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Site-specific genome editing provides a promising approach for achieving long-term, stable therapeutic gene expression. Genome editing has been successfully applied in a variety of preclinical models, generally focused on targeting the diseased locus itself; however, limited targeting efficiency or insufficient expression from the endogenous promoter may impede the translation of these approaches, particularly if the desired editing event does not confer a selective growth advantage. Here we report a general strategy for liver-directed protein replacement therapies that addresses these issues: zinc finger nuclease (ZFN) -mediated site-specific integration of therapeutic transgenes within the albumin gene. By using adeno-associated viral (AAV) vector delivery in vivo, we achieved long-term expression of human factors VIII and IX (hFVIII and hFIX) in mouse models of hemophilia A and B at therapeutic levels. By using the same targeting reagents in wild-type mice, lysosomal enzymes were expressed that are deficient in Fabry and Gaucher diseases and in Hurler and Hunter syndromes. The establishment of a universal nuclease-based platform for secreted protein production would represent a critical advance in the development of safe, permanent, and functional cures for diverse genetic and nongenetic diseases., (© 2015 by The American Society of Hematology.)

AML1-ETO (RUNX1-ETO) fusion proteins are generated by the 8;21 translocation, commonly found in acute myeloid leukemia, which fuses the AML1 (RUNX1) and ETO (MTG8, RUNX1T1) genes. Previous studies have shown that AML1-ETO interferes with AML1 function but requires additional cooperating mutations to induce leukemia development. In mouse models, AML1-ETO forms lacking the C-terminus have been shown to have greatly enhanced leukemogenic potential. Here, we investigate the role of 2 AML1-ETO C-terminal-interacting proteins, N-CoR, a transcriptional corepressor, and SON, a splicing/transcription factor required for cell cycle progression, in AML1-ETO-induced leukemia development. AML1-ETO-W692A loses N-CoR binding at NHR4, displays attenuated transcriptional repression ability and decreased cellular dysregulation, and promotes leukemia in vivo. These results support the importance of the degree of dysregulation by AML1-ETO in cellular transformation and demonstrate that AML1-ETO-W692A can be used as an effective experimental model for determining which factors compromise the leukemogenic potential of AML1-ETO.