Molecular Cloning and Post-transcriptional Regulation of Macrophage Inflammatory Protein-1α in Alveolar Macrophages

Macrophage inflammatory protein-1α (MIP-1α) belongs to the "chemokine" superfamily of chemoattractant pro-inflammatory cytokines. MIP-lα is chemotactic for monocytes and neutrophils and thus, plays an important role in initiation and control of inflammation. We have isolated and sequenced a cDNA clone encoding rat MIP-1α. This 0.75 kb cDNA includes a single open reading frame of 92 amino acids. Expression of MIP-1α mRNA was characterized in NR8383, a rat alveolar macrophage cell line (RAM). In resting RAM cells, MIP-1α mRNA decayed rapidly, with a half life of less than 2 hours. Lipopolysaccharide (LPS) treatment of RAM cells resulted in a dose-dependent increase in MIP-1α steady state mRNA expression. The induction of MIP-1α mRNA by LPS was partially the result of mRNA stabilization, as half life increased to over 6 hours.