Sharper Tools for Gene Editing: TALEN and Zinc Finger Make a Safer Cut
Gene editing using artificial restriction enzymes (also known as artificial nucleases) has revolutionised the life sciences, with far-reaching applications across agriculture, medicine and biotechnology. By editing the genes of microorganisms, plants and animals, scientists can introduce specific mutations such as deletions or insertions, precisely at the target gene, effectively disrupting (knocking out) its function. It is also possible to insert foreign genes into a specific locus, achieving what is known as a gene knock-in.
Among the various gene editing tools available, CRISPR-Cas9 stands out for its high efficiency and ease of use. However, it is not without challenges. Concerns over safety, off-target effects, and costly licensing alongside a web of intellectual property issues limit its broader adoption. There are concerns about therapeutic safety because the recognition region of the target sequence is generally shorter than that of other gene editing tools, and the off-target risk is generally higher.
In response to these challenges, Japan-based PtBio Inc is advancing two homegrown alternatives that promise greater sustainability and safety: Platinum TALEN and ZF-ND1. Founded in 2019 in Hiroshima, PtBio is a biotechnology start-up dedicated to solving real-world problems through cutting-edge innovation. While CRISPR-Cas9 continues to dominate the field, PtBio’s proprietary platforms are gaining ground by offering precision tools that could circumvent the limitations of current technologies.
Platinum TALEN: Precision Without the Patent Headache
Platinum TALEN is a next-generation version of the traditional TALEN (Transcription Activator-Like Effector Nucleases). By tweaking the amino acid sequences of its DNA-binding module of TALEN, PtBio achieved modification activity comparable to CRISPR-Cas9, with greater specificity and less risk of off-target effects. Its activity was evaluated in cultured cells
Their custom-built Platinum Gate system shortens TALEN production to just 1–2 weeks, streamlining research timelines. The tool has been tested with success in frogs, rats, chickens, potatoes, Nannochloropsis, fungi, mouse and even sea urchins. In frogs and rats high mutagenic efficiency of more than 50% was observed using Platinum TALENs
One notable achievement: PtBio used Platinum TALEN to knock out the OVM gene in chickens, which is responsible for a major egg allergen. The edited eggs were protein-tested, and neither OVM nor unwanted by-products were found. Genome analysis confirmed no off-target mutations. This allergy-free egg model underscores Platinum TALEN’s potential in agri-biotech innovation.
ZF-ND1: A Homegrown Gene Editing Solution for Medicine
PtBio’s second innovation is ZF-ND1, which combines zinc finger proteins with a novel nuclease (ND1) licensed from Hiroshima University. This system improves on traditional ZFNs by increasing DNA cleavage efficiency without compromising safety.
The conventional ZFN consists of ZF, which recognises and binds to a target sequence, and a nuclease (FokI Nuclease Domain), which cleaves DNA, and this nuclease heterodimerises to break double-stranded DNA in cells. PtBio has obtained an exclusive license for FirmCut nuclease ND1(ND1), a novel nuclease developed by Hiroshima University, and by combining it with ZF, has developed ZF-ND1, a purely domestic gene editing tool, and is promoting its medical application. ZF-ND1 has high specificity, inducing DNA cleavage only when nucleases are paired as heterodimers.
In addition, unlike conventional ZFNs, ZF-ND1 does not decrease nuclease activity upon heterodimerisation. In practice, PtBio designed and produced functional ZF-ND1 for human and mouse target genes and evaluated its activity in cultured cells. In an experiment targeting a human gene, cleavage activity of more than 45% was obtained, which is useful for medical applications, and in an experiment targeting a mouse gene, cleavage activity comparable to that of CRISPR-Cas9 was also obtained.
Furthermore, the efficacy of ZF-ND1 has been confirmed in animal experiments using fertilized eggs of mice, and its clinical application is expected in the future. Because of these advantages, ZF-ND1 has potential medical applications as a safe genome editing tool with reduced off-target risk.
The Bigger Picture
Both Platinum TALEN and ZF-ND1 offer significant advantages for institutions and researchers concerned about the limitations of CRISPR, particularly in industries like medicine and agriculture where safety, regulatory hurdles and costs matter.
PtBio’s innovations could democratise access to gene editing across Asia and beyond, fuelling next-generation research while avoiding the financial and legal complexities of CRISPR’s patent landscape.
If your institution is exploring gene editing but wary of CRISPR’s baggage that comes in the form of licensing fees and off-target issues, it might be time to take a serious look at PtBio’s rising stars.
