The translation inhibitor anisomycin induces Elk-1-mediated transcriptional activation of egr-1 through multiple mitogen-activated protein kinase pathways.
The early growth response-1 gene (egr-1) encodes a zinc-finger transcription factor Egr-1 and is rapidly inducible by a variety of extracellular stimuli. Anisomycin (ANX), a protein synthesis inhibitor, stimulates mitogen-activated protein kinase (MAPK) pathways and thereby causes a rapid induction of immediate-early response genes. We found that anisomycin treatment of U87MG glioma cells resulted in a marked, time-dependent increase in levels of Egr-1 protein. The results of Northern blot analysis and reporter gene assay of egr-1 gene promoter (Pegr-1) activity indicate that the ANX- induced increase in Egr-1 occurs at the transcriptional level. Deletion of the serum response element (SRE) in the 5'-flanking region of egr-1 gene abolished ANX-induced Pegr-1 activity. ANX induced the phosphorylation of the ERK1/2, JNK, and p38 MAPKs in a time-dependent manner and also induced transactivation of Gal4-Elk-1, suggesting that Elk-1 is involved in SRE-mediated egr-1 transcription. Transient transfection of dominant-negative constructs of MAPK pathways blocked ANX-induced Pegr-1 activity. Furthermore, pretreatment with specific MAPK pathway inhibitors, including the MEK inhibitor U0126, the JNK inhibitor SP600125, and the p38 kinase inhibitor SB202190, completely inhibited ANX-inducible expression of Egr-1. Taken together, these results suggest that all three MAPK pathways play a crucial role in ANX-induced transcriptional activation of Pegr-1 through SRE-mediated transactivation of Elk-1.
Shin
Soon Young
SY
Division of Molecular and Life Sciences, College of Science and Technology, Hanyang University, Ansan 426-791, Korea.
Lee
Joon Ho
JH
Min
Byung
B
Lee
Young Han
YH
D000841:Anisomycin / Q000494:pharmacology*; D045744:Cell Line, Tumor; D051766:Early Growth Response Protein 1 / Q000235:genetics / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000235:genetics; D014176:Protein Biosynthesis / Q000187:drug effects*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D027602:Serum Response Element; D015533:Transcriptional Activation / Q000187:drug effects*; D050807:ets-Domain Protein Elk-1 / Q000235:genetics / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
D051766:Early Growth Response Protein 1; D047428:Protein Kinase Inhibitors; D050807:ets-Domain Protein Elk-1; D000841:Anisomycin; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases