Systems Biology

A Sticky-End Probe Biosensor for Homogeneous Detection of Transcription Factor Binding Activity

Tue, 2023-05-23 06:00

SLAS Technol. 2023 May 21:S2472-6303(23)00033-X. doi: 10.1016/j.slast.2023.05.001. Online ahead of print.

ABSTRACT

Transcription factors are essential regulators of various physiological and pathological processes. However, detecting transcription factor-DNA binding activities is often time-consuming and labor-intensive. Homogeneous biosensors that are compatible with mix-and-measure protocols have the potential to simplify the workflow for therapeutic screening and disease diagnostics. In this study, we apply a combined computational-experimental approach to investigate the design of a sticky-end probe biosensor, where the transcription factor-DNA complex stabilizes the fluorescence resonance energy transfer signal of the donor-acceptor pair. We design a sticky-end biosensor for the SOX9 transcription factor based on the consensus sequence and characterize its sensing performance. A systems biology model is also developed to investigate the reaction kinetics and optimize the operating conditions. Taken together, our study provides a conceptual framework for the design and optimization of sticky-end probe biosensors for homogeneous detection of transcription factor-DNA binding activity.

PMID:37220830 | DOI:10.1016/j.slast.2023.05.001

Categories: Literature Watch

A multi-scale map of protein assemblies in the DNA damage response

Tue, 2023-05-23 06:00

Cell Syst. 2023 May 16:S2405-4712(23)00116-3. doi: 10.1016/j.cels.2023.04.007. Online ahead of print.

ABSTRACT

The DNA damage response (DDR) ensures error-free DNA replication and transcription and is disrupted in numerous diseases. An ongoing challenge is to determine the proteins orchestrating DDR and their organization into complexes, including constitutive interactions and those responding to genomic insult. Here, we use multi-conditional network analysis to systematically map DDR assemblies at multiple scales. Affinity purifications of 21 DDR proteins, with/without genotoxin exposure, are combined with multi-omics data to reveal a hierarchical organization of 605 proteins into 109 assemblies. The map captures canonical repair mechanisms and proposes new DDR-associated proteins extending to stress, transport, and chromatin functions. We find that protein assemblies closely align with genetic dependencies in processing specific genotoxins and that proteins in multiple assemblies typically act in multiple genotoxin responses. Follow-up by DDR functional readouts newly implicates 12 assembly members in double-strand-break repair. The DNA damage response assemblies map is available for interactive visualization and query (ccmi.org/ddram/).

PMID:37220749 | DOI:10.1016/j.cels.2023.04.007

Categories: Literature Watch

Rational Design of Covalent Kinase Inhibitors by an Integrated Computational Workflow (Kin-Cov)

Tue, 2023-05-23 06:00

J Med Chem. 2023 May 23. doi: 10.1021/acs.jmedchem.3c00088. Online ahead of print.

ABSTRACT

Covalent kinase inhibitors (CKIs) hold great promise for drug development. However, examples of computationally guided design of CKIs are still scarce. Here, we present an integrated computational workflow (Kin-Cov) for rational design of CKIs. The design of the first covalent leucine-zipper and sterile-α motif kinase (ZAK) inhibitor was presented as an example to showcase the power of computational workflow for CKI design. The two representative compounds, 7 and 8, inhibited ZAK kinase with half-maximal inhibitory concentration (IC50) values of 9.1 and 11.5 nM, respectively. Compound 8 displayed an excellent ZAK target specificity in Kinome profiling against 378 wild-type kinases. Structural biology and cell-based Western blot washout assays validated the irreversible binding characteristics of the compounds. Our study presents a rational approach for the design of CKIs based on the reactivity and accessibility of nucleophilic amino acid residues in a kinase. The workflow is generalizable and can be applied to facilitate CKI-based drug design.

PMID:37220641 | DOI:10.1021/acs.jmedchem.3c00088

Categories: Literature Watch

Integrating multiomics data accelerates elucidation of plant primary and secondary metabolic pathways

Tue, 2023-05-23 06:00

aBIOTECH. 2023 Jan 11;4(1):47-56. doi: 10.1007/s42994-022-00091-4. eCollection 2023 Mar.

ABSTRACT

Plants are the most important sources of food for humans, as well as supplying many ingredients that are of great importance for human health. Developing an understanding of the functional components of plant metabolism has attracted considerable attention. The rapid development of liquid chromatography and gas chromatography, coupled with mass spectrometry, has allowed the detection and characterization of many thousands of metabolites of plant origin. Nowadays, elucidating the detailed biosynthesis and degradation pathways of these metabolites represents a major bottleneck in our understanding. Recently, the decreased cost of genome and transcriptome sequencing rendered it possible to identify the genes involving in metabolic pathways. Here, we review the recent research which integrates metabolomic with different omics methods, to comprehensively identify structural and regulatory genes of the primary and secondary metabolic pathways. Finally, we discuss other novel methods that can accelerate the process of identification of metabolic pathways and, ultimately, identify metabolite function(s).

PMID:37220537 | PMC:PMC10199974 | DOI:10.1007/s42994-022-00091-4

Categories: Literature Watch

Membrane Ruffling is a Mechanosensor of Extracellular Fluid Viscosity

Tue, 2023-05-23 06:00

Nat Phys. 2022 Sep;18(9):1112-1121. doi: 10.1038/s41567-022-01676-y. Epub 2022 Jul 25.

ABSTRACT

Cell behaviour is affected by the physical forces and mechanical properties of the cells and of their microenvironment. The viscosity of extracellular fluid - a component of the cellular microenvironment - can vary by orders of magnitude, but its effect on cell behaviour remains largely unexplored. Using bio-compatible polymers to increase the viscosity of the culture medium, we characterize how viscosity affects cell behaviour. We find that multiple types of adherent cells respond in an unexpected but similar manner to elevated viscosity. In a highly viscous medium, cells double their spread area, exhibit increased focal adhesion formation and turnover, generate significantly greater traction forces, and migrate nearly two times faster. We observe that when cells are immersed in regular medium, these viscosity-dependent responses require an actively ruffling lamellipodium - a dynamic membrane structure at the front of the cell. We present evidence that cells utilize membrane ruffling to sense changes in extracellular fluid viscosity and to trigger adaptive responses.

PMID:37220497 | PMC:PMC10202009 | DOI:10.1038/s41567-022-01676-y

Categories: Literature Watch

Metabolome plasticity in 241 Arabidopsis thaliana accessions reveals evolutionary cold adaptation processes

Tue, 2023-05-23 06:00

Plant Physiol. 2023 May 23:kiad298. doi: 10.1093/plphys/kiad298. Online ahead of print.

ABSTRACT

Acclimation and adaptation of metabolism to a changing environment are key processes for plant survival and reproductive success. In the present study, 241 natural accessions of Arabidopsis (Arabidopsis thaliana) were grown under two different temperature regimes, 16 °C and 6 °C, and growth parameters were recorded, together with metabolite profiles, to investigate the natural genome × environment effects on metabolome variation. The plasticity of metabolism, which was captured by metabolic distance measures, varied considerably between accessions. Both relative growth rates and metabolic distances were predictable by the underlying natural genetic variation of accessions. Applying machine learning methods, climatic variables of the original growth habitats were tested for their predictive power of natural metabolic variation among accessions. We found specifically habitat temperature during the first quarter of the year to be the best predictor of the plasticity of primary metabolism, indicating habitat temperature as the causal driver of evolutionary cold adaptation processes. Analyses of epigenome- and genome-wide associations revealed accession-specific differential DNA-methylation levels as potentially linked to the metabolome and identified FUMARASE2 as strongly associated with cold adaptation in Arabidopsis accessions. These findings were supported by calculations of the biochemical Jacobian matrix based on variance and covariance of metabolomics data, which revealed that growth under low temperatures most substantially affects the accession-specific plasticity of fumarate and sugar metabolism. Our findings indicate that the plasticity of metabolic regulation is predictable from the genome and epigenome and driven evolutionarily by Arabidopsis growth habitats.

