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1.
Nature ; 2024 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-39385025

RESUMO

The interplay between translation and mRNA decay is widespread in human cells1-3. In quality-control pathways, exonucleolytic degradation of mRNA associated with translating ribosomes is mediated largely by the cytoplasmic exosome4-9, which includes the exoribonuclease complex EXO10 and the helicase complex SKI238 (refs. 10-16). The helicase can extract mRNA from the ribosome and is expected to transfer it to the exoribonuclease core through a bridging factor, HBS1L3 (also known as SKI7), but the mechanisms of this molecular handover remain unclear7,17,18. Here we reveal how human EXO10 is recruited by HBS1L3 (SKI7) to an active ribosome-bound SKI238 complex. We show that rather than a sequential handover, a direct physical coupling mechanism takes place, which culminates in the formation of a cytoplasmic exosome-ribosome supercomplex. Capturing the structure during active decay reveals a continuous path in which an RNA substrate threads from the 80S ribosome through the SKI2 helicase into the exoribonuclease active site of the cytoplasmic exosome complex. The SKI3 subunit of the complex directly binds to HBS1L3 (SKI7) and also engages a surface of the 40S subunit, establishing a recognition platform in collided disomes. Exosome and ribosome thus work together as a single structural and functional unit in co-translational mRNA decay, coordinating their activities in a transient supercomplex.

2.
J Nucl Med ; 2024 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-39327016

RESUMO

In nuclear medicine, estimating the number of radioactive decays that occur in a source organ per unit administered activity of a radiopharmaceutical (i.e., the time-integrated activity coefficient [TIAC]) is an essential task within the internal dosimetry workflow. TIAC estimation is commonly derived by least-squares fitting of various exponential models to organ time-activity data (radiopharmaceutical biodistribution). Rarely, however, are methods used to objectively determine the model that best characterizes the data. Additionally, the uncertainty associated with the resultant TIAC is generally not evaluated. As part of the MIRDsoft initiative, MIRDfit has been developed to offer a biodistribution fitting software solution that provides the following essential features and advantages for internal dose assessment: nuclear medicine-appropriate fit functions; objective metrics for guiding best-fit selection; TIAC uncertainty calculation; quality control and data archiving; integration with MIRDcalc software for dose calculation; and a user-friendly Excel-based interface. For demonstration and comparative validation of MIRDfit's performance, TIACs were derived from serial imaging studies involving 18F-FDG and 177Lu-DOTATATE using MIRDfit. These TIACs were then compared with TIAC estimates obtained using other software. In most cases, the TIACs agreed within approximately 10% between MIRDfit and the other software. MIRDfit has been endorsed by the MIRD Committee of the Society of Nuclear Medicine and Molecular Imaging and has been integrated into the MIRDsoft suite of free dosimetry software; it is available for download at no user cost (https://mirdsoft.org/).

3.
mBio ; : e0098124, 2024 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-39235249

RESUMO

Cellular responses to external stress allow microorganisms to adapt to a vast array of environmental conditions, including infection sites. The molecular mechanisms behind these responses are studied to gain insight into microbial pathogenesis, which could lead to new antimicrobial therapies. Here, we explore a role for arrestin protein-mediated ubiquitination in stress response and pathogenesis in the pathogenic fungus Cryptococcus neoformans. In a previous study, we identified four arrestin-like proteins in C. neoformans and found that one of these is required for efficient membrane synthesis, likely by directing interaction between fatty acid synthases and the Rsp5 E3 ubiquitin ligase. Here, we further explore Cn Rsp5 function and determine that this single Ub ligase is absolutely required for pathogenesis and survival in the presence of cellular stress. Additionally, we show that a second arrestin-like protein, Ali2, similarly facilitates interaction between Rsp5 and some of its protein targets. Of the four postulated C. neoformans arrestin-like proteins, Ali2 appears to contribute the most to C. neoformans pathogenesis, likely by directing Rsp5 to pathogenesis-related ubiquitination targets. A proteomics-based differential ubiquitination screen revealed that several known cell surface proteins are ubiquitinated by Rsp5 and a subset also requires Ali2 for their ubiquitination. Rsp5-mediated ubiquitination alters the stability and the localization of these proteins. A loss of Rsp5-mediated ubiquitination results in cell wall defects that increase susceptibility to external stresses. These findings support a model in which arrestin-like proteins guide Rsp5 to ubiquitinate specific target proteins, some of which are required for survival during stress. IMPORTANCE: Microbial proteins involved in human infectious diseases often need to be modified by specific chemical additions to be fully functional. Here, we explore the role of a particular protein modification, ubiquitination, in infections due to the human fungal pathogen Cryptococcus neoformans. We identified a complex of proteins responsible for adding ubiquitin groups to fungal proteins, and this complex is required for virulence. These proteins are fungal specific and might be targets for novel anti-infection therapy.

