N6-Methyladenosine (m6A) is the predominant internal RNA modification in eukaryotic messenger RNAs (mRNAs) and plays a crucial role in mRNA stability. Here, using human cells, we reveal that m6A sites in the coding sequence (CDS) trigger CDS-m6A decay (CMD), a pathway that is distinct from previously reported m6A-dependent degradation mechanisms. Importantly, CDS m6A sites act considerably faster and more efficiently than those in the 3' untranslated region, which to date have been considered the main effectors. Mechanistically, CMD depends on translation, whereby m6A deposition in the CDS triggers ribosome pausing and transcript destabilization. The subsequent decay involves the translocation of the CMD target transcripts to processing bodies (P-bodies) and recruitment of the m6A reader protein YT521-B homology domain family protein 2 (YTHDF2). Our findings highlight CMD as a previously unknown pathway, which is particularly important for controlling the expression of developmental regulators and retrogenes.

• MeSH
• 3' nepřekládaná oblast MeSH
• adenosin * analogy a deriváty   metabolismus   genetika   MeSH
• HEK293 buňky MeSH
• HeLa buňky MeSH
• lidé MeSH
• messenger RNA * genetika   metabolismus   MeSH
• otevřené čtecí rámce * MeSH
• proteiny vázající RNA * genetika   metabolismus   MeSH
• proteosyntéza * MeSH
• ribozomy metabolismus   genetika   MeSH
• stabilita RNA * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

In animals and plants, Dicer enzymes collaborate with double-stranded RNA-binding domain (dsRBD) proteins to convert precursor-microRNAs (pre-miRNAs) into miRNA duplexes. We report six cryo-EM structures of Drosophila Dicer-1 that show how Dicer-1 and its partner Loqs-PB cooperate (1) before binding pre-miRNA, (2) after binding and in a catalytically competent state, (3) after nicking one arm of the pre-miRNA, and (4) following complete dicing and initial product release. Our reconstructions suggest that pre-miRNA binds a rare, open conformation of the Dicer-1⋅Loqs-PB heterodimer. The Dicer-1 dsRBD and three Loqs-PB dsRBDs form a tight belt around the pre-miRNA, distorting the RNA helix to place the scissile phosphodiester bonds in the RNase III active sites. Pre-miRNA cleavage shifts the dsRBDs and partially closes Dicer-1, which may promote product release. Our data suggest a model for how the Dicer-1⋅Loqs-PB complex affects a complete cycle of pre-miRNA recognition, stepwise endonuclease cleavage, and product release.

• MeSH
• Drosophila genetika   MeSH
• mikro RNA * genetika   metabolismus   MeSH
• proteiny Drosophily * genetika   metabolismus   MeSH
• proteiny vázající RNA metabolismus   MeSH
• ribonukleasa III genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, N.I.H., Intramural MeSH

MicroRNA (miRNA) and RNA interference (RNAi) pathways rely on small RNAs produced by Dicer endonucleases. Mammalian Dicer primarily supports the essential gene-regulating miRNA pathway, but how it is specifically adapted to miRNA biogenesis is unknown. We show that the adaptation entails a unique structural role of Dicer's DExD/H helicase domain. Although mice tolerate loss of its putative ATPase function, the complete absence of the domain is lethal because it assures high-fidelity miRNA biogenesis. Structures of murine Dicer•-miRNA precursor complexes revealed that the DExD/H domain has a helicase-unrelated structural function. It locks Dicer in a closed state, which facilitates miRNA precursor selection. Transition to a cleavage-competent open state is stimulated by Dicer-binding protein TARBP2. Absence of the DExD/H domain or its mutations unlocks the closed state, reduces substrate selectivity, and activates RNAi. Thus, the DExD/H domain structurally contributes to mammalian miRNA biogenesis and underlies mechanistical partitioning of miRNA and RNAi pathways.

