Molecular cloning and characterization of a murine LPS-inducible cDNA.
Murine macrophages respond to endotoxins by inducing a vast array of genes that play a major role in the host's response to infection and tumor growth. We have isolated and characterized a 1.8-kb cDNA, designated IRG2, from a cDNA library prepared from RNA isolated from the murine cell line, RAW 264.7, after bacterial LPS stimulation. The cDNA encodes a protein of 47 kDa that is the murine homologue of a small family of proteins described from IFN-induced human cells. The IRG2 message does not appear until 3 h after LPS exposure and its induction is dependent on new protein synthesis. IRG2 induction by LPS is slightly inhibited by the anti-inflammatory steroid, dexamethasone. Increasing cytosolic cAMP with either forskolin, dibutyryl cAMP, or 8-(4-chlorophenylthio)-cAMP caused marked inhibition of the LPS induction of IRG2. In contrast, activation of PKC with phorbol ester potentiated the LPS response. Removing extracellular Ca2+ with EGTA inhibited IRG2 induction; increasing intracellular calcium with the calcium ionophore A23187 led to enhanced levels of the IRG2 transcript. These data suggest that the induction of IRG2 occurs via a PKC pathway.
Lee
C G
CG
Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030.
Demarquoy
J
J
Jackson
M J
MJ
O'Brien
W E
WE
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics*; D003907:Dexamethasone / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008262:Macrophage Activation / Q000187:drug effects* / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D015290:Second Messenger Systems / Q000187:drug effects / Q000235:genetics; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D018076:DNA, Complementary; C087697:Ifit3 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008070:Lipopolysaccharides; D011506:Proteins; D012333:RNA, Messenger; D003907:Dexamethasone