Project description:Zebrafish (Danio Rerio) have the capacity for successful adult optic nerve regeneration. In contrast, mammals lack this intrinsic ability and undergo irreversible neurodegeneration seen in glaucoma and other optic neuropathies. Optic nerve regeneration is often studied using optic nerve crush, a mechanical neurodegenerative model. Untargeted metabolomic studies within successful regenerative models are deficient. Evaluation of tissue metabolomic changes in active zebrafish optic nerve regeneration can elucidate prioritized metabolite pathways that can be targeted in mammalian systems for therapeutic development. Female and male (6 month to 1 year old) right Zebrafish (Tg(gap43:GFP)) optic nerves were crushed and collected three days after. Contralateral, uninjured optic nerves were collected as controls. The tissue was dissected from euthanized fish and frozen on dry ice. Samples were pooled for each category (female crush, female control, male crush, male control) and pooled at n = 31 to obtain sufficient metabolite concentrations for analysis. Optic nerve regeneration was verified by microscope visualization of GFP fluorescence. Metabolites were extracted using a Precellys Homogenizer and a serial extraction method: (1) 1:1 Methanol/Water and (2) 8:1:1 Acetonitrile/Methanol/Acetone. Metabolites were analyzed by untargeted liquid chromatography-mass spectrometry (LC MS-MS) profiling using a Q-Exactive Orbitrap instrument coupled with Vanquish Horizon Binary UHPLC LC-MS system. Metabolites were identified and quantified using Compound Discoverer 3.3 and isotopic internal metabolites standards.
Project description:Background: Acrylamide (ACR) is a broadly spread neurotoxic chemical of public health concern, as occupational or environmental exposure of humans to ACR may lead to a synaptopathy characterized by ataxia, skeletal muscles weakness and numbness of the extremities. Currently, only the mildly affected patients undergo complete recovery, and identification of new molecules with therapeutic bioactivity against ACR acute neurotoxicity is urgently needed. Objectives: We aimed to develop a zebrafish model for human ACR neurotoxicity. Methods: Adverse effects have been assessed at different levels, including analysis of the motor function (basal locomotor activity, visual motor response, kinematic of the touch-evoked escape response), histopathological evaluation (toluidine blue and whole-mount immunofluorescence), analysis of neural transcriptional markers (qPCR), proteomic analysis (μLC-MS-MS) and neurotransmitters profile (LC-MS/MS). Results: Our results show that zebrafish mimics most of the pathophysiological processes described in humans and mammalian models. Motor function was altered, including the response to sudden changes in light intensity. Specific effects were found on the presynaptic nerve terminals at the neuromuscular junction level, but not on the axonal tracts or myelin sheath integrity. Transcriptional markers of proteins involved in synaptic vesicle cycle were selectively altered, and the proteomic analysis showed that ACR-adducts were formed on cysteine residues of some synaptic proteins. Finally, analysis of neurotransmitters profile showed a significant effect found on cholinergic and dopaminergic systems. Conclusions: Thus, the zebrafish model for ACR acute neurotoxicity is suitable to be used larvae for in vivo high-throughput screening of small molecule libraries for identifying new drugs against this synaptopathy.
Project description:The ribosome is a translational apparatus that comprises about 80 ribosomal proteins and four rRNAs. Recent studies reported that ubiquitination of the ribosomal proteins plays a pivotal role in translational control and ribosome-associated quality control (RQC). However, little is known about the dynamics of ribosome ubiquitination under complex biological processes of multicellular organisms. To study ribosome ubiquitination during animal development, we generated a zebrafish strain that expresses a FLAG-tagged ribosomal protein Rpl36/eL36 from its endogenous locus. Combining affinity purification of ribosomes from rpl36-FLAG zebrafish embryos with immunoblotting analysis, we analyzed ribosome ubiquitination during zebrafish development. Our data showed that ubiquitination of ribosomal proteins dynamically changed as development proceeded. We further revealed that Znf598, an E3 ubiquitin ligase that triggers RQC, contributed to the ribosome ubiquitination during zebrafish development. LC-MS/MS analysis and immunoblotting analysis identified lysines 139 of ribosomal protein Rps10/eS10 as pivotal ubiquitination sites on the ribosome during development. Finally, we demonstrated that an Rps10 K139/140R mutation reduced overall ribosome ubiquitination pattern. Collectively, these results reveal dynamics and complexity of ribosome ubiquitination in zebrafish development.
Project description:Adult zebrafish, in contrast to mammals, are able to regenerate their hearts in response to injury or experimental amputation. Our understanding of the cellular and molecular bases that underlie this process, although fragmentary, has increased significantly over the last years. However, the role of the extracellular matrix (ECM) during zebrafish heart regeneration has been comparatively rarely explored. Here, we set out to characterize the ECM protein composition in adult zebrafish hearts, and whether it changed during the regenerative response. For this purpose, we first established a decellularization protocol of adult zebrafish ventricles that significantly enriched the yield of ECM proteins. We then performed proteomic analyses of decellularized control hearts and at different times of regeneration. Our results show a dynamic change in ECM protein composition, most evident at the earliest (7 days post-amputation) time-point analyzed. Regeneration associated with sharp increases in specific ECM proteins, and with an overall decrease in collagens and cytoskeletal proteins. We finally tested by atomic force microscopy that the changes in ECM composition translated to decreased ECM stiffness. Our cumulative results identify changes in the protein composition and mechanical properties of the zebrafish heart ECM during regeneration.
