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Author Kharb, Surender ♦ Rubin, Eric ♦ Dafta, Rakesh ♦ Hass, Raif ♦ Sukhatme, Vikas ♦ Kufe, Donald
Source CiteSeerX
Content type Text
File Format PDF
Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science
Subject Keyword Okadaic Acid ♦ Early Growth Response ♦ Human Myeloid Leukemia Cell ♦ Transcriptional Regulation ♦ Egr-1 Transcription ♦ Okadaic Acid Inducibility ♦ Carg Box ♦ Okadaic Acid-treated Cell ♦ Acid-induced Signal ♦ Minimal Thymidine Kinase Gene Promoter ♦ Present Work ♦ Monocytic Differentiation ♦ Untreated U-937 Cell ♦ First Carg Element ♦ Single Carg Element ♦ Carg Sequence ♦ 40-base Pair Oligomer ♦ Transient Increase ♦ U-937 Cell ♦ U-937 Myeloid Leukemia Cell ♦ Okadaic Acid-induced Egr-1 Transcription ♦ Egr-1 Mrna Level ♦ Nuclear Run-on Assay ♦ Egr-1 Expression ♦ First Carg Sequence ♦ Nuclear Protein ♦ Diverse Cell Type ♦ Similar Oligomer ♦ Mitogenic Stimulation ♦ Egr-1 Promoter Contains ♦ Deletion Analysis
Abstract The early growth response 1 (EGR-1) gene is induced after mitogenic stimulation of diverse cell types. The present work has examined the effeds of okadaic acid, an inhibitor of protein phosphatases 1 and 2A, on EGR-1 expression during monocytic differentiation of U-937 myeloid leukemia cells. Treatment of U-937 cells with okadaic acid was associated with transient increases in EGR-1 mRNA levels. These increases were maximal at 6 h and occurred in the absence of de novo protein synthesis. Nuclear run-on assays demonstrated that although EGR-1 transcription is detedable in untreated U-937 cells, this rate is increased 6-fold by okadaic acid. Sequences responsive to okadaic acid-induced signals were determined by deletion analysis of the EGR- 1 promoter. The results demonstrate that okadaic acid-induced EGR-1 transcription is dependent on the presence of CC (AlT)6 GG (CArG) motifs. The EGR-1 promoter contains six CArG boxes. However, only the 5’-most distal (first) CArG sequence conferred okadaic acid inducibility. A 40-base pair oligomer corresponding to the first CArG element also conferred okadaic acid inducibility of the minimal thymidine kinase gene promoter. In contrast, there was no inducibility using a similar oligomer containing a mutated CArG box. Finally, binding of nuclear proteins to the first CArG sequence was similar for control and okadaic acid-treated cells. Taken together, these results suggest that okadaic acid adivates EGR-1 transcription and that this event is mediated at least in part by a single CArG element.
Educational Role Student ♦ Teacher
Age Range above 22 year
Educational Use Research
Education Level UG and PG ♦ Career/Technical Study