4.
Leukemia ; 2024 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-39261602

RESUMO

SF3B1 mutations are recurrent in chronic lymphocytic leukemia (CLL), particularly enriched in clinically aggressive stereotyped subset #2. To investigate their impact, we conducted RNA-sequencing of 18 SF3B1MUT and 17 SF3B1WT subset #2 cases and identified 80 significant alternative splicing events (ASEs). Notable ASEs concerned exon inclusion in the non-canonical BAF (ncBAF) chromatin remodeling complex subunit, BRD9, and splice variants in eight additional ncBAF complex interactors. Long-read RNA-sequencing confirmed the presence of splice variants, and extended analysis of 139 CLL cases corroborated their association with SF3B1 mutations. Overexpression of SF3B1K700E induced exon inclusion in BRD9, resulting in a novel splice isoform with an alternative C-terminus. Protein interactome analysis of the BRD9 splice isoform revealed augmented ncBAF complex interaction, while exhibiting decreased binding of auxiliary proteins, including SPEN, BRCA2, and CHD9. Additionally, integrative multi-omics analysis identified a ncBAF complex-bound gene quartet on chromosome 1 with higher expression levels and more accessible chromatin in SF3B1MUT CLL. Finally, Cancer Dependency Map analysis and BRD9 inhibition displayed BRD9 dependency and sensitivity in cell lines and primary CLL cells. In conclusion, spliceosome dysregulation caused by SF3B1 mutations leads to multiple ASEs and an altered ncBAF complex interactome, highlighting a novel pathobiological mechanism in SF3B1MUT CLL.

5.
Chemphyschem ; : e202400761, 2024 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-39219146

RESUMO

The quantification of Lewis acidity is of fundamental and applied importance in chemistry. While the computed fluoride ion affinity (FIA) is the most widely accepted thermodynamic metric, only sparse experimental values exist. Accordingly, a benchmark of methods for computing Lewis pair formation enthalpies, also with a broader set of Lewis bases against experimental data, is missing. Herein, we evaluate different density functionals against a set of 112 experimentally determined Lewis acid/base binding enthalpies and gauge influences such as solvation correction in structure optimization. From that, we can recommend r2SCAN-3c for robust quantification of this omnipresent interaction.

6.
Nat Commun ; 15(1): 7951, 2024 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-39261483

RESUMO

The nuclear spin, being much more isolated from the environment than its electronic counterpart, presents opportunities for quantum experiments with prolonged coherence times. Electron spin resonance (ESR) combined with scanning tunnelling microscopy (STM) provides a bottom-up platform to study the fundamental properties of nuclear spins of single atoms on a surface. However, access to the time evolution of nuclear spins remained a challenge. Here, we present an experiment resolving the nanosecond coherent dynamics of a hyperfine-driven flip-flop interaction between the spin of an individual nucleus and that of an orbiting electron. We use the unique local controllability of the magnetic field emanating from the STM probe tip to bring the electron and nuclear spins in tune, as evidenced by a set of avoided level crossings in ESR-STM. Subsequently, we polarize both spins through scattering of tunnelling electrons and measure the resulting free evolution of the coupled spin system using a DC pump-probe scheme. The latter reveals a complex pattern of multiple interfering coherent oscillations, providing unique insight into hyperfine physics on a single atom level.

7.
Molecules ; 29(16)2024 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-39202885

RESUMO

1,2,3,4,5-pentathiepines (PTEs) are naturally occurring polysulfides of increasing scientific interest based on their identified pharmacological activities. Artificial PTEs with N-heterocyclic backbones are efficiently synthesized via mediation by a molybdenum-oxo-bistetrasulfido complex. A common feature of all precursor alkynes successfully used to date in this reaction is the presence of a -CH(OEt)2 group since the previously postulated mechanism requires the presence of one OEt- as the leaving group, and the second must become a transient ethoxonium moiety. This raised the question of whether there really is a need for two, maybe only one, or possibly even zero ethoxy substituents. This research problem was systematically addressed by respective variations in the precursor-alkyne derivatives and by employing one related allene species. It was found that the total absence of ethoxy substituents prevents the formation of PTEs entirely, while the presence of a single ethoxy group results in the possibility to distinctly functionalize the position on the resulting N-heterocyclic pyrrole five ring in the target compound. This position was previously exclusively occupied by an -OEt for all products of the molybdenum-mediated reaction. The allene was applied with similar success as precursor as with the related alkyne. The now-employable significant change in precursor composition gives access to a whole new PTE subfamily, allowing further modulation of (physico)-chemical properties such as solubility, and provides additional insight into the mechanism of PTE formation; it comprises a merely partial validation of the previous hypothesis. The new alkyne precursors and pentathiepines were characterized by a variety of instrumental analyses (NMR, mass spec, UV-vis) and in six cases (one alkyne precursor, one unexpected side product, and four PTEs) by single-crystal X-ray diffraction. Syntheses, isolation procedures, analytical data, and the impact of the findings on the previously proposed mechanism are described in detail herein.

8.
Drug Saf ; 2024 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-39102176

RESUMO

BACKGROUND AND OBJECTIVE: Missing data and unmeasured confounding are key challenges for external comparator studies. This work evaluates bias and other performance characteristics depending on missingness and unmeasured confounding by means of two case studies and simulations. METHODS: Two case studies were constructed by taking the treatment arms from two randomised controlled trials and an external real-world data source that exhibited substantial missingness. The indications of the randomised controlled trials were multiple myeloma and metastatic hormone-sensitive prostate cancer. Overall survival was taken as the main endpoint. The effects of missing data and unmeasured confounding were assessed for the case studies by reporting estimated external comparator versus randomised controlled trial treatment effects. Based on the two case studies, simulations were performed broadening the settings by varying the underlying hazard ratio, the sample size, the sample size ratio between the experimental arm and the external comparator, the number of missing covariates and the percentage of missingness. Thereby, bias and other performance metrics could be quantified dependent on these factors. RESULTS: For the multiple myeloma external comparator study, results were in line with the randomised controlled trial, despite missingness and potential unmeasured confounding, while for the metastatic hormone-sensitive prostate cancer case study missing data led to a low sample size, leading overall to inconclusive results. Furthermore, for the metastatic hormone-sensitive prostate cancer study, missing data in important eligibility criteria led to further limitations. Simulations were successfully applied to gain a quantitative understanding of the effects of missing data and unmeasured confounding. CONCLUSIONS: This exploratory study confirmed external comparator strengths and limitations by quantifying the impact of missing data and unmeasured confounding using case studies and simulations. In particular, missing data in key eligibility criteria were seen to limit the ability to derive the external comparator target analysis population accurately, while simulations demonstrated the magnitude of bias to expect for various settings.

