Related Experiment Videos
Regulation of platelet-activating factor receptor gene expression in vivo by endotoxin, platelet-activating factor
Abstract:
A competitive PCR assay was developed to quantify platelet-activating factor (PAF) receptor (PAF-R) transcripts in rat tissues using a synthetic RNA as a competitor. We found PAF-R mRNA constitutively expressed in the eight organs tested, with the ileum containing the highest concentration [(3.49+/-0.15) x 10(7) molecules/microg of RNA]. Significant but lower levels were also detected in the jejunum, spleen, lungs, kidneys, heart, stomach and liver. Furthermore we defined the regulatory role of inflammatory mediators in ileal PAF-R gene expression using a rat model of intestinal injury induced by PAF or lipopolysaccharide (LPS). Injection of LPS or low-dose PAF resulted in a marked increase in ileal PAF-R mRNA within 30 min. The up-regulation on PAF-R elicited by PAF was biphasic, peaking first at 90 min, then again at 6 h. In contrast, LPS elicited a weak monophasic response. The second phase of PAF-R mRNA increase after PAF administration was completely abolished by WEB 2170, a PAF antagonist, and partially inhibited by antitumour necrosis factor (TNF) antibody. These observations indicate the involvement of endogenous PAF and TNF in this event. In conclusion, we found: (a) preferential PAF-R expression in the ileum, suggesting a role for PAF in intestinal inflammation; (b) induction of PAF-R expression in vivo by its own agonist; (c) a complex regulation of PAR-R gene expression in vivo involving a network of various pro-inflammatory mediators.
Insights
Platelet-activating factor receptor (PAF-R) mRNA is highest in the ileum and its expression is increased by inflammatory mediators like PAF and LPS. PAF-R gene expression involves a complex network of pro-inflammatory mediators.
Area of Science:
- Molecular Biology
- Immunology
- Gastroenterology
Background:
- Platelet-activating factor receptor (PAF-R) plays a role in inflammatory responses.
- Understanding PAF-R gene expression is crucial for studying inflammatory conditions.
Purpose of the Study:
- To develop a competitive PCR assay for quantifying PAF-R transcripts.
- To investigate the constitutive expression of PAF-R mRNA in rat tissues.
- To define the regulatory role of inflammatory mediators on ileal PAF-R gene expression.
Main Methods:
- Developed a competitive PCR assay using synthetic RNA as a competitor.
- Quantified PAF-R mRNA levels in eight rat organs.
- Induced intestinal injury in rats using PAF or lipopolysaccharide (LPS) to study gene expression.
Main Results:
- PAF-R mRNA was constitutively expressed in all tested organs, with the highest concentration in the ileum.
- LPS and PAF significantly increased ileal PAF-R mRNA levels within 30 minutes.
- PAF-induced PAF-R upregulation was biphasic, while LPS induced a monophasic response; WEB 2170 and anti-TNF antibody affected PAF-R expression.
Conclusions:
- PAF-R is preferentially expressed in the ileum, suggesting a role in intestinal inflammation.
- PAF-R expression can be induced in vivo by its own agonist.
- PAF-R gene expression is complexly regulated by pro-inflammatory mediators including PAF and TNF.