Ligand dimerization represents a powerful strategy to enhance avidity, potency, and selectivity. Leveraging the natural-product molecular glue rocaglamide (RocA), we identified BisRoc, a dimeric rocaglate ligand that potently and durably suppresses translation and exhibits greater specificity across a cancer cell line panel than the monomeric RocA. CRISPRi screening revealed that BisRoc activity is influenced by cellular context, including IFITM-mediated uptake, ABC-type efflux transporters, and the translation initiation factor eIF4A2. Mechanistic studies showed that the paralogs eIF4A1 and eIF4A2 are differentially sensitive to BisRoc-induced dimerization. Owing to the presence of multiple binding sites on RNAs, BisRoc-bridged eIF4A-RNA motifs assemble into higher-order complexes that promote stress-granule formation more efficiently than monomeric RocA. Given the widespread multivalency of RNA-RBP interactions, this ligand dimerization strategy may be extended to modulate the higher-order assembly of other RNA-binding proteins.
Jie Liu, Megan K. Moore, Kevin Lou et al.· ACS Central Science· 0 citations
Mutations in leucine-rich repeat kinase 2 (LRRK2) are the second most common cause of autosomal-dominant Parkinson's disease (PD), and increased LRRK2 kinase activity is also observed in idiopathic PD, making LRRK2 a major actionable therapeutic target. LRRK2 is a 286-kDa multidomain enzyme containing a Ras-like GTPase (ROC) and a kinase domain. Using cryo-electron microscopy (cryo-EM), biochemical reconstitution, and cell-based assays, we show that the ROC GTPase governs switching between autoinhibited and active states: GTP binding promotes activation, whereas GDP binding enforces autoinhibition. Two common PD-linked mutations, G2019S and R1441C/G/H, activate LRRK2 through distinct structural mechanisms, revealing genotype-specific routes to dysregulation. These findings provide a unified framework for understanding LRRK2 regulation with broad therapeutic implications. Stabilizing the guanosine diphosphate (GDP)-bound state may inhibit LRRK2 by maintaining autoinhibition, whereas promoting the GTP-bound state could be advantageous in specific cellular contexts, such as the lung, where increased LRRK2 kinase activity may play protective or regulatory roles.
Amalia Villagran Suarez, Kathryn S. Hatch, Tatyana Bodrug et al.· Cell· 0 citations
Maternal inflammatory response (MIR) during early mouse gestation induces a cascade of physiological and behavioral changes associated with autism spectrum disorder (ASD). We have shown that mild MIR causes chronic systemic and brain inflammation, mTOR pathway activation, mild brain overgrowth with regionally specific volumetric changes, sensory processing dysregulation, and repetitive behavior abnormalities. Prior rapamycin studies in autism models focused on chronic treatments that alter or prevent physical brain changes. Here, we focus on acute rapamycin effects to uncover novel mTOR pathway-mediated mechanisms of dysfunction. Within 2 hours, rapamycin rescues neuronal hyperexcitability, seizure susceptibility, functional network connectivity, brain community structure, repetitive behaviors, and sensory over-responsivity in adult MIR offspring. These CNS-mediated effects coincide with altered expression of genes associated with ASD, ion channels, and epilepsy. Our findings demonstrate that mTOR dysregulation drives dysfunctional brain development in MIR offspring but the adult brain remains amenable to rapid functional normalization, rescuing core and comorbid ASD-associated brain and behavior phenotypes. Restoring excitatory/inhibitory imbalance and sensory functional network modularity may be important targets for therapeutically addressing multiple ASD phenotypes. Here authors show acute rapamycin transiently rescues neuron hyperexcitability, network connectivity, repetitive behaviors, and sensory over-responsivity in an acquired model of autism, showing mTOR-driven phenotypes can be treatment responsive in the mature brain.
Janel Le Belle, M. Condro, C. Cepeda et al.· Nature Communications· 0 citations