Abstract
We have studied the effect of the adenylate cyclase-stimulating agent forskolin on expression of components of the plasminogen activation system in the human fibrosarcoma cell line HT-1080. By enzyme-linked immunosorbent assays, forskolin was found to cause a 2 to 4-fold decrease in intracellular and culture medium levels of type-1 inhibitor of plasminogen activators (PAI-1) and tissue-type plasminogen activator (t-PA). This was true for cells not treated with other agents and for cells, in which the PAI-1 and t-PA levels had been increased 5 to 10-fold by treatment with dexamethasone. This down-regulation could be traced back to corresponding decreases in the cellular levels of PAI-1 and t-PA mRNAs. Of the two PAI-1 mRNAs, the 2.4 kb species was 5-fold decreased by forskolin in cells treated with dexamethasone, while the 3.4 kb transcript was unaffected; in cells not treated with dexamethasone, forskolin affected the two PAI-1 transcripts in parallel. These studies show that in addition to the many inducers of PAI-1, PAI-1 gene expression is also subject to negative modulation by cyclic AMP. They also show that t-PA gene expression, in contrast to the induction by cyclic AMP observed in many other cell lines, may also be subject to negative regulation by cyclic AMP. Thus, hormonal agents acting with cyclic AMP as a second messenger may be involved in down-regulating PAI-1 and t-PA expression in vivo.
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.