Project description:Adult zebrafish, in contrast to mammals, are able to regenerate their hearts in response to injury or experimental amputation. Our understanding of the cellular and molecular bases that underlie this process, although fragmentary, has increased significantly over the last years. However, the role of the extracellular matrix (ECM) during zebrafish heartregeneration has been comparatively rarely explored. Here, we set out to characterize theECM protein composition inadult zebrafish hearts, and whether it changed during the regenerative response. For this purpose, we first established a decellularization protocol of adult zebrafish ventricles that significantly enriched the yield of ECM proteins. We then performed proteomic analyses of decellularized control hearts and at different times of regeneration. Our results show a dynamic change in ECM protein composition, most evident at the earliest (7 dayspost-amputation) time-point analyzed. Regeneration associated withsharp increases inspecific ECM proteins, and with an overall decrease in collagens and cytoskeletal proteins. We finally tested by atomic force microscopythat the changes in ECM composition translatedto decreased ECM stiffness. Our cumulative results identify changes in the protein composition and mechanical properties of the zebrafish heart ECM during regeneration.
Project description:The zebrafish (Danio rerio) is a popular animal model in studies of vertebrate development and organogenesis. Recent research has shown a similarity of approximately 70% between the human and zebrafish genomes and of 84% in human disease-causing genes, specifically. Zebrafish embryos have a number of desirable features, including transparency, a large size, and rapid embryogenesis. Protein phosphorylation is a well-known post-translational modification (PTM), which performs various biological functions. Recent mass spectrometry (MS) developments have enabled the study of global phosphorylation patterns by using MS-based proteomics coupled with TiO2 phosphopeptide enrichment. In the present study, we identified 3,500 non-redundant phosphorylation sites on 2,166 phosphoproteins and 1,564 quantified phosphoproteins in zebrafish embryos.
Project description:A transgenic line cmlc2:TRAP was made to express EGFP-fused ribosomal protein L10a (EGFP-L10a) in zebrafish cardiomyocytes. Then ribosome-associated RNAs were immuoprecipitated from uninjured and injured adult cmlc2:TRAP fish to determine the differential expression changes during zebrafish heart regeneration.
Project description:Hypoplastic left heart syndrome (HLHS) is characterized by underdevelopment of left sided structures including the ventricle, valves, and aorta1. Although the mechanisms of disease pathogenesis remain elusive due to a paucity of candidate genes and animal models, prevailing paradigm suggests that HLHS is a multigenic disease of co-occurring phenotypes2,3. Here, we report that zebrafish lacking two orthologs of the RNA binding protein RBFOX2, a gene previously linked to HLHS in humans4,5, display cardiovascular defects overlapping those in HLHS patients. In contrast to current models, we demonstrate that co-existing ventricular, valve, and aortic deficiencies in rbfox mutant zebrafish arise secondary to impaired myocardial function as all three phenotypes are rescued when Rbfox is expressed specifically in the myocardium. On a molecular and cellular level, we find diminished expression and alternative splicing of sarcomere and mitochondrial components in rbfox-deficient hearts that compromise sarcomere assembly and mitochondrial respiration, respectively. Injection of human RBFOX2 mRNA restores ventricular structure and function in rbfox mutant zebrafish, while HLHS-linked RBFOX2 variants fail to rescue. Taken together, our data suggest that mutations in RBFOX2 are causal for HLHS pathogenesis and provide a complimentary paradigm for HLHS emergence where co-existing ventricular, valve, and aortic deficiencies have a monogenic etiology caused by myocardial dysfunction.
Project description:Silver nanoparticles cause toxicity in exposed organisms and are an environmental health concern. The mechanisms of silver nanoparticle toxicity, however, remain unclear. We examined the effects of exposure to silver in nano-, bulk- and ionic forms on zebrafish embryos (Danio rerio) using a Next Generation Sequencing approach in an Illumina platform (High-Throughput SuperSAGE). Significant alterations in gene expression were found for all treatments and many of the gene pathways affected, most notably those associated with oxidative phosphorylation and protein synthesis, overlapped strongly between the three treatments indicating similar mechanisms of toxicity for the three forms of silver studied. Changes in oxidative phosphorylation indicated a down-regulation of this pathway at 24h of exposure, but with a recovery at 48h. This finding was consistent with a dose-dependent decrease in oxygen consumption at 24h, but not at 48h, following exposure to silver ions. Overall, our data provide support for the hypothesis that the toxicity caused by silver nanoparticles is principally associated with bioavailable silver ions in exposed zebrafish embryos. These findings are important in the evaluation of the risk that silver particles may pose to exposed vertebrate organisms. mRNA profiles of whole zebrafish embryos at 24 and 48 hours post-fertilisation (hpf) exposed to silver in nano, bulk and ionic forms were generated by deep sequencing using HT-SuperSAGE (Illumina GA2).
Project description:Polycomb group (PcG) proteins are transcriptional repressors important to maintain cell identity during embryonic development. Ezh2, the catalytic subunit of the Polycomb Repressive Complex 2, is responsible for placing the epigenetic repressive mark histone H3 lysine 27 trimethylation (H3K27me3). In contrast to results in mouse models, zebrafish embryos mutant for both maternal and zygotic ezh2 (MZezh2) can form a normal body plan at 1 day post fertilization (dpf) but die at 2 dpf, exhibiting pleiotropic phenotypes. To elucidate the specificity of PcG-mediated repression during early zebrafish development, we conducted in depth analysis of the transcriptome, epigenome, and proteome of the MZezh2 mutant embryos at 1 dpf. We found that, despite modifications in the epigenetic landscape, transcriptome and proteome analysis revealed only minor changes in gene and protein expression levels.