Characterization of the murine Icam-1 gene

Intercellular adhesion molecule-1 (ICAM-1, CD54) is a cell adhesion molecule that interacts with the leukocyte β₂ integrins, LFA-1 and Mac-1. Murine inflammatory models are being utilized increasingly to define the role that ICAM-1 induction plays in the initiation of inflammation. We have isolated murine genomic clones that contain the Icam-1 gene including over 2 kb of 5′ flanking sequence. The gene for murine Icam-1 spans over 13 kb and is composed of seven exons and six introns. Each of the extracellular immunoglobulin-like domains of ICAM-1 is encoded by a single exon that ends with the first base of the next codon. Examination of ICAM-1 expression in vivo shows that mRNA levels of ICAM-1 are low in all organs except for the lung but increase markedly in multiple organs at 3 h after administration of endotoxin. The 5′ flanking region of the murine gene contains a putative TATA box and potential SP-1, AP-1, and AP-3 sites in positions nearly identical to those in the human gene.