Plasminogen gene expression is regulated by nerve growth factor.
BACKGROUND
Studies have documented a requirement for an intact plasminogen (Plg) activation system in neurite outgrowth induced by nerve growth factor (NGF).


OBJECTIVE
In this study we addressed the effect of NGF on Plg synthesis in model NGF-responsive PC-12 cells.


METHODS
The effect of NGF on Plg gene expression was assessed using Western blotting, quantitative polymerase chain reaction, luciferase reporter assays, site directed mutagenesis, electrophoretic mobility shift assays and chromatin immunoprecipitation.


RESULTS
NGF treatment increased Plg expression 3-fold and steady state levels of Plg mRNA were increased 6.82-fold. This effect also was observed in cortical neurons. PC-12 cells transfected with a luciferase reporter gene under the control of a 2400 bp fragment of the murine Plg promoter exhibited a 5-fold increase in luciferase activity following treatment with NGF. This response was dependent on Ras/ERK and PI3 K signaling because treatment with PD98059 together with wortmannin decreased promoter activity, in response to NGF, to the level exhibited by untreated cells. Furthermore, co-transfection with a dominant-negative mutant Ha-Ras completely blocked NGF-induced luciferase activity. In deletional and mutational studies we identified two Sp1 binding sites located between nucleotides -255 and -106 of the Plg promoter that were required for the full response of the Plg promoter to NGF. In chromatin immunoprecipitation assays the Sp1 transcription factor bound to the endogenous Plg promoter.


CONCLUSIONS
These results suggest that Plg gene expression is up-regulated by neurotrophins that may provide a previously unrecognized mechanism for enhancing the effects of neurotrophins via the proteolytic activity of plasmin.
Division of Vascular Biology, Department of Cell Biology, The Scripps Research Institute, La Jolla, CA, USA.
A
A
Gutiérrez-Fernández
R J
RJ
Parmer
L A
LA
Miles
D000818:Animals; D047369:Chromatin Immunoprecipitation; D004252:DNA Mutational Analysis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D008954:Models, Biological; D020932:Nerve Growth Factor / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D016716:PC12 Cells; D010957:Plasmids / Q000378:metabolism; D010958:Plasminogen / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction; D016329:Sp1 Transcription Factor / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
D004791:Enzyme Inhibitors; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D010958:Plasminogen; D020932:Nerve Growth Factor