POSTTRANSCRIPTIONAL REGULATION OF TRANSFORMING GROWTH FACTOR-BETA 1

转化生长因子-BETA 1 的转录后调控

• 批准号: 3774813
• 负责人: L M WAKEFIELD
• 金额: --
• 依托单位: DIVISION OF CANCER EPIDEMIOLOGY AND GENETICS
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3774813
• 关键词: RNA splicing; blood proteins; complementary DNA; gene induction /repression; genetic manipulation; genetic regulation; genetic translation; growth inhibitors; hormone regulation /control mechanism; human tissue; messenger RNA; posttranscriptional RNA processing; protein biosynthesis; steroid hormone; tissue /cell culture; transcription factor; transfection; transforming growth factors

In many cell types there is a large discrepancy between the measured levels of TGF-beta1 mRNA and protein. Furthermore, TGF-beta1 is generally secreted in a bio-logically latent form that must be activated prior to binding to the cell surface. This suggests that translational or post- translational mechanisms play an important role in the regulation of TGF- beta1 production. Clinically important members of the steroid hormone superfamily affect both these processes. To investigate translational regulation, expression constructs have been made in which various portions of the 5' and 3' untranslated regions (UTRs) of the TGF-beta1 cDNA have been deleted. The intrinsic translatability of the mRNAs is determined by in vitro translation, while in vivo translation efficiency of the same constructs in stably transfected breast cancer cell lines gives information on involvement of any transacting factors. Results are complex but indicate that (i) translational efficiency depends on which of the alternate transcriptional start sites are employed, (ii) the 3'-UTR stimulates translation, and (iii) the 3' and 5'-UTRs combined have non- additive effects, suggesting cross-talk between the two ends of the mRNA. Methodology has been developed for accurate measurement of TGF-betas in the plasma of human subjects. Normal controls show significant levels of circulating TGF-beta1 in the plasma (2.5 +/- 1.4 ng/ml; n=37). This suggests a hitherto unsuspected endocrine role for TGF-beta. Circulating TGF-beta is in the biologically latent form and is not associated with alpha-2-macroglobulin. An understanding of the mechanisms whereby steroids and related compounds regulate the production and activity of the TGF-beta family of growth inhibitors may allow the rational design of more potent pharmacological agents for use in chemoprevention or chemotherapy of cancer.

在许多细胞类型中，所测量的 TGF-β 1 mRNA和蛋白水平。 此外，TGF-β 1通常是 以生物学上的潜伏形式分泌，必须在 与细胞表面结合。 这表明，翻译或后- 翻译机制在TGF-β 1的调节中起重要作用。 beta1生产 类固醇激素的临床重要成员 超家族影响这两个过程。 研究翻译 为了调节，已经制备了表达构建体，其中各个部分 TGF-β 1 cDNA的5'和3'非翻译区（UTR）中， 被删除了。 mRNA的内在可翻译性由以下决定： 体外翻译，而体内翻译效率相同 在稳定转染的乳腺癌细胞系中的构建体提供了 涉及任何交易因素的信息。 结果 复杂，但表明（i）翻译效率取决于 使用交替的转录起始位点，（ii）3’-UTR 刺激翻译，和（iii）组合的3'和5'-UTR具有非- 累加效应，表明mRNA两端之间的串扰。 已经开发了用于准确测量TGF-β的方法， 人体的血浆 正常对照显示出显著水平的 血浆中的循环TGF-β 1（2.5 +/- 1.4 ng/ml; n=37）。 这 提示TGF-β在内分泌中的作用迄今未被怀疑。 循环 TGF-β是生物学上的潜伏形式， α 2-巨球蛋白 对这些机制的理解 类固醇和相关化合物调节这些激素的产生和活性。 TGF-β家族的生长抑制剂可能允许合理设计更多的 用于化学预防或化学治疗的有效药理学试剂 癌症。