• MeSH
• mikro RNA * genetika   metabolismus   MeSH
• myši MeSH
• ribonukleasa III * metabolismus   MeSH
• RNA interference MeSH
• savci metabolismus   MeSH
• transportní proteiny metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• komentáře MeSH
• práce podpořená grantem MeSH

Calcium influx through plasma membrane calcium release-activated calcium (CRAC) channels, which are formed of hexamers of Orai1, is a potent trigger for many important biological processes, most notably in T cell-mediated immunity. Through a bioinformatics-led cell biological screen, we have identified Orai1 as a substrate for the rhomboid intramembrane protease RHBDL2. We show that RHBDL2 prevents stochastic calcium signaling in unstimulated cells through conformational surveillance and cleavage of inappropriately activated Orai1. A conserved disease-linked proline residue is responsible for RHBDL2's recognizing the active conformation of Orai1, which is required to sharpen switch-like signaling triggered by store-operated calcium entry. Loss of RHBDL2 control of CRAC channel activity causes severe dysregulation of downstream CRAC channel effectors, including transcription factor activation, inflammatory cytokine expression, and T cell activation. We propose that this surveillance function may represent an ancient activity of rhomboid proteases in degrading unwanted signaling proteins.

• MeSH
• aktivace lymfocytů MeSH
• buněčná membrána metabolismus   MeSH
• Drosophila melanogaster MeSH
• gating iontového kanálu MeSH
• HEK293 buňky MeSH
• konformace proteinů MeSH
• lidé MeSH
• membránové proteiny metabolismus   MeSH
• mutace MeSH
• proteasy chemie   MeSH
• protein ORAI1 chemie   MeSH
• serinové endopeptidasy metabolismus   MeSH
• signální transdukce MeSH
• stochastické procesy MeSH
• vápník metabolismus   MeSH
• vápníková signalizace fyziologie   MeSH
• vápníkové kanály chemie   MeSH
• vazba proteinů MeSH
• výpočetní biologie MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

DDX3X is a ubiquitously expressed RNA helicase involved in multiple stages of RNA biogenesis. DDX3X is frequently mutated in Burkitt lymphoma, but the functional basis for this is unknown. Here, we show that loss-of-function DDX3X mutations are also enriched in MYC-translocated diffuse large B cell lymphoma and reveal functional cooperation between mutant DDX3X and MYC. DDX3X promotes the translation of mRNA encoding components of the core translational machinery, thereby driving global protein synthesis. Loss-of-function DDX3X mutations moderate MYC-driven global protein synthesis, thereby buffering MYC-induced proteotoxic stress during early lymphomagenesis. Established lymphoma cells restore full protein synthetic capacity by aberrant expression of DDX3Y, a Y chromosome homolog, the expression of which is normally restricted to the testis. These findings show that DDX3X loss of function can buffer MYC-driven proteotoxic stress and highlight the capacity of male B cell lymphomas to then compensate for this loss by ectopic DDX3Y expression.

• MeSH
• B-buněčný lymfom enzymologie   genetika   patologie   MeSH
• B-lymfocyty enzymologie   patologie   MeSH
• DEAD-box RNA-helikasy genetika   metabolismus   MeSH
• dítě MeSH
• dospělí MeSH
• homeostáze proteinů MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mutace ztráty funkce MeSH
• myši transgenní MeSH
• nádorové buněčné linie MeSH
• nádorové proteiny biosyntéza   genetika   MeSH
• předškolní dítě MeSH
• proteom MeSH
• proteosyntéza MeSH
• protoonkogenní proteiny c-myc genetika   metabolismus   MeSH
• regulace genové exprese enzymů MeSH
• regulace genové exprese u nádorů MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• stres endoplazmatického retikula MeSH
• vedlejší histokompatibilní antigeny genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

RelA-SpoT Homolog (RSH) enzymes control bacterial physiology through synthesis and degradation of the nucleotide alarmone (p)ppGpp. We recently discovered multiple families of small alarmone synthetase (SAS) RSH acting as toxins of toxin-antitoxin (TA) modules, with the FaRel subfamily of toxSAS abrogating bacterial growth by producing an analog of (p)ppGpp, (pp)pApp. Here we probe the mechanism of growth arrest used by four experimentally unexplored subfamilies of toxSAS: FaRel2, PhRel, PhRel2, and CapRel. Surprisingly, all these toxins specifically inhibit protein synthesis. To do so, they transfer a pyrophosphate moiety from ATP to the tRNA 3' CCA. The modification inhibits both tRNA aminoacylation and the sensing of cellular amino acid starvation by the ribosome-associated RSH RelA. Conversely, we show that some small alarmone hydrolase (SAH) RSH enzymes can reverse the pyrophosphorylation of tRNA to counter the growth inhibition by toxSAS. Collectively, we establish RSHs as RNA-modifying enzymes.

