A research team of Shanghai Institute of Materia Medica(CAS), Peking University and Fudan University has identified a non-steroidal, anti-inflammatory drug meclofenamic acid (MA) that could highly selectively inhibit FTO demethylation over ALKBH5. Drs. YANG Caiguang, LUO Cheng and JIA Guifang conceived this project with the help from Dr. ZHOU Hu and GAN Jianhua.
Two human demethylases, including FTO and ALKBH5, oxidatively demethylate abundant N6-methyladenosine (m6A) residues in mRNA. Achieving a method for selective inhibition of FTO over ALKBH5 remains a challenge. Here, the team has identified MA as a selective inhibitor of FTO. Mechanistic studies indicate that MA competes with FTO binding for the m6A-containing nucleic acid.
The crystal structure of FTO/MA complex has uncovered a unique inhibitor-binding lid in FTO, which has helped elucidate the underlying principles that account for the exquisite selectivity that FTO, given its inhibiting function, has over ALKBH5. Treatment of HeLa cells with ethyl ester form of MA has led to elevated levels of m6A modification in mRNA.
These collective results shed light on the development of functional probes of FTO enzyme for use in biology and for the rational design of potent, specific inhibitors of FTO for use in medicine.
Fig. Mechlofenamic acid (MA) selectively inhibits demethylation of m6A in mRNA. A, Scheme of the oxidative demethyaltion of m6A catalyzed by FTO or ALKBH5. The chemical structure of MA is shown. B, MA could inhibit FTO demethylation of m6A in ssDNA. C, MA fails to inhibit ALKBH5 demethylation. D, Structural complex of FTO/MA reveals the mechanistic insights into the selective inhibiton of FTO over ALKBH5. E-G, MA elevates the cellular levels of m6A in mRNA, which is related to the abundance and activity of FTO, indicating MA selective inhibition of FTO demethylation rather than other m6A demethylases inside cells.（Image by SIMM）
