28zt
Crystal structure of human DHX9 in complex with ATX-968 and ADP
Structural highlights
FunctionDHX9_HUMAN Unwinds double-stranded DNA and RNA in a 3' to 5' direction. Alteration of secondary structure may subsequently influence interactions with proteins or other nucleic acids. Functions as a transcriptional activator. Component of the CRD-mediated complex that promotes MYC mRNA stability. Involved with LARP6 in the stabilization of type I collagen mRNAs for CO1A1 and CO1A2. As component of a large PER complex is involved in the inhibition of 3' transcriptional termination of circadian target genes such as PER1 and NR1D1 and the control of the circadian rhythms. Positively regulates HIV-1 LTR-directed gene expression.[1] [2] [3] Publication Abstract from PubMedHuman DHX8 is a spliceosomal DEAH-box RNA helicase involved in releasing mRNA from the spliceosome and crucial in ensuring splicing fidelity. DHX8 was identified as a promising therapeutic oncology target due to its role in regulating stress-adaptive gene expression, including HSF1-dependent transcription, while having broader transcriptional effects in cells under oncogenic stress. We report the discovery of novel RNA-competitive DHX8 inhibitors based on a 2-(phenethylthio)nicotinic acid scaffold, which were optimized using a structure-guided design approach, following a biophysical fragment screen. This yielded compound 53 with nanomolar biochemical potency, good in vitro PK, and activity in a cellular target engagement assay. Optimizing inhibitor binding between Arg647 and the nonconserved His693, coupled with extending into a pocket in the DHX8 Winged-Helix domain, was crucial for potency improvement. By binding in the Winged-Helix domain, these inhibitors restrict the helicase domain's conformational plasticity, stabilizing a closed, inactive conformation while sterically blocking ssRNA translocation. Fragment-Based Discovery of Potent RNA-Competitive Inhibitors of the DEAH-Box RNA Helicase DHX8.,Read BJ, Ewens C, Gigante F, Thomas J, Felisberto-Rodrigues C, Alvarez Peres S, Tighe C, de Las Heras Ruiz E, Schiemann K, Malcolm AG, McAndrew PC, Stubbs M, Patani H, Costa HDS, Stoodley K, Pickard L, Busch M, Gunnell E, Silva S, Knopp A, Hallett ST, Augustin M, Lammens A, Carter M, Meniconi M, Ballarotto M, Ainsley J, Meister P, Sethi D, Burke R, Scarpino A, Le Bihan YV, Gradler U, Blagg J, Workman P, Clarke PA, Blum A, Esdar C, Bhalay G, van Montfort RLM J Med Chem. 2026 Aug 13;69(15):18277-18299. doi: 10.1021/acs.jmedchem.6c00732. PMID:42593941[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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