PMID:37220420 | DOI:10.1093/plphys/kiad298

Categories: Literature Watch

Hypoxia extends lifespan and neurological function in a mouse model of aging

Tue, 2023-05-23 06:00

PLoS Biol. 2023 May 23;21(5):e3002117. doi: 10.1371/journal.pbio.3002117. eCollection 2023 May.

ABSTRACT

There is widespread interest in identifying interventions that extend healthy lifespan. Chronic continuous hypoxia delays the onset of replicative senescence in cultured cells and extends lifespan in yeast, nematodes, and fruit flies. Here, we asked whether chronic continuous hypoxia is beneficial in mammalian aging. We utilized the Ercc1 Δ/- mouse model of accelerated aging given that these mice are born developmentally normal but exhibit anatomic, physiological, and biochemical features of aging across multiple organs. Importantly, they exhibit a shortened lifespan that is extended by dietary restriction, the most potent aging intervention across many organisms. We report that chronic continuous 11% oxygen commenced at 4 weeks of age extends lifespan by 50% and delays the onset of neurological debility in Ercc1 Δ/- mice. Chronic continuous hypoxia did not impact food intake and did not significantly affect markers of DNA damage or senescence, suggesting that hypoxia did not simply alleviate the proximal effects of the Ercc1 mutation, but rather acted downstream via unknown mechanisms. To the best of our knowledge, this is the first study to demonstrate that "oxygen restriction" can extend lifespan in a mammalian model of aging.

PMID:37220109 | DOI:10.1371/journal.pbio.3002117

Categories: Literature Watch

Differentiation and single-cell RNA-seq analyses of human pluripotent-stem-cell-derived renal organoids

Tue, 2023-05-23 06:00

STAR Protoc. 2023 May 22;4(2):102314. doi: 10.1016/j.xpro.2023.102314. Online ahead of print.

ABSTRACT

Here, we present a protocol for the maintenance and differentiation of human pluripotent stem cells into renal organoids. We describe steps for using a series of readily made differentiation media, multiplexed sample single-cell RNA-seq analysis, quality control, and validation of organoids using immunofluorescence. This provides a rapid and reproducible model of human kidney development and renal disease modeling. Finally, we detail genome engineering using CRISPR-Cas9 homology-directed repair for the generation of renal disease models. For complete details on the use and execution of this protocol, please refer to Pietrobon et al.1.

PMID:37220001 | DOI:10.1016/j.xpro.2023.102314

Categories: Literature Watch

The latest advances in high content screening in microfluidic devices

Tue, 2023-05-23 06:00

Expert Opin Drug Discov. 2023 May 23:1-15. doi: 10.1080/17460441.2023.2216013. Online ahead of print.

ABSTRACT

INTRODUCTION: High content screening (HCS) is an important tool for drug screening. However, the potential of HCS in the field of drug screening and synthetic biology is limited by traditional culture platforms that use multi-well plates, which have several disadvantages. Recently, microfluidic devices have gradually been applied in HCS, which significantly reduces experimental costs, increases assay throughput, and improves the accuracy of drug screening.

AREAS COVERED: This review provides an overview of microfluidic devices for high-content screening in drug discovery platforms, including droplet, microarray, and organs-on-chip technologies.

EXPERT OPINION: HCS is a promising technology increasingly adopted by the pharmaceutical industry as well as academic researchers for drug discovery and screening. In particular, microfluidic-based HCS shows unique advantages, and microfluidics technology has promoted significant advancements and broader usage and applicability of HCS in drug discovery. With the integration of stem cell, gene editing technology, and other biological technologies, microfluidics-based HCS will expand the application scope of personalized disease and drug screening models. The authors anticipate rapid developments in this field, with microfluidic-based approaches becoming increasingly important in HCS applications.

PMID:37219918 | DOI:10.1080/17460441.2023.2216013

Categories: Literature Watch

Arabidopsis thaliana B-GATA factors repress starch synthesis and gravitropic growth responses

Tue, 2023-05-23 06:00

New Phytol. 2023 May 23. doi: 10.1111/nph.18992. Online ahead of print.

ABSTRACT

Plants perceive the direction of gravity during skotomorphogenic growth, and of gravity and light during photomorphogenic growth. Gravity perception occurs through the sedimentation of starch granules in shoot endodermal and root columella cells. In this study, we demonstrate that the Arabidopsis thaliana GATA factors GNC (GATA, NITRATE-INDUCIBLE, CARBON METABOLISM-INVOLVED) and GNL/CGA1 (GNC-LIKE/CYTOKININ-RESPONSIVE GATA1) repress starch granule growth and amyloplast differentiation in endodermal cells. In our comprehensive study, we analysed gravitropic responses in the shoot, root and hypocotyl. We performed an RNA-seq analysis, used advanced microscopy techniques to examine starch granule size, number and morphology and quantified transitory starch degradation patterns. Using transmission electron microscopy, we examined amyloplast development. Our results indicate that the altered gravitropic responses in hypocotyls, shoots and roots of gnc gnl mutants and GNL overexpressors are due to the differential accumulation of starch granules observed in the GATA genotypes. At the whole-plant level, GNC and GNL play a more complex role in starch synthesis, degradation and starch granule initiation. Our findings suggest that the light-regulated GNC and GNL help balance phototropic and gravitropic growth responses after the transition from skotomorphogenesis to photomorphogenesis by repressing the growth of starch granules.

PMID:37219878 | DOI:10.1111/nph.18992

Categories: Literature Watch

SnRK1 inhibits anthocyanin biosynthesis through both transcriptional regulation and direct phosphorylation and dissociation of the MYB/bHLH/TTG1 MBW complex

Tue, 2023-05-23 06:00

Plant J. 2023 May 23. doi: 10.1111/tpj.16312. Online ahead of print.

ABSTRACT

Plants have evolved an extensive specialized secondary metabolism. The colorful flavonoid anthocyanins, for example, not only stimulate flower pollination and seed dispersal but also protect different tissues against high light, UV- and oxidative stress. Their biosynthesis is highly regulated by environmental and developmental cues and induced by high sucrose levels. Expression of the biosynthetic enzymes involved is controlled by a transcriptional MBW complex, comprising (R2R3) MYB- and bHLH-type transcription factors (TF) and the WD40 repeat protein TTG1. Anthocyanin biosynthesis is obviously useful but also carbon- and energy-intensive and non-vital. Consistently, the SnRK1 protein kinase, a metabolic sensor activated in carbon- and energy-depleting stress conditions, represses anthocyanin biosynthesis. Here we show that Arabidopsis SnRK1 represses MBW complex activity both at the transcriptional and post-translational level. In addition to repressing expression of the key transcription factor MYB75/PAP1, SnRK1 activity triggers MBW complex dissociation, associated with loss of target promoter binding, MYB75 protein degradation and nuclear export of TTG1. We also provide evidence for direct interaction with and phosphorylation of multiple MBW complex proteins. These results indicate that repression of expensive anthocyanin biosynthesis is an important strategy to save energy and redirect carbon flow to more essential processes for survival in metabolic stress conditions.

PMID:37219821 | DOI:10.1111/tpj.16312

Categories: Literature Watch

Antibacterial, bacteriolytic, and antibiofilm activities of the essential oil of temu giring (<em>Curcuma heyneana</em> Val.) against foodborne pathogens

Tue, 2023-05-23 06:00

Food Sci Technol Int. 2023 May 22:10820132231178060. doi: 10.1177/10820132231178060. Online ahead of print.

ABSTRACT

Foodborne pathogens may cause foodborne illness, which is among the major health problems worldwide. Since the therapeutic options for the treatment of the disease are becoming limited as a result of antibacterial resistance, there is an increasing interest to search for new alternatives of antibacterial. Bioactive essential oils from Curcuma sp become potential sources of novel antibacterial substances. The antibacterial activity of Curcuma heyneana essential oil (CHEO) was evaluated against Escherichia coli, Salmonella typhi, Shigella sonnei, and Bacillus cereus. The principal constituents of CHEO are ar-turmerone, β-turmerone, α-zingiberene, α-terpinolene, 1,8-cineole, and camphor. CHEO exhibited the strongest antibacterial activity against E. coli with a MIC of 3.9 µg/mL, which is comparable to that of tetracycline. The combination of CHEO (0.97 µg/mL) and tetracycline (0.48 µg/mL) produced a synergistic effect with a FICI of 0.37. Time-kill assay confirmed that CHEO enhanced the activity of tetracycline. The mixture disrupted membrane permeability of E. coli and induced cell death. CHEO at MIC of 3.9 and 6.8 µg/mL significantly reduced the formation of biofilm in E. coli. The findings suggest that CHEO has the potential to be an alternative source of antibacterial agents against foodborne pathogens, particularly E. coli.

PMID:37218156 | DOI:10.1177/10820132231178060

Categories: Literature Watch

Intrinsic suppression of type I interferon production underlies the therapeutic efficacy of IL-15-producing natural killer cells in B-cell acute lymphoblastic leukemia

Mon, 2023-05-22 06:00

J Immunother Cancer. 2023 May;11(5):e006649. doi: 10.1136/jitc-2022-006649.

ABSTRACT

BACKGROUND: Type I interferons (IFN-Is), secreted by hematopoietic cells, drive immune surveillance of solid tumors. However, the mechanisms of suppression of IFN-I-driven immune responses in hematopoietic malignancies including B-cell acute lymphoblastic leukemia (B-ALL) are unknown.

METHODS: Using high-dimensional cytometry, we delineate the defects in IFN-I production and IFN-I-driven immune responses in high-grade primary human and mouse B-ALLs. We develop natural killer (NK) cells as therapies to counter the intrinsic suppression of IFN-I production in B-ALL.

RESULTS: We find that high expression of IFN-I signaling genes predicts favorable clinical outcome in patients with B-ALL, underscoring the importance of the IFN-I pathway in this malignancy. We show that human and mouse B-ALL microenvironments harbor an intrinsic defect in paracrine (plasmacytoid dendritic cell) and/or autocrine (B-cell) IFN-I production and IFN-I-driven immune responses. Reduced IFN-I production is sufficient for suppressing the immune system and promoting leukemia development in mice prone to MYC-driven B-ALL. Among anti-leukemia immune subsets, suppression of IFN-I production most markedly lowers the transcription of IL-15 and reduces NK-cell number and effector maturation in B-ALL microenvironments. Adoptive transfer of healthy NK cells significantly prolongs survival of overt ALL-bearing transgenic mice. Administration of IFN-Is to B-ALL-prone mice reduces leukemia progression and increases the frequencies of total NK and NK-cell effectors in circulation. Ex vivo treatment of malignant and non-malignant immune cells in primary mouse B-ALL microenvironments with IFN-Is fully restores proximal IFN-I signaling and partially restores IL-15 production. In B-ALL patients, the suppression of IL-15 is the most severe in difficult-to-treat subtypes with MYC overexpression. MYC overexpression promotes sensitivity of B-ALL to NK cell-mediated killing. To counter the suppressed IFN-I-induced IL-15 production in MYChigh human B-ALL, we CRISPRa-engineered a novel human NK-cell line that secretes IL-15. CRISPRa IL-15-secreting human NK cells kill high-grade human B-ALL in vitro and block leukemia progression in vivo more effectively than NK cells that do not produce IL-15.

