ER-targeted Intrabodies Mediating Specific In Vivo Knockdown of Transitory Proteins in Comparison to RNAi

Abstract

In animals and mammalian cells, protein function can be analyzed by nucleotide se‐ quence-based methods such as gene knockout, targeted gene disruption, CRISPR/Cas, TALEN, zinc finger nucleases, or the RNAi technique. Alternatively, protein knock‐ down approaches are available based on direct interference of the target protein with the inhibitor. Among protein knockdown techniques, the endoplasmic reticulum (ER) intrabodies are potent molecules for protein knockdown in vitro and in vivo. These molecules are in‐ creasingly used for protein knockdown in living cells and transgenic mice. ER intra‐ body knockdown technique is based on the retention of membrane proteins and secretory proteins inside the ER, mediated by recombinant antibody fragments. In con‐ trast to nucleotide sequence-based methods, the intrabody-mediated knockdown acts only on the posttranslational level. In this review, the ER intrabody technology has been compared with the RNAi techni‐ que on the molecular level. The generation of intrabodies and RNAi has also been dis‐ cussed. Specificity and off-target effects (OTE) of these molecules as well as the therapeutic potential of ER intrabodies and RNAi have been compared.