Biology subjects

Bartel, D.

Publications and source records attributed to Bartel, D..

9 recordsLinked to original sources

bioRxiv2025

mRNA poly(A)-tail length is a battleground for coronavirus-host competition

Most eukaryotic mRNAs contain a poly(A) tail, which in post-embryonic cells enhances their stability. Many cytoplasmic RNA viruses also harbor poly(A) tails on their genomic RNA and mRNAs. Here, we report that coronavirus infection causes cytoplasmic poly(A)-binding protein (PABPC) activity to become limiting, which preferentially destabilizes short-tailed host mRNAs, occurring before the action of virally encoded mRNA-decay factor nsp1. In this environment hostile to poly(A) tails, viral RNAs maintain a narrow tail-length distribution centering on 70-80 nucleotides across infection cycles. They do this through two mechanisms. First, viral tails are extended during RNA synthesis within double-membrane vesicles; second, viral tails are capped by a complex that includes PABPC1 and CSDE1 and slows tail shortening. Our findings suggest poly(A)-tail length is an arena of host- virus conflict, in which preserving tail lengths of viral mRNAs promotes their cytoplasmic dominance. HighlightsO_LIPABPC1 becomes limiting during coronavirus infection C_LIO_LILimiting PABPC1 promotes decay of short-tailed host mRNAs--independently of nsp1 C_LIO_LIThe tail lengths of coronaviral mRNAs are extended during their synthesis in DMVs C_LIO_LIViral tails are capped by PABPC1 and CSDE1, which protects against deadenylation C_LI

molecular biology↗

bioRxiv2025

Lysosomal RNA profiling reveals targeting of specific types of RNAs for degradation

Autophagy targets a wide variety of substrates for degradation within lysosomes1. While lysosomes are known to possess RNase activity2, the role of lysosomal RNA degradation in post-transcriptional gene regulation is not well understood. Here, we define RNASET2, PLD3, and both endogenous and exogenous RNase A family members as lysosomal RNases. Cells lacking these RNases accumulated large amounts of lysosomal RNA. Although all types of RNA can be found within lysosomes, SRP RNAs, Y RNAs, 5' TOP mRNAs, long-lived mRNAs, and mRNAs encoding membrane and secreted proteins were specifically enriched. All types of RNA depend on autophagy for lysosomal targeting, but the lysosomally-enriched RNAs are more sensitive to loss of autophagy, implying that selective mechanisms mediate their lysosomal entry. RNA stability measurements revealed that lysosomally-degraded transcripts also had autophagy-dependent changes in stability. In exploring how specific RNAs are targeted for lysosomal degradation, we found that the Alu domain of SRP RNAs is sufficient for targeting these RNAs to lysosomes in fashion that depends on its interactions with the SRP9 and SRP14 proteins. For mRNAs, 5' TOP motifs are sufficient to increase their targeting to lysosomes for degradation in a LARP1-dependent manner. Altogether, our results establish lysosomes as selective modulators of cellular RNA content.

molecular biology↗

bioRxiv2025

Global inhibition of deadenylation stabilizes the transcriptome in mitotic cells

In the presence of cell division errors, mammalian cells can pause in mitosis for tens of hours with little to no transcription, while still requiring continued translation for viability. These unique aspects of mitosis require substantial adaptations to the core gene expression programs. Indeed, during interphase, the homeostatic control of mRNA levels involves a constant balance of transcription and degradation, with a median mRNA half-life of [~]2-4 hours. If such short mRNA half-lives persisted in mitosis, cells would be expected to quickly deplete their transcriptome in the absence of new transcription. Here, we report that the transcriptome is globally stabilized during prolonged mitotic delays. Typical mRNA half-lives are increased >4-fold in mitosis compared to interphase, thereby buffering mRNA levels in the absence of new synthesis. Moreover, the poly(A)-tail-length profile of mRNAs changes in mitosis, strongly suggesting a mitotic repression of deadenylation. We further show that mRNA stabilization in mitosis is dependent on cytoplasmic poly(A)-binding proteins PABPC1&4. Depletion of PABPC1&4 disrupts the maintenance of mitotic arrest, highlighting the critical physiological role of mitotic transcriptome buffering. HighlightsO_LIThe cellular transcriptome is globally stabilized during prolonged mitotic arrest C_LIO_LIDistinct poly(A)-tail-length profile of mRNAs in mitosis suggests repression of deadenylation C_LIO_LImRNA stabilization in mitosis is dependent on PABPC1 and PABPC4 C_LIO_LIDegradation of mRNAs during mitosis compromises maintenance of mitotic arrest C_LI