CONCLUSION: We find that restoration of the intrinsically suppressed IFN-I production in B-ALL underlies the therapeutic efficacy of IL-15-producing NK cells and that such NK cells represent an attractive therapeutic solution for the problem of drugging MYC in high-grade B-ALL.

PMID:37217248 | DOI:10.1136/jitc-2022-006649

Categories: Literature Watch

BRK confers tamoxifen-resistance in breast cancer via regulation of tyrosine phosphorylation of CDK1

Mon, 2023-05-22 06:00

Cell Signal. 2023 May 20:110723. doi: 10.1016/j.cellsig.2023.110723. Online ahead of print.

ABSTRACT

Tamoxifen (Tam) has been the first-line therapy for estrogen receptor-positive breast cancer since its FDA-approval in 1998. Tam-resistance, however, presents a challenge and the mechanisms that drive it have yet to be fully elucidated. The non-receptor tyrosine kinase BRK/PTK6 is a promising candidate as previous research has shown that BRK knockdown resensitizes Tam-resistant breast cancer cells to the drug. However, the specific mechanisms that drive its importance to resistance remain to be investigated. Here, we investigate the role and mechanism of action of BRK in Tam-resistant (TamR), ER+, and T47D breast cancer cells using phosphopeptide enrichment and high throughput phopshoproteomics analysis. We conducted BRK-specific shRNA knockdown in TamR T47D cells and compared phosphopeptides identified in these cells with their Tam-resistant counterpart and parental, Tam-sensitive cells (Par). A total of 6492 STY phosphosites were identified. Of these sites, 3739 high-confidence pST sites and 118 high-confidence pY sites were analyzed for significant changes in phosphorylation levels to identify pathways that were differentially regulated in TamR versus Par and to investigate changes in these pathways when BRK is knocked down in TamR. We observed and validated increased CDK1 phosphorylation at Y15 in TamR cells compared to BRK-depleted TamR cells. Our data suggest that BRK is a potential Y15-directed CDK1 regulatory kinase in Tam-resistant breast cancer.

PMID:37216999 | DOI:10.1016/j.cellsig.2023.110723

Categories: Literature Watch

Genomic Insights into Adaptation to Karst Limestone and Incipient Speciation in East Asian Platycarya spp. (Juglandaceae)

Mon, 2023-05-22 06:00

Mol Biol Evol. 2023 May 22:msad121. doi: 10.1093/molbev/msad121. Online ahead of print.

ABSTRACT

When challenged by similar environmental conditions, phylogenetically distant taxa often independently evolve similar traits (convergent evolution). Meanwhile, adaptation to extreme habitats might lead to divergence between taxa that are otherwise closely related. These processes have long existed in the conceptual sphere, yet molecular evidence, especially for woody perennials, is scarce. The karst endemic Platycarya longipes, and its only congeneric species, P. strobilacea, which is widely distributed in the mountains in East Asia, provide an ideal model for examining the molecular basis of both convergent evolution and speciation. Using chromosome-level genome assemblies of both species, and whole genome resequencing data from 207 individuals spanning their entire distribution range, we demonstrate that P. longipes and P. strobilacea form two species-specific clades, which diverged around 2.09 million years ago. We find an excess of genomic regions exhibiting extreme interspecific differentiation, potentially due to long-term selection in P. longipes, likely contributing to the incipient speciation of the genus Platycarya. Interestingly, our results unveil underlying karst adaptation in both copies of the calcium influx channel gene TPC1 in P. longipes. TPC1 has previously been identified as a selective target in certain karst-endemic herbs, indicating a convergent adaptation to high calcium stress among karst-endemic species. Our study reveals the genic convergence of TPC1 among karst endemics, and the driving forces underneath the incipient speciation of the two Platycarya lineages.

