Modeling Diamond Blackfan anemia in the zebrafish

The Function and the Affecting Factors of the Zebrafish Gut Microbiota

Gut microbiota has become a topical issue in unraveling the research mechanisms underlying disease onset and progression. As an important and potential "organ," gut microbiota plays an important role in regulating intestinal epithelial cell differentiation, proliferation, metabolic function and immune response, angiogenesis and host growth. More recently, zebrafish models have been used to study the interactions between gut microbiota and hosts. It has several advantages, such as short reproductive cycle, low rearing cost, transparent larvae, high genomic similarity to humans, and easy construction of germ-free (GF) and transgenic zebrafish. In our review, we reviewed a large amount of data focusing on the close relationship between gut microbiota and host health. Moreover, we outlined the functions of gut microbiota in regulating intestinal epithelial cell differentiation, intestinal epithelial cell proliferation, metabolic function, and immune response. More, we summarized major factors that can influence the composition, abundance, and diversity of gut microbiota, which will help us to understand the significance of gut microbiota in regulating host biological functions and provide options for maintaining the balance of host health.

Bisphenol-A alters hematopoiesis through EGFR/ERK signaling to induce myeloblastic condition in zebrafish model

Experimental evidence from the etiology of cancer studies suggests that a correlation between Bisphenol-A (BPA) exposure and alterations in hematopoiesis leads to blood cancer. In our study zebrafish were used to assess the lethality, developmental effect, embryonic apoptosis and changes in transcription factor of hematopoiesis through EGFR/ERK signaling pathways in response to BPA. The in silico interaction of EGFR and BPA was analysed by molecular dynamic simulation. According to our results, BPA induced a significant lethal effect in hatching retardation, reduction in heart rate and teratogenic effects on zebrafish embryos and larvae at three different concentrations 100, 500 and 2500 μg/L. The mortality of adult zebrafish exposed to the acute toxicity of BPA from 5 to 30 mg/L concentrations was determined for 96 h. The peripheral blood cells and vital organs such as kidney, liver and spleen from BPA exposed fish showed predominantly abnormal myeloid blast cells along with severe morphological changes in erythrocytes at sublethal concentration 245 μg/L. The BPA showed the highest binding affinity to zebrafish EGFR with a docking score of -7.5 kcal/mol with an RMSD of 3.0 nm during MD simulation. We found that EGFR/ERK overexpression leads to induce hematopoietic cell proliferation and impaired differentiation, which enhances the myeloid repopulating activity and the accumulation of immature myeloblast cells. BPA also caused a corresponding increase in expression of hematopoietic transcription factor c-MYB and RUNX-1 leading to polychromasia, poikilocytosis, acanthocytes and anisocytosis and promoted myeloblastosis by inhibiting GATA-1 expression. These morphological changes often resulted in the prior condition of acute myeloid leukemia (AML). Comprehensively, our data suggest that BPA can trigger the malignancy of AML cells by alteration of respective hematopoietic transcription factors via EGFR/ERK signaling in the zebrafish model.

New tools for 'ZEBRA-FISHING'

Zebrafish has been established as a classical model for developmental studies, yet in the past years, with the explosion of novel technological methods, the use of zebrafish as a model has expanded. One of the prominent fields that took advantage of zebrafish as a model organism early on is hematopoiesis, the process of blood cell generation from hematopoietic stem and progenitor cells (HSPCs). In zebrafish, HSPCs are born early during development in the aorta-gonad-mesonephros region and then translocate to the caudal hematopoietic tissue, where they expand and finally take residence in the kidney marrow. This journey is tightly regulated at multiple levels from extracellular signals to chromatin. In order to delineate the mechanistic underpinnings of this process, next-generation sequencing techniques could be an important ally. Here, we describe genome-wide approaches that have been undertaken to delineate zebrafish hematopoiesis.

Modeling hematopoietic disorders in zebrafish

Zebrafish offer a powerful vertebrate model for studies of development and disease. The major advantages of this model include the possibilities of conducting reverse and forward genetic screens and of observing cellular processes by in vivo imaging of single cells. Moreover, pathways regulating blood development are highly conserved between zebrafish and mammals, and several discoveries made in fish were later translated to murine and human models. This review and accompanying poster provide an overview of zebrafish hematopoiesis and discuss the existing zebrafish models of blood disorders, such as myeloid and lymphoid malignancies, bone marrow failure syndromes and immunodeficiencies, with a focus on how these models were generated and how they can be applied for translational research.

Summary: This At A Glance article and poster summarize the last 20 years of research in zebrafish models for hematopoietic disorders, highlighting how these models were created and are being applied for translational research.