• MeSH
• bakteriální toxiny genetika   metabolismus   farmakologie   MeSH
• fosforylace účinky léků   MeSH
• grampozitivní nesporulující tyčinky chemie   metabolismus   MeSH
• guanosinpentafosfát chemie   metabolismus   MeSH
• inhibitory syntézy proteinů farmakologie   MeSH
• ligasy chemie   genetika   metabolismus   MeSH
• proteosyntéza účinky léků   fyziologie   MeSH
• pyrofosfatasy MeSH
• ribozomy metabolismus   MeSH
• RNA transferová metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Mammalian DNA base excision repair (BER) is accelerated by poly(ADP-ribose) polymerases (PARPs) and the scaffold protein XRCC1. PARPs are sensors that detect single-strand break intermediates, but the critical role of XRCC1 during BER is unknown. Here, we show that protein complexes containing DNA polymerase β and DNA ligase III that are assembled by XRCC1 prevent excessive engagement and activity of PARP1 during BER. As a result, PARP1 becomes "trapped" on BER intermediates in XRCC1-deficient cells in a manner similar to that induced by PARP inhibitors, including in patient fibroblasts from XRCC1-mutated disease. This excessive PARP1 engagement and trapping renders BER intermediates inaccessible to enzymes such as DNA polymerase β and impedes their repair. Consequently, PARP1 deletion rescues BER and resistance to base damage in XRCC1-/- cells. These data reveal excessive PARP1 engagement during BER as a threat to genome integrity and identify XRCC1 as an "anti-trapper" that prevents toxic PARP1 activity.

• MeSH
• buněčné linie MeSH
• DNA vazebné proteiny metabolismus   MeSH
• DNA-ligasa ATP metabolismus   MeSH
• DNA-polymerasa beta metabolismus   MeSH
• DNA genetika   MeSH
• fibroblasty účinky léků   metabolismus   MeSH
• jednořetězcové zlomy DNA MeSH
• lidé MeSH
• oprava DNA účinky léků   genetika   MeSH
• PARP inhibitory farmakologie   MeSH
• poly(ADP-ribosa)polymerasa 1 metabolismus   MeSH
• poly(ADP-ribosa)polymerasy metabolismus   MeSH
• poškození DNA účinky léků   genetika   MeSH
• protein XRCC1 metabolismus   MeSH
• vazba proteinů účinky léků   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

Formation of co-transcriptional R-loops underlies replication fork stalling upon head-on transcription-replication encounters. Here, we demonstrate that RAD51-dependent replication fork reversal induced by R-loops is followed by the restart of semiconservative DNA replication mediated by RECQ1 and RECQ5 helicases, MUS81/EME1 endonuclease, RAD52 strand-annealing factor, the DNA ligase IV (LIG4)/XRCC4 complex, and the non-catalytic subunit of DNA polymerase δ, POLD3. RECQ5 disrupts RAD51 filaments assembled on stalled forks after RECQ1-mediated reverse branch migration, preventing a new round of fork reversal and facilitating fork cleavage by MUS81/EME1. MUS81-dependent DNA breaks accumulate in cells lacking RAD52 or LIG4 upon induction of R-loop formation, suggesting that RAD52 acts in concert with LIG4/XRCC4 to catalyze fork religation, thereby mediating replication restart. The resumption of DNA synthesis after R-loop-associated fork stalling also requires active transcription, the restoration of which depends on MUS81, RAD52, LIG4, and the transcription elongation factor ELL. These findings provide mechanistic insights into transcription-replication conflict resolution.