PMID:37216901 | DOI:10.1093/molbev/msad121

Categories: Literature Watch

Brain matters: unveiling the distinct contributions of region, age, and sex to glia diversity and CNS function

Mon, 2023-05-22 06:00

Acta Neuropathol Commun. 2023 May 22;11(1):84. doi: 10.1186/s40478-023-01568-z.

ABSTRACT

The myelinated white matter tracts of the central nervous system (CNS) are essential for fast transmission of electrical impulses and are often differentially affected in human neurodegenerative diseases across CNS region, age and sex. We hypothesize that this selective vulnerability is underpinned by physiological variation in white matter glia. Using single nucleus RNA sequencing of human post-mortem white matter samples from the brain, cerebellum and spinal cord and subsequent tissue-based validation we found substantial glial heterogeneity with tissue region: we identified region-specific oligodendrocyte precursor cells (OPCs) that retain developmental origin markers into adulthood, distinguishing them from mouse OPCs. Region-specific OPCs give rise to similar oligodendrocyte populations, however spinal cord oligodendrocytes exhibit markers such as SKAP2 which are associated with increased myelin production and we found a spinal cord selective population particularly equipped for producing long and thick myelin sheaths based on the expression of genes/proteins such as HCN2. Spinal cord microglia exhibit a more activated phenotype compared to brain microglia, suggesting that the spinal cord is a more pro-inflammatory environment, a difference that intensifies with age. Astrocyte gene expression correlates strongly with CNS region, however, astrocytes do not show a more activated state with region or age. Across all glia, sex differences are subtle but the consistent increased expression of protein-folding genes in male donors hints at pathways that may contribute to sex differences in disease susceptibility. These findings are essential to consider for understanding selective CNS pathologies and developing tailored therapeutic strategies.

PMID:37217978 | DOI:10.1186/s40478-023-01568-z

Categories: Literature Watch

Metabolic landscape of the male mouse gut identifies different niches determined by microbial activities

Mon, 2023-05-22 06:00

Nat Metab. 2023 May 22. doi: 10.1038/s42255-023-00802-1. Online ahead of print.

ABSTRACT

Distinct niches of the mammalian gut are populated by diverse microbiota, but the contribution of spatial variation to intestinal metabolism remains unclear. Here we present a map of the longitudinal metabolome along the gut of healthy colonized and germ-free male mice. With this map, we reveal a general shift from amino acids in the small intestine to organic acids, vitamins and nucleotides in the large intestine. We compare the metabolic landscapes in colonized versus germ-free mice to disentangle the origin of many metabolites in different niches, which in some cases allows us to infer the underlying processes or identify the producing species. Beyond the known impact of diet on the small intestinal metabolic niche, distinct spatial patterns suggest specific microbial influence on the metabolome in the small intestine. Thus, we present a map of intestinal metabolism and identify metabolite-microbe associations, which provide a basis to connect the spatial occurrence of bioactive compounds to host or microorganism metabolism.

PMID:37217759 | DOI:10.1038/s42255-023-00802-1

Categories: Literature Watch

Spatial dysregulation of T follicular helper cells impairs vaccine responses in aging

Mon, 2023-05-22 06:00

Nat Immunol. 2023 May 22. doi: 10.1038/s41590-023-01519-9. Online ahead of print.

ABSTRACT

The magnitude and quality of the germinal center (GC) response decline with age, resulting in poor vaccine-induced immunity in older individuals. A functional GC requires the co-ordination of multiple cell types across time and space, in particular across its two functionally distinct compartments: the light and dark zones. In aged mice, there is CXCR4-mediated mislocalization of T follicular helper (TFH) cells to the dark zone and a compressed network of follicular dendritic cells (FDCs) in the light zone. Here we show that TFH cell localization is critical for the quality of the antibody response and for the expansion of the FDC network upon immunization. The smaller GC and compressed FDC network in aged mice were corrected by provision of TFH cells that colocalize with FDCs using CXCR5. This demonstrates that the age-dependent defects in the GC response are reversible and shows that TFH cells support stromal cell responses to vaccines.

