METTL1/WDR4 Complex: A Novel Epitranscriptomic Target at the Crossroads of RNA Methylation and Drug Discovery.

METTL1, in complex with its partner protein WDR4, is the principal writer of internal and RNA-associated N7-methylguanosine (m7G), an epitranscriptomic modification that remodels translation, RNA stability, and stress-response pathways. Across diverse cancer types, including hepatocellular carcinoma, cholangiocarcinoma, lung and bladder cancer, glioma, AML, and prostate cancer, METTL1/WDR4-driven expansion of m7G-modified tRNAs and stabilization of codon-biased mRNAs amplifies oncogenic programs governing cell-cycle progression, EMT, DNA repair, and immune evasion. Context-specific roles extend to autoimmune, cardiovascular, and neurological disorders, where METTL1 regulates hypertrophy, fibrosis, angiogenesis, neurodevelopment, and inflammation. Recent advances have established METTL1 as a tractable methyltransferase target: fragment-derived SAM-pocket ligands provide optimal starting points, and recently disclosed THIQ-based inhibitors report nanomolar inhibition, robust cellular target engagement, and functional suppression of tRNA m7G in cells. These advances provide the first chemical foothold for therapeutic modulation of m7G pathways and underscore METTL1 as a promising yet complex target requiring careful biological stratification.