Stress granules (SGs) are transient ribonucleoprotein (RNP) aggregates that form during cellular stress and are increasingly implicated in human neurodegeneration. To study the proteome and ...compositional diversity of SGs in different cell types and in the context of neurodegeneration-linked mutations, we used ascorbate peroxidase (APEX) proximity labeling, mass spectrometry, and immunofluorescence to identify ∼150 previously unknown human SG components. A highly integrated, pre-existing SG protein interaction network in unstressed cells facilitates rapid coalescence into larger SGs. Approximately 20% of SG diversity is stress or cell-type dependent, with neuronal SGs displaying a particularly complex repertoire of proteins enriched in chaperones and autophagy factors. Strengthening the link between SGs and neurodegeneration, we demonstrate aberrant dynamics, composition, and subcellular distribution of SGs in cells from amyotrophic lateral sclerosis (ALS) patients. Using three Drosophila ALS/FTD models, we identify SG-associated modifiers of neurotoxicity in vivo. Altogether, our results highlight SG proteins as central to understanding and ultimately targeting neurodegeneration.
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•APEX proximity labeling reveals ∼150 unknown SG proteins in a dense protein network•SG composition varies by stress and cell type, especially in neuronal cells•ALS motor neurons contain SGs with distinct content and subcellular distribution•SG proteins modify ALS-mutant-mediated toxicity in fly models of neurodegeneration
Interactions between stress granule proteins exist ahead of a stress response and candidate SG proteins modify disease phenotypes in vivo.
Stress granules (SGs) form during cellular stress and are implicated in neurodegenerative diseases such as amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD). To yield insights into ...the role of SGs in pathophysiology, we performed a high-content screen to identify small molecules that alter SG properties in proliferative cells and human iPSC-derived motor neurons (iPS-MNs). One major class of active molecules contained extended planar aromatic moieties, suggesting a potential to intercalate in nucleic acids. Accordingly, we show that several hit compounds can prevent the RNA-dependent recruitment of the ALS-associated RNA-binding proteins (RBPs) TDP-43, FUS, and HNRNPA2B1 into SGs. We further demonstrate that transient SG formation contributes to persistent accumulation of TDP-43 into cytoplasmic puncta and that our hit compounds can reduce this accumulation in iPS-MNs from ALS patients. We propose that compounds with planar moieties represent a promising starting point to develop small-molecule therapeutics for treating ALS/FTD.
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•∼100 small-molecule compounds modulate SGs in HEK293xT cells, NPCs, and iPS-MNs•ALS-associated RBPs accumulate in SGs during prolonged stress•Molecules with planar moieties disrupt accumulation of ALS-associated RBPs in SGs•Compounds reduce TDP-43 accumulation in cytoplasmic puncta in ALS mutant iPS-MNs
Using high-content screening, we identified a class of planar small molecules that can (1) modulate the dynamics of neurodegeneration-linked stress granules (SGs), (2) reduce SG association of ALS-linked RNA-binding proteins, and (3) prevent accumulation of TDP-43 within persistent cytoplasmic puncta.
RNA-programmed genome editing using CRISPR/Cas9 from Streptococcus pyogenes has enabled rapid and accessible alteration of specific genomic loci in many organisms. A flexible means to target RNA ...would allow alteration and imaging of endogenous RNA transcripts analogous to CRISPR/Cas-based genomic tools, but most RNA targeting methods rely on incorporation of exogenous tags. Here, we demonstrate that nuclease-inactive S. pyogenes CRISPR/Cas9 can bind RNA in a nucleic-acid-programmed manner and allow endogenous RNA tracking in living cells. We show that nuclear-localized RNA-targeting Cas9 (RCas9) is exported to the cytoplasm only in the presence of sgRNAs targeting mRNA and observe accumulation of ACTB, CCNA2, and TFRC mRNAs in RNA granules that correlate with fluorescence in situ hybridization. We also demonstrate time-resolved measurements of ACTB mRNA trafficking to stress granules. Our results establish RCas9 as a means to track RNA in living cells in a programmable manner without genetically encoded tags.
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•RNA-targeting Cas9 (RCas9) enabled recognition of endogenous, unmodified mRNAs•RCas9 did not influence mRNA abundance or amount of translated protein•Subcellular distribution of RCas9 was highly correlated with RNA-FISH•RCas9 revealed trafficking of mRNAs to stress granules in live cells
RNA-targeting Cas9 enables tracking of endogenous, untagged mRNA, establishing CRISPR/Cas9 as a programmable system to recognize RNA in live cells.
As RNA-binding proteins (RBPs) play essential roles in cellular physiology by interacting with target RNA molecules, binding site identification by UV crosslinking and immunoprecipitation (CLIP) of ...ribonucleoprotein complexes is critical to understanding RBP function. However, current CLIP protocols are technically demanding and yield low-complexity libraries with high experimental failure rates. We have developed an enhanced CLIP (eCLIP) protocol that decreases requisite amplification by ∼1,000-fold, decreasing discarded PCR duplicate reads by ∼60% while maintaining single-nucleotide binding resolution. By simplifying the generation of paired IgG and size-matched input controls, eCLIP improves specificity in the discovery of authentic binding sites. We generated 102 eCLIP experiments for 73 diverse RBPs in HepG2 and K562 cells (available at https://www.encodeproject.org), demonstrating that eCLIP enables large-scale and robust profiling, with amplification and sample requirements similar to those of ChIP-seq. eCLIP enables integrative analysis of diverse RBPs to reveal factor-specific profiles, common artifacts for CLIP and RNA-centric perspectives on RBP activity.
The therapeutic potential of Wnt proteins has long been recognized but challenges associated with in vivo stability and delivery have hindered their development as drug candidates. By exploiting the ...hydrophobic nature of the protein we provide evidence that exogenous Wnt3a can be delivered in vivo if it is associated with a lipid vesicle. Recombinant Wnt3a associates with the external surface of the lipid membrane; this association stabilizes the protein and leads to prolonged activation of the Wnt pathway in primary cells. We demonstrate the consequences of Wnt pathway activation in vivo using a bone marrow engraftment assay. These data provide validation for the development of WNT3A as a therapeutic protein.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Wnt signaling is required for both the development and homeostasis of the skin, yet its contribution to skin wound repair remains controversial. By employing Axin2(LacZ/+) reporter mice we evaluated ...the spatial and temporal distribution patterns of Wnt responsive cells, and found that the pattern of Wnt responsiveness varies with the hair cycle, and correlates with wound healing potential. Using Axin2(LacZ/LacZ) mice and an ear wound model, we demonstrate that amplified Wnt signaling leads to improved healing. Utilizing a biochemical approach that mimics the amplified Wnt response of Axin2(LacZ/LacZ) mice, we show that topical application of liposomal Wnt3a to a non-healing wound enhances endogenous Wnt signaling, and results in better skin wound healing. Given the importance of Wnt signaling in the maintenance and repair of skin, liposomal Wnt3a may have widespread application in clinical practice.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Precise control of the timing and magnitude of Notch signaling is essential for the normal development of many tissues, but the feedback loops that regulate Notch are poorly understood. Developing T ...cells provide an excellent context to address this issue. Notch1 signals initiate T-cell development and increase in intensity during maturation of early T-cell progenitors (ETP) to the DN3 stage. As DN3 cells undergo beta-selection, during which cells expressing functionally rearranged TCRbeta proliferate and differentiate into CD4(+)CD8(+) progeny, Notch1 signaling is abruptly down-regulated. In this report, we investigate the mechanisms that control Notch1 expression during thymopoiesis. We show that Notch1 and E2A directly regulate Notch1 transcription in pre-beta-selected thymocytes. Following successful beta-selection, pre-TCR signaling rapidly inhibits Notch1 transcription via signals that up-regulate Id3, an E2A inhibitor. Consistent with a regulatory role for Id3 in Notch1 down-regulation, post-beta-selected Id3-deficient thymocytes maintain Notch1 transcription, whereas enforced Id3 expression decreases Notch1 expression and abrogates Notch1-dependent T-cell survival. These data provide new insights into Notch1 regulation in T-cell progenitors and reveal a direct link between pre-TCR signaling and Notch1 expression during thymocyte development. Our findings also suggest new strategies for inhibiting Notch1 signaling in pathologic conditions.
