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14 result(s) for "Ruiz, Lorena Andrade"
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Vertebrate centromere architecture: from chromatin threads to functional structures
Centromeres are chromatin structures specialized in sister chromatid cohesion, kinetochore assembly, and microtubule attachment during chromosome segregation. The regional centromere of vertebrates consists of long regions of highly repetitive sequences occupied by the Histone H3 variant CENP-A, and which are flanked by pericentromeres. The three-dimensional organization of centromeric chromatin is paramount for its functionality and its ability to withstand spindle forces. Alongside CENP-A, key contributors to the folding of this structure include components of the Constitutive Centromere-Associated Network (CCAN), the protein CENP-B, and condensin and cohesin complexes. Despite its importance, the intricate architecture of the regional centromere of vertebrates remains largely unknown. Recent advancements in long-read sequencing, super-resolution and cryo-electron microscopy, and chromosome conformation capture techniques have significantly improved our understanding of this structure at various levels, from the linear arrangement of centromeric sequences and their epigenetic landscape to their higher-order compaction. In this review, we discuss the latest insights on centromere organization and place them in the context of recent findings describing a bipartite higher-order organization of the centromere.
cGAS–STING drives the IL-6-dependent survival of chromosomally instable cancers
Chromosomal instability (CIN) drives cancer cell evolution, metastasis and therapy resistance, and is associated with poor prognosis 1 . CIN leads to micronuclei that release DNA into the cytoplasm after rupture, which triggers activation of inflammatory signalling mediated by cGAS and STING 2 , 3 . These two proteins are considered to be tumour suppressors as they promote apoptosis and immunosurveillance. However, cGAS and STING are rarely inactivated in cancer 4 , and, although they have been implicated in metastasis 5 , it is not known why loss-of-function mutations do not arise in primary tumours 4 . Here we show that inactivation of cGAS–STING signalling selectively impairs the survival of triple-negative breast cancer cells that display CIN. CIN triggers IL-6–STAT3-mediated signalling, which depends on the cGAS–STING pathway and the non-canonical NF-κB pathway. Blockade of IL-6 signalling by tocilizumab, a clinically used drug that targets the IL-6 receptor (IL-6R), selectively impairs the growth of cultured triple-negative breast cancer cells that exhibit CIN. Moreover, outgrowth of chromosomally instable tumours is significantly delayed compared with tumours that do not display CIN. Notably, this targetable vulnerability is conserved across cancer types that express high levels of IL-6 and/or IL-6R in vitro and in vivo. Together, our work demonstrates pro-tumorigenic traits of cGAS–STING signalling and explains why the cGAS–STING pathway is rarely inactivated in primary tumours. Repurposing tocilizumab could be a strategy to treat cancers with CIN that overexpress IL-6R. The survival of cells with chromosomal instability (CIN) depends on the cGAS–STING pathway, in which IL-6 and its receptor have a key role; this vulnerability can be exploited to treat tumours that display CIN.
Condensin reorganizes centromeric chromatin during mitotic entry into a bipartite structure stabilized by cohesin
The Structural Maintenance of Chromosomes (SMC) complexes cohesin and condensin establish the 3D organization of mitotic chromosomes. Cohesin is essential to maintain sister chromatid pairing until anaphase onset4, while condensin is important for mitotic centromere structure and elastic resistance to spindle forces. Both complexes are also important to form productive kinetochore-spindle attachments. How condensin and cohesin work together to shape the mitotic centromere to ensure faithful chromosome segregation remains unclear. Here we show by super-resolution imaging, Capture-C analysis and polymer modeling that vertebrate centromeres are partitioned into two distinct condensin-dependent subdomains during mitosis. This bipartite sub-structure is found in human, mouse and chicken centromeres and also in human neocentromeres devoid of satellite repeats, and is therefore a fundamental feature of vertebrate centromere identity. Super-resolution imaging reveals that bipartite centromeres assemble bipartite kinetochores with each subdomain capable of binding a distinct microtubule bundle. Cohesin helps to link the centromere subdomains, limiting their separation in response to mitotic spindle forces. In its absence, separated bipartite kinetochores frequently engage in merotelic spindle attachments. Consistently, uncoupling of centromere subdomains is a common feature of lagging chromosomes in cancer cells. The two-domain structure of vertebrate regional centromeres described here incorporates architectural roles for both condensin and cohesin and may have implications for avoiding chromosomal instability in cancer cells. Competing Interest Statement The authors have declared no competing interest.
