ABSTRACT
Introduction: The pregnant state may cause or exacerbate existing neurological disease. Gliomas appear to be influenced by the physiological changes that occur during pregnancy. The pregnant state may also cause seizures, including status epilepticus. There are currently no defined treatment guidelines to direct clinical decision making, and many of the commonly employed therapies are contraindicated during pregnancy. Case Presentation: The current article describes the case of a 40-year-old G3P1101 female at 10 weeks' gestation, who sought medical care for recurrent left hemifacial twitching, eventually leading to nonconvulsive status epilepticus. Intubation and sedation were required to achieve seizure cessation. Imaging revealed a lobulated cystic mass in the right parietal lobe, suspicious for low-grade glioma. Despite thorough explanation of the potential risks, the patient adamantly wished to pursue surgical intervention. An uneventful craniotomy was performed for resection of a low-grade glioma. No patient or fetal complications were encountered, and the patient has not had any reported seizures since surgery. Discussion: Managing complex neurosurgical diseases in pregnant patients provides both clinical and ethical quandaries. We describe the successful management of a patient presenting with status epilepticus caused by an underlying glioma during pregnancy. Although challenging, favorable neurosurgical outcomes are possible during pregnancy.
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INTRODUCTION: Thrombectomy for medium vessel occlusion is a topic of great interest. We describe a single-center experience with the Penumbra 3-MAX aspiration catheter in stroke thrombectomy of medium vessel occlusion(MeVO). We investigated the use of 3-MAX as a de-novo first pass catheter and as a rescue aspiration device following attempted thrombectomy with other devices. This is the first description of the first pass effect and successful recanalization rate of the 3-MAX catheter in de-novo vs. rescue use of this catheter. METHODS: From January 2017 to January 2023, 84 patients underwent mechanical thrombectomy with use of a Penumbra 3MAX aspiration catheter at our comprehensive stroke center. Patient charts were retrospectively reviewed. Primary efficacy outcome was successful recanalization following mechanical thrombectomy. Primary safety outcome was intracerebral hemorrhage. RESULTS: A total of 84 patients underwent MT with the 3MAX device. It was used as a de novo catheter in 27(32.1%) and as a rescue catheter in 57(67.9%) patients. 35(41.6%) patients achieved angiographic TICI grade ≥ 2c. De novo 3MAX use led to 68.18% successful recanalization and rescue use led to 72.22% recanalization (p = 0.67) as measured by TICI score of 2c or better. Parenchymal intracerebral hemorrhages (PH) were present in 8 patients (9.5%). CONCLUSION: The Penumbra 3MAX catheter is safe and effective when used as a first pass or a rescue device in mechanical thrombectomy. We found similar rates of successful recanalization and minimal hemorrhagic risk when comparing the 3MAX as a rescue or de novo aspiration catheter.
ABSTRACT
Biomolecular condensates, such as the nucleoli or P-bodies, are non-membrane-bound assemblies of proteins and nucleic acids that facilitate specific cellular processes. Like eukaryotic P-bodies, the recently discovered bacterial ribonucleoprotein bodies (BR-bodies) organize the mRNA decay machinery, yet the similarities in molecular and cellular functions across species have been poorly explored. Here, we examine the functions of BR-bodies in the nitrogen-fixing endosymbiont Sinorhizobium meliloti, which colonizes the roots of compatible legume plants. Assembly of BR-bodies into visible foci in S. meliloti cells requires the C-terminal intrinsically disordered region (IDR) of RNase E, and foci fusion is readily observed in vivo, suggesting they are liquid-like condensates that form via mRNA sequestration. Using Rif-seq to measure mRNA lifetimes, we found a global slowdown in mRNA decay in a mutant deficient in BR-bodies, indicating that compartmentalization of the degradation machinery promotes efficient mRNA turnover. While BR-bodies are constitutively present during exponential growth, the abundance of BR-bodies increases upon cell stress, whereby they promote stress resistance. Finally, using Medicago truncatula as host, we show that BR-bodies enhance competitiveness during colonization and appear to be required for effective symbiosis, as mutants without BR-bodies failed to stimulate plant growth. These results suggest that BR-bodies provide a fitness advantage for bacteria during infection, perhaps by enabling better resistance against the host immune response.
ABSTRACT
Bacterial ribonucleoprotein bodies (BR-bodies) are non-membrane-bound structures that facilitate mRNA decay by concentrating mRNA substrates with RNase E and the associated RNA degradosome machinery. However, the full complement of proteins enriched in BR-bodies has not been defined. Here, we define the protein components of BR-bodies through enrichment of the bodies followed by mass spectrometry-based proteomic analysis. We find 111 BR-body-enriched proteins showing that BR-bodies are more complex than previously assumed. We identify five BR-body-enriched proteins that undergo RNA-dependent phase separation in vitro with a complex network of condensate mixing. We observe that some RNP condensates co-assemble with preferred directionality, suggesting that RNA may be trafficked through RNP condensates in an ordered manner to facilitate mRNA processing/decay, and that some BR-body-associated proteins have the capacity to dissolve the condensate. Altogether, these results suggest that a complex network of protein-protein and protein-RNA interactions controls BR-body phase separation and RNA processing.
