CAF1-knockout mice are more susceptive to lipopolysaccharide-induced acute lung injury.

The carbon catabolite repressor protein 4 (CCR4)-negative on TATA (NOT) complex includes multiple subunits and is conserved in the eukaryotic cells. The CCR4-NOT complex can regulate gene expression at different levels. Two subunits of the CCR4-NOT complex, CCR4 and CCR4-associated factor 1 (CAF1), possess deadenylase activity. In yeast, the deadenylase activity is mainly provided by the CCR4 subunit; however, the deadenylase activity is provided by both CCR4 and CAF1 in other eukaryotes. A previous study reported that CAF1 but not CCR4 is required for the decay of a reporter mRNA with AU-rich elements. Our previous study showed that CAF1 is involved in the regulation of intercellular adhesion molecule-1 (ICAM-1) and interleukin-8 (IL-8) expression. Both ICAM-1 and IL-8 play crucial roles in acute lung injury. In the present study, we examined the effects of CAF1 deficiency on IL-8 and ICAM-1 expression and acute lung injury in mice. Here we showed that there were no differences between the wild-type and CAF1-knockout mice on phenotypes. The lung histology and protein and mRNA levels of IL-8 and ICAM-1 in unstimulated wild-type mice were comparable to those in unstimulated CAF1-knockout mice. However, lipopolysaccharide stimulation led to more severe lung histological injury and greatly higher IL-8 and ICAM-1 expression in CAF1-knockout mice compared to the wild-type mice. These results, together with our previous study, suggest that CAF1 is involved in the regulation of lipopolysaccharide-stimulated IL-8 and ICAM-1 expression in vivo and affects the progression of acute lung injury.