Project description:Cystic fibrosis, the most commonly inherited lethal pulmonary disorder in Caucasians, is caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). To identify genomic responses to the presence or absence of CFTR in pulmonary tissues in vivo, microarray analyses of lung mRNAs were performed on whole lung tissue from mice lacking (CFTR(-)) or expressing mouse CFTR (CFTR(+)). Whereas the histology of lungs from CFTR(-) and CFTR(+) mice was indistinguishable, statistically significant increases in the relative abundance of 29 and decreases in 25 RNAs were identified by RNA microarray analysis. Of RNAs whose expression was consistently altered by the absence of CFTR, functional classes of genes influencing gene transcription, inflammation, intracellular trafficking, signal transduction, and ion transport were identified. RNAs encoding the transcription factor CCAAT enhancer-binding protein (CEBP) delta and interleukin (IL) 1beta, both known to regulate CFTR expression, were induced, perhaps indicating adaptation to the lack of CFTR. RNAs mediating lung inflammation including calgranulin-S100 family members, IL-1beta and IL-4, were increased. Likewise, expression of several membrane transport proteins that interact directly with CFTR were increased, suggesting that CFTR-protein complexes initiate genomic responses. Absence of CFTR influenced the expression of genes modulating diverse pulmonary cell functions that may ameliorate or contribute to the pathogenesis of CF. Lungs from sex-matched littermates at 3, 6, and 11 weeks of agewere carefully dissected and the conducting airways and mediastinal structures removed.
Project description:Many biological processes are regulated by RNA-RNA interactions 1, nonetheless it remains formidable to analyze the entire RNA interactome. We developed a method, MARIO (MApping Rna-rna Interactions in vivO), to map protein-assisted RNA-RNA interactions in vivo. By circumventing the selection for a specific RNA-binding protein 2-5, our approach vastly expands the identifiable portion of the RNA interactome. Using this technology, we mapped the RNA interactome in mouse embryonic stem cells, which was composed of 46,780 RNA-RNA interactions. The RNA interactome was a scale-free network, with several lincRNAs and mRNAs emerging as hubs. We validated an interaction between two hubs, Malat1 and Slc2a3 using single molecule RNA fluorescence in situ hybridization. Base pairing was observed at the interaction sites of long RNAs, and was particularly strong in transposonRNA-mRNA and lincRNA-mRNA interactions. This reveals a new type of regulatory sequences acting in trans. Consistent with their hypothesized roles, the RNA interaction sites were more evolutionarily conserved than other regions of the transcripts. MARIO also provided new information on RNA structures, by simultaneously revealing the footprint of single stranded regions and the spatially proximal sites of each RNA. The unbiased mapping of the protein-assisted RNA interactome with minimum perturbation of cell physiology will greatly expand our capacity to investigate RNA functions. Three (3) ESC samples with different treatment (different digestion size and/or crosslinking method) and one (1) MEF sample were included to test our new approach for RNA-interactome mapping and the different samples were analyzed to show RNA interactome differences between them.
Project description:The proteins interacting with CFTR and its mutants have been intensively studied using different experimental approaches, enabling to better understand the cellular processes leading to proper protein folding, routing to the plasma membrane, recycling, activation and degradation. Recently, several strategies have been developed based on the proximity labelling of protein partners or proteins in close vicinity and their subsequent identification by mass spectrometry. In this study, we evaluate TurboID and APEX2 proximity labelling approaches on WT CFTR and compare results to those obtained by co-immunoprecipitation and in databases. We then compared the CFTR-WT interactome to two mutants of CFTR (G551D and W1282X) and the structurally unrelated potassium channel KCNK3. The two methods efficiently identified both known and novel CFTR protein partners and in proximity such as multiple SLC transporters. Hence proximity labelling approaches enable to obtain a wider picture of the CFTR interactome, feeding databases and giving a better understanding of the CFTR environment.
