Publications by authors named "Xiaoting Chen"

123 Publications

Porcine-Stimulated Human Tr1 Cells Showed Enhanced Suppression in Xenoantigen Stimulation Response.

Comput Math Methods Med 2021 8;2021:2725799. Epub 2021 Nov 8.

Department of Urology, Institute of Urology, West China Hospital, Sichuan University, Chengdu, China.

Type 1 regulatory T (Tr1) cells play a fundamental role in maintaining and inducing immune tolerance. Our preliminary study demonstrated that an interleukin- (IL-) 10-mediated pathway is a possible regulatory mechanism underlying the xenoantigen-specific human Treg enhanced suppressive capacity. Here, we developed a feasible protocol for expanding IL-10-induced xenoantigen-specific human Tr1 cells in vitro which would be more efficient in transplantation immunotherapy efficiency. In this study, xenoantigen-specific Tr1 cells are generated from human naive CD4 T cells expanded for two subsequent xenoantigen-stimulation cycles with recombinant human IL-10. The phenotype and suppressive capacity of xenoantigen-stimulated Tr1 cells are assessed, and the mechanism of their suppression is studied. Tr1 cells can be induced by porcine xenoantigen stimulation combined with IL-10, IL-2, and IL-15, displaying an increased expression of CD49b, CTLA-4, and LAG-3 without expressing Foxp3 which also showed an effector memory Treg phenotype and expressed high levels of CD39. After xenoantigen stimulation, the IL-10 and IL-5 gene expression in Tr1 cells increased, secreting more IL-10, and xenoantigen-stimulated Tr1 cells changed their T cell receptor (TCR) V repertoire, increasing the expression of TCR V2, TCR V9, and TCR V13. In a pig to human mixed lymphocyte reaction (MLR), xenoantigen-stimulated Tr1 cells displayed enhanced suppressive capacity via CD39 in a dose-dependent manner. Moreover, IL-5 could affect the proliferation of xenoantigen-specific Tr1 cells, but not their phenotypes' expression. This study provides a theory and feasible method for immune tolerance induction in clinical xenotransplantation.
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http://dx.doi.org/10.1155/2021/2725799DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8592757PMC
November 2021

Identification of MDM2, YTHDF2 and DDX21 as potential biomarkers and targets for treatment of type 2 diabetes.

Biochem Biophys Res Commun 2021 Dec 9;581:110-117. Epub 2021 Oct 9.

Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, China; Center for Diabetes and Metabolism Research, Division of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, China. Electronic address:

Type 2 diabetes (T2D) is a multifactorial and polygenetic disease, although its exact etiology remains poorly understood. The objective of this study was to identify key biomarkers and potential molecular mechanisms in the development of T2D. Human RNA-Seq datasets across different tissues (GSE18732, GSE41762, and GSE78721) were collected from the Gene Expression Omnibus (GEO) database and differentially expressed genes (DEGs) between T2D and controls were identified using differential analysis. A total of 90 overlapping DEGs were identified, among which YTHDF2, DDX21, and MDM2 were considered as key genes due to their central positions in the PPI network and the same regulatory pattern in T2D. Logistic regression analysis showed that low expression of the key genes increased the risk of T2D. Enrichment analysis revealed that the key genes are involved in various important biological functions and signaling pathways including Notch, Fork head box O (FOXO), and phosphoinositide 3-kinase (PI3K)-Akt. RT-qPCR and Western blot analysis showed that all three key genes were down-regulated in pancreatic islets of both prediabetic and diabetic mouse models. Finally, the insulin-sensitizer, pioglitazone was used to treat db/db mice and immunofluorescence analysis showed that the expression of all three key genes was significantly down-regulated in db/db islets, an effect that was overcome by pioglitazone treatment. Together, these results suggest that the identified key genes could be involved in the development of T2D and serve as potential biomarkers and therapeutic targets for this disease.
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http://dx.doi.org/10.1016/j.bbrc.2021.10.019DOI Listing
December 2021

Short Chain Fatty Acids Prevent Glyoxylate-Induced Calcium Oxalate Stones by GPR43-Dependent Immunomodulatory Mechanism.