9.
J Magn Reson Imaging ; 2024 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-39166882

RESUMO

Whole-heart 4D-flow MRI is a valuable tool for advanced visualization and quantification of blood flow in cardiovascular imaging. Despite advantages over 2D-phase-contrast flow, clinical implementation remains only partially exploited due to many hurdles in all steps, from image acquisition, reconstruction, postprocessing and analysis, clinical embedment, reporting, legislation, and regulation to data storage. The intent of this manuscript was 1) to evaluate the extent of clinical implementation of whole-heart 4D-flow MRI, 2) to identify hurdles hampering clinical implementation, and 3) to reach consensus on requirements for clinical implementation of whole-heart 4D-flow MRI. This study is based on Delphi analysis. This study involves a panel of 18 experts in the field on whole-heart 4D-flow MRI. The experience with and opinions of experts (mean 13 years of experience, interquartile range 6) in the field were aggregated. This study showed that among experts in the cardiovascular field, whole-heart 4D-flow MRI is currently used for both clinical and research purposes. Overall, the panelists agreed that major hurdles currently hamper implementation and utilization. The sequence-specific hurdles identified were long scan time and lack of standardization. Further hurdles included cumbersome and time-consuming segmentation and postprocessing. The study concludes that implementation of whole-heart 4D-flow MRI in clinical routine is feasible, but the implementation process is complex and requires a dedicated, multidisciplinary team. A predefined plan, including risk assessment and technique validation, is essential. The reported consensus statements may guide further tool development and facilitate broader implementation and clinical use. LEVEL OF EVIDENCE: NA TECHNICAL EFFICACY: Stage 5.

10.
Nat Commun ; 15(1): 6819, 2024 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-39122689

RESUMO

Organic electrochemical transistors (OECTs) underpin a range of emerging technologies, from bioelectronics to neuromorphic computing, owing to their unique coupling of electronic and ionic charge carriers. In this context, various OECT systems exhibit significant hysteresis in their transfer curve, which is frequently leveraged to achieve non-volatility. Meanwhile, a general understanding of its physical origin is missing. Here, we introduce a thermodynamic framework that readily explains the emergence of bistable OECT operation via the interplay of enthalpy and entropy. We validate this model through temperature-resolved characterizations, material manipulation, and thermal imaging. Further, we reveal deviations from Boltzmann statistics for the subthreshold swing and reinterpret existing literature. Capitalizing on these findings, we finally demonstrate a single-OECT Schmitt trigger, thus compacting a multi-component circuit into a single device. These insights provide a fundamental advance for OECT physics and its application in non-conventional computing, where symmetry-breaking phenomena are pivotal to unlock new paradigms of information processing.

11.
Crit Care ; 28(1): 269, 2024 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-39217380

RESUMO

This review explores the complex interactions between sedation and invasive ventilation and examines the potential of volatile anesthetics for lung- and diaphragm-protective sedation. In the early stages of invasive ventilation, many critically ill patients experience insufficient respiratory drive and effort, leading to compromised diaphragm function. Compared with common intravenous agents, inhaled sedation with volatile anesthetics better preserves respiratory drive, potentially helping to maintain diaphragm function during prolonged periods of invasive ventilation. In turn, higher concentrations of volatile anesthetics reduce the size of spontaneously generated tidal volumes, potentially reducing lung stress and strain and with that the risk of self-inflicted lung injury. Taken together, inhaled sedation may allow titration of respiratory drive to maintain inspiratory efforts within lung- and diaphragm-protective ranges. Particularly in patients who are expected to require prolonged invasive ventilation, in whom the restoration of adequate but safe inspiratory effort is crucial for successful weaning, inhaled sedation represents an attractive option for lung- and diaphragm-protective sedation. A technical limitation is ventilatory dead space introduced by volatile anesthetic reflectors, although this impact is minimal and comparable to ventilation with heat and moisture exchangers. Further studies are imperative for a comprehensive understanding of the specific effects of inhaled sedation on respiratory drive and effort and, ultimately, how this translates into patient-centered outcomes in critically ill patients.


