Novel photoreactive probe enables sensitive detection of epigenetic intermediates

Epigenetic modifications comparable to DNA methylation play a key function in regulating gene expression. Emerging proof means that intermediates generated throughout DNA demethylation could have distinct organic roles. However, their detection stays difficult resulting from their low abundance. Now, researchers from Japan have developed a novel light-sensitive oligonucleotide probe that selectively crosslinks with 5-formylcytosine, an epigenetically necessary intermediate, enabling its detection in goal DNA and complicated organic samples.

Novel Photoreactive Probe for the Detection of Epigenetic Modifications

Epigenetic modifications, that are reversible adjustments to DNA, management when and the place genes are switched on or off, enjoying a crucial function in human progress and illness improvement. DNA methylation is one such key mechanism that provides methyl teams to DNA. These methyl teams are extra generally added on the 5-position of cytosine to kind 5-methylcytosine (5mC), localized at gene promoter areas, leading to gene silencing. Conversely, demethylation or the elimination of methyl teams prompts gene transcription.

Mounting proof means that the cytosine intermediates generated through the oxidation and subsequent demethylation of 5-position of cytosine could serve distinct epigenetic roles in organic processes. Detecting and understanding these intermediates could open new avenues for illness administration. However, the low abundance of these intermediates makes their detection troublesome.

To overcome this problem, a analysis workforce led by Professor Asako Yamayoshi from the Department of Life Science and Technology, Institute of Science Tokyo (Science Tokyo), Japan, has developed a novel photochemical sensor that may detect cytosine derivatives utilizing mild. Their findings had been made obtainable on-line on January 07, 2026, and revealed in Volume 148, Issue 2 of the Journal of the American Chemical Society on January 21, 2026. The researchers display the selective crosslinking of a light-sensitive oligonucleotide probe with 5-formylcytosine (5fC), a 5mC spinoff central to demethylation and epigenetic regulation.

“Our work introduces a new concept for light-driven detection of 5fC, offering a spatiotemporally controllable probe for epigenetic analysis,” explains Yamayoshi.

The workforce designed and synthesized oligonucleotide probes containing trioxsalen—a psoralen (Ps) spinoff—which is a pure compound that may insert itself into DNA. The Ps-conjugated oligonucleotides bear “photo-cycloaddition” or crosslink with the goal DNA upon publicity to ultraviolet (UV) radiation at 365 nm. The researchers beforehand used these Ps-oligos to detect oncogenic mutations and epigenetic modifications.

In the present examine, they assessed the photo-crosslinking effectivity of the probes tagged with a fluorophore, mixed with completely different cytosine derivatives within the goal DNA. Notably, the fluorescence depth was the best for 5fC in comparison with the opposite derivatives comparable to 5-hydroxymethylcytosine (5hmC) and 5-carboxylcytosine (5caC). Further, the cross-linking effectivity between the probe and 5hmC or 5caC decreased considerably as sodium-ion focus and temperature had been lowered. Conversely, cross-linking between the probe and 5fC remained largely unchanged throughout ionic and temperature variations, indicating a extra secure interplay.

In distinction to photo-cycloaddition, publicity to shorter-wavelength UV radiation can induce “cycloreversion” by weakening interactions between the goal DNA and the probe. To assess stability, the researchers irradiated the cross-linked merchandise with UV radiation at 254 nm. Notably, the fluorescence depth of the probe and 5fC crosslinked product remained unchanged, whereas a lower was noticed for the opposite cytosine derivatives, indicating higher stability of 5fC.

Finally, the researchers demonstrated the sensible feasibility of 5fC detection by establishing a DNA chip sensor fabricated with the oligonucleotide probe. They noticed sturdy fluorescence for 5mC and 5fC after crosslinking. Additionally, the fluorescence depth of goal 5mC lowered considerably after making use of UV radiation at 254 nm, whereas that of 5fC remained fixed, highlighting selective photo-reactivity of the probe in the direction of 5fC.

Overall, these findings spotlight the distinctive potential of the photo-crosslinkable oligonucleotide probe within the selective detection of 5fC within the goal DNA. “We aim to extend the method to complex biological samples and improve detection sensitivity by enriching 5fC-containing DNA fragments, ultimately translating the technology into research and diagnostic tools across life sciences and medicine,” concludes Yamayoshi.

Authors:

¹Yu Mikame, ¹Hiroaki Shirahama, ²Kinuka Doi, ²Nagisa Maekawa, ³Hiroki Kanazawa, ²Tsuyoshi Yamamoto, ⁴Chikara Dohno, ³Jiro Kondo, ⁵Takehiko Wada, and ¹Asako Yamayoshi

Title:

Detection of Epigenetically Important 5-Formylcytosine Modifications Using Novel Photoreactive Oligonucleotides Containing a Trioxsalen-Conjugated Guanosine

Journal:

Journal of the American Chemical Society

Affiliations:

¹Department of Life Science and Technology, Institute of Science Tokyo , Japan
²Graduate School of Biomedical Science, Nagasaki University, Japan
³Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Japan
⁴SANKEN (The Institute of Scientific and Industrial Research), Osaka University, Japan
⁵IMRAM (Institute of Multidisciplinary Research for Advanced Materials) and INGEM (the Advanced Research Center for Innovations in Next-Generation Medicine), Tohoku University, Japan