Project description:Deciphering the complex biology of cell migration is key to understand human-related disorders. During angiogenesis, endothelial cells engage in coordinated migration events to form new blood vessels from parental counterparts. However, while subcellular localisation of mRNAs and localised translation are fundamental steps between gene transcription and protein activity, whether local regulation of gene expression controls the complex morphogenetic process of angiogenesis has never been addressed. Here, we set out to investigate the cytoplasmic distribution of mRNAs in migratory endothelial cells. We isolated RNA from endothelial cell protrusions from their cell bodies and used RNA-sequencing to identify asymmetrically distributed transcripts. These studies identified a set of transcripts enriched in endothelial cell protrusions over cell bodies, which included classically protrusion-enriched mRNAs and other intriguing transcripts encoding proteins implicated in cell migration.
Project description:We used a fractionation scheme to isolate protrusions and cell bodies from control or APC knockdown fibroblasts, which were induced to extend protrusions in response to addition of lysophosphatidic acid (LPA). Four replicate protrusion and cell body samples for each cell type were analyzed by RNA-Seq. To identify RNAs enriched in protrusions, a protrusion/cell body ratio was calculated. We find that ca. 7% of detected RNAs were enriched in protrusions of control cells. Knockdown of APC reduced the protrusion enrichement of a subset of these RNAs, indicating that they are dependent on APC for their localization. Localization of the remaining RNAs was not significantly affected upon APC knockdown suggesting that their localization is mediated by an APC-independent mechanism.
Project description:Transcriptome analysis of specific mRNA interacting with KIF1C-GFP in HeLa Cells. RNA localization and local translation are involved in a wide range of cellular functions. In mammals, a class of mRNAs localize to cytoplasmic protrusions in an APC dependent manner, with important roles during cell migration. Here, we investigated this localization mechanism. We found that the KIF1C motor interacts with many APC-dependent mRNAs and is required for their localization. Live cell imaging of localizing mRNAs further revealed rapid, active transport of single mRNAs over long distances, and showed that this requires both microtubules and KIF1C. Moreover, two color imaging directly revealed single mRNAs transported by single KIF1C motors, with the 3’UTR of localized mRNAs being sufficient to trigger KIF1C-dependent RNA transport and localization. These results reveal a general RNA transport pathway in mammalian cells, in which the KIF1C motor transports RNAs to cytoplasmic protrusions. Interestingly, KIF1C also transported its own mRNA suggesting a possible feedback loop acting at the level of mRNA transport.
Project description:We generated fibroblast lines overexpressing beta-globin constructs under a doxycycline-inducible promoter. These constructs contain the beta-globin coding sequence followed by either a control 3'UTR (HBB) or the Pkp4 3'UTR. The Pkp4 3'UTR carries a protrusion-targeting element and is expected to compete with localization of endogenous protrusion-localized mRNAs. We used a fractionation scheme to isolate protrusions and cell bodies from HBB and Pkp4 UTR-expressing fibroblasts, which were induced to extend protrusions in response to addition of lysophosphatidic acid (LPA). 4 replicate protrusion and cell body samples for each cell type were analyzed by RNA-Seq. To identify RNAs enriched in protrusions, a protrusion/cell body ratio was calculated. We find that ca. 4.5% of detected RNAs were enriched in protrusions of control HBB cells. Overexpression of the Pkp4 UTR reduced the protrusion enrichement of a subset of these RNAs, while the degree of localization of the remaining RNAs was not significantly affected.
Project description:Translation of Ribosomal Protein coding mRNAs (RP-mRNAs) constitutes a key step in regulation of ribosome biogenesis in human cells, but the exact mechanisms which modulate RP-mRNAs translation under various cellular and environmental conditions remain poorly understood. Here we show that the subcellular localisation of RP-mRNAs acts as a key regulator of their translation in mesenchymal-like migratory cells. As cells invade into their surroundings, RP-mRNAs localise to the actin-rich protrusions at the front of the cells. This localisation is mediated by La related protein-6 (LARP6), an RNA Binding Protein (RBP) that is enriched in protrusions. Importantly, translation initiation and elongation factors are also enriched in protrusions. LARP6 dependent localisation of RP-mRNAs enhances their translation, leading to up-regulation of ribosome biogenesis and increased overall protein synthesis. In breast carcinomas, enhanced expression of LARP6 is associated with Epithelial to Mesenchymal Transition (EMT), and can be therapeutically targeted by a small molecule inhibitor which interferes with LARP6 RNA binding. These findings reveal an RNA localisation based post-transcriptional mechanism that governs ribosome biogenesis in migratory cells, and implicate a role for this process in cancer progression downstream of EMT.
Project description:Subcellular localization of messenger RNA (mRNA) is a widespread phenomenon that can impact the regulation and function of the encoded protein. In non-neuronal cells, a subset of mRNAs localize to cell protrusions and proper mRNA localization is required for cell migration. However, the mechanisms by which mRNA localization regulates protein function in this setting remain unclear. Here, we examined the functional consequences of localization of the mRNA encoding KIF1C. KIF1C is a kinesin motor protein required for cell migration and mRNA trafficking, including trafficking of its own mRNA. We show that Kif1c mRNA localization does not regulate KIF1C protein abundance, distribution, οr ability to traffic other mRNAs. Conversely, robust Kif1c mRNA localization is required for directed cell migration. We used mass spectrometry to identify binding partners of endogenous KIF1C, which revealed dramatic dysregulation of the number and identity of KIF1C interactors in response to Kif1c mRNA mis-localization. These results therefore uncovered a mechanistic connection between mRNA localization to cell protrusions and the specificity of protein-protein interactions. We anticipate that this mechanism is not limited to Kif1c and is likely to be a general principle used by protrusion-enriched mRNAs in non-neuronal cells.
Project description:3' mRNA-seq of protrusions and cell bodies of nt or LARP6 siRNA transfected MDA-MB231 cells. These data show that Ribosomal protein (RP) -mRNAs localization to cell protrusions is mediated by LARP6.
Project description:Like neurons, oligodendrocytes (OL) are cells with elaborate morphology that probably require asymmetrical spatial regulation of biological processes. Formation of membrane protrusions is critical for OL development and interaction with axons. We hypothesized that the enrichment of specific mRNAs in protrusions of oligodendrocyte precursor cells (OPC) is important for morphological differentiation, thus having an impact in myelination. To explore this hypothesis, we established a modified Boyden chamber system to physically separate soma from membrane protrusions of rat primary OPC cultured in vitro for 24h. We performed a whole transcriptome analysis (RNAseq) of primary rat OPC soma and membrane protrusion fractions and found a subcellular enrichment of mRNAs in these structures during initial protrusion formation. At the very initial stage of OPC protrusion extension, there is a significant subcellular enrichment of transcripts encoding proteins related to cellular component assembly and cytoskeleton organization, particularly of actin-related molecules. This suggests that the regulation of the cytoskeleton dynamics may be locally controlled in OPCs and probably relevant for their differentiation program.
Project description:3' mRNA-seq of protrusions and cell bodies of a panel of normal and malignant cell lines. These data show that Ribosomal protein (RP) -mRNAs localization to cell protrusions is a conserved phenomenon.