• MeSH
• DNA opravný a rekombinační protein Rad52 metabolismus   MeSH
• DNA vazebné proteiny metabolismus   MeSH
• DNA-ligasy metabolismus   MeSH
• DNA-polymerasa III metabolismus   MeSH
• endodeoxyribonukleasy metabolismus   MeSH
• endonukleasy genetika   metabolismus   MeSH
• genetická transkripce genetika   MeSH
• HeLa buňky MeSH
• helikasy RecQ metabolismus   fyziologie   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• R-smyčka genetika   fyziologie   MeSH
• rekombinasa Rad51 genetika   metabolismus   fyziologie   MeSH
• replikace DNA genetika   fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Peptide drugs targeting class B1 G-protein-coupled receptors (GPCRs) can treat multiple diseases; however, there remains substantial interest in the development of orally delivered non-peptide drugs. Here, we reveal unexpected overlap between signaling and regulation of the glucagon-like peptide-1 (GLP-1) receptor by the non-peptide agonist PF 06882961 and GLP-1 that was not observed for another compound, CHU-128. Compounds from these patent series, including PF 06882961, are currently in clinical trials for treatment of type 2 diabetes. High-resolution cryoelectron microscopy (cryo-EM) structures reveal that the binding sites for PF 06882961 and GLP-1 substantially overlap, whereas CHU-128 adopts a unique binding mode with a more open receptor conformation at the extracellular face. Structural differences involving extensive water-mediated hydrogen bond networks could be correlated to functional data to understand how PF 06882961, but not CHU-128, can closely mimic the pharmacological properties of GLP-1. These findings will facilitate rational structure-based discovery of non-peptide agonists targeting class B GPCRs.

• MeSH
• elektronová kryomikroskopie metody   MeSH
• glukagonu podobný peptid 1 chemie   metabolismus   MeSH
• lidé MeSH
• peptidy chemie   MeSH
• receptor pro glukagonu podobný peptid 1 agonisté   chemie   metabolismus   MeSH
• receptory spřažené s G-proteiny agonisté   chemie   metabolismus   MeSH
• vazebná místa fyziologie   MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Translational control targeting the initiation phase is central to the regulation of gene expression. Understanding all of its aspects requires substantial technological advancements. Here we modified yeast translation complex profile sequencing (TCP-seq), related to ribosome profiling, and adapted it for mammalian cells. Human TCP-seq, capable of capturing footprints of 40S subunits (40Ss) in addition to 80S ribosomes (80Ss), revealed that mammalian and yeast 40Ss distribute similarly across 5'TRs, indicating considerable evolutionary conservation. We further developed yeast and human selective TCP-seq (Sel-TCP-seq), enabling selection of 40Ss and 80Ss associated with immuno-targeted factors. Sel-TCP-seq demonstrated that eIF2 and eIF3 travel along 5' UTRs with scanning 40Ss to successively dissociate upon AUG recognition; notably, a proportion of eIF3 lingers on during the initial elongation cycles. Highlighting Sel-TCP-seq versatility, we also identified four initiating 48S conformational intermediates, provided novel insights into ATF4 and GCN4 mRNA translational control, and demonstrated co-translational assembly of initiation factor complexes.

• MeSH
• 5' nepřekládaná oblast MeSH
• eukaryotický iniciační faktor 2 genetika   metabolismus   MeSH
• eukaryotický iniciační faktor 3 genetika   metabolismus   MeSH
• HEK293 buňky MeSH
• iniciační faktory genetika   metabolismus   MeSH
• kodon iniciační MeSH
• lidé MeSH
• malé podjednotky ribozomu eukaryotické genetika   metabolismus   MeSH
• multiproteinové komplexy genetika   metabolismus   MeSH
• proteosyntéza * MeSH
• ribozomy genetika   metabolismus   MeSH
• Saccharomyces cerevisiae - proteiny genetika   metabolismus   MeSH
• Saccharomyces cerevisiae genetika   MeSH
• transkripční faktor ATF4 genetika   metabolismus   MeSH
• transkripční faktory bZIP genetika   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH