Glucose dissociates DDX21 dimers to regulate mRNA splicing and tissue differentiation

Miao W, Porter DF, Lopez-Pajares V, Siprashvili Z, Meyers RM, Bai Y, Nguyen DT, Ko LA, Zarnegar BJ, Ferguson ID, Mills MM, Jilly-Rehak CE, Wu CG, Yang YY, Meyers JM, Hong AW, Reynolds DL, Ramanathan M, Tao S, Jiang S, Flynn RA, Wang Y, Nolan GP, Khavari PA.


Glucose is a universal bioenergy source; however, its role in controlling protein interactions is unappreciated, as are its actions during differentiation-associated intracellular glucose elevation. Azido-glucose click chemistry identified glucose binding to a variety of RNA binding proteins (RBPs), including the DDX21 RNA helicase, which was found to be essential for epidermal differentiation. Glucose bound the ATP-binding domain of DDX21, altering protein conformation, inhibiting helicase activity, and dissociating DDX21 dimers. Glucose elevation during differentiation was associated with DDX21 re-localization from the nucleolus to the nucleoplasm where DDX21 assembled into larger protein complexes containing RNA splicing factors. DDX21 localized to specific SCUGSDGC motif in mRNA introns in a glucose-dependent manner and promoted the splicing of key pro-differentiation genes, including GRHL3, KLF4, OVOL1, and RBPJ. These findings uncover a biochemical mechanism of action for glucose in modulating the dimerization and function of an RNA helicase essential for tissue differentiation.