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2,934 result(s) for "endogenous factors"
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Tumor innate immunity primed by specific interferon-stimulated endogenous retroviruses
Mesenchymal tumor subpopulations secrete pro-tumorigenic cytokines and promote treatment resistance 1 – 4 . This phenomenon has been implicated in chemorefractory small cell lung cancer and resistance to targeted therapies 5 – 8 , but remains incompletely defined. Here, we identify a subclass of endogenous retroviruses (ERVs) that engages innate immune signaling in these cells. Stimulated 3 prime antisense retroviral coding sequences (SPARCS) are oriented inversely in 3′ untranslated regions of specific genes enriched for regulation by STAT1 and EZH2. Derepression of these loci results in double-stranded RNA generation following IFN-γ exposure due to bi-directional transcription from the STAT1-activated gene promoter and the 5′ long terminal repeat of the antisense ERV. Engagement of MAVS and STING activates downstream TBK1, IRF3, and STAT1 signaling, sustaining a positive feedback loop. SPARCS induction in human tumors is tightly associated with major histocompatibility complex class 1 expression, mesenchymal markers, and downregulation of chromatin modifying enzymes, including EZH2. Analysis of cell lines with high inducible SPARCS expression reveals strong association with an AXL/MET-positive mesenchymal cell state. While SPARCS-high tumors are immune infiltrated, they also exhibit multiple features of an immune-suppressed microenviroment. Together, these data unveil a subclass of ERVs whose derepression triggers pathologic innate immune signaling in cancer, with important implications for cancer immunotherapy. Retroelements located in antisense orientation within interferon-regulated genes are reactivated in a subset of cancer cells and initiate a STING- and MAVS-dependent feed-forward inflammatory loop, driving antitumor immunity and exhaustion.
Local lung hypoxia determines epithelial fate decisions during alveolar regeneration
After influenza infection, lineage-negative epithelial progenitors (LNEPs) exhibit a binary response to reconstitute epithelial barriers: activating a Notch-dependent ΔNp63/cytokeratin 5 (Krt5) remodelling program or differentiating into alveolar type II cells (AEC2s). Here we show that local lung hypoxia, through hypoxia-inducible factor (HIF1α), drives Notch signalling and Krt5 pos basal-like cell expansion. Single-cell transcriptional profiling of human AEC2s from fibrotic lungs revealed a hypoxic subpopulation with activated Notch, suppressed surfactant protein C (SPC), and transdifferentiation toward a Krt5 pos basal-like state. Activated murine Krt5 pos LNEPs and diseased human AEC2s upregulate strikingly similar core pathways underlying migration and squamous metaplasia. While robust, HIF1α-driven metaplasia is ultimately inferior to AEC2 reconstitution in restoring normal lung function. HIF1α deletion or enhanced Wnt/β-catenin activity in Sox2 pos LNEPs blocks Notch and Krt5 activation, instead promoting rapid AEC2 differentiation and migration and improving the quality of alveolar repair. Xi et al.  show that after influenza infection, hypoxia drives Notch signalling to expand Krt5 + basal-like cells in the lung. On HIF1α loss, epithelial progenitors directly differentiate into alveolar type II cells and promote functional regeneration.
Guidelines and definitions for research on epithelial–mesenchymal transition
Epithelial–mesenchymal transition (EMT) encompasses dynamic changes in cellular organization from epithelial to mesenchymal phenotypes, which leads to functional changes in cell migration and invasion. EMT occurs in a diverse range of physiological and pathological conditions and is driven by a conserved set of inducing signals, transcriptional regulators and downstream effectors. With over 5,700 publications indexed by Web of Science in 2019 alone, research on EMT is expanding rapidly. This growing interest warrants the need for a consensus among researchers when referring to and undertaking research on EMT. This Consensus Statement, mediated by ‘the EMT International Association’ (TEMTIA), is the outcome of a 2-year-long discussion among EMT researchers and aims to both clarify the nomenclature and provide definitions and guidelines for EMT research in future publications. We trust that these guidelines will help to reduce misunderstanding and misinterpretation of research data generated in various experimental models and to promote cross-disciplinary collaboration to identify and address key open questions in this research field. While recognizing the importance of maintaining diversity in experimental approaches and conceptual frameworks, we emphasize that lasting contributions of EMT research to increasing our understanding of developmental processes and combatting cancer and other diseases depend on the adoption of a unified terminology to describe EMT.In this Consensus Statement, the authors (on behalf of the EMT International Association) propose guidelines to define epithelial–mesenchymal transition, its phenotypic plasticity and the associated multiple intermediate epithelial–mesenchymal cell states. Clarification of nomenclature and definitions will help reduce misinterpretation of research data generated in different experimental model systems and promote cross-disciplinary collaboration.
The whole-genome landscape of medulloblastoma subtypes
Current therapies for medulloblastoma, a highly malignant childhood brain tumour, impose debilitating effects on the developing child, and highlight the need for molecularly targeted treatments with reduced toxicity. Previous studies have been unable to identify the full spectrum of driver genes and molecular processes that operate in medulloblastoma subgroups. Here we analyse the somatic landscape across 491 sequenced medulloblastoma samples and the molecular heterogeneity among 1,256 epigenetically analysed cases, and identify subgroup-specific driver alterations that include previously undiscovered actionable targets. Driver mutations were confidently assigned to most patients belonging to Group 3 and Group 4 medulloblastoma subgroups, greatly enhancing previous knowledge. New molecular subtypes were differentially enriched for specific driver events, including hotspot in-frame insertions that target KBTBD4 and ‘enhancer hijacking’ events that activate PRDM6 . Thus, the application of integrative genomics to an extensive cohort of clinical samples derived from a single childhood cancer entity revealed a series of cancer genes and biologically relevant subtype diversity that represent attractive therapeutic targets for the treatment of patients with medulloblastoma. Genomic analysis of 491 medulloblastoma samples, including methylation profiling of 1,256 cases, effectively assigns candidate drivers to most tumours across all molecular subgroups. Genomic landscapes of medulloblastomas Medulloblastomas are highly malignant brain tumours that develop during childhood. Paul Northcott and colleagues analysed the whole-genome sequences of 491 medulloblastomas in order to characterize the genomic landscape across tumours and identify new drivers and mutational signatures. Their integrative genomic analyses, including methylation profiling of 1,256 medulloblastomas, identifies subgroup-specific driver mutations and suggests additional tumour subtypes. The authors assign driver mutations to a high proportion of the less well characterized Group 3 and Group 4, which together contribute to more than 60% of all medulloblastomas.
The power of genetic diversity in genome-wide association studies of lipids
Increased blood lipid levels are heritable risk factors of cardiovascular disease with varied prevalence worldwide owing to different dietary patterns and medication use 1 . Despite advances in prevention and treatment, in particular through reducing low-density lipoprotein cholesterol levels 2 , heart disease remains the leading cause of death worldwide 3 . Genome-wideassociation studies (GWAS) of blood lipid levels have led to important biological and clinical insights, as well as new drug targets, for cardiovascular disease. However, most previous GWAS 4 – 23 have been conducted in European ancestry populations and may have missed genetic variants that contribute to lipid-level variation in other ancestry groups. These include differences in allele frequencies, effect sizes and linkage-disequilibrium patterns 24 . Here we conduct a multi-ancestry, genome-wide genetic discovery meta-analysis of lipid levels in approximately 1.65 million individuals, including 350,000 of non-European ancestries. We quantify the gain in studying non-European ancestries and provide evidence to support the expansion of recruitment of additional ancestries, even with relatively small sample sizes. We find that increasing diversity rather than studying additional individuals of European ancestry results in substantial improvements in fine-mapping functional variants and portability of polygenic prediction (evaluated in approximately 295,000 individuals from 7 ancestry groupings). Modest gains in the number of discovered loci and ancestry-specific variants were also achieved. As GWAS expand emphasis beyond the identification of genes and fundamental biology towards the use of genetic variants for preventive and precision medicine 25 , we anticipate that increased diversity of participants will lead to more accurate and equitable 26 application of polygenic scores in clinical practice. A genome-wide association meta-analysis study of blood lipid levels in roughly 1.6 million individuals demonstrates the gain of power attained when diverse ancestries are included to improve fine-mapping and polygenic score generation, with gains in locus discovery related to sample size.
Defining inflammatory cell states in rheumatoid arthritis joint synovial tissues by integrating single-cell transcriptomics and mass cytometry
To define the cell populations that drive joint inflammation in rheumatoid arthritis (RA), we applied single-cell RNA sequencing (scRNA-seq), mass cytometry, bulk RNA sequencing (RNA-seq) and flow cytometry to T cells, B cells, monocytes, and fibroblasts from 51 samples of synovial tissue from patients with RA or osteoarthritis (OA). Utilizing an integrated strategy based on canonical correlation analysis of 5,265 scRNA-seq profiles, we identified 18 unique cell populations. Combining mass cytometry and transcriptomics revealed cell states expanded in RA synovia: THY1(CD90) + HLA-DRA hi sublining fibroblasts, IL1B + pro-inflammatory monocytes, ITGAX + TBX21 + autoimmune-associated B cells and PDCD1 + peripheral helper T (T PH ) cells and follicular helper T (T FH ) cells. We defined distinct subsets of CD8 + T cells characterized by GZMK + , GZMB + , and GNLY + phenotypes. We mapped inflammatory mediators to their source cell populations; for example, we attributed IL6 expression to THY1 + HLA-DRA hi fibroblasts and IL1B production to pro-inflammatory monocytes. These populations are potentially key mediators of RA pathogenesis. Defining cell types and their activation status in rheumatoid arthritis (RA) is critical to understanding this disease. Raychaudhuri and colleagues leverage several single-cell -omics approaches to define the cellular processes and pathways in the human RA joint.
The influence of the endogenous and exogenous factors on hematological parameters in different fish species: a review
Hematological studies of fishes are useful in the diagnosis of many diseases as well as investigation of the extent of damage to the blood. These parameters act as efficient and insightful index to examine health status, physiological and pathological changes occurring in various fishes, i.e., metabolic perturbations in fish body thereby acting as non-specific biomarkers in the field of environmental toxicology, deficiencies and chronic stress in natural as well as aquaculture systems and checking water quality. The assessments of these blood parameters help the biologists to understand the fish homeostasis and biomonitoring of severe and chronic patho-physiological changes inferable to nutrition, water quality, or disease so as to establish the normal reference values of different species and determine systematic relationships among them. Lot of work on various aspects of hematological parameters and their relation with ecological factors has been reported on several fish species from different parts of the world. Each study attributes one or other factors responsible for variation in hematological parameters among different fish species. Therefore, in the present study, an attempt has been made to compile the information about the hematological studies of various fish species reported from different parts of the world, and through this study, a general overview has been generated about the major factors responsible for the variation in hematological parameters of fish. The review provides an insight to the characteristics of hematological values showing that fluctuating internal environment of the fish, along with other intrinsic (age, body size, the cycle of sexual maturity, health condition, nutritional state, species) and extrinsic factors (temperature, stress, season, dissolved oxygen, water quality, lotic or lentic environment, stocking density, photoperiod, sampling conditions, laboratory techniques), are the reasons of huge variability of hematological parameters in fishes.
Adventitious Rooting in Populus Species: Update and Perspectives
Populus spp. are among the most economically important species worldwide. These trees are used not only for wood and fiber production, but also in the rehabilitation of degraded lands. Since they are clonally propagated, the ability of stem cuttings to form adventitious roots is a critical point for plant establishment and survival in the field, and consequently for the forest industry. Adventitious rooting in different Populus clones has been an agronomic trait targeted in breeding programs for many years, and many factors have been identified that affect this quantitative trait. A huge variation in the rooting capacity has been observed among the species in the Populus genus, and the responses to some of the factors affecting this trait have been shown to be genotype-dependent. This review analyses similarities and differences between results obtained from studies examining the role of internal and external factors affecting rooting of Populus species cuttings. Since rooting is the most important requirement for stand establishment in clonally propagated species, understanding the physiological and genetic mechanisms that promote this trait is essential for successful commercial deployment.
Suppressing neutrophil-dependent angiogenesis abrogates resistance to anti-VEGF antibody in a genetic model of colorectal cancer
We tested cis-ApcΔ716/Smad4 +/− and cis-ApcΔ716/Smad4 +/− KrasG12D mice, which recapitulate key genetic abnormalities accumulating during colorectal cancer (CRC) tumorigenesis in humans, for responsiveness to anti-VEGF therapy. We found that even tumors in cis-ApcΔ716/Smad4 +/− KrasG12D mice, although highly aggressive, were suppressed by anti-VEGF treatment. We tested the hypothesis that inflammation, a major risk factor and trigger for CRC, may affect responsiveness to anti-VEGF. Chemically induced colitis (CIC) in cis-ApcΔ716/Smad4 +/− and cis-ApcΔ716/Smad4 +/− KrasG12D mice promoted development of colon tumors that were largely resistant to anti-VEGF treatment. The myeloid growth factor G-CSF was markedly increased in the serum after induction of colitis. Antibodies blocking G-CSF, or its target Bv8/PROK2, suppressed tumor progression and myeloid cell infiltration when combined with anti-VEGF in CIC-associated CRC and in anti-VEGF-resistant CRC liver metastasis models. In a series of CRC specimens, tumor-infiltrating neutrophils strongly expressed Bv8/PROK2. CRC patients had significantly higher plasma Bv8/PROK2 levels than healthy volunteers and high plasma Bv8/PROK2 levels were inversely correlated with overall survival. Our findings establish Bv8/PROK2 as a translational target in CRC, in combination with anti-VEGF agents.
Gut microbiota from multiple sclerosis patients enables spontaneous autoimmune encephalomyelitis in mice
There is emerging evidence that the commensal microbiota has a role in the pathogenesis of multiple sclerosis (MS), a putative autoimmune disease of the CNS. Here, we compared the gut microbial composition of 34 monozygotic twin pairs discordant for MS. While there were no major differences in the overall microbial profiles, we found a significant increase in some taxa such as Akkermansia in untreated MS twins. Furthermore, most notably, when transplanted to a transgenic mouse model of spontaneous brain autoimmunity, MS twin-derived microbiota induced a significantly higher incidence of autoimmunity than the healthy twinderived microbiota. The microbial profiles of the colonized mice showed a high intraindividual and remarkable temporal stability with several differences, including Sutterella, an organism shown to induce a protective immunoregulatory profile in vitro. Immune cells from mouse recipients of MS-twin samples produced less IL-10 than immune cells from mice colonized with healthy-twin samples. IL-10 may have a regulatory role in spontaneous CNS autoimmunity, as neutralization of the cytokine in mice colonized with healthy-twin fecal samples increased disease incidence. These findings provide evidence that MS-derived microbiota contain factors that precipitate an MS-like autoimmune disease in a transgenic mouse model. They hence encourage the detailed search for protective and pathogenic microbial components in human MS.