Assuntos
Anestésicos Inalatórios , Diafragma , Respiração Artificial , Humanos , Diafragma/efeitos dos fármacos , Anestésicos Inalatórios/administração & dosagem , Anestésicos Inalatórios/farmacologia , Respiração Artificial/métodos , Pulmão/efeitos dos fármacos , Pulmão/fisiologia
12.
Cell Rep Med ; 5(9): 101699, 2024 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-39208801

RESUMO

Fibrolamellar carcinoma (FLC) is a rare, lethal, early-onset liver cancer with a critical need for new therapeutics. The primary driver in FLC is the fusion oncoprotein, DNAJ-PKAc, which remains challenging to target therapeutically. It is critical, therefore, to expand understanding of the FLC molecular landscape to identify druggable pathways/targets. Here, we perform the most comprehensive integrative proteo-metabolomic analysis of FLC. We also conduct nutrient manipulation, respirometry analyses, as well as key loss-of-function assays in FLC tumor tissue slices from patients. We propose a model of cellular energetics in FLC pointing to proline anabolism being mediated by ornithine aminotransferase hyperactivity and ornithine transcarbamylase hypoactivity with serine and glutamine catabolism fueling the process. We highlight FLC's potential dependency on voltage-dependent anion channel (VDAC), a mitochondrial gatekeeper for anions including pyruvate. The metabolic rewiring in FLC that we propose in our model, with an emphasis on mitochondria, can be exploited for therapeutic vulnerabilities.


Assuntos
Aminoácidos , Carcinoma Hepatocelular , Metabolômica , Mitocôndrias , Humanos , Mitocôndrias/metabolismo , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patologia , Metabolômica/métodos , Aminoácidos/metabolismo , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patologia , Canais de Ânion Dependentes de Voltagem/metabolismo , Canais de Ânion Dependentes de Voltagem/genética , Proteômica/métodos , Feminino
13.
Cancer Discov ; 14(9): 1699-1716, 2024 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-39193992

RESUMO

Upregulation of MYC is a hallmark of cancer, wherein MYC drives oncogenic gene expression and elevates total RNA synthesis across cancer cell transcriptomes. Although this transcriptional anabolism fuels cancer growth and survival, the consequences and metabolic stresses induced by excess cellular RNA are poorly understood. Herein, we discover that RNA degradation and downstream ribonucleotide catabolism is a novel mechanism of MYC-induced cancer cell death. Combining genetics and metabolomics, we find that MYC increases RNA decay through the cytoplasmic exosome, resulting in the accumulation of cytotoxic RNA catabolites and reactive oxygen species. Notably, tumor-derived exosome mutations abrogate MYC-induced cell death, suggesting excess RNA decay may be toxic to human cancers. In agreement, purine salvage acts as a compensatory pathway that mitigates MYC-induced ribonucleotide catabolism, and inhibitors of purine salvage impair MYC+ tumor progression. Together, these data suggest that MYC-induced RNA decay is an oncogenic stress that can be exploited therapeutically. Significance: MYC is the most common oncogenic driver of poor-prognosis cancers but has been recalcitrant to therapeutic inhibition. We discovered a new vulnerability in MYC+ cancer where MYC induces cell death through excess RNA decay. Therapeutics that exacerbate downstream ribonucleotide catabolism provide a therapeutically tractable approach to TNBC (Triple-negative Breast Cancer) and other MYC-driven cancers.


Assuntos
Neoplasias da Mama , Proteínas Proto-Oncogênicas c-myc , Estabilidade de RNA , Ribonucleotídeos , Humanos , Feminino , Neoplasias da Mama/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Proteínas Proto-Oncogênicas c-myc/metabolismo , Proteínas Proto-Oncogênicas c-myc/genética , Ribonucleotídeos/farmacologia , Linhagem Celular Tumoral , Camundongos , Regulação Neoplásica da Expressão Gênica , Animais
14.
Chem Sci ; 15(28): 10803-10809, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39027292

RESUMO

The dimerization of nitrogen monoxide (NO) is highly relevant in homo- and heterogeneous biochemical and environmental redox processes, but a broader understanding is challenged by the endergonic nature of this equilibrium. The present work describes NO-dimerization leveraged by structurally constrained aluminum and metal-ligand cooperativity at the anionic calix[4]pyrrolato aluminate(III). Quantum chemical calculations reveal the driving force for N-N bond formation, while reactivity tests shed light on subsequent redox chemistry and NO decomposition at metal surfaces. Inhibiting the dimerization pathway by saturating NO's unpaired electron with a phenyl group (nitrosobenzene) allows trapping the 1,2-adduct as a key intermediate. Elevated temperatures result in an unprecedented and high-yielding rearrangement of the calix[4]pyrrolato ligand scaffold. Kinetic and theoretical studies provide a comprehensive picture of the rearrangement mechanism and delineate systematics for ring modification of the prominent calix[4]pyrrole macrocycle.

