Editing of the heavy chain gene of Bombyx mori using transcription activator like effector nucleases

The silk gland of Bombyx mori represents an established in vivo system for producing recombinant proteins. However, low yields of recombinant proteins have limited the system's further development because endogenous silk proteins were present. Transcription activator-like effector nucleases (TALENs) tool which work in pairs to bind and cleave DNA at specific sites, have recently been shown to be effective for genome editing in various organisms, including silkworms. To improve the yield of recombinant proteins synthesized in the silkworm by eliminated competition with endogenous fibroin synthesis, the heavy chain (H-chain) gene was knocked out using transcription activator-like effector nucleases (TALENs). A pair of TALENs that targets the 1st exon in the H-chain gene was synthesized and microinjected into silkworm embryos; the injected silkworms were screened for H-chain gene knock out (H-KO) based on their sericin cocoon-making characteristics. Sequence analysis revealed that the H-chain of the mutation was successfully edited. The TALENs was very efficient in editing the genome DNA of silkworm. By being eliminated competition with the H-chain, the production of recombinant proteins would be expected to increase markedly if this H-KO system is used.

PK modulation of haptenylated peptides via non-covalent antibody complexation

We applied noncovalent complexes of digoxigenin (Dig) binding antibodies with digoxigeninylated peptide derivatives to modulate their pharmacokinetic properties. A peptide derivative which activates the Y2R receptor was selectively mono-digoxigeninylated by reacting a NHS-Dig derivative with an ε-amino group of lysine 2. This position tolerates modifications without destroying receptor binding and functionality of the peptide. Dig-peptide derivatives can be loaded onto Dig-binding IgGs in a simple and robust reaction, thereby generating peptide-IgG complexes in a defined two to one molar ratio. This indicates that each antibody arm becomes occupied by one haptenylated peptide. In vitro receptor binding and signaling assays showed that Dig-peptides as well as the peptide-antibody complexes retain better potency than the corresponding pegylated peptides. In vivo analyses revealed prolonged serum half-life of antibody-complexed peptides compared to unmodified peptides. Thus, complexes are of sufficient stability for PK modulation. We observed more prolonged weight reduction in a murine diet-induced obesity (DIO) model with antibody-complexed peptides compared to unmodified peptides. We conclude that antibody-hapten complexation can be applied to modulate the PK of haptenylated peptides and in consequence improve the therapeutic efficacy of therapeutic peptides.