Biology subjects

Dever, T. E.

Publications and source records attributed to Dever, T. E..

6 recordsLinked to original sources

bioRxiv2025

Harnessing the Evolution of Proteostasis Networks to Reverse Cognitive Dysfunction

The integrated stress response (ISR) is a highly conserved network essential for maintaining cellular homeostasis and cognitive function. Here, we investigated how persistent ISR activation impacts cognitive performance, primarily focusing on a PPP1R15BR658C genetic variant associated with intellectual disability. By generating a novel mouse model that mimics this human condition, we revealed that this variant destabilizes the PPP1R15B*PP1 phosphatase complex, resulting in chronic ISR activation, impaired protein synthesis, and deficits in long-term memory. Importantly, we found that the cognitive and synaptic deficits in Ppp1r15bR658C mice are directly due to ISR activation. Leveraging insights from evolutionary biology, we characterized DP71L, a viral orthologue of PPP1R15B, through detailed molecular and structural analyses, uncovering its mechanism of action as a potent pan-ISR inhibitor. Remarkably, we found that DP71L not only buffers cognitive decline associated with a wide array of conditions--including Down syndrome, Alzheimers disease and aging--but also enhances long-term synaptic plasticity and memory in healthy mice. These findings highlight the promise of utilizing evolutionary insight to inform innovative therapeutic strategies.

neuroscience↗

bioRxiv2024

eIF1 and eIF5 dynamically control translation start site fidelity

Translation initiation defines the identity of a synthesized protein through selection of a translation start site on a messenger RNA. This process is essential to well-controlled protein synthesis, modulated by stress responses, and dysregulated in many human diseases. The eukaryotic initiation factors eIF1 and eIF5 interact with the initiator methionyl-tRNAiMet on the 40S ribosomal subunit to coordinate start site selection. Here, using single-molecule analysis of in vitro reconstituted human initiation combined with translation assays in cells, we examine eIF1 and eIF5 function. During translation initiation on a panel of RNAs, we monitored both proteins directly and in real time using single-molecule fluorescence. As expected, eIF1 loaded onto mRNAs as a component of the 43S initiation complex. Rapid ([~] 2 s) eIF1 departure required a translation start site and was delayed by alternative start sites and a longer 5 untranslated region (5UTR). After its initial departure, eIF1 rapidly and transiently sampled initiation complexes, with more prolonged sampling events on alternative start sites. By contrast, eIF5 only transiently bound initiation complexes late in initiation immediately prior to association of eIF5B, which allowed joining of the 60S ribosomal subunit. eIF5 association required the presence of a translation start site and was inhibited and destabilized by alternative start sites. Using both knockdown and overexpression experiments in human cells, we validated that eIF1 and eIF5 have opposing roles during initiation. Collectively, our findings demonstrate how multiple eIF1 and eIF5 binding events control start-site selection fidelity throughout initiation, which is tuned in response to changes in the levels of both proteins.

biophysics↗

bioRxiv2022

Arginine-dependent hypusination of the eukaryotic translation initiation factor (eIF)5A drives erythroid lineage differentiation

Metabolic programs contribute to hematopoietic stem and progenitor cell (HSPC) fate but it is not known whether the metabolic regulation of protein synthesis controls HSPC differentiation. We discovered that SLC7A1/CAT1-dependent arginine uptake and its catabolism to spermidine control the erythroid specification of HSPCs via activation of eukaryotic translation initiation factor 5A (eIF5A). eIF5A activity is dependent on the metabolism of spermidine to hypusine and inhibiting hypusine synthesis abrogates erythropoiesis and diverts EPO-stimulated HSPCs to a myeloid fate. Proteomic profiling reveals mitochondrial translation to be a critical target of hypusinated eIF5A and induction of mitochondrial function partially rescues erythropoiesis in the absence of hypusine. Within the hypusine network, ribosomal proteins are highly enriched and we identify defective eIF5A hypusination in erythroid pathologies caused by abnormal ribosome biogenesis. Thus, eIF5A-dependent protein synthesis is critical in the branching of erythro-myeloid differentiation and attenuated eIF5A activity characterizes ribosomal protein-linked disorders of ineffective erythropoiesis.

physiology↗

bioRxiv2021

eIF5B and eIF1A remodel human translation initiation complexes to mediate ribosomal subunit joining

Joining of the ribosomal subunits at a translation start site on a messenger RNA during initiation commits the ribosome to synthesize a protein. Here, we combined single-molecule spectroscopy and structural methods using an in vitro reconstituted system to examine how the human ribosomal subunits join. Single-molecule fluorescence revealed when universally-conserved eukaryotic initiation factors (eIFs) eIF1A and eIF5B associate with and depart from initiation complexes. Guided by single-molecule dynamics, we examined initiation complexes that contained both eIF1A and eIF5B using single-particle electron cryo-microscopy. The resulting structure illuminated how eukaryote-specific contacts between eIF1A and eIF5B remodel the initiation complex to orient initiator tRNA in a conformation compatible with ribosomal subunit joining. Collectively, our findings provide a quantitative and architectural framework for the molecular choreography orchestrated by eIF1A and eIF5B during human translation initiation.

biophysics↗

bioRxiv2021

Rapid 40S scanning and its regulation by mRNA structure during eukaryotic translation initiation

How the eukaryotic 43S preinitiation complex scans along the 5' untranslated region (5'UTR) of a capped mRNA to locate the correct start codon remains elusive. Here, we directly track yeast 43S-mRNA binding, scanning, and 60S subunit joining by real-time single-molecule fluorescence spectroscopy. Once engaged with the mRNA, 43S scanning occurs at >100 nucleotides per second, independent of multiple cycles of ATP-hydrolysis by RNA helicases. The scanning ribosomes can proceed through RNA secondary structures, but 5'UTR hairpin sequences near start codons drive scanning ribosomes at start codons back in the 5' direction, requiring rescanning to arrive once more at a start codon. Direct observation of scanning ribosomes provides a mechanistic framework for translational regulation by 5'UTR structures and upstream near-cognate start codons. One Sentence SummaryDirect observation of scanning eukaryotic ribosomes establishes a quantitative framework of scanning and its regulation.

biophysics↗

bioRxiv2020

Conserved +1 translational frameshifting in the S. cerevisiae gene encoding YPL034W

Living cells have developed exquisite mechanisms to ensure accurate translation of mRNA. Many of them are dedicated to preventing the change in reading frame during translation elongation. A minority of chromosomally encoded genes have evolved sequences that subvert standard decoding to program +1 translational frameshifting, either constitutively or in response to external stimuli. In the yeast Saccharomyces cerevisiae, three chromosomal genes are known to employ programmed +1 translational frameshifting for expression of full-length functional products. Here we identify a fourth yeast gene, YFS1, encompassing the existing predicted open reading frame YPL034W, with conserved programmed +1 frameshifting. Like the previously known examples, it appears to exploit peculiarities in tRNA abundance in S. cerevisiae.

molecular biology↗