Cancer tolerance to chromosomal instability is driven by Stat1 inactivation in vivo
Chromosomal instability is a hallmark of cancer, but also an instigator of aneuploidy-induced stress, reducing cellular fitness. To better understand how cells with CIN adjust to aneuploidy and adopt a malignant fate in vivo, we performed a genome-wide mutagenesis screen in mice. We find that specifically aneuploid tumors inactivate Stat1 signaling in combination with increased Myc activity. By contrast, loss of p53 is common, but not enriched in CIN tumors. Validation in another tissue type confirmed that CIN promotes immune cell infiltration, which is alleviated by Stat1 loss combined with Myc activation, but not with p53 inactivation, or Myc activation alone. Importantly, we find that this mechanism is preserved in human aneuploid cancers. We conclude that aneuploid cancers inactivate Stat1 signaling to circumvent immune surveillance. Competing Interest Statement M.A.T.M.v.V. has acted on the Scientific Advisory Board of Repare Therapeutics, which is unrelated to this work. The other authors declare no conflict of interest.
Targeting Neutrophil Extracellular Trap Formation: Exploring Promising Pharmacological Strategies for the Treatment of Preeclampsia
Neutrophils, which constitute the most abundant leukocytes in human blood, emerge as crucial players in the induction of endothelial cell death and the modulation of endothelial cell responses under both physiological and pathological conditions. The hallmark of preeclampsia is endothelial dysfunction induced by systemic inflammation, in which neutrophils, particularly through the formation of neutrophil extracellular traps (NETs), play a pivotal role in the development and perpetuation of endothelial dysfunction and the hypertensive state. Considering the potential of numerous pharmaceutical agents to attenuate NET formation (NETosis) in preeclampsia, a comprehensive assessment of the extensively studied candidates becomes imperative. This review aims to identify mechanisms associated with the induction and negative regulation of NETs in the context of preeclampsia. We discuss potential drugs to modulate NETosis, such as NF-κβ inhibitors, vitamin D, and aspirin, and their association with mutagenicity and genotoxicity. Strong evidence supports the notion that molecules involved in the activation of NETs could serve as promising targets for the treatment of preeclampsia.
A rapid calprotectin test for the diagnosis of pleural effusion
In previous studies, measuring the levels of calprotectin in patients with pleural effusion (PE) was an exceptionally accurate way to predict malignancy. Here, we evaluated a rapid method for the measurement of calprotectin levels as a useful parameter in the diagnosis of malignant pleural effusion (MPE) in order to minimise invasive diagnostic tests. Calprotectin levels were measured with Quantum Blue ® sCAL (QB ® sCAL) and compared with the gold standard reference ELISA method. Calprotectin levels in patients with benign pleural effusion (BPE) were significantly higher ( p < 0.0001) than for MPE patients. We measured the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and positive and negative likelihood ratios (LRs) for a cut-off value of ≤ 14,150 ng/mL; the diagnostic accuracy was 64%. The odds ratio for PE calprotectin levels was 10.938 (95% CI [4.133 − 28.947]). The diagnostic performance of calprotectin concentration was better for predicting MPE compared to other individual parameters. Comparison of two assays showed a slope of 1.084, an intercept of 329.7, and a Pearson correlation coefficient of 0.798. The Bland–Altman test showed a positive bias for the QB ® sCAL method compared to ELISA fCAL ® . Clinical concordance between both these methods was 88.5% with a Cohen kappa index of 0.76 (95% CI [0.68 − 0.84]). We concluded that QB ® sCAL is a fast, reliable, and non-invasive diagnostic tool for diagnosing MPE and represents an alternative to ELISA that could be implemented in medical emergencies.
Clinical profile, associated events and safety of vericiguat in a real‐world cohort: The VERITA study
Aims The aim of this study was to determine the clinical profile, associated events and safety of vericiguat in a real‐world cohort of patients with heart failure with reduced ejection fraction (HFrEF). Methods This study is a prospective and observational cohort study of patients with HFrEF and recent HF worsening episodes requiring intravenous therapy who initiated vericiguat in an HF outpatient clinic. A subanalysis of patients with ≥6 months' follow‐up was performed separately. Results Out of 103 patients initially included, 52 had a follow‐up of at least 6 months (median follow‐up of 303 days). At baseline, the mean age was 71.3 ± 9.4 years, 27.2% were women, the median left ventricular ejection fraction was 34% (28%–39%) and 99% were taking beta‐blockers, 96.1% sodium‐glucose cotransporter‐2 (SGLT2) inhibitors, 95.1% sacubitril–valsartan, 90.3% aldosterone antagonists and 93.2% loop diuretics. During follow‐up, New York Heart Association (NYHA) functional class improved (from 67.3% and 32.7% in classes III and II, respectively, to 22.4% and 75.5% at study end; P < 0.001), as did the EuroQol‐5D (EQ‐5D) and visual analogue scale (VAS) scores (from 0.83 ± 0.13 to 0.87 ± 0.12, P = 0.032, and from 60 to 79, P = 0.005, respectively). Vericiguat was well tolerated (13.5% had symptomatic hypotension, and 11.5% had discontinued treatment), and 78.8% of patients achieved the target dose of 10 mg. The number of HF‐related hospitalizations/decompensations within the previous 12 months was 2.3 ± 1.4 and decreased with vericiguat to 0.79 ± 1.14 (P < 0.001). At study end, 7.7% died (50% for HF). Conclusions In clinical practice, treatment with vericiguat is associated with substantial improvements in functional class and quality of life and a reduction in hospitalizations for HF, with a low risk of adverse effects.
