Submitted on May 21, 2008
Revised on December 17, 2008
Accepted on January 18, 2009
LPS dependent interaction between PU.1 and cJun determines production of lipocalin-type prostaglandin D synthase and prostaglandin D2 in Macrophages
Myungsoo Joo1*, Minjae Kwon2, Yong-Jig Cho2, Ningning Hu2, Tetyana V Pedchenko2, Ruxana T Sadikot3, Timothy S. Blackwell2, and John W. Christman3
1 Pusan National University
2 Vanderbilt University School of Medicine
3 University of Illinois
* To whom correspondence should be addressed. E-mail: mjoo{at}pusan.ac.kr.
Previously, we reported that expression of lipocalin-prostaglandin D synthase (L-PGDS) is inducible in macrophages and protects from Pseudomonas pneumonia. Here, we investigated the mechanism, by which L-PGDS gene expression is induced in macrophages. A promoter analysis of the murine L-PGDS promoter located a binding site of PU.1, a transcription factor essential for macrophage development and inflammatory gene expression. A chromatin immunoprecipitation assay showed that PU.1 bound to the cognate site in the endogenous L-PGDS promoter in response to lipopolysaccharide (LPS). Over-expression of PU.1, but not of PU.1S148A, a mutant inert to casein kinase II (CKII) or NF-
B-inducing kinase (NIK), induced L-PGDS in RAW 264.7 cells. Conversely, siRNA silencing of PU.1 expression blunted productions of L-PGDS and prostaglandin D2 (PGD2). LPS treatment induced formation of the complex of PU.1 and cJun on the PU.1 site, but inactivation of cJun by treatment with JNK or p38 kinase inhibitor abolished the complex, and suppressed PU.1 transcriptional activity for L-PGDS gene expression. Together, these results show that PU.1, activated by CKII or NIK, cooperates with MAPK-activated cJun to maximally induce L-PGDS expression in macrophages following LPS treatment, and suggest that PU.1 participates in innate immunity through the production of L-PGDS and PGD2.
