Abstract
We examined the effects of increasing intracellular cyclic AMP levels on the expression of human PAF receptor (hPAF-R). Peripheral blood monocytes constitutively expressed hPAF-R mRNA transcripts. A transiently elevated intracellular concentration of AMP induced with prostaglandin E2, cholera toxin, or forskolin was a sufficient signal to inhibit PAF-R expression. To determine the mechanisms of this inhibition, human monocytes were treated with dibutyryl cAMP, a cell-permeable cAMP analogue. cAMP reduced the expression of hPAF-R in a concentration- and a time-dependent manner. The effect was seen as early as 1 h and was essentially total by 4 h. Stability of hPAF-R mRNA was not markedly decreased by cAMP, as assessed by measuring the half-lives of the transcripts. Moreover, the nuclear transcription rate of the hPAF-R gene was reduced as early as 30 min after stimulation with cAMP. The inhibition of hPAF-R mRNA accumulation was associated with diminished responsiveness to PAF, as assayed by intracellular Ca2+ fluxes, decreased number of binding sites, and decreased hPAF-R protein expression on the cell surface, as assessed by flow cytometry using a polyclonal anti-hPAF-R antibody. These data indicate that PAF-R expression can be regulated at the transcriptional and possibly post-transcriptional levels by elevation of intracellular cAMP.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.