Front Immunol 2021 5;12:729382. Epub 2021 Oct 5.

Department of Urology, Institute of Urology (Laboratory of Reconstructive Urology), West China Hospital, Sichuan University, Chengdu, China.

Calcium oxalate (CaOx) stones are the most common type of kidney stones and are associated with high recurrence, short chain fatty acids (SCFAs), and inflammation. However, it remains uncertain whether SCFAs affect the formation of CaOx stones through immunomodulation. We first performed mass cytometry (CyTOF) and RNA sequencing on kidney immune cells with glyoxylate-induced CaOx crystals (to elucidate the landscape of the associated immune cell population) and explored the role of SCFAs in renal CaOx stone formation through immunomodulation. We identified 29 distinct immune cell subtypes in kidneys with CaOx crystals, where CX3CR1CD24 macrophages significantly decreased and GR1 neutrophils significantly increased. In accordance with the CyTOF data, RNA sequencing showed that most genes involved were related to monocytes and neutrophils. SCFAs reduced kidney CaOx crystals by increasing the frequency of CX3CR1CD24 macrophages and decreasing GR1 neutrophil infiltration in kidneys with CaOx crystals, which was dependent on the gut microbiota. GPR43 knockdown by transduction with adeno-associated virus inhibited the alleviation of crystal formation and immunomodulatory effects in the kidney, due to SCFAs. Moreover, CX3CR1CD24 macrophages regulated GR1 neutrophils GPR43. Our results demonstrated a unique trilateral relationship among SCFAs, immune cells, and the kidneys during CaOx formation. These findings suggest that future immunotherapies may be used to prevent kidney stones using SCFAs.
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http://dx.doi.org/10.3389/fimmu.2021.729382DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8523925PMC
October 2021

Self-Stabilized Supramolecular Assemblies Constructed from PEGylated Dendritic Peptide Conjugate for Augmenting Tumor Retention and Therapy.

Adv Sci (Weinh) 2021 11 7;8(22):e2102741. Epub 2021 Oct 7.

Huaxi MR Research Center (HMRRC), Department of Radiology, National Clinical Research Center for Geriatrics, Frontiers Science Center for Disease-Related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China.

Supramolecular self-assemblies of dendritic peptides with well-organized nanostructures have great potential as multifunctional biomaterials, yet the complex self-assembly mechanism hampers their wide exploration. Herein, a self-stabilized supramolecular assembly (SSA) constructed from a PEGylated dendritic peptide conjugate (PEG-dendritic peptide-pyropheophorbide a, PDPP), for augmenting tumor retention and therapy, is reported. The supramolecular self-assembly process of PDPP is concentration-dependent with multiple morphologies. By tailoring the concentration of PDPP, the supramolecular self-assembly is driven by noncovalent interactions to form a variety of SSAs (unimolecular micelles, oligomeric aggregates, and multi-aggregates) with different sizes from nanometer to micrometer. SSAs at 100 nm with a spherical shape possess extremely high stability to prolong blood circulation about 4.8-fold higher than pyropheophorbide a (Ppa), and enhance tumor retention about eight-fold higher than Ppa on day 5 after injection, which leads to greatly boosting the in vivo photodynamic therapeutic efficiency. RNA-seq demonstrates that these effects of SSAs are related to the inhibition of MET-PI3K-Akt pathway. Overall, the supramolecular self-assembly mechanism for the synthetic PEGylated dendritic peptide conjugate sheds new light on the development of supramolecular assemblies for tumor therapy.
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http://dx.doi.org/10.1002/advs.202102741DOI Listing
November 2021

Chromium biogeochemical behaviour in soil-plant systems and remediation strategies: A critical review.

J Hazard Mater 2021 Sep 15;424(Pt A):127233. Epub 2021 Sep 15.

