A Robust Closed-Tube Method for Resolving tp53M214K Genotypes.

The tp53M214K zebrafish mutant is a versatile platform with which to model a diverse spectrum of human diseases. However, currently available genotyping methods for this mutant require lengthy hands-on processes such as restriction digests and outsourced Sanger sequencing. To address this deficiency, we leveraged high-resolution melting analysis technology in conjunction with a parallel, in-tandem wild-type spike-in approach to develop a robust genotyping protocol capable of discriminating tp53M214K zygosity. In this study, we describe our method in detail. We anticipate that our genotyping protocol will benefit researchers utilizing the tp53M214K zebrafish mutant by offering reliable results with a shorter turnaround time, lower personnel involvement, and higher throughput than traditional methods, thereby decreasing the burden of genotyping and maximizing research efficiency.

A robust closed-tube method for resolving tp53 M214K genotypes.

The tp53 M214K zebrafish mutant developed by Berghmans et al 2005 1 is a versatile platform with which to model a diverse spectrum of human diseases. However, currently available genotyping methods for this mutant require lengthy processes such as restriction digests and outsourced Sanger sequencing. To address this deficiency, we leveraged high-resolution melting analysis (HRMA) technology in conjunction with a parallel, in-tandem wildtype spike-in approach to develop a robust genotyping protocol capable of discriminating tp53 M214K zygosity. Here, we describe our method in detail. We anticipate that our genotyping protocol will benefit researchers utilizing the tp53 M214K zebrafish mutant by offering reliable results with a faster turnaround time than conventional approaches.

VGLL2-NCOA2 leverages developmental programs for pediatric sarcomagenesis.

Clinical sequencing efforts are rapidly identifying sarcoma gene fusions that lack functional validation. An example is the fusion of transcriptional coactivators, VGLL2-NCOA2, found in infantile rhabdomyosarcoma. To delineate VGLL2-NCOA2 tumorigenic mechanisms and identify therapeutic vulnerabilities, we implement a cross-species comparative oncology approach with zebrafish, mouse allograft, and patient samples. We find that VGLL2-NCOA2 is sufficient to generate mesenchymal tumors that display features of immature skeletal muscle and recapitulate the human disease. A subset of VGLL2-NCOA2 zebrafish tumors transcriptionally cluster with embryonic somitogenesis and identify VGLL2-NCOA2 developmental programs, including a RAS family GTPase, ARF6. In VGLL2-NCOA2 zebrafish, mouse, and patient tumors, ARF6 is highly expressed. ARF6 knockout suppresses VGLL2-NCOA2 oncogenic activity in cell culture, and, more broadly, ARF6 is overexpressed in adult and pediatric sarcomas. Our data indicate that VGLL2-NCOA2 is an oncogene that leverages developmental programs for tumorigenesis and that reactivation or persistence of ARF6 could represent a therapeutic opportunity.

Zebrafish her3 knockout impacts developmental and cancer-related gene signatures.

HES3 is a basic helix-loop-helix transcription factor that regulates neural stem cell renewal during development. HES3 overexpression is predictive of reduced overall survival in patients with fusion-positive rhabdomyosarcoma, a pediatric cancer that resembles immature and undifferentiated skeletal muscle. However, the mechanisms of HES3 cooperation in fusion-positive rhabdomyosarcoma are unclear and are likely related to her3/HES3's role in neurogenesis. To investigate HES3's function during development, we generated a zebrafish CRISPR/Cas9 null mutation of her3, the zebrafish ortholog of HES3. Loss of her3 is not embryonic lethal and adults exhibit expected Mendelian ratios. Embryonic her3 zebrafish mutants exhibit dysregulated neurog1 expression, a her3 target gene, and the mutant her3 fails to bind the neurog1 promoter sequence. Further, her3 mutants are significantly smaller than wildtype and a subset present with lens defects as adults. Transcriptomic analysis of her3 mutant embryos indicates that genes involved in organ development, such as pctp and grinab, are significantly downregulated. Further, differentially expressed genes in her3 null mutant embryos are enriched for Hox and Sox10 motifs. Several cancer-related gene pathways are impacted, including the inhibition of matrix metalloproteinases. Altogether, this new model is a powerful system to study her3/HES3-mediated neural development and its misappropriation in cancer contexts.