cell biology↗

bioRxiv2024

PAL-AI reveals genetic determinants that control poly(A)-tail length during oocyte maturation with relevance to human fertility

In oocytes of mammals and other animals, gene regulation is mediated primarily through changes in poly(A)-tail length1-9. Here, we introduce PAL-AI, an integrated neural network machine-learning model that accurately predicts tail-length changes in maturing oocytes of frogs and mammals. We show that PAL-AI learned known and previously unknown sequence elements and their contextual features that control poly(A)-tail length, enabling it to predict tail-length changes resulting from 3'-untranslated region (3'-UTR) single-nucleotide substitutions. It also predicted tail-length-mediated translational changes, allowing us to nominate genes important for oocyte maturation. When comparing predicted tail-length changes in human oocytes with genomic datasets of the All of Us Research Program10 and gnomAD11, we found that genetic variants predicted to disrupt tail lengthening have been under negative selection in the human population, thereby linking mRNA tail lengthening to human female fertility.

bioinformatics↗

bioRxiv2023

Control of poly(A)-tail length and translation in vertebrate oocytes and early embryos

During oocyte maturation and early embryogenesis, changes in mRNA poly(A)-tail lengths strongly influence translation, but how these tail-length changes are orchestrated has been unclear. Here, we performed tail-length and translational profiling of mRNA reporter libraries (each with millions of 3'-UTR sequence variants) in frog oocytes and embryos, and fish embryos. We found that the UUUUA element, together with the polyadenylation signal (AAUAAA or AUUAAA), specifies cytoplasmic polyadenylation, and identified contextual features that modulate the activity of both elements. In maturing oocytes, this tail lengthening occurs against a backdrop of global deadenylation and the action of C-rich elements that specify tail-length-independent translational repression. In embryos, cytoplasmic polyadenylation becomes more permissive, and additional elements specify waves of stage-specific deadenylation. Together, these findings largely explain the complex tapestry of tail-length changes observed in early frog and fish development, with strong evidence of conservation in both mice and humans. HighlightsO_LIUUUUA, modulated by contextual features, specifies most cytoplasmic polyadenylation C_LIO_LIStage-specific sequence motifs drive waves of tail-length shortening in embryos C_LIO_LIUUUUA and C-rich motifs can direct tail-length-independent translational repression C_LIO_LITail-length control is conserved in oocytes of frogs, mice, and humans C_LI

molecular biology↗

bioRxiv2023

The widespread influence of ZSWIM8 on microRNAs during mouse embryonic development

MicroRNAs (miRNAs) pair to sites in mRNAs to direct the degradation of these RNA transcripts. Conversely, certain RNA transcripts can direct the degradation of particular miRNAs. This target-directed miRNA degradation (TDMD) requires the ZSWIM8 E3 ubiquitin ligase. Here, we report the function of ZSWIM8 in the mouse embryo. Zswim8-/- embryos were smaller than their littermates and died near the time of birth. This highly penetrant perinatal lethality was apparently caused by a lung sacculation defect attributed to failed maturation of alveolar epithelial cells. Some mutant individuals also had heart ventricular septal defects. These developmental abnormalities were accompanied by aberrant accumulation of >50 miRNAs observed across 12 tissues, which often led to enhanced repression of their mRNA targets. These ZSWIM8-sensitive miRNAs were preferentially produced from genomic miRNA clusters, and in some cases, ZSWIM8 caused a switch in the dominant strand that accumulated from a miRNA hairpin--observations suggesting that TDMD provides a mechanism to uncouple co-produced miRNAs from each other. Overall, our findings indicate that the regulatory influence of TDMD in mammalian biology is widespread and posit the existence of many yet-unidentified transcripts that trigger miRNA degradation.