Bloody Zebrafish: Novel Methods in Normal and Malignant Hematopoiesis

Hematopoiesis is an optimal system for studying stem cell maintenance and lineage differentiation under physiological and pathological conditions. In vertebrate organisms, billions of differentiated hematopoietic cells need to be continuously produced to replenish the blood cell pool. Disruptions in this process have immediate consequences for oxygen transport, responses against pathogens, maintenance of hemostasis and vascular integrity. Zebrafish is a widely used and well-established model for studying the hematopoietic system. Several new hematopoietic regulators were identified in genetic and chemical screens using the zebrafish model. Moreover, zebrafish enables in vivo imaging of hematopoietic stem cell generation and differentiation during embryogenesis, and adulthood. Finally, zebrafish has been used to model hematopoietic diseases. Recent technological advances in single-cell transcriptome analysis, epigenetic regulation, proteomics, metabolomics, and processing of large data sets promise to transform the current understanding of normal, abnormal, and malignant hematopoiesis. In this perspective, we discuss how the zebrafish model has proven beneficial for studying physiological and pathological hematopoiesis and how these novel technologies are transforming the field.

Model organism data evolving in support of translational medicine

Model organism databases (MODs) have been collecting and integrating biomedical research data for 30 years and were designed to meet specific needs of each model organism research community. The contributions of model organism research to understanding biological systems would be hard to overstate. Modern molecular biology methods and cost reductions in nucleotide sequencing have opened avenues for direct application of model organism research to elucidating mechanisms of human diseases. Thus, the mandate for model organism research and databases has now grown to include facilitating use of these data in translational applications. Challenges in meeting this opportunity include the distribution of research data across many databases and websites, a lack of data format standards for some data types, and sustainability of scale and cost for genomic database resources like MODs. The issues of widely distributed data and application of data standards are some of the challenges addressed by FAIR (Findable, Accessible, Interoperable, and Re-usable) data principles. The Alliance of Genome Resources is now moving to address these challenges by bringing together expertly curated research data from fly, mouse, rat, worm, yeast, zebrafish, and the Gene Ontology consortium. Centralized multi-species data access, integration, and format standardization will lower the data utilization barrier in comparative genomics and translational applications and will provide a framework in which sustainable scale and cost can be addressed. This article presents a brief historical perspective on how the Alliance model organisms are complementary and how they have already contributed to understanding the etiology of human diseases. In addition, we discuss four challenges for using data from MODs in translational applications and how the Alliance is working to address them, in part by applying FAIR data principles. Ultimately, combined data from these animal models are more powerful than the sum of the parts.

The transcriptional response of skin to fluorescent light exposure in viviparous (Xiphophorus) and oviparous (Danio, Oryzias) fishes

Differences in light sources are common in animal facilities and potentially can impact experimental results. Here, the potential impact of lighting differences on skin transcriptomes has been tested in three aquatic animal models commonly utilized in biomedical research, (Xiphophorus maculatus (platyfish), Oryzias latipes (medaka) and Danio rerio (zebrafish). Analysis of replicate comparative RNA-Seq data showed the transcriptional response to commonly utilized 4100K or "cool white" fluorescent light (FL) is much greater in platyfish and medaka than in zebrafish. FL induces genes associated with inflammatory and immune responses in both medaka and zebrafish; however, the platyfish exhibit suppression of genes involved with immune/inflammation, as well as genes associated with cell cycle progression. Furthermore, comparative analyses of gene expression data from platyfish UVB exposures, with medaka and zebrafish after exposure to 4100K FL, show comparable effects on the same stress pathways. We suggest the response to light is conserved, but that long-term adaptation to species specific environmental niches has resulted in a shifting of the wavelengths required to incite similar "genetic" responses in skin. We forward the hypothesis that the "genetic perception" of light may have evolved differently than ocular perception and suggest that light type (i.e., wavelengths emitted) is an important parameter to consider in experimental design.

