Project description:The canonical mammalian mRNA export process is thought to terminate at the cytoplasmic face of the nuclear pore complex through mRNP remodeling. We conducted a stringent affinity-purification mass-spectrometry-based screen of the physical interactions of human RNA-binding E3 ubiquitin ligases. The resulting protein-interaction network revealed unexpected interactions between the RNA-binding E3 ubiquitin ligase MKRN2 and GLE1, a DEAD-box helicase activator implicated in mRNA export termination. We assessed MKRN2 epistasis with GLE1 in a genetically tractable zebrafish model. Strikingly, morpholino-mediated knockdown or CRISPR/Cas9-based knockout of MKRN2 partially rescued retinal developmental defects seen upon GLE1 depletion. Next, using iCLIP, we showed that MKRN2 binds preferentially to the 3'UTR of a diverse subset of mRNAs. Next-generation sequencing of fractionated cell extracts revealed that nuclear export of MKRN2-associated mRNAs is enhanced upon knockdown of MKRN2. Taken together, these results indicate that MKRN2 selectively interacts with GLE1 to regulate mRNA nuclear export and retinal development.
Project description:The canonical mammalian mRNA export process is thought to terminate at the cytoplasmic face of the nuclear pore complex through mRNP remodeling. We conducted a stringent affinity-purification mass-spectrometry-based screen of the physical interactions of human RNA-binding E3 ubiquitin ligases. The resulting protein-interaction network revealed unexpected interactions between the RNA-binding E3 ubiquitin ligase MKRN2 and GLE1, a DEAD-box helicase activator implicated in mRNA export termination. We assessed MKRN2 epistasis with GLE1 in a genetically tractable zebrafish model. Strikingly, morpholino-mediated knockdown or CRISPR/Cas9-based knockout of MKRN2 partially rescued retinal developmental defects seen upon GLE1 depletion. Next, using iCLIP, we showed that MKRN2 binds preferentially to the 3'UTR of a diverse subset of mRNAs. Next-generation sequencing of fractionated cell extracts revealed that nuclear export of MKRN2-associated mRNAs is enhanced upon knockdown of MKRN2. Taken together, these results indicate that MKRN2 selectively interacts with GLE1 to regulate mRNA nuclear export and retinal development.
Project description:Numerous RNAs copurify with RNase P and are affected by temperture sensitive mutations in conserved residues with the essential RNA and protein subunits. Specifically, RNase P physically interacts with ribosomal protein mRNAS and the intron-encoded box C/D snoRNAs. Keywords: RNA copurification, temperature sensitive mutants ORF and intergenic regions were analyzed in order to determine which RNAs were affected in RNase P strains.
Project description:The nuclear export of messenger RNAs (mRNAs) is intimately coupled to their synthesis. pre-mRNAs assemble into dynamic ribonucleoparticles as they are being transcribed, processed and exported. The role of ubiquitylation in this process is increasingly recognized as the ubiquitylation of many key players have been shown to affect mRNA nuclear export. While a few E3 ligases have been shown to regulate nuclear export, evidence for deubiquitylases is currently lacking. Here, we identified the deubiquitylase Ubp15 as a regulator of nuclear export in Saccharomyces cerevisiae. Ubp15 interacts both with RNA polymerase II and with the nuclear pore complex, and its deletion reverts the nuclear export defect of mutants of the E3 ligase Rsp5. The deletion of UBP15 leads to hyper-ubiquitylation of the main nuclear export receptor Mex67 and affects its association with THO, a complex coupling transcription to mRNA processing and involved in the recruitment of mRNA export factors to nascent transcripts. Collectively, our data support a role for Ubp15 in coupling transcription to mRNA export.
Project description:PIWI-interacting RNAs (piRNAs) guide transposon silencing in animals. The 22-30nt piRNAs are processed in the cytoplasm from long non-coding RNAs. How piRNA precursors, which often lack RNA processing hallmarks of export-competent transcripts, achieve nuclear export is unknown. Here, we uncover the RNA export pathway specific for piRNA precursors in the Drosophila germline. This pathway requires Nxf3-Nxt1, a variant of the hetero-dimeric mRNA export receptor Nxf1-Nxt1. Nxf3 interacts with UAP56, a nuclear RNA helicase essential for mRNA export, and CG13741/Bootlegger, which recruits Nxf3-Nxt1 and UAP56 to heterochromatic piRNA source loci. Upon RNA cargo binding, Nxf3 achieves nuclear export via the exportin Crm1, and accumulates together with Bootlegger in peri-nuclear nuage, suggesting that after export, Nxf3-Bootlegger delivers precursor transcripts to the piRNA processing sites. Our findings indicate that the piRNA pathway bypasses nuclear RNA surveillance systems to achieve export of heterochromatic, unprocessed transcripts to the cytoplasm, a strategy also exploited by retroviruses.
Project description:Retinal microvascularization can provide important informations to systemic vascular phenomena. The non-invasive quantitative description of the retinal vascularization is now possible by performing OCT-angiography and their image analysis software (vascular density and retinal perfusion). Systemic microvacular changes during the establishment of oncological treatment by targeted antiangiogenic therapy are little described in the literature. The objective of this pilot study is to describe the evolution of the retinal vascular density of patients with antiangiogenic drugs. In addition, the evolution of the retinal vascular density of patients on antiangiogenic drugs will study as a function of the response to the treatment and the toxicity of these treatments.
Project description:Increased p21-activated kinase (PAK) signaling and expression have been identified in the invasive fronts of aggressive papillary thyroid cancers (PTCs), including those with RET/PTC, BRAFV600E, and mutant RAS expression. Functionally, thyroid cancer cell motility in vitro is dependent on group 1 PAKs, particularly PAK1. In this study, we hypothesize that BRAF, a central kinase in PTC tumorigenesis and invasion, regulates thyroid cancer cell motility in part through PAK activation. Using three well-characterized human thyroid cancer cell lines, we demonstrated in all cell lines that BRAF knockdown reduced PAK phosphorylation of direct downstream targets. In contrast, inhibition of MEK activity either pharmacologically or with siRNA did not reduce PAK activity, indicating MEK is dispensable for PAK activity. Inhibition of cell migration through BRAF loss is rescued by overexpression of either constitutive active MEK1 or PAK1, demonstrating that both signaling pathways are involved in BRAF-regulated cell motility. To further characterize BRAF-PAK signaling, immunofluorescence and immunoprecipitation demonstrated that both exogenously overexpressed and endogenous PAK1 and BRAF co-localize and physically interact, and that this interaction was enhanced in mitosis. Finally, we demonstrated that acute induction of BRAFV600E expression in vivo in murine thyroid glands results in increased PAK expression and activity confirming a positive signaling relationship in vivo. In conclusion, we have identified a signaling pathway in thyroid cancer cells which BRAF activates and physically interacts with PAK and regulates cell motility.
Project description:Numerous RNAs copurify with RNase P and are affected by temperture sensitive mutations in conserved residues with the essential RNA and protein subunits. Specifically, RNase P physically interacts with ribosomal protein mRNAS and the intron-encoded box C/D snoRNAs. Keywords: RNA copurification, temperature sensitive mutants