Translational control of gene expression in maturing erythroid cells

mRNA翻译的调节对于红系细胞是必不可少的，因为它们的前体细胞在核排斥的情况下失去了mRNA合成能力。我们研究的网织红细胞15-脂氧合酶（r15-LOX）mRNA的时间翻译沉默是这方面的代表。最近，基于人K562细胞，我们建立了一个诱导型红系细胞系统，该系统表现出终末红系细胞成熟的特征性的形态和蛋白表达的变化：核排斥，hr 15-LOX的表达受hnRNP K和hnRNP E1的调控以及线粒体的丧失。采用这个系统，我们确定了新的相互作用的80 S核糖体的形成和迄今未知的蛋白质与hnRNP K和hnRNP E1合作，在维持hr 15-LOX mRNA沉默，这将是其特征。此外，除了hr 15-LOX-和c-Src mRNA，我们确定了新的mRNA，这是差异丰富的hnRNP K-含mRNP成熟过程中。将研究这种相互作用对蛋白质表达的功能相关性。我们可以证明hnRNP K和hnRNP E1在K562细胞诱导过程中被降解，并检测到hnRNP K的特异性肽。我们将鉴定和表征hnRNP K裂解活性，并研究hnRNP E1在红系细胞成熟中是如何加工的。

Regulation of mRNA translation is essential for erythroid cells because their precursors loose mRNA synthesis capacity with nuclear exclusion. Temporal translational silencing of reticulocyte 15-Lipoxygenase (r15-LOX) mRNA, which we have studied is representative for that. Recently, based on human K562 cells we set up an inducible erythroid cell system, which exhibits changes in morphology and protein expression that are characteristic for terminal erythroid cell maturation: nuclear exclusion, expression of hr15-LOX regulated by hnRNP K and hnRNP E1 and loss of mitochondria. Employing this system we identified new interacting factors involved in 80S ribosome formation and so far unknown proteins cooperating with hnRNP K and hnRNP E1 in maintaining hr15-LOX mRNA silencing, which will now be characterized. Furthermore, besides hr15-LOX- and c-Src mRNA we identified new mRNAs, which are differentially enriched in hnRNP K-containing mRNPs during maturation. The functional relevance of this interaction for protein expression will be studied. We could show that hnRNP K and hnRNP E1 are degraded during K562 cell induction and detected a specific peptide for hnRNP K. We will identify and characterize the hnRNP K cleaving activity and investigate how hnRNP E1 is processed in erythroid cell maturation.