Comparative genomics of the major fungal agents of human and animal Sporotrichosis: Sporothrix schenckii and Sporothrix brasiliensis
Background The fungal genus Sporothrix includes at least four human pathogenic species. One of these species, S. brasiliensis , is the causal agent of a major ongoing zoonotic outbreak of sporotrichosis in Brazil. Elsewhere, sapronoses are caused by S. schenckii and S. globosa. The major aims on this comparative genomic study are: 1) to explore the presence of virulence factors in S. schenckii and S. brasiliensis ; 2) to compare S. brasiliensis, which is cat-transmitted and infects both humans and cats with S. schenckii , mainly a human pathogen; 3) to compare these two species to other human pathogens (Onygenales) with similar thermo-dimorphic behavior and to other plant-associated Sordariomycetes. Results The genomes of S. schenckii and S. brasiliensis were pyrosequenced to 17x and 20x coverage comprising a total of 32.3 Mb and 33.2 Mb, respectively. Pair-wise genome alignments revealed that the two species are highly syntenic showing 97.5% average sequence identity. Phylogenomic analysis reveals that both species diverged about 3.8-4.9 MYA suggesting a recent event of speciation. Transposable elements comprise respectively 0.34% and 0.62% of the S. schenckii and S. brasiliensis genomes and expansions of Gypsy -like elements was observed reflecting the accumulation of repetitive elements in the S. brasiliensis genome. Mitochondrial genomic comparisons showed the presence of group-I intron encoding homing endonucleases (HE’s) exclusively in S. brasiliensis . Analysis of protein family expansions and contractions in the Sporothrix lineage revealed expansion of LysM domain-containing proteins, small GTPases, PKS type1 and leucin-rich proteins. In contrast, a lack of polysaccharide lyase genes that are associated with decay of plants was observed when compared to other Sordariomycetes and dimorphic fungal pathogens, suggesting evolutionary adaptations from a plant pathogenic or saprobic to an animal pathogenic life style. Conclusions Comparative genomic data suggest a unique ecological shift in the Sporothrix lineage from plant-association to mammalian parasitism, which contributes to the understanding of how environmental interactions may shape fungal virulence. . Moreover, the striking differences found in comparison with other dimorphic fungi revealed that dimorphism in these close relatives of plant-associated Sordariomycetes is a case of convergent evolution, stressing the importance of this morphogenetic change in fungal pathogenesis.
A rapid calprotectin test for the diagnosis of pleural effusion
In previous studies, measuring the levels of calprotectin in patients with pleural effusion (PE) was an exceptionally accurate way to predict malignancy. Here, we evaluated a rapid method for the measurement of calprotectin levels as a useful parameter in the diagnosis of malignant pleural effusion (MPE) in order to minimise invasive diagnostic tests. Calprotectin levels were measured with Quantum Blue® sCAL (QB®sCAL) and compared with the gold standard reference ELISA method. Calprotectin levels in patients with benign pleural effusion (BPE) were significantly higher (p < 0.0001) than for MPE patients. We measured the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and positive and negative likelihood ratios (LRs) for a cut-off value of ≤ 14,150 ng/mL; the diagnostic accuracy was 64%. The odds ratio for PE calprotectin levels was 10.938 (95% CI [4.133 − 28.947]). The diagnostic performance of calprotectin concentration was better for predicting MPE compared to other individual parameters. Comparison of two assays showed a slope of 1.084, an intercept of 329.7, and a Pearson correlation coefficient of 0.798. The Bland–Altman test showed a positive bias for the QB®sCAL method compared to ELISA fCAL®. Clinical concordance between both these methods was 88.5% with a Cohen kappa index of 0.76 (95% CI [0.68 − 0.84]). We concluded that QB®sCAL is a fast, reliable, and non-invasive diagnostic tool for diagnosing MPE and represents an alternative to ELISA that could be implemented in medical emergencies.