| Autor: |
Kavanaugh, W M, Harsh, G R, Starksen, N F, Rocco, C M, Williams, L T |
| Zdroj: |
Journal of Biological Chemistry; June 1988, Vol. 263 Issue: 17 p8470-8472, 3p |
| Abstrakt: |
Platelet-derived growth factor is expressed as dimers of two homologous polypeptide chains, termed A and B, encoded by different genes. A and B chain mRNA levels in microvascular endothelial cells are increased by phorbol ester, thrombin, and transforming growth factor-beta (TGF-beta) and are reduced by agents that elevate cyclic AMP. In this report, we investigated the effects of these regulatory agents on A and B chain transcription rates. By nuclear run-on analysis, TGF-beta stimulated transcription of both A and B chain genes. Thrombin and phorbol ester stimulated B chain transcription and had little or no detectable effect on A chain transcription. Pretreatment of cultures with 50 microM forskolin, a potent activator of adenylyl cyclase, completely blocked B chain transcription by thrombin and TGF-beta, but did not inhibit A chain transcription induced by TGF-beta. These results show that expression of platelet-derived growth factor mRNA involves both positive and negative transcriptional regulation and that there are differences in the transcriptional control of the A and B chain genes. |
| Databáze: |
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