Teleost introns are characterized by a high A+T content

Nanocapsule-delivered Sleeping Beauty mediates therapeutic Factor VIII expression in liver sinusoidal endothelial cells of hemophilia A mice

Liver sinusoidal endothelial cells are a major endogenous source of Factor VIII (FVIII), lack of which causes the human congenital bleeding disorder hemophilia A. Despite extensive efforts, gene therapy using viral vectors has shown little success in clinical hemophilia trials. Here we achieved cell type-specific gene targeting using hyaluronan- and asialoorosomucoid-coated nanocapsules, generated using dispersion atomization, to direct genes to liver sinusoidal endothelial cells and hepatocytes, respectively. To highlight the therapeutic potential of this approach, we encapsulated Sleeping Beauty transposon expressing the B domain-deleted canine FVIII in cis with Sleeping Beauty transposase in hyaluronan nanocapsules and injected them intravenously into hemophilia A mice. The treated mice exhibited activated partial thromboplastin times that were comparable to those of wild-type mice at 5 and 50 weeks and substantially shorter than those of untreated controls at the same time points. Further, plasma FVIII activity in the treated hemophilia A mice was nearly identical to that in wild-type mice through 50 weeks, while untreated hemophilia A mice exhibited no detectable FVIII activity. Thus, Sleeping Beauty transposon targeted to liver sinusoidal endothelial cells provided long-term expression of FVIII, without apparent antibody formation, and improved the phenotype of hemophilia A mice.

Erythroid-specific expression of beta-globin by the sleeping beauty transposon for Sickle cell disease

Sickle cell disease (SCD) results predominately from a single monogenic mutation that affects thousands of individuals worldwide. Gene therapy approaches have focused on using viral vectors to transfer wild-type beta- or gamma-globin transgenes into hematopoietic stem cells for long-term expression of the recombinant globins. In this study, we investigated the use of a novel nonviral vector system, the Sleeping Beauty (SB) transposon (Tn) to insert a wild-type beta-globin expression cassette into the human genome for sustained expression of beta-globin. We initially constructed a beta-globin expression vector composed of the hybrid cytomegalovirus (CMV) enhancer chicken beta-actin promoter (CAGGS) and full-length beta-globin cDNA, as well as truncated forms lacking either the 3' or 3' and 5' untranslated regions (UTRs), to optimize expression of beta-globin. Beta-globin with its 5' UTR was efficiently expressed from its cDNA in K-562 cells induced with hemin. However, expression was constitutive and not erythroid-specific. We then constructed cis SB-Tn-beta-globin plasmids using a minimal beta-globin gene driven by hybrid promoter IHK (human ALAS2 intron 8 erythroid-specific enhancer, HS40 core element from human alphaLCR, ankyrin-1 promoter), IHbetap (human ALAS2 intron 8 erythroid-specific enhancer, HS40 core element from human alphaLCR, beta-globin promoter), or HS3betap (HS3 core element from human betaLCR, beta-globin promoter) to establish erythroid-specific expression of beta-globin. Stable genomic insertion of the minimal gene and expression of the beta-globin transgene for >5 months at a level comparable to that of the endogenous gamma-globin gene were achieved using a SB-Tn beta-globin cis construct. Interestingly, erythroid-specific expression of beta-globin driven by IHK was regulated primarily at the translational level, in contrast to post-transcriptional regulation in non-erythroid cells. The SB-Tn system is a promising nonviral vector for efficient genomic insertion conferring stable, persistent erythroid-specific expression of beta-globin.

Genomic organization of the CYP19b genes in the rainbow trout (Oncorhynchus mykiss Walbaum)

We report the occurrence of two CYP19b genes, namely CYP19b-I and CYP19b-II, encoding forms I and II of cytochrome P450aromB, the prevalently cerebral variant of aromatase in fish, in the nuclear genome of the rainbow trout. The CYP19b-I gene is 7.6 kbp-long, more than double the size of the known fish CYP19a and b genes, owing to the presence of three introns (1, 4 and 5) that enclose repeated sequences and are longer than 1 kbp. Unlike the CYP19a genes, but similarly to the CYP19b gene of the Nile tilapia, it contains 10, and not 9, exons, including an untranslated exon 1 (83 bp), as found also in the 5' non-coding region of mammalian CYP19 genes. The 5'-UTR is composed by exon 1 and the first 41 bp of exon 2 (150 bp), whose coding region covers the first 36 amino acid residues that incorporate the transmembrane domain. The CYP19b-II gene is only 2.5 kbp-long, because it contains only one intron, corresponding to the third intron of CYP19b-I, and lacks also its first two exons. Thus, it encodes for a presumably soluble protein. Apart from this difference, the rest of the coding region is virtually the same as that of the CYP19b-I gene. The 5'-UTR corresponds in part to the 3'-end (132 bp) of the second intron of the CYP19b-I gene, while the remaining portion (208 bp) bears no homology. CYP19b-II could be regarded as a pseudogene of the CYP19b-I gene, though it is unclear whether it is a processed or a duplicated pseudogene. Moreover, since it is transcriptionally active, it may retain a functional role for the overall brain aromatase activity in the rainbow trout.

Comparative analysis of a 229-kb medaka genomic region, containing the zic1 and zic4 genes, with Fugu , human, and mouse

Medaka is one of the prominent model animals, which also include other fishes such as Fugu and zebrafish. Its genome is relatively compact but has not been well characterized. Here we have sequenced a 229-kb region of medaka, containing the Double anal fin (Da) locus, and compared its structure to those in Fugu, human, and mouse. This region, representing a gene-poor region, contains no major rearrangements and can be readily compared among different species. Comparison of G+C contents and repeats suggested that medaka and Fugu are highly related as expected and that medaka is more similar to mammals than Fugu is. Sequence comparisons of developmental genes zic1 and zic4, identified within this region, revealed that zic1, but not zic4, is highly conserved among vertebrates. The 5' coding region of zic4 is, however, extremely homologous among fishes with little synonymous substitutions, implying its distinct function in fish.