TALE nucleases: tailored genome engineering made easy

Custom-made designer nucleases have evolved into an indispensable platform to precisely alter complex genomes for basic research, biotechnology, synthetic biology, or human gene therapy. In this review we describe how transcription activator-like effector nucleases (TALENs) have rapidly developed into a chief technology for targeted genome editing in different model organisms as well as human stem cells. We summarize the technological background and provide an overview of the current state-of-the-art of TALENs with regard to activity and specificity of these nucleases for targeted genome engineering.

TALEN-mediated genome engineering. After a TALEN pair has cleaved the target locus, the resulting DNA double strand break will be repaired by either homologous recombination (HR)-based repair or non-homologous end-joining (NHEJ). In the absence of a repair template, the broken chromosome is re-ligated by the error-prone NHEJ pathway. The resulting small insertions and deletions (asterisk) will disrupt the open reading frame. Targeted deletions can be obtained by expressing two TALEN pairs that cut two adjacent sites on a chromosome. In the presence of donor DNA, the homologous sequences can either be employed to correct a mutation (asterisk) in the genome or to target integration of a transgene into a chosen site.Figure optionsDownload high-quality image (125 K)Download as PowerPoint slideHighlights
► Design of customized transcription activator-like effector nucleases (TALENs).
► Potential of TALENs in genome editing applications.
► Comparison to other designer nuclease platforms, such as zinc-finger nucleases.