School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510006, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510006, China. Electronic address:

Chromium (Cr) is a toxic heavy metal that is heavily discharged into the soil environment due to its widespread use and mining. High Cr levels may pose toxic hazards to plants, animals and humans, and thus have attracted global attention. Recently, much progress has been made in elucidating the mechanisms of Cr uptake, transport and accumulation in soil-plant systems, aiming to reduce the toxicity and ecological risk of Cr in soil; however, these topics have not been critically reviewed and summarised to date. Accordingly, based on available data-especially from the last five years (2017-2021)-this review traces a plausible link among Cr sources, levels, chemical forms, and phytoavailability in soil; Cr accumulation and translocation in plants; and Cr phytotoxicity and detoxification in plants. Additionally, given the toxicity and hazard posed by Cr(VI) in soils and the application of reductant materials to reduce Cr(VI) to Cr(III) for the remediation of Cr(VI)-contaminated soils, the reduction and immobilisation mechanisms by organic and inorganic reductants are summarised. Finally, some priority research challenges concerning the biogeochemical behaviour of Cr in soil-plant systems are highlighted, as well as the environmental impacts resulting from the application of reductive materials and potential research prospects.
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http://dx.doi.org/10.1016/j.jhazmat.2021.127233DOI Listing
September 2021

DG-8d, a novel diosgenin derivative, decreases the proliferation and induces the apoptosis of A549 cells by inhibiting the PI3k/Akt signaling pathway.

Steroids 2021 Oct 30;174:108898. Epub 2021 Jul 30.

Qiqihaer Medical University, Heilongjiang Qiqihaer 161006, China. Electronic address:

Lung neoplasm has a relatively poor prognosis, and the clinical efficacy of targeted medicine remains unsatisfactory. Therefore, the development of novel efficient anti-lung cancer drugs is urgently needed. In our previous study, we showed that a novel diosgenin derivative 8d (DG-8d), which contained 5-(3-pyridyl)-1,3,4-thiadiazole moiety, had significant cytotoxic activity on human tumor cells, especially the A549 cells. However, the underlying mechanism of DG-8d was unknown. In this study, the pharmacological effect of DG-8d on the A549 cells was inspected.

Method: Cell viability and apoptosis were detected by CCK-8 assays, morphological changes and quantitative analysis of flow cytometry. Levels of gene and protein expression of apoptosis-related and PI3k/Akt pathway were evaluated by qRT-PCR, immunostaining and Western blot analysis.

Result: The findings proved that DG-8d could inhibit cell growth and induce apoptosis. The effect of DG-8d on the proliferation and apoptosis in the A549 cells were improved with LY294002 (PI3K inhibitor). Moreover, the effect of DG-8d on apoptosis was further confirmed by AO-EB dye, mitochondrial depolarization and accrued intracellular ROS. Gene and protein detection showed that DG-8d or DG-8d combined with LY294002 could down-regulate signaling molecules of Bcl-2, PI3k, p-Akt, p-FoxO3a and up-regulate signaling molecules of Bax snd Bim. In addition, nuclear translocation of FoxO3a was observed significantly in the cells.

Conclusion: DG-8d could inhibit the proliferation and induce the apoptosis of the A549 cells, which maybe mainly because of the suppression of the PI3k/Akt pathways. Finally, we believe that DG-8d can be developed as a possible agent for carcinoma therapy.
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http://dx.doi.org/10.1016/j.steroids.2021.108898DOI Listing
October 2021

Smoking induces the occurrence of colorectal cancer via changing the intestinal permeability.

J BUON 2021 May-Jun;26(3):1009-1015

Department of Hepatobiliary Surgery, Baogang Hospital, Baogang, China.

Purpose: Colorectal cancer (CRC) is the third most frequent cancer. Its occurrence is closely linked to lifestyle and diet habits, such as excessive intake of high-fat food, but their impact on CRC, however, remain unclear.

Methods: Eligible CRC patients were retrospectively analyzed. Overall survival (OS) and recurrence-free survival (RFS) in smokers and non-smokers of CRC patients were assessed. APCmin/+ mice were exposed to cigarette smoking, followed by detection of CRC growth and intestinal permeability.