The zebrafish: A fintastic model for hematopoietic development and disease

Hematopoiesis is a complex process with a variety of different signaling pathways influencing every step of blood cell formation from the earliest precursors to final differentiated blood cell types. Formation of blood cells is crucial for survival. Blood cells carry oxygen, promote organ development and protect organs in different pathological conditions. Hematopoietic stem and progenitor cells (HSPCs) are responsible for generating all adult differentiated blood cells. Defects in HSPCs or their downstream lineages can lead to anemia and other hematological disorders including leukemia. The zebrafish has recently emerged as a powerful vertebrate model system to study hematopoiesis. The developmental processes and molecular mechanisms involved in zebrafish hematopoiesis are conserved with higher vertebrates, and the genetic and experimental accessibility of the fish and the optical transparency of its embryos and larvae make it ideal for in vivo analysis of hematopoietic development. Defects in zebrafish hematopoiesis reliably phenocopy human blood disorders, making it a highly attractive model system to screen small molecules to design therapeutic strategies. In this review, we summarize the key developmental processes and molecular mechanisms of zebrafish hematopoiesis. We also discuss recent findings highlighting the strengths of zebrafish as a model system for drug discovery against hematopoietic disorders. This article is categorized under: Adult Stem Cells, Tissue Renewal, and Regeneration > Stem Cell Differentiation and Reversion Vertebrate Organogenesis > Musculoskeletal and Vascular Nervous System Development > Vertebrates: Regional Development Comparative Development and Evolution > Organ System Comparisons Between Species.

Lymphoblastoid cell lines from Diamond Blackfan anaemia patients exhibit a full ribosomal stress phenotype that is rescued by gene therapy

Diamond Blackfan anaemia (DBA) is a congenital bone marrow failure syndrome characterised by selective red cell hypoplasia. DBA is most often due to heterozygous mutations in ribosomal protein (RP) genes that lead to defects in ribosome biogenesis and function and result in ribosomal stress and p53 activation. The molecular mechanisms underlying this pathology are still poorly understood and studies on patient erythroid cells are hampered by their paucity. Here we report that RP-mutated lymphoblastoid cell lines (LCLs) established from DBA patients show defective rRNA processing and ribosomal stress features such as reduced proliferation, decreased protein synthesis, and activation of p53 and its target p21. These phenotypic alterations were corrected by gene complementation. Our data indicate that DBA LCLs could be a useful model for molecular and pharmacological investigations.

Understanding the regulation of vertebrate hematopoiesis and blood disorders - big lessons from a small fish

Hematopoietic stem cells (HSCs) give rise to all differentiated blood cells. Understanding the mechanisms that regulate self-renewal and lineage specification of HSCs is key for developing treatments for many human diseases. Zebrafish have emerged as an excellent model for studying vertebrate hematopoiesis. This review will highlight the unique strengths of zebrafish and important findings that have emerged from studies of blood development and disorders using this system. We discuss recent advances in our understanding of hematopoiesis, including the origin of HSCs, molecular control of their development, and key signaling pathways involved in their regulation. We highlight significant findings from zebrafish models of blood disorders and discuss their application for investigating stem cell dysfunction in disease and for the development of new therapeutics.

Development of Soft Tissue Sarcomas in Ribosomal Proteins L5 and S24 Heterozygous Mice

Diamond-Blackfan anemia (DBA) is an inherited bone marrow failure syndrome associated with ribosomal protein (RP) gene mutations. Recent studies have also demonstrated an increased risk of cancer predisposition among DBA patients. In this study, we report the formation of soft tissue sarcoma in the Rpl5 and Rps24 heterozygous mice. Our observation suggests that even though one wild-type allele of the Rpl5 or Rps24 gene prevents anemia in these mice, it still predisposes them to cancer development.

Neurological Deficits of an Rps19(Arg67del) Model of Diamond-Blackfan Anaemia

Diamond-Blackfan anaemia is a rare disease caused by insufficient expression of ribosomal proteins and is characterized by erythroid hypoplasia often accompanied by growth retardation, congenital craniofacial and limb abnormalities. In addition, Diamond-Blackfan anaemia patients also exhibit a number of behavioural abnormalities. In this study we describe the behavioural effects observed in a new mouse mutant carrying a targeted single amino acid deletion in the ribosomal protein RPS19. This mutant, created by the deletion of arginine 67 in RPS19, exhibits craniofacial, skeletal, and brain abnormalities, accompanied by various neurobehavioural malfunctions. A battery of behavioural tests revealed a moderate cognitive impairment and neuromuscular dysfunction resulting in profound gait abnormalities. This novel Rps19 mutant shows behavioural phenotypes resembling that of the human Diamond-Blackfan anaemia syndrome, thus creating the possibility to use this mutant as a unique murine model for studying the molecular basis of ribosomal protein deficiencies.

Marrow failure: a window into ribosome biology

Diamond-Blackfan anemia, Shwachman-Diamond syndrome, and dyskeratosis congenita are inherited syndromes characterized by marrow failure, congenital anomalies, and cancer predisposition. Genetic and molecular studies have uncovered distinct abnormalities in ribosome biogenesis underlying each of these 3 disorders. How defects in ribosomes, the essential organelles required for protein biosynthesis in all cells, cause tissue-specific abnormalities in human disease remains a question of fundamental scientific and medical importance. Here we review the overlapping and distinct clinical features of these 3 syndromes and discuss current knowledge regarding the ribosomal pathways disrupted in each of these disorders. We also explore the increasing complexity of ribosome biology and how this informs our understanding of developmental biology and human disease.

