Prof. Dr. Hüttelmaier
PROJECT INFORMATION :
The regulation of mRNA fate is essentially controlled by the interplay of mRNA-binding proteins (mRBPs) and trans-acting noncoding RNAs including microRNAs and lncRNAs (long noncoding RNAs). In the cytoplasm, the regulation of mRNA translation and turnover is largely regulated via mRNPs comprising mRNA-specific mRBP-assemblies.
In recent studies, we identified that various mRBPs associate with noncoding Y RNAs. The Y3** promotes the 3’-end processing of replication dependent histone pre-mRNA by modulating the assembly of CPSF-associated complexes and their delivery to histone locus bodies (HLBs), the site of histone mRNA synthesis and 3’-end processing. In contrast to Y3**, Y1 as well as Y3 are mainly cytoplasmic. Both Y RNAs associate with various mRBPs in Y RNPs comprising mRBPs largely associating via the single-stranded loop of Y RNAs, Ro60 binding at the stem and La associating via a polyU-rich stretch at Y RNAs’ 3’-end. We propose that Y RNPs are essential modulators of mRNP assembly controlling the subcellular sorting of mRBPs, their turnover, post-translational modification and/or complex formation. Accordingly, Y RNPs are expected to modulate the cytoplasmic fate of mRNAs and thus the post-transcriptional control of gene expression by scaffolding, sequestering and/or chaperoning mRBPs. This proposal aims at deciphering the molecular mechanisms underlying Y RNP-directed regulation of mRNP/mRBP function by focusing on the following aspects: 1) Characterization and validation of the Y RNA protein-interactome; 2) The role of Y RNAs in modulating the mRNP-association of mRBPs; 3) The role of Y RNAs in modulating subcellular sorting of mRBPs; 4) The role of Y RNAs in modulating mRBP protein turnover and modification; 5) The role of Y RNAs in controlling mRBP-directed control of cytoplasmic mRNA fate.
We expect that the proposed studies will reveal important insights into the regulation of mRBP/mRNP function, in particular in cancer-derived cells. In the latter, upregulated expression of Y RNAs, in particular Y1 and Y3 along with several mRBPs has been reported. Accordingly, the proposed studies will set the stage for evaluating the role of Y RNA-controlled mRBP/mRNP function in cancer.
KEY TECHNOLOGIES :
- Purification of RNPs (RNA pulldown, immunopurification, density gradient centrifugation)
- Imaging technologies (live cell microscopy, photoconvertable fluorescence)
- Gene expression profiling by NGS technologies
Hüttelmaier S., Zenklusen D., Lederer M., Dictenberg J, Lorenz M, Meng X., Bassell G., Condeelis J., Singer RH*. Spatial regulation of b-actin translation by Src-dependent phosphorylation of ZBP1. Nature, 2005 Nov., Vol. 438: 512-515.
Köhn M, Lederer M, Wächter K, Hüttelmaier S. Near-infrared (NIR) dye-labeled RNAs identify binding of ZBP1 to the noncoding Y3-RNA. RNA. 2010 Jul;16(7):1420-8.
Köhn M, Pazaitis N, Hüttelmaier S. Why Y RNAs? About Versatile RNAs and Their Functions. Biomolecules. 2013; 3(1):143-156.
Wächter K, Köhn M, Stöhr N, Hüttelmaier S. Subcellular localization and RNP formation of IGF2BPs (IGF2 mRNA-binding proteins) is modulated by distinct RNA-binding domains. Biol Chem. 2013 Aug;394(8):1077-90.
Köhn M, Ihling C, Sinz A, Krohn K, Hüttelmaier S. The Y3** ncRNA promotes the 3’-end processing of histone mRNAs. Genes and Development 2015; in press