Subject(s)
Proteome , RNA , Proteome/metabolism , Proteomics , Ribonucleoproteins/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolismABSTRACT
Bacterial translation is thought to initiate by base pairing of the 16S rRNA and the Shine-Dalgarno sequence in the mRNA's 5' untranslated region (UTR). However, transcriptomics has revealed that leaderless mRNAs, which completely lack any 5' UTR, are broadly distributed across bacteria and can initiate translation in the absence of the Shine-Dalgarno sequence. To investigate the mechanism of leaderless mRNA translation initiation, synthetic in vivo translation reporters were designed that systematically tested the effects of start codon accessibility, leader length, and start codon identity on leaderless mRNA translation initiation. Using these data, a simple computational model was built based on the combinatorial relationship of these mRNA features that can accurately classify leaderless mRNAs and predict the translation initiation efficiency of leaderless mRNAs. Thus, start codon accessibility, leader length, and start codon identity combine to define leaderless mRNA translation initiation in bacteria.
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An evolutionarily conserved feature of introns is their ability to enhance expression of genes that harbor them. Introns have been shown to regulate gene expression at the transcription and post-transcription level. The general perception is that a promoter-proximal intron is most efficient in enhancing gene expression and the effect diminishes with the increase in distance from the promoter. Here we show that the intron regains its positive influence on gene expression when in proximity to the terminator. We inserted ACT1 intron into different positions within IMD4 and INO1 genes. Transcription Run-On (TRO) analysis revealed that the transcription of both IMD4 and INO1 was maximal in constructs with a promoter-proximal intron and decreased with the increase in distance of the intron from the promoter. However, activation was partially restored when the intron was placed close to the terminator. We previously demonstrated that the promoter-proximal intron stimulates transcription by affecting promoter directionality through gene looping-mediated recruitment of termination factors in the vicinity of the promoter region. Here we show that the terminator-proximal intron also enhances promoter directionality and results in compact gene architecture with the promoter and terminator regions in close physical proximity. Furthermore, we show that both the promoter and terminator-proximal introns facilitate assembly or stabilization of the preinitiation complex (PIC) on the promoter. On the basis of these findings, we propose that proximity to both the promoter and the terminator regions affects the transcription regulatory potential of an intron, and the terminator-proximal intron enhances transcription by affecting both the assembly of preinitiation complex and promoter directionality.
ABSTRACT
Biomolecular condensates play a key role in organizing RNAs and proteins into membraneless organelles. Bacterial RNP-bodies (BR-bodies) are a biomolecular condensate containing the RNA degradosome mRNA decay machinery, but the biochemical function of such organization remains poorly defined. Here, we define the RNA substrates of BR-bodies through enrichment of the bodies followed by RNA sequencing (RNA-seq). We find that long, poorly translated mRNAs, small RNAs, and antisense RNAs are the main substrates, while rRNA, tRNA, and other conserved non-coding RNAs (ncRNAs) are excluded from these bodies. BR-bodies stimulate the mRNA decay rate of enriched mRNAs, helping to reshape the cellular mRNA pool. We also observe that BR-body formation promotes complete mRNA decay, avoiding the buildup of toxic endo-cleaved mRNA decay intermediates. The combined selective permeability of BR-bodies for both enzymes and substrates together with the stimulation of the sub-steps of mRNA decay provide an effective organization strategy for bacterial mRNA decay.
Subject(s)
Caulobacter crescentus/metabolism , Endoribonucleases/metabolism , Escherichia coli/metabolism , Multienzyme Complexes/metabolism , Organelles/metabolism , Polyribonucleotide Nucleotidyltransferase/metabolism , RNA Helicases/metabolism , RNA Stability , RNA, Messenger/metabolism , Caulobacter crescentus/genetics , Caulobacter crescentus/growth & development , Endoribonucleases/genetics , Escherichia coli/genetics , Escherichia coli/growth & development , Humans , Multienzyme Complexes/genetics , Organelles/genetics , Polyribonucleotide Nucleotidyltransferase/genetics , RNA Helicases/genetics , RNA, Antisense/genetics , RNA, Antisense/metabolism , RNA, Messenger/genetics , RNA, Ribosomal/genetics , RNA, Ribosomal/metabolism , RNA, Small Untranslated/genetics , RNA, Small Untranslated/metabolism , RNA, Transfer/genetics , RNA, Transfer/metabolism , RNA, Untranslated/genetics , RNA, Untranslated/metabolismABSTRACT
Caulobacter crescentus is a model for the bacterial cell cycle which culminates in asymmetric cell division, yet little is known about the absolute levels of protein synthesis of the cellular parts needed to complete the cell cycle. Here we utilize ribosome profiling to provide absolute measurements of mRNA translation in C. crescentus, providing an important resource with quantitative genome-wide measurements of protein output across individual genes. Analysis of protein synthesis rates revealed â¼4.5% of cellular protein synthesis is for genes related to vitamin B12 import (btuB) and B12-independent methionine biosynthesis (metE) when grown in common growth media lacking B12 While its facultative B12 lifestyle provides a fitness advantage in the absence of B12, we find that it provides a fitness disadvantage of the cells in the presence of B12, potentially explaining why many Caulobacter species have lost the metE gene and become obligates for B12 IMPORTANCE Caulobacter crescentus is a model system of the bacterial cell cycle culminating in asymmetric cell division, with each daughter cell inheriting a distinct set of proteins. While a genetic network of master transcription factors coordinates the cell cycle timing of transcription for nearly 20% of Caulobacter genes, we lack knowledge of how many of each protein "part" encoded in the genome are synthesized. Therefore, to determine the absolute production rates across the genome, we performed ribosome profiling, providing, for the first time, a quantitative resource with measurements of each protein "part" needed to generate daughter cells. This resource furthers the goal of a systems-level understanding of the genetic network controlling asymmetric cell division. To highlight the utility of this data set, we probe the protein synthesis cost of a B12 utilization pathway and provide new insights into Caulobacter's adaptation to its natural environments.