Small interfering RNAs (siRNAs) guide mRNA cleavage by human Argonaute2 (hAgo2), leading to targeted gene silencing. Despite their laboratory and clinical impact, structural insights into human siRNA catalytic activity remain elusive. Here, we show that disrupting siRNA 3'-end binding by hAgo2 accelerates target cleavage and stabilizes its catalytic conformation, enabling detailed structural analysis. A 3.16 Å global resolution cryo-EM reconstruction reveals that distortion of the siRNA-target duplex at position 6 allows target RNA entry into the catalytic cleft and shifts Lysine-709, a previously unrecognized catalytic residue, into the active site. A pyrimidine at target nucleotide t10 positions another unrecognized catalytic residue, Arginine-710, for optimal cleavage. Expansion of the guide-target duplex major groove docks the scissile phosphate for hydrolysis and subsequent groove compression after position 16 permits target RNAs to exit the catalytic cleft. These findings reveal how hAgo2 catalyzes siRNA target hydrolysis, providing a high-resolution model for therapeutic design.
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http://dx.doi.org/10.1101/2024.12.05.627081 | DOI Listing |
Front Cell Dev Biol
December 2024
Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL, Canada.
PIWI-interacting RNAs (piRNAs) are small non-coding RNAs that bind to the PIWI subclass of the Argonaute protein family and are essential for maintaining germline integrity. Initially discovered in , PIWI proteins safeguard piRNAs, forming ribonucleoprotein (RNP) complexes, crucial for regulating gene expression and genome stability, by suppressing transposable elements (TEs). Recent insights revealed that piRNAs and PIWI proteins, known for their roles in germline maintenance, significantly influence mRNA stability, translation and retrotransposon silencing in both stem cells and bodily tissues.
View Article and Find Full Text PDFBrain Pathol
December 2024
Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, China.
Brain injury represents the leading cause of mortality and disability after cardiopulmonary resuscitation (CPR) from cardiac arrest (CA), in which the accumulation of dying cells aggravate tissue injury by releasing proinflammatory intracellular components. Microglia play an essential role in maintaining brain homeostasis via milk fat globule epidermal growth factor 8 (MFG-E8)-opsonized efferocytosis, the engulfment of dying cells and debris. This study investigates whether potentiating microglia efferocytosis by MFG-E8 provides neuroprotection after CA/CPR.
View Article and Find Full Text PDFCurr Drug Metab
December 2024
Department of Pharmaceutics, Sri Shanmugha College of Pharmacy, Sankari Tiruchengode Main Road, Pullipalayam, Morur (PO), Sankari, Salem, Tamil Nadu, Tamil Nadu, India.
Gene silencing is the characteristic that inhibits gene expression afforded by siRNA interference. The efficacy of the delivery system in terms of precision, efficacy, and stability can be enhanced by genebased drug delivery options. The delivery challenges and their associated side effects create a challenge for the delivery of gene-based drug delivery carriers.
View Article and Find Full Text PDFCurr Neurovasc Res
December 2024
Department of Neurosurgery, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, 050000, China.
Background: Stroke, primarily known as ischemic stroke, is a leading cause of mortality and disability worldwide. Reperfusion after the ischemia stroke resolves is necessary for maintaining the health of brain tissues; however, it also induces inflammation and oxidative stress, resulting in brain injury. This study aimed to investigate the role of circ0001679 in the pathology of I/R (Ischemia/Reperfusion)-induced brain injury and explore its therapeutic potential for I/R injury.
View Article and Find Full Text PDFGenome Med
December 2024
Department of Biomedical Engineering, Tel Aviv University, Tel-Aviv, 6997801, Israel.
Background: CRISPR is widely used to silence genes by inducing mutations expected to nullify their expression. While numerous computational tools have been developed to design single-guide RNAs (sgRNAs) with high cutting efficiency and minimal off-target effects, only a few tools focus specifically on predicting gene knockouts following CRISPR. These tools consider factors like conservation, amino acid composition, and frameshift likelihood.
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