Gene delivery of albumin binding peptide-interferon-gamma fusion protein with improved pharmacokinetic properties and sustained biological activity.

We have demonstrated that gene delivery of a fusion protein of mouse interferon (IFN) γ with mouse serum albumin (IFNγ-MSA) was effective in prolonging the circulation half-life of IFNγ in mice. However, the fusion to MSA greatly reduced the biological activity of IFNγ to less than 1%. In this study, we designed IFNγ fusion proteins with a 20 amino-acid long albumin-binding peptide (ABP) to prolong the in vivo half-life of IFNγ without reducing its biological activity. IFNγ-ABP and ABP-IFNγ, two fusion proteins with the ABP being fused to the C- or N-terminal of IFNγ, retained 40%-50% biological activities determined using a gamma-activated sequence-dependent luciferase assay. These fusion proteins exhibited the ability to bind to MSA. Gene delivery of IFNγ-ABP or ABP-IFNγ to mice using the hydrodynamic injection method resulted in a sustained concentration of IFNγ in the serum compared with gene delivery of IFNγ. In addition, the growth of mouse colon carcinoma CT-26 cells in the lung was efficiently inhibited by gene delivery of the IFNγ fusion proteins. These results indicate that the fusion of ABP is a useful approach to achieving prolonged retention in the blood circulation through binding to serum albumin and retaining biological activity.

Prolonged circulation half-life of interferon γ activity by gene delivery of interferon γ-serum albumin fusion protein in mice.

Gene delivery of mouse interferon (IFN) γ has been shown to inhibit metastatic tumor growth and onset of atopic dermatitis in mouse models. In this study, we tried to increase the circulation half-life of IFNγ after its gene delivery by designing a novel fusion protein of IFNγ with mouse serum albumin (MSA). Western blot analysis confirmed that IFNγ-MSA was expressed as a fusion protein, but hardly formed dimer as IFNγ did. The biological activity of IFNγ-MSA, which was examined using a plasmid expressing luciferase under the control of gamma-activated sequence elements, was about 200-fold lower than the activity of IFNγ. Intravenous injection of the proteins into mice confirmed that the circulation half-life of IFNγ was significantly prolonged by the modification. A hydrodynamic injection of a plasmid expressing IFNγ-MSA resulted in a sustained concentration in mouse serum; it resulted in about sixfold greater area under the concentration-time curve and about threefold longer mean residence time of IFNγ activity than those of IFNγ. Gene delivery of IFNγ-MSA inhibited tumor metastasis to a similar level to that of IFNγ despite the reduced activity of IFNγ-MSA. These results indicate that gene delivery of IFNγ-MSA is a promising approach to prolong the circulation half-life of IFNγ activity.

Fgf4 is required for left-right patterning of visceral organs in zebrafish.

Fgf signaling plays essential roles in many developmental events. To investigate the roles of Fgf4 signaling in zebrafish development, we generated Fgf4 knockdown embryos by injection with Fgf4 antisense morpholino oligonucleotides. Randomized LR patterning of visceral organs including the liver, pancreas, and heart was observed in the knockdown embryos. Prominent expression of Fgf4 was observed in the posterior notochord and Kupffer's vesicle region in the early stages of segmentation. Lefty1, lefty2, southpaw, and pitx2 are known to play crucial roles in LR patterning of visceral organs. Fgf4 was essential for the expression of lefty1, which is necessary for the asymmetric expression of southpaw and pitx2 in the lateral plate mesoderm, in the posterior notochord, and the expression of lefty2 and lefty1 in the left cardiac field. Fgf8 is also known to be crucial for the formation of Kupffer's vesicle, which is needed for the LR patterning of visceral organs. In contrast, Fgf4 was required for the formation of cilia in Kupffer's vesicle, indicating that the role of Fgf4 in the LR patterning is quite distinct from that of Fgf8. The present findings indicate that Fgf4 plays a unique role in the LR patterning of visceral organs in zebrafish.