Ribosomopathies: mechanisms of disease

Ribosomopathies are diseases caused by alterations in the structure or function of ribosomal components. Progress in our understanding of the role of the ribosome in translational and transcriptional regulation has clarified the mechanisms of the ribosomopathies and the relationship between ribosomal dysfunction and other diseases, especially cancer. This review aims to discuss these topics with updated information.

Defects of protein production in erythroid cells revealed in a zebrafish Diamond-Blackfan anemia model for mutation in RPS19

Diamond–Blackfan anemia (DBA) is a rare congenital red cell aplasia that classically presents during early infancy in DBA patients. Approximately, 25% of patients carry a mutation in the ribosomal protein (RP) S19 gene; mutations in RPS24, RPS17, RPL35A, RPL11, and RPL5 have been reported. How ribosome protein deficiency causes defects specifically to red blood cells in DBA has not been well elucidated. To genetically model the predominant ribosome defect in DBA, we generated an rps19 null mutant through the use of TALEN-mediated gene targeting in zebrafish. Molecular characterization of this mutant line demonstrated that rps19 deficiency reproduced the erythroid defects of DBA, including a lack of mature red blood cells and p53 activation. Notably, we found that rps19 mutants' production of globin proteins was significantly inhibited; however, globin transcript level was either increased or unaffected in rps19 mutant embryos. This dissociation of RNA/protein levels of globin genes was confirmed in another zebrafish DBA model with defects in rpl11. Using transgenic zebrafish with specific expression of mCherry in erythroid cells, we showed that protein production in erythroid cells was decreased when either rps19 or rpl11 was mutated. L-Leucine treatment alleviated the defects of protein production in erythroid cells and partially rescued the anemic phenotype in both rps19 and rpl11 mutants. Analysis of this model suggests that the decreased protein production in erythroid cells likely contributes to the blood-specific phenotype of DBA. Furthermore, the newly generated rps19 zebrafish mutant should serve as a useful animal model to study DBA. Our in vivo findings may provide clues for the future therapy strategy for DBA.

Nonregenerative anemia: mechanisms of decreased or ineffective erythropoiesis

In veterinary medicine, anemia without an appropriate compensatory hematopoietic response is termed nonregenerative. Nonregenerative anemia is a common clinical entity, occurring as a result of diminished or ineffective erythropoiesis in association with many types of pathology. This article reviews nonregenerative anemia in domestic animals, emphasizing mechanisms of disease, and also covers other conditions associated with nonregenerative anemia in people. Many aspects of nonregenerative anemia in animals are worthy of further investigation, from molecular mechanisms of disease to epidemiologic impacts.

Hooked! Modeling human disease in zebrafish

Zebrafish have been widely used as a model system for studying developmental processes, but in the last decade, they have also emerged as a valuable system for modeling human disease. The development and function of zebrafish organs are strikingly similar to those of humans, and the ease of creating mutant or transgenic fish has facilitated the generation of disease models. Here, we highlight the use of zebrafish for defining disease pathways and for discovering new therapies.

Tbl3 regulates cell cycle length during zebrafish development

The regulation of cell cycle rate is essential for the correct timing of proliferation and differentiation during development. Changes to cell cycle rate can have profound effects on the size, shape and cell types of a developing organ. We previously identified a zebrafish mutant ceylon (cey) that has a severe reduction in T cells and hematopoietic stem/progenitor cells (HSPCs). Here we find that the cey phenotype is due to absence of the gene transducin (beta)-like 3 (tbl3). The tbl3 homolog in yeast regulates the cell cycle by maintaining rRNA levels and preventing p53-induced cell death. Zebrafish tbl3 is maternally expressed, but later in development its expression is restricted to specific tissues. Tissues expressing tbl3 are severely reduced in cey mutants, including HSPCs, the retina, exocrine pancreas, intestine, and jaw cartilage. Specification of these tissues is normal, suggesting the reduced size is due to a reduced number of differentiated cells. Tbl3 MO injection into either wild-type or p53-/- mutant embryos phenocopies cey, indicating that loss of tbl3 causes specific defects in cey. Progression of both hematopoietic and retinal development is delayed beginning at 3 day post fertilization due to a slowing of the cell cycle. In contrast to yeast, reduction of Tbl3 causes a slowing of the cell cycle without a corresponding increase in p53 induced cell death. These data suggest that tbl3 plays a tissue-specific role regulating cell cycle rate during development.