Project description:Cystic fibrosis (CF) is one of the most prevalent lethal genetic diseases with over 2000 identified genetic variants in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Pharmacological chaperones such as Lumacaftor (VX-809), Tezacaftor (VX-661) and Elexacaftor (VX-445) treat mutation-induced defects by stabilizing CFTR and are called correctors. These correctors improve proper folding and thus facilitate processing and trafficking to increase the amount of functional CFTR on the cell surface. Yet, CFTR variants display differential responses to each corrector. Here, we report variants P67L and L206W respond similarly to VX-809 but divergently to VX-445 with P67L exhibiting little rescue when treated with VX-445. We investigate the underlying cellular mechanisms of how CFTR biogenesis is altered by correctors in these variants. Affinity purification-mass spectrometry (AP-MS) multiplexed with isobaric Tandem Mass Tags (TMT) was used to quantify CFTR protein-protein interaction changes between variants P67L and L206W. VX-445 facilitates unique proteostasis factor interactions especially in translation, folding, and degradation pathways in a CFTR variant-dependent manner. A number of these interacting proteins knocked down by siRNA, such as ribosomal subunit proteins, moderately rescued fully glycosylated P67L. Importantly, these knock-downs sensitize P67L to VX-445 and further enhance the correction of this variant. Our results provide a better understanding of VX-445 biological mechanism of action and reveal cellular targets that may sensitize unresponsive CFTR variants to known and available correctors.
Project description:Individuals with cystic fibrosis (CF) experience elevated inflammation in multiple organs, but whether this reflects an inherent feature of CF cells or is a consequence of a pro-inflammatory environment is not clear. Using CRISPR/Cas9-mediated mutagenesis of CFTR, 17 subclonal cell lines were generated from Caco-2 cells. Clonal lines with functional CFTR (CFTR+) were compared to those without (CFTR-) to directly address the role of CFTR in inflammatory gene regulation. All lines maintained CFTR mRNA production and formation of tight junctions. CFTR+ lines displayed short circuit currents in response to forskolin, while the CFTR- lines did not. Baseline expression of both cytokines was not different between the lines regardless of CFTR genotype. All lines responded to TNFa and IL1b by increasing IL6 and CXCL8 (IL8) mRNA levels, but the CFTR- lines produced more CXCL8 mRNA than the CFTR+ lines. Transcriptomes of 6 CFTR- and 6 CFTR+ lines, before and after stimulation by TNFa, were compared for differential expression as a function of CFTR genotype. While some genes appeared to be differentially expressed simply because of CFTR’s absence, others required stimulation for differences to be apparent. Together, these data suggest cells respond to CFTR’s absence by modulating transcriptional networks, some of which are only apparent when cells are exposed to different environmental contexts, such as inflammation. With regards to inflammation, these data suggest a model in which CFTR’s absence leads to a poised, pro-inflammatory state of cells that is only revealed by stimulation.
Project description:To gain insights into the interactome of wild-type (WT) and S102P mutant GATAD1, we utilized the BioID method, which enables the study of protein-protein interactions. Specifically, we performed BioID proximity labeling experiments in stable Flp-In cells expressing different GATAD1 variants fused to BirA*_FLAG. These variants included BirA*_FLAG_GATAD1-WT, BirA*_FLAG_GATAD1-S102P, BirA*_FLAG_GATAD1-S102D, and BirA*_FLAG_GATAD1-S102A. By employing this approach, we aimed to characterize the protein interactors associated with these GATAD1 variants and gain insights into the functional consequences of the S102P mutation.
Project description:In the clinical setting, mutations in the CFTR gene enhance the inflammatory response to P. aeruginosa (PA01) infection, but measurements of the inflammatory response to pathogen stimulation by isolated airway epithelia can yield variable results. In this series, we exposed CFBE41o- cells over-expressing ∆F508/∆F508 CFTR and CFBE41o- cells rescued with wt-CFTR to P. aeruginosa biofilms. P. aeruginosa elicited a more robust increase in cytokine and chemokine expression (e.g., IL-8, CXCL2, CXCL3, CXCR4 and TNF-α) in CFBE-wt-CFTR cells compared to CFBE-∆F508-CFTR cells. These results demonstrate that CFBE41o- cells complemented with wt-CFTR mount a more robust inflammatory response to P. aeruginosa than CFBE41o- ∆F508/∆F508-CFTR cells.
Project description:Identification of Genes Responsive to the Expression of Normal Human CFTR Experiment Overall Design: To discern the effects of increased expression of normal human CFTR, lung mRNA levels were assessed in mice expressing the normal human CFTR cDNA under control of the Sftpc gene promoter in respiratory epithelial cells of adult mice. Triplicate samples from SP-C-hCFTRtg/tg, SP-C-hCFTRtg/-, and wild type mice were compared.