Novel vectors for homologous recombination strategies in mouse embryonic stem cells: an ES cell line expressing EGFP under control of the 5T4 promoter

Application of oligonucleotides to construct a conditional targeting vector for porcine IκBα

Conditional gene targeting at porcine IκBα may be a solution to delayed xenograft rejection, the main barrier to xenotransplantation. An oligonucleotide‑based method was applied to construct the vector for conditional targeting of porcine IκBα. This method was free from PCR amplification during the assembling of the different vector elements, avoiding introduction of unwanted mutations. With the help of short double‑stranded DNA fragments produced by annealing oligonucleotides, nondirectional cloning has also been avoided. By making the best of directional cloning, a highly complex targeting vector was built within 3 weeks. The present study also explained why the two recombination‑based methods (recombineering and gateway recombination), although having demonstrated to be highly efficient in constructing ordinary targeting vectors, were not appropriate in this context. The description in the present study of an additional method to efficiently construct targeting vectors is suggested to introduce more flexibility in the field therefore helping to meet the different needs of the researchers.

The histone acetyl transferase activity of monocytic leukemia zinc finger is critical for the proliferation of hematopoietic precursors

The monocytic leukemia zinc finger (MOZ) gene encodes a large multidomain protein that contains, besides other domains, 2 coactivation domains for the transcription factor Runx1/acute myeloid leukemia 1 and a histone acetyl transferase (HAT) catalytic domain. Recent studies have demonstrated the critical requirement for the complete MOZ protein in hematopoietic stem cell development and maintenance. However, the specific function of the HAT activity of MOZ remains unknown, as it has been shown that MOZ HAT activity is not required either for its role as Runx1 coactivator or for the leukemic transformation induced by MOZ transcriptional intermediary factor 2 (TIF2). To assess the specific requirement for this HAT activity during hematopoietic development, we have generated embryonic stem cells and mouse lines carrying a point mutation that renders the protein catalytically inactive. We report in this study that mice exclusively lacking the HAT activity of MOZ exhibit significant defects in the number of hematopoietic stem cells and hematopoietic committed precursors as well as a defect in B-cell development. Furthermore, we demonstrate that the failure to maintain a normal number of hematopoietic precursors is caused by the inability of HAT(-/-) cells to expand. These results indicate a specific role of MOZ-driven acetylation in controlling a desirable balance between proliferation and differentiation during hematopoiesis.

Isolation and enrichment of stem cells

Stem cells have the potential to revolutionize tissue regeneration and engineering. Both general types of stem cells, those with pluripotent differentiation potential as well as those with multipotent differentiation potential, are of equal interest. They are important tools to further understanding of general cellular processes, to refine industrial applications for drug target discovery and predictive toxicology, and to gain more insights into their potential for tissue regeneration. This chapter provides an overview of existing sorting technologies and protocols, outlines the phenotypic characteristics of a number of different stem cells, and summarizes their potential clinical applications.