PMID:37217705 | DOI:10.1038/s41590-023-01519-9

Categories: Literature Watch

Base editing-mediated one-step inactivation of the Dnmt gene family reveals critical roles of DNA methylation during mouse gastrulation

Mon, 2023-05-22 06:00

Nat Commun. 2023 May 22;14(1):2922. doi: 10.1038/s41467-023-38528-z.

ABSTRACT

During embryo development, DNA methylation is established by DNMT3A/3B and subsequently maintained by DNMT1. While much research has been done in this field, the functional significance of DNA methylation in embryogenesis remains unknown. Here, we establish a system of simultaneous inactivation of multiple endogenous genes in zygotes through screening for base editors that can efficiently introduce a stop codon. Embryos with mutations in Dnmts and/or Tets can be generated in one step with IMGZ. Dnmt-null embryos display gastrulation failure at E7.5. Interestingly, although DNA methylation is absent, gastrulation-related pathways are down-regulated in Dnmt-null embryos. Moreover, DNMT1, DNMT3A, and DNMT3B are critical for gastrulation, and their functions are independent of TET proteins. Hypermethylation can be sustained by either DNMT1 or DNMT3A/3B at some promoters, which are related to the suppression of miRNAs. The introduction of a single mutant allele of six miRNAs and paternal IG-DMR partially restores primitive streak elongation in Dnmt-null embryos. Thus, our results unveil an epigenetic correlation between promoter methylation and suppression of miRNA expression for gastrulation and demonstrate that IMGZ can accelerate deciphering the functions of multiple genes in vivo.

PMID:37217538 | DOI:10.1038/s41467-023-38528-z

Categories: Literature Watch

Vitamin K1 and progression of cardiovascular calcifications in hemodialysis patients: the VitaVasK randomized controlled trial

Mon, 2023-05-22 06:00

Clin Kidney J. 2022 Aug 24;15(12):2300-2311. doi: 10.1093/ckj/sfac184. eCollection 2022 Dec.

ABSTRACT

BACKGROUND: Cardiovascular calcifications are prevented by matrix Gla protein (MGP), a vitamin K-dependent protein. Haemodialysis patients exhibit marked vitamin K deficiency. The randomized, prospective, open-label, multicentre VitaVasK trial analysed whether vitamin K1 supplementation reduces progression of coronary artery calcifications (CACs) and thoracic aortic calcifications (TACs).

METHODS: Patients with pre-existing CACs were randomized to continue on standard care or to additionally receive 5 mg of vitamin K1 orally thrice weekly. Hierarchically ordered primary endpoints were progression of TAC and CAC in computed tomography scans at 18 months. Linear mixed effects models with repeated measures at baseline and 12 and 18 months assessed treatment effects after adjusting for study site.

RESULTS: Of 60 randomized patients, 20 dropped out for reasons unrelated to vitamin K1, resulting in 23 control and 17 vitamin K1 patients. The trial was stopped early due to slow recruitment. At 18 months, the average TAC progression was 56% lower in the vitamin K1 compared with the control group (p = .039). CAC significantly progressed within the control group, but not within the vitamin K1 group. Average progression at 18 months was 68% lower in the vitamin K1 compared to the control group (P = .072). Vitamin K1 reduced plasma levels of pro-calcific uncarboxylated MGP by 69% at 18 months. No treatment-related adverse events were noted.

CONCLUSION: Vitamin K1 intervention is a potent, safe and cost-effective approach to correct vitamin K deficiency and to potentially reduce cardiovascular calcification in this high-risk population.

PMID:37216675 | PMC:PMC9664584 | DOI:10.1093/ckj/sfac184

Categories: Literature Watch

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