15.
J Crit Care ; 83: 154853, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-38955117

RESUMO

PURPOSE: Cardiac surgery, post-cardiotomy cardiogenic shock (PCCS), and temporary mechanical circulatory support (tMCS) provoke substantial inflammation. We therefore investigated whether a selenium-based, anti-inflammatory strategy would benefit PCCS patients treated with tMCS in a post-hoc analysis of the sustain CSX trial. METHODS: Post-hoc analysis of patients receiving tMCS for PCCS in the Sustain CSX trial, which investigated the effects of high-dose selenium on postoperative organ dysfunction in cardiac surgery patients. PRIMARY OUTCOME: duration of tMCS therapy. SECONDARY OUTCOMES: postoperative organ dysfunction and 30-day mortality. RESULTS: Thirty-nine patients were treated with tMCS for PCCS. There was no difference in the median duration of tMCS between the selenium and the placebo group (3 days [IQR: 1-6] vs. 2 days [IQR: 1-7], p = 0.52). Median dialysis duration was longer in the selenium group (1.5 days [0-21.8] vs. 0 days [0-1.8], p = 0.048). There was no difference in 30-day mortality (53% vs. 41%, OR 1.44, 95% CI 0.32-6.47, p = 0.62). CONCLUSION: In this explorative study, a perioperative high-dose selenium-supplementation did not show beneficial effects on organ dysfunctions and mortality rates in patients with PCCS receiving tMCS.


Assuntos
Procedimentos Cirúrgicos Cardíacos , Complicações Pós-Operatórias , Selênio , Choque Cardiogênico , Humanos , Choque Cardiogênico/mortalidade , Choque Cardiogênico/terapia , Masculino , Feminino , Selênio/administração & dosagem , Selênio/uso terapêutico , Pessoa de Meia-Idade , Idoso , Complicações Pós-Operatórias/mortalidade , Complicações Pós-Operatórias/prevenção & controle , Coração Auxiliar , Insuficiência de Múltiplos Órgãos/mortalidade , Insuficiência de Múltiplos Órgãos/prevenção & controle , Insuficiência de Múltiplos Órgãos/etiologia
16.
bioRxiv ; 2024 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-38979371

RESUMO

Sporadic early-onset Alzheimer's disease (sEOAD) represents a significant but less-studied subtype of Alzheimer's disease (AD). Here, we generated a single-nucleus multiome atlas derived from the postmortem prefrontal cortex, entorhinal cortex, and hippocampus of nine individuals with or without sEOAD. Comprehensive analyses were conducted to delineate cell type-specific transcriptomic changes and linked candidate cis- regulatory elements (cCREs) across brain regions. We prioritized seven conservative transcription factors in glial cells in multiple brain regions, including RFX4 in astrocytes and IKZF1 in microglia, which are implicated in regulating sEOAD-associated genes. Moreover, we identified the top 25 altered intercellular signaling between glial cells and neurons, highlighting their regulatory potential on gene expression in receiver cells. We reported 38 cCREs linked to sEOAD-associated genes overlapped with late-onset AD risk loci, and sEOAD cCREs enriched in neuropsychiatric disorder risk loci. This atlas helps dissect transcriptional and chromatin dynamics in sEOAD, providing a key resource for AD research.