Results: A total of 416 eligible CRC patients were recruited, involving 218 (52.4%) smokers and 198 (47.6%) non-smokers. OS was shorter in CRC smokers than in non-smokers (p=0.005), whereas smoking did not affect RFS in CRC patients (p=0.251). Cigarette smoking increased CRC tumor numbers of CRC in APCmin/+ mice. Proliferation and apoptosis of colorectal epithelial cells, and inflammatory response in mice were changed following smoking. Notably, the treatment of probiotics mixture VSL#3 decreased the number of CRC tissues and intestinal permeability in APCmin/+ mice exposed to cigarette smoking.

Conclusions: Smoking increases the susceptibility to CRC through damaging the intestinal permeability. Protecting the intestinal permeability significantly protects intestinal tracts.
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July 2021

TSLP disease-associated genetic variants combined with airway TSLP expression influence asthma risk.

J Allergy Clin Immunol 2021 Jun 7. Epub 2021 Jun 7.

Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio; Division of Asthma Research, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio. Electronic address:

Background: Thymic stromal lymphopoietin (TSLP) is an epithelial-derived cytokine important in initiation of allergic inflammation. Single nucleotide polymorphisms (SNPs) in TSLP are associated with asthma, yet studies have shown inconsistent associations between circulating TSLP and asthma. Studies that integrate the combined effects of TSLP genotype, TSLP mRNA, circulating TSLP levels, and asthma outcome are lacking.

Objectives: This study sought to recruit a novel cohort based on asthma-relevant TSLP SNPs and determine their impact on TSLP mRNA expression and TSLP circulating protein levels, and their individual and combined effects on asthma.

Methods: This study developed an algorithm to prioritize TSLP SNPs and recruited 51 carriers and noncarriers based on TSLP genotypes. TSLP mRNA was quantified in nasal epithelial cells and circulating TSLP levels in plasma. This study determined the associations of defined TSLP risk genotypes and/or TSLP mRNA and protein levels with asthma.

Results: TSLP mRNA expression, but not circulating TSLP, was significantly increased in people who are asthmatic compared with in people who are nonasthmatic (P = .007; odds ratio, 1.44). Notably, 90% of children with the defined TSLP risk genotypes and high nasal TSLP mRNA expression (top tertile) had asthma compared with 40% of subjects without risk genotypes and with low TSLP expression (bottom tertile) (P = .024). No association between circulating TSLP and asthma was observed.

Conclusions: Collectively, these data suggest childhood asthma is modified by the combined effects of TSLP genotype and TSLP expression in the nasal epithelium. The increased asthma risk likely manifests when genetic variation enables expression quantitative trait loci in the TSLP locus to elevate TSLP. It is important to consider both biomarkers when factoring asthma risk.
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http://dx.doi.org/10.1016/j.jaci.2021.05.033DOI Listing
June 2021

METTL3 Promotes Esophageal Squamous Cell Carcinoma Metastasis Through Enhancing GLS2 Expression.

Front Oncol 2021 19;11:667451. Epub 2021 May 19.

Clinical Department of Guangdong Metabolic Disease Research Centre of Integrated Chinese and Western Medicine, The First Affiliated Hospital of Guangdong Pharmaceutical University, Guangzhou, China.

Recent studies have identified pleiotropic roles of methyltransferase-like 3 (METTL3) in tumor progression. However, the roles of METTL3 in esophageal squamous cell carcinoma (ESCC) are still unclear. Here, we investigated the function and mechanism of METTL3 in ESCC tumorigenesis. We reported that higher METTL3 expression was found in ESCC tissues and was markedly associated with depth of invasion and poor prognosis. Loss- and gain-of function studies showed that METTL3 promoted the migration and invasion of ESCC cells . Integrated methylated RNA immunoprecipitation sequencing (MeRIP-Seq) and RNA sequencing (RNA-Seq) analysis first demonstrated that glutaminase 2 (GLS2) was regulated by METTL3 m6A modification. Our findings identified METTL3/GLS2 signaling as a potential therapeutic target in antimetastatic strategies against ESCC.
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http://dx.doi.org/10.3389/fonc.2021.667451DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8170325PMC
May 2021

PKM2-dependent metabolic skewing of hepatic Th17 cells regulates pathogenesis of non-alcoholic fatty liver disease.