molecular biology↗

bioRxiv2020

Are fleas highly modified Mecoptera? Phylogenomic resolution of Antliophora (Insecta: Holometabola)

Insect orders have been defined and stable for decades, with few notable exceptions (e.g., Blattodea and Psocoptera). One of the few remaining questions of order-level monophyly is that of Mecoptera in respect to the phylogenetic placement of Siphonaptera (fleas). We used a large set of transcriptomic nucleotide sequence data representing 56 species and more than 3,000 single-copy genes to resolve the evolutionary history of Antliophora, including fleas (Siphonaptera), scorpionflies and relatives (Mecoptera), and true flies (Diptera). We find that fleas and mecopterans together are the sister group of flies. However, our data and/or analyses are unable to distinguish whether fleas are sister to a monophyletic Mecoptera, or whether they arose from within extant mecopteran families, rendering Mecoptera paraphyletic. We did not detect parameter bias in our dataset after applying a broad range of detection methods. Counter to a previous hypothesis that placed fleas within Mecoptera as the sister group to wingless boreids (snow fleas), we found a potential sister group relationship between fleas and the enigmatic family Nannochoristidae. Although we lack conclusive evidence, it seems possible that fleas represent the most-species rich group of modern mecopterans and that their parasitic lifestyle and morphological adaptations have simply made them unrecognizable in respect to their order-level classification.

evolutionary biology↗

bioRxiv2019

Global analyses of the dynamics of mammalian microRNA metabolism

Rates of production and degradation together specify microRNA (miRNA) abundance and dynamics. Here, we used approach-to-equilibrium metabolic labeling to assess these rates for 176 miRNAs in contact-inhibited mouse embryonic fibroblasts (MEFs), 182 miRNAs in dividing MEFs, and 136 miRNAs in mouse embryonic stem cells (mESCs). MicroRNA duplexes, each comprising a mature miRNA and its passenger strand, are produced at rates as fast as 114 {+/-} 49 copies/cell per min, which exceeds rates reported for any mRNAs. These duplexes are rapidly loaded into Argonaute, with <10 min typically required for duplex loading and silencing-complex maturation. Within Argonaute, guide strands have stabilities that vary by 100-fold. Half-lives also vary globally between cell lines, with median values ranging from 6.3 to 34 h in mESCs and contact-inhibited MEFs, respectively. Moreover, relative half-lives for individual miRNAs vary between cell types, implying the influence of cell-specific factors in dictating turnover rate. The apparent influence of miRNA regions most important for targeting, together with the effect of one target on miR-7a-5p accumulation, suggest that targets fulfill this role. Analysis of the tailing and trimming of miRNA 3' termini showed that the flux was typically greatest through the isoform tailed with a single uridine, although changes in this flux did not correspond to changes in stability, which suggested that the processes of tailing and trimming might be independent from that of decay. Together these results establish a framework for describing the dynamics and regulation of miRNAs throughout their lifecycle.

molecular biology↗

bioRxiv2017

kpLogo: positional k-mer analysis reveals hidden specificity in biological sequences

Motifs of only 1-4 letters can play important roles when present at key locations within macromolecules. Because existing motif-discovery tools typically miss these position-specific short motifs, we developed kpLogo, a probability-based logo tool for integrated detection and visualization of position-specific ultra-short motifs. kpLogo also overcomes the limitations of conventional motif-visualization tools in handling positional interdependencies and utilizing ranked or weighted sequences increasingly available from high-throughput assays.

bioinformatics↗