An inducible kras(V12) transgenic zebrafish model for liver tumorigenesis and chemical drug screening.

Because Ras signaling is frequently activated by major hepatocellular carcinoma etiological factors, a transgenic zebrafish constitutively expressing the kras(V12) oncogene in the liver was previously generated by our laboratory. Although this model depicted and uncovered the conservation between zebrafish and human liver tumorigenesis, the low tumor incidence and early mortality limit its use for further studies of tumor progression and inhibition. Here, we employed a mifepristone-inducible transgenic system to achieve inducible kras(V12) expression in the liver.

A high level of liver-specific expression of oncogenic Kras(V12) drives robust liver tumorigenesis in transgenic zebrafish.

Human liver cancer is one of the deadliest cancers worldwide, with hepatocellular carcinoma (HCC) being the most common type. Aberrant Ras signaling has been implicated in the development and progression of human HCC, but a complete understanding of the molecular mechanisms of this protein in hepatocarcinogenesis remains elusive. In this study, a stable in vivo liver cancer model using transgenic zebrafish was generated to elucidate Ras-driven tumorigenesis in HCC.

One step forward: the use of transgenic zebrafish tumor model in drug screens.

The zebrafish (Danio rerio) has been an experimental model in the developmental biology and toxicology since the 1950s. In recent years, with the aid of transgenic technology, it has also gained an increasing popularity to model human diseases, including various cancers. As a feasible vertebrate model for large-scale chemical screens, the zebrafish has also given us a new option for the search of potential anticancer drugs.

Cre/loxP-regulated transgenic zebrafish model for neural progenitor-specific oncogenic Kras expression.

Ras proteins regulate signaling pathways that control many cellular responses, such as proliferation, survival, and differentiation. However, there are intriguing questions about the relationship between the developmental timing of specific mutations and the resultant phenotypes in individual cells. In this study, we used the Cre/loxP system for maintaining transgenic zebrafish lines harboring oncogenic Kras(V12) under the nestin promoter, and investigated the developmental effects of Ras activation in neural progenitor cells.

Generation of oocyte-specifically expressed cre transgenic zebrafish for female germline excision of loxP-flanked transgene.

In this communication, we report the generation of a cre transgenic zebrafish line under an oocyte-specific promoter, zp3. The transgenic line Tg(zp3:cre; krt8:rfp) also contains a co-integrated rfp transgene under the skin epithelial promoter krt8 to allow selection of cre transgenic fish based on RFP fluorescence in the skin. We demonstrated in this transgenic line that cre mRNA was specifically expressed in growing oocytes like endogenous zp3 mRNA.

Mifepristone-inducible LexPR system to drive and control gene expression in transgenic zebrafish.

Effective transgenesis methods have been successfully employed in many organisms including zebrafish. However, accurate spatiotemporal control of transgene expression is still difficult to achieve. Here we describe a system for chemical-inducible gene expression and demonstrate its feasibility for generating transgenic driver lines in zebrafish.

Transposable elements in fish functional genomics: technical challenges and perspectives.

The recent introduction of several transposable elements in zebrafish opens new frontiers for genetic manipulation in this important vertebrate model. This review discusses transposable elements as mutagenesis tools for fish functional genomics. We review various mutagenesis strategies that were previously applied in other genetic models, such as Drosophila, Arabidopsis, and mouse, that may be beneficial if applied in fish.

Trans-kingdom transposition of the maize dissociation element.

Transposons are very valuable tools for genetic manipulation. However, the number of transposable elements that have been suitably adapted for experimental use is insufficient and the spectrum of heterologous hosts in which they have been deployed is restricted. To date, only transposons from animal hosts have been utilized in heterologous animal species and transposons of plant origin have been used in plant genetics.

New ways to admire zebrafish: progress in functional genomics research methodology.

The main challenge of the post-genomic era is to functionally characterize genes identified by the genome sequencing projects. Model organisms, including zebrafish, are indispensable for this demanding task. Zebrafish has been successfully incorporated into large-scale genetic screens due to the optical clarity of the embryos and their accessibility to various experimental techniques throughout development.

Tol2 transposon-mediated enhancer trap to identify developmentally regulated zebrafish genes in vivo.

We have used the Tol2 transposable element to design and perform effective enhancer trapping in zebrafish. Modified transposon DNA and transposase RNA were delivered into zebrafish embryos by microinjection to produce heritable insertions in the zebrafish genome. The enhancer trap construct carries the EGFP gene controlled by a partial epithelial promoter from the keratin8 gene.