The Streptococcus pyogenes CRISPR‐Cas system has gained widespread application as a genome editing and gene regulation tool as simultaneous cellular delivery of the Cas9 protein and guide RNAs ...enables recognition of specific DNA sequences. The recent discovery that Cas9 can also bind and cleave RNA in an RNA‐programmable manner indicates the potential utility of this system as a universal nucleic acid‐recognition technology. RNA‐targeted Cas9 (RCas9) could allow identification and manipulation of RNA substrates in live cells, empowering the study of cellular gene expression, and could ultimately spawn patient‐ and disease‐specific diagnostic and therapeutic tools. Here we describe the development of RCas9 and compare it to previous methods for RNA targeting, including engineered RNA‐binding proteins and other types of CRISPR‐Cas systems. We discuss potential uses ranging from live imaging of transcriptional dynamics to patient‐specific therapies and applications in synthetic biology.
Malpractice claims place heavy economic and emotional burdens on both dentists and patients. Recently, medical malpractice lawsuits are decreasing in prevalence but increasing in severity. The ...percentage of dental malpractice payments is also growing among the health profession. The present study aimed to explore criminal convictions in dental malpractice litigation and to analyze the factors affecting the judgment in dental disputes in Taiwan.
The keywords “dentist,” “professional negligence,” “medical malpractice,” and “professional liability” were used to search Taiwan's Law and Regulations Retrieving System for criminal dental malpractice cases in all district courts from January 1, 2000 to June 30, 2021. The eligible judgments were summarized and analyzed.
Overall, 425 cases were identified, with 28 dental disputes included in the final analysis. The dentists lost in 10 cases (35.7%). The average claim time was 36.75 ± 16.34 months. Taipei and Taichung dealt with more lawsuit cases (n = 8). Local clinics were the most common institution of the defendants (75%) and had the highest number of convictions (n = 9). Implant dentistry was the most common specialty involved. Expert testimony of the Medical Review Committee (MRC) had a high K coefficient of agreement with court judgments regarding professional negligence (p < 0.001).
The overall criminal conviction rate was 35.7%. Implant therapy and local clinics had the highest rate of lawsuits and a considerably higher conviction rate. All guilty dentists were fined or given probation. The court judgments were highly consistent with the expert testimony of the MRC.
Right-sided cardiac thrombus is rare and may be caused by venous thromboembolism, in association with medical devices or stasis of blood in atrial fibrillation (AF) and cardiomyopathies. ...Complications include pulmonary embolism (PE) and paradoxical stroke. Current data are limited and mostly from case series and PE registries. We aimed to describe the clinical characteristics, echocardiographic features, treatments, and outcomes of right-sided cardiac thrombus patients.
This was a retrospective observational study of 97 consecutive patients with right-sided cardiac thrombus detected on echocardiography. We studied co-morbidities, predisposing factors, thrombus characteristics, and therapeutic interventions and assessed their associations with the development of PE, paradoxical stroke, circulatory collapse, and all-cause mortality.
The mean age was 58.7 years, and 55/97 (56.7%) of the participants were female. Ischemic heart disease (IHD), heart failure, chronic kidney disease, and malignancy were common co-morbidities. Right atrial (RA) thrombus was often associated with medical devices, while right ventricular (RV) thrombus was more commonly associated with cardiomyopathy. Thrombus mobility did not affect embolic events but was associated with greater short-term mortality. On multivariable analysis, anticoagulation (HR 0.25, 95% CI 0.09–0.68) and thrombus resolution (HR 0.28, 95% CI 0.13–0.62) were associated with greater survival.
Right-sided cardiac thrombus is rare but may have potentially life-threatening complications such as PE and paradoxical stroke. Further research is needed to determine the optimal therapeutic strategies for this poorly studied population.
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