A versatile, automated and high-throughput drug screening platform for zebrafish embryos

Zebrafish provide a unique opportunity for drug screening in living animals, with the fast developing, transparent embryos allowing for relatively high-throughput, microscopy-based screens. However, the limited availability of rapid, flexible imaging and analysis platforms has limited the use of zebrafish in drug screens. We have developed an easy-to-use, customisable automated screening procedure suitable for high-throughput phenotype-based screens of live zebrafish. We utilised the WiScan® Hermes High Content Imaging System to rapidly acquire brightfield and fluorescent images of embryos, and the WiSoft® Athena Zebrafish Application for analysis, which harnesses an Artificial Intelligence-driven algorithm to automatically detect fish in brightfield images, identify anatomical structures, partition the animal into regions, and exclusively select the desired side-oriented fish. Our initial validation combined structural analysis with fluorescence images to enumerate GFP-tagged haematopoietic stem and progenitor cells in the tails of embryos, which correlated with manual counts. We further validated this system to assess the effects of genetic mutations and x-ray irradiation in high content using a wide range of assays. Further, we performed simultaneous analysis of multiple cell types using dual fluorophores in high throughput. In summary, we demonstrate a broadly applicable and rapidly customisable platform for high-content screening in zebrafish

TLR7 ligation augments hematopoiesis in Rps14 (uS11) deficiency via paradoxical suppression of inflammatory signaling

Myelodysplastic syndrome (MDS) is a hematological malignancy characterized by blood cytopenias and predisposition to acute myeloid leukemia (AML). Therapies for MDS are lacking, particularly those that have an impact in the early stages of disease. We developed a model of MDS in zebrafish with knockout of Rps14, the primary mediator of the anemia associated with del(5q) MDS. These mutant animals display dose- and age-dependent abnormalities in hematopoiesis, culminating in bone marrow failure with dysplastic features. We used Rps14 knockdown to undertake an in vivo small-molecule screening, to identify compounds that ameliorate the MDS phenotype, and we identified imiquimod, an agonist of Toll-like receptor-7 (TLR7) and TLR8. Imiquimod alleviates anemia by promoting hematopoietic stem and progenitor cell expansion and erythroid differentiation, the mechanism of which is dependent on TLR7 ligation and Myd88. TLR7 activation in this setting paradoxically promoted an anti-inflammatory gene signature, indicating cross talk via TLR7 between proinflammatory pathways endogenous to Rps14 loss and the NF-κB pathway. Finally, in highly purified human bone marrow samples from anemic patients, imiquimod led to an increase in erythroid output from myeloerythroid progenitors and common myeloid progenitors. Our findings have both specific implications for the development of targeted therapeutics for del(5q) MDS and wider significance identifying a potential role for TLR7 ligation in modifying anemia

Monitoring intracellular oxygen concentration: Implications for hypoxia studies and real-time oxygen monitoring

The metabolic properties of cancer cells have been widely accepted as a hallmark of cancer for a number of years and have shown to be of critical importance in tumour development. It is generally accepted that tumour cells exhibit a more glycolytic phenotype than normal cells. In this study, we investigate the bioenergetic phenotype of two widely used cancer cell lines, RD and U87MG, by monitoring intracellular oxygen concentrations using phosphorescent Pt-porphyrin based intracellular probes. Our study demonstrates that cancer cell lines do not always exhibit an exclusively glycolytic phenotype. RD demonstrates a reliance on oxidative phosphorylation whilst U87MG display a more glycolytic phenotype. Using the intracellular oxygen sensing probe we generate an immediate readout of intracellular oxygen levels, with the glycolytic lines reflecting the oxygen concentration of the environment, and cells with an oxidative phenotype having significantly lower levels of intracellular oxygen. Inhibition of oxygen consumption in lines with high oxygen consumption increases intracellular oxygen levels towards environmental levels. We conclude that the use of intracellular oxygen probes provides a quantitative assessment of intracellular oxygen levels, allowing the manipulation of cellular bioenergetics to be studied in real time

PRR14L mutations are associated with chromosome 22 acquired uniparental disomy, age-related clonal hematopoiesis and myeloid neoplasia

