRNA level of CINC-2 remained high 24 h after stimulation, in contrast to that of CINC-1 or CINC-3. These data indicate the expression of CINC-2 is regulated differently among the CINCs.