Project description:The cytoplasm contains membrane-bound organelles and membraneless compartments. The TIS granule network is formed through assembly of the RNA-binding protein TIS11B together with its bound mRNAs and associates with a portion of the rough endoplasmic reticulum (ER) – one of the major sites of protein synthesis. Subcellular mRNA localization is widespread in polarized cells. However, it is largely unknown if mRNA localization is also widespread in non-polarized cells and if the location of protein synthesis has biological consequences. To identify compartment-specific cellular functions, we used fluorescent particle sorting to isolate TIS granules, the ER surface, and the cytosol and determined their mRNA contents.
Project description:The cytoplasm contains membrane-bound organelles and membraneless compartments. The TIS granule network is formed through assembly of the RNA-binding protein TIS11B together with its bound mRNAs and associates with a portion of the rough endoplasmic reticulum (ER) – one of the major sites of protein synthesis. Subcellular mRNA localization is widespread in polarized cells. However, it is largely unknown if mRNA localization is also widespread in non-polarized cells and if the location of protein synthesis has biological consequences. To identify compartment-specific cellular functions, we used fluorescent particle sorting to isolate TIS granules, the ER surface, and the cytosol and determined their mRNA contents.
Project description:METTL16 was previously identified as an m6A methyltransferase. In this study, we validated the cytoplasmic location of METTL16 and explored its function in the cytoplasm. We found that METTL16 promoted translation by sequestering eIF4E2, a translation initiation repressor, from the 5' cap structure.
Project description:Post-transcriptional regulation of cellular mRNA is essential for protein synthesis. Here we describe the importance of mRNA translational repression and mRNA subcellular location for protein expression during B lymphocyte activation and the DNA damage response. Cytoplasmic RNA granules are formed upon cell activation with mitogens, including stress granules that contain the RNA binding protein Tia1. Tia1 binds to a subset of transcripts involved in cell stress, including p53 mRNA, and controls translational silencing and RNA granule localization. DNA damage promotes mRNA relocation and translation in part due to dissociation of Tia1 from its mRNA targets. Upon DNA damage, p53 mRNA is released from stress granules and associates with polyribosomes to increase protein synthesis. Global analysis of cellular mRNA abundance and translation indicates that this is an extended ATM-dependent mechanism to increase protein expression of key modulators of the DNA damage response.
Project description:CNBP is a eukaryote-conserved nucleic-acid binding protein required in mammals for embryonic development. It contains seven CCHC-type zinc-finger domains and was suggested to act as a nucleic acid chaperone, as well as a transcription factor. Here, we identify all CNBP isoforms as cytoplasmic messenger RNA (mRNA)-binding proteins. Using Photoactivatable Ribonucleoside Enhanced Cross-linking and Immunoprecipitation, we mapped its binding sites on RNA at nucleotide-level resolution on a genome-wide scale and find that CNBP interacted with 3961 mRNAs in human cell lines, preferentially at a G-rich motif close to the AUG start codon on mature mRNAs. Loss- and gain-of-function analyses coupled with system-wide RNA and protein quantification revealed that CNBP did not affect RNA abundance, but rather promoted translation of its targets. This is consistent with an RNA chaperone function of CNBP helping to resolve secondary structures, thus promoting translation. CNBP PAR-CLIP