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[Biological regulation with platelet activating factor--molecular cloning and signal transduction of PAF]
Abstract:
The cDNA encoding the platelet-activating factor (PAF) receptor was cloned from a guinea pig lung cDNA library by using a Xenopus laevis oocyte expression system. In the CHO cells which expressed guinea-pig PAF receptor, PAF triggered production of inositol phosphates, the release of arachidonic acid, and inhibited cyclic AMP accumulation. PAF also activated mitogen-activated protein (MAP) kinase and MAP kinase kinase in the CHO cells. These effects were partially regulated by pertussis toxin-sensitive G proteins. The analysis of the human PAF receptor gene revealed that it contains no intron in its coding region, but introns are distributed in the 5'-untranslated region. Two 5'-noncoding exons were identified, which are alternatively spliced to a common splice acceptor site on the third exon to yield two different species of functional mRNA. Existence of distinct promoters may regulated the PAF receptor gene expression in different tissues and cells.
Insights
Researchers cloned the platelet-activating factor (PAF) receptor gene and identified its unique structure. This discovery sheds light on PAF receptor gene regulation and its role in cellular signaling pathways.
Area of Science:
- Molecular Biology
- Pharmacology
Context:
- Platelet-activating factor (PAF) is a potent lipid mediator involved in inflammation and allergic responses.
- Understanding the PAF receptor's structure and function is crucial for developing targeted therapies.
Purpose:
- To clone the guinea pig platelet-activating factor (PAF) receptor cDNA.
- To investigate the signaling pathways activated by PAF in cells expressing the receptor.
- To analyze the structural organization and gene expression regulation of the human PAF receptor.
Summary:
- The platelet-activating factor (PAF) receptor was successfully cloned from guinea pig lung using a Xenopus laevis oocyte expression system.
- Expression of the guinea pig PAF receptor in CHO cells induced inositol phosphate production, arachidonic acid release, and inhibited cyclic AMP accumulation in response to PAF.
- PAF also activated mitogen-activated protein (MAP) kinase and MAP kinase kinase, with partial regulation by pertussis toxin-sensitive G proteins.
- The human PAF receptor gene lacks introns in its coding region but possesses introns in the 5'-untranslated region.
- Alternative splicing of two 5'-noncoding exons generates distinct functional mRNA species, suggesting complex gene regulation.
- Distinct promoters likely control PAF receptor gene expression across different tissues and cell types.
Impact:
- Provides insights into the molecular mechanisms of PAF signaling.
- Identifies potential targets for therapeutic intervention in PAF-mediated diseases.
- Elucidates the complex transcriptional regulation of the PAF receptor gene.