17.
bioRxiv ; 2024 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-38826218

RESUMO

Analysis of lung alveolar type 2 (AT2) progenitor stem cells has highlighted fundamental mechanisms that direct their differentiation into alveolar type 1 cells (AT1s) in lung repair and disease. However, microRNA (miRNA) mediated post-transcriptional mechanisms which govern this nexus remain understudied. We show here that the let-7 miRNA family serves a homeostatic role in governance of AT2 quiescence, specifically by preventing the uncontrolled accumulation of AT2 transitional cells and by promoting AT1 differentiation to safeguard the lung from spontaneous alveolar destruction and fibrosis. Using mice and organoid models with genetic ablation of let-7a1/let-7f1/let-7d cluster (let-7afd) in AT2 cells, we demonstrate prevents AT1 differentiation and results in aberrant accumulation of AT2 transitional cells in progressive pulmonary fibrosis. Integration of enhanced AGO2 UV-crosslinking and immunoprecipitation sequencing (AGO2-eCLIP) with RNA-sequencing from AT2 cells uncovered the induction of direct targets of let-7 in an oncogene feed-forward regulatory network including BACH1/EZH2 which drives an aberrant fibrotic cascade. Additional analyses by CUT&RUN-sequencing revealed loss of let-7afd hampers AT1 differentiation by eliciting aberrant histone EZH2 methylation which prevents the exit of AT2 transitional cells into terminal AT1s. This study identifies let-7 as a key gatekeeper of post-transcriptional and epigenetic chromatin signals to prevent AT2-driven pulmonary fibrosis.

18.
Materials (Basel) ; 17(12)2024 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-38930392

RESUMO

In general, formed components are lightweight as well as highly economic and resource efficient. However, forming-induced ductile damage, which particularly affects the formation and growth of pores, has not been considered in the design of components so far. Therefore, an evaluation of forming-induced ductile damage would enable an improved design and take better advantage of the lightweight nature as it affects the static and dynamic mechanical material properties. To quantify the amount, morphology and distribution of the pores, advanced scanning electron microscopy (SEM) methods such as scanning transmission electron microscopy (STEM) and electron channeling contrast imaging (ECCI) were used. Image segmentation using a deep learning algorithm was applied to reproducibly separate the pores from inclusions such as manganese sulfide inclusions. This was achieved via layer-by-layer ablation of the case-hardened steel 16MnCrS5 (DIN 1.7139, AISI/SAE 5115) with a focused ion beam (FIB). The resulting images were reconstructed in a 3D model to gain a mechanism-based understanding beyond the previous 2D investigations.

19.
Genes (Basel) ; 15(6)2024 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-38927741

RESUMO

Bronchopulmonary dysplasia (BPD) is a chronic lung disease commonly affecting premature infants, with limited therapeutic options and increased long-term consequences. Adrenomedullin (Adm), a proangiogenic peptide hormone, has been found to protect rodents against experimental BPD. This study aims to elucidate the molecular and cellular mechanisms through which Adm influences BPD pathogenesis using a lipopolysaccharide (LPS)-induced model of experimental BPD in mice. Bulk RNA sequencing of Adm-sufficient (wild-type or Adm+/+) and Adm-haplodeficient (Adm+/-) mice lungs, integrated with single-cell RNA sequencing data, revealed distinct gene expression patterns and cell type alterations associated with Adm deficiency and LPS exposure. Notably, computational integration with cell atlas data revealed that Adm-haplodeficient mouse lungs exhibited gene expression signatures characteristic of increased inflammation, natural killer (NK) cell frequency, and decreased endothelial cell and type II pneumocyte frequency. Furthermore, in silico human BPD patient data analysis supported our cell type frequency finding, highlighting elevated NK cells in BPD infants. These results underscore the protective role of Adm in experimental BPD and emphasize that it is a potential therapeutic target for BPD infants with an inflammatory phenotype.


Assuntos
Adrenomedulina , Displasia Broncopulmonar , Adrenomedulina/genética , Adrenomedulina/metabolismo , Displasia Broncopulmonar/genética , Displasia Broncopulmonar/patologia , Displasia Broncopulmonar/metabolismo , Animais , Camundongos , Humanos , Análise de Sequência de RNA/métodos , Modelos Animais de Doenças , Lipopolissacarídeos , Pulmão/metabolismo , Pulmão/patologia , Células Matadoras Naturais/metabolismo , Células Matadoras Naturais/imunologia , Transcriptoma
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