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:RNA localization and local translation are important for numerous cellular functions. In mammals, a class of mRNAs localize to cytoplasmic protrusions in an APC-dependent manner, with roles during cell migration. Here, we investigated this localization mechanism. We found that the KIF1C motor interacts with APC-dependent mRNAs and is required for their localization. Live cell imaging revealed rapid, active transport of single mRNAs over long distances that requires both microtubules and KIF1C. Two-color imaging directly revealed single mRNAs transported by single KIF1C motors, with the 3'UTR being sufficient to trigger KIF1C-dependent RNA transport and localization. Moreover, KIF1C remained associated with peripheral, multimeric RNA clusters and was required for their formation. These results reveal a widespread RNA transport pathway in mammalian cells, in which the KIF1C motor has a dual role in transporting RNAs and clustering them within cytoplasmic protrusions. Interestingly, KIF1C also transports its own mRNA, suggesting a possible feedback loop acting at the level of mRNA transport.
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:Through the asymmetric distribution of messenger RNAs (mRNAs), cells spatially regulate gene expression to create cytoplasmic domains with specialized functions. In neurons, mRNA localization is required for essential processes such as cell polarization, migration, and synaptic plasticity underlying long-term memory formation. The essential components driving cytoplasmic mRNA transport in neurons and mammalian cells are not known. We report the first reconstitution of a mammalian mRNA transport system revealing that the tumor suppressor adenomatous polyposis coli (APC) forms stable complexes with the axonally localized ?-actin and ?2B-tubulin mRNAs, which are linked to a kinesin-2 via the cargo adaptor KAP3. APC activates kinesin-2, and both proteins are sufficient to drive specific transport of defined mRNA packages. Guanine-rich sequences located in 3'UTRs of axonal mRNAs increase transport efficiency and balance the access of different mRNAs to the transport system. Our findings reveal a minimal set of proteins sufficient to transport mammalian mRNAs.
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:Specific mRNAs are transported from the cell body to synapses where their translation can modify communication of pre-existing synapses and induce formation of new synaptic connections in response to learning. Little is known, however, about the identity of the RNAs that are actively transported and when and how these RNAs are utilized during learning. By focusing on RNAs that are associated with kinesin, a motor protein that transports gene products from the cell body to synapses, we have now applied microarrays and 454 sequencing to identify actively transported RNAs from the Aplysia central nervous system. Using a library prepared from the kinesin complex immunoprecipitated from the central nervous system (CNS), we have identified thousands of unique transcripts, of which ~600 mRNAs were annotated. Two sample comparison: kinesin IP vs. control.
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:Specific mRNAs are transported from the cell body to synapses where their translation can modify communication of pre-existing synapses and induce formation of new synaptic connections in response to learning. Little is known, however, about the identity of the RNAs that are actively transported and when and how these RNAs are utilized during learning. By focusing on RNAs that are associated with kinesin, a motor protein that transports gene products from the cell body to synapses, we have now applied microarrays and 454 sequencing to identify actively transported RNAs from the Aplysia central nervous system. Using a library prepared from the kinesin complex immunoprecipitated from the central nervous system (CNS), we have identified thousands of unique transcripts, of which ~600 mRNAs were annotated.
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.