TY - JOUR
T1 - Differential expression of interferon regulatory factor 1 (IRF-1), IRF-2, and interferon consensus sequence binding protein genes in lipopolysaccharide (LPS)-responsive and LPS-hyporesponsive macrophages
AU - Barber, S. A.
AU - Fultz, M. J.
AU - Salkowski, C. A.
AU - Vogel, S. N.
PY - 1995
Y1 - 1995
N2 - Macrophages secrete interferon (IFN), as well as other cytokines, following lipopolysaccharide stimulation. The interferon regulatory factors (IRFs) comprise a family of DNA-binding proteins that have been implicated in the transcriptional regulation of IFN and certain IFN-inducible genes. We therefore characterized basal and LPS-inducible levels of IRF-1, IRF-2, and interferon consensus sequence binding protein (ICSBP) mRNA in LPS-responsive macrophages and compared the expression of these genes in macrophages that typify two murine models of LPS hyporesponsiveness. In the first model, the LPS-hyporesponsive phenotype of the C3H/HeJ mouse is genetically determined and maps to the Lps locus on mouse chromosome 4. In the second model, normally LPS-responsive macrophages acquire a transient LPS-hyporesponsive phenotype following a prior exposure to LPS, a phenomenon referred to as 'endotoxin tolerance.' Using reverse transcription PCR, we detected basal levels of IRF-1 mRNA in LPS-responsive (Lps(n)) macrophages that were approximately 15 times higher than those found in LPS-hyporesponsive (Lps(d)) macrophages. Conversely, Lps(d) macrophages expressed basal levels of IRF-2 mRNA that were approximately 18 times higher than those expressed in Lps(n) macrophages. LPS stimulation resulted in a dose- and time-dependent accumulation of IRF-1, IRF-2, and ICSBP mRNA only in Lps(n) macrophages. Cycloheximide inhibited the accumulation of LPS-stimulated IRF-2 and ICSBP mRNA, but not IRF-1 mRNA, thus designating IRF-I an immediate-early, LPS- inducible gene. Finally, macrophages rendered tolerant to endotoxin expressed elevated but nonmaximal mRNA levels for all three transcription factors that are not reinduced upon secondary challenge with LPS. Thus, the IRFs may represent yet an additional molecular pathway in the complex response to LPS.
AB - Macrophages secrete interferon (IFN), as well as other cytokines, following lipopolysaccharide stimulation. The interferon regulatory factors (IRFs) comprise a family of DNA-binding proteins that have been implicated in the transcriptional regulation of IFN and certain IFN-inducible genes. We therefore characterized basal and LPS-inducible levels of IRF-1, IRF-2, and interferon consensus sequence binding protein (ICSBP) mRNA in LPS-responsive macrophages and compared the expression of these genes in macrophages that typify two murine models of LPS hyporesponsiveness. In the first model, the LPS-hyporesponsive phenotype of the C3H/HeJ mouse is genetically determined and maps to the Lps locus on mouse chromosome 4. In the second model, normally LPS-responsive macrophages acquire a transient LPS-hyporesponsive phenotype following a prior exposure to LPS, a phenomenon referred to as 'endotoxin tolerance.' Using reverse transcription PCR, we detected basal levels of IRF-1 mRNA in LPS-responsive (Lps(n)) macrophages that were approximately 15 times higher than those found in LPS-hyporesponsive (Lps(d)) macrophages. Conversely, Lps(d) macrophages expressed basal levels of IRF-2 mRNA that were approximately 18 times higher than those expressed in Lps(n) macrophages. LPS stimulation resulted in a dose- and time-dependent accumulation of IRF-1, IRF-2, and ICSBP mRNA only in Lps(n) macrophages. Cycloheximide inhibited the accumulation of LPS-stimulated IRF-2 and ICSBP mRNA, but not IRF-1 mRNA, thus designating IRF-I an immediate-early, LPS- inducible gene. Finally, macrophages rendered tolerant to endotoxin expressed elevated but nonmaximal mRNA levels for all three transcription factors that are not reinduced upon secondary challenge with LPS. Thus, the IRFs may represent yet an additional molecular pathway in the complex response to LPS.
UR - http://www.scopus.com/inward/record.url?scp=0028924980&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0028924980&partnerID=8YFLogxK
M3 - Article
C2 - 7822029
AN - SCOPUS:0028924980
SN - 0019-9567
VL - 63
SP - 601
EP - 608
JO - Infection and Immunity
JF - Infection and Immunity
IS - 2
ER -