Acquired uniparental disomy (aUPD, also known as copy-neutral loss of heterozygosity) is a common feature of cancer cells and characterized by extended tracts of somatically-acquired homozygosity without any concurrent loss or gain of genetic material. The presumed genetic targets of many regions of aUPD remain unknown. Here we describe the association of chromosome 22 aUPD with mutations that delete the C-terminus of PRR14L in patients with chronic myelomonocytic leukemia (CMML), related myeloid neoplasms and age-related clonal hematopoiesis (ARCH). Myeloid panel analysis identified a median of three additional mutated genes (range 1–6) in cases with a myeloid neoplasm (n = 8), but no additional mutations in cases with ARCH (n = 2) suggesting that mutated PRR14L alone may be sufficient to drive clonality. PRR14L has very limited homology to other proteins and its function is unknown. ShRNA knockdown of PRR14L in human CD34+ cells followed by in vitro growth and differentiation assays showed an increase in monocytes and decrease in neutrophils, decrease in neutrophils, consistent with a CMML-like phenotype. RNA-Seq and cellular localization studies suggest a role for PRR14L in cell division. PRR14L is thus a novel, biallelically mutated gene and potential founding abnormality in myeloid neoplasms

PRR14L mutations are associated with chromosome 22 acquired uniparental disomy, age-related clonal hematopoiesis and myeloid neoplasia

Acquired uniparental disomy (aUPD, also known as copy-neutral loss of heterozygosity) is a common feature of cancer cells and characterized by extended tracts of somatically-acquired homozygosity without any concurrent loss or gain of genetic material. The presumed genetic targets of many regions of aUPD remain unknown. Here we describe the association of chromosome 22 aUPD with mutations that delete the C-terminus of PRR14L in patients with chronic myelomonocytic leukemia (CMML), related myeloid neoplasms and age-related clonal hematopoiesis (ARCH). Myeloid panel analysis identified a median of three additional mutated genes (range 1–6) in cases with a myeloid neoplasm (n = 8), but no additional mutations in cases with ARCH (n = 2) suggesting that mutated PRR14L alone may be sufficient to drive clonality. PRR14L has very limited homology to other proteins and its function is unknown. ShRNA knockdown of PRR14L in human CD34+ cells followed by in vitro growth and differentiation assays showed an increase in monocytes and decrease in neutrophils, decrease in neutrophils, consistent with a CMML-like phenotype. RNA-Seq and cellular localization studies suggest a role for PRR14L in cell division. PRR14L is thus a novel, biallelically mutated gene and potential founding abnormality in myeloid neoplasms

Genome-wide association study identifies novel susceptibility loci for <em>KIT</em> D816V positive mastocytosis.

Mastocytosis is a rare myeloid neoplasm characterized by uncontrolled expansion of mast cells, driven in &gt;80% of affected individuals by acquisition of the KIT D816V mutation. To explore the hypothesis that inherited variation predisposes to mastocytosis, we performed a two-stage genome-wide association study, analyzing 1,035 individuals with KIT D816V positive disease and 17,960 healthy control individuals from five European populations. After quality control, we tested 592,007 SNPs at stage 1 and 75 SNPs at stage 2 for association by using logistic regression and performed a fixed effects meta-analysis to combine evidence across the two stages. From the meta-analysis, we identified three intergenic SNPs associated with mastocytosis that achieved genome-wide significance without heterogeneity between cohorts: rs4616402 (pmeta = 1.37 × 10−15, OR = 1.52), rs4662380 (pmeta = 2.11 × 10−12, OR = 1.46), and rs13077541 (pmeta = 2.10 × 10−9, OR = 1.33). Expression quantitative trait analyses demonstrated that rs4616402 is associated with the expression of CEBPA (peQTL = 2.3 × 10−14), a gene encoding a transcription factor known to play a critical role in myelopoiesis. The role of the other two SNPs is less clear: rs4662380 is associated with expression of the long non-coding RNA gene TEX41 (peQTL = 2.55 × 10−11), whereas rs13077541 is associated with the expression of TBL1XR1, which encodes transducin (β)-like 1 X-linked receptor 1 (peQTL = 5.70 × 10−8). In individuals with available data and non-advanced disease, rs4616402 was associated with age at presentation (p = 0.009; beta = 4.41; n = 422). Additional focused analysis identified suggestive associations between mastocytosis and genetic variation at TERT, TPSAB1/TPSB2, and IL13. These findings demonstrate that multiple germline variants predispose to KIT D816V positive mastocytosis and provide novel avenues for functional investigation