REDUNDANCY OF C EBP-ALPHA, C/EBP-BETA, AND C/EBP-DELTA IN SUPPORTING THE LIPOPOLYSACCHARIDE-INDUCED TRANSCRIPTION OF IL-6 AND MONOCYTE CHEMOATTRACTANT PROTEIN-1/

C/EBP alpha, -beta, and -delta are members of the CCAAT/enhancer bindi ng protein family of transcriptional regulators. All three of these fa ctors are expressed by bone marrow-derived macrophages, with the DNA b inding activity of C/EBP beta and -delta increased by treatment with L PS while that of C/EBP alpha is decreased, We have ectopically express ed each C/EBP protein in P388 lymphoblasts, The expression of any of t hese transcription factors is sufficient to confer the LPS-inducible e xpression of IL-6 and monocyte chemoattractant protein-1 to lymphoblas ts, which normally lack C/EBP factors and do not display LPS induction of proinflammatory cytokines, Thus, the activities of C/EBP alpha, -b eta, and -delta are redundant in regard to the expression of IL-6 and monocyte chemoattractant protein-1. Since C/EBP beta-deficient mice ha ve been reported to be largely normal in their expression of proinflam matory cytokines, it is likely that the lark of C/EBP beta is compensa ted for by the induction of C/EBP delta upon LPS treatment.