Cell Metab 2021 06 17;33(6):1187-1204.e9. Epub 2021 May 17.

Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45220, USA; Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Medical Scientist Training Program, Cincinnati Children's Hospital Medical Center and the University of Cincinnati College of Medicine, Cincinnati, OH 45220, USA; Immunology Graduate Program, Cincinnati Children's Hospital Medical Center and the University of Cincinnati College of Medicine, Cincinnati, OH 45220, USA; The Center for Inflammation and Tolerance, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA. Electronic address:

Emerging evidence suggests a key contribution to non-alcoholic fatty liver disease (NAFLD) pathogenesis by Th17 cells. The pathogenic characteristics and mechanisms of hepatic Th17 cells, however, remain unknown. Here, we uncover and characterize a distinct population of inflammatory hepatic CXCR3Th17 (ihTh17) cells sufficient to exacerbate NAFLD pathogenesis. Hepatic ihTh17 cell accrual was dependent on the liver microenvironment and CXCR3 axis activation. Mechanistically, the pathogenic potential of ihTh17 cells correlated with increased chromatin accessibility, glycolytic output, and concomitant production of IL-17A, IFNγ, and TNFα. Modulation of glycolysis using 2-DG or cell-specific PKM2 deletion was sufficient to reverse ihTh17-centric inflammatory vigor and NAFLD severity. Importantly, ihTh17 cell characteristics, CXCR3 axis activation, and hepatic expression of glycolytic genes were conserved in human NAFLD. Together, our data show that the steatotic liver microenvironment regulates Th17 cell accrual, metabolism, and competence toward an ihTh17 fate. Modulation of these pathways holds potential for development of novel therapeutic strategies for NAFLD.
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http://dx.doi.org/10.1016/j.cmet.2021.04.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8237408PMC
June 2021

Thyroid Hormone-Regulated Expression of Period2 Promotes Liver Urate Production.

Front Cell Dev Biol 2021 1;9:636802. Epub 2021 Apr 1.

Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China.

The relationship between thyroid hormones and serum urate is unclear. Our aim is to analyze the correlation between uric acid and thyroid hormones in gout patients and to explore the effect and mechanism of triiodothyronine on liver uric acid production. Eighty men patients with gout were selected to analyze the correlation between blood urate and thyroid function-related hormone levels. Stepwise multiple linear regression was used to analyze factors affecting blood urate in patients with gout. Levels of urate in serum, liver, and cell culture supernatant were measured after triiodothyronine treatment. Purine levels (adenine, guanine, and hypoxanthine) were also measured. Expression levels of Period2 and nucleotide metabolism enzymes were analyzed after triiodothyronine treatment and Period2-shRNA lentivirus transduction. Chromatin immunoprecipitation was used to analyze the effects of triiodothyronine and thyroid hormone receptor-β on Period2 expression. The results showed that in patients FT3 influenced the serum urate level. Furthermore, urate level increased in mouse liver and cell culture supernatant following treatment with triiodothyronine. Purine levels in mouse liver increased, accompanied by upregulation of enzymes involved in nucleotide metabolism. These phenomena were reversed in Period2 knockout mice. Triiodothyronine promoted the binding of thyroid hormone receptor-β to the Period2 promoter and subsequent transcription of Period2. Triiodothyronine also enhanced nuclear expression of Sirt1, which synergistically enhanced Period2 expression. The study demonstrated that triiodothyronine is independently positively correlated with serum urate and liver uric acid production through Period2, providing novel insights into the purine metabolism underlying hyperuricemia/gout pathophysiology.
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http://dx.doi.org/10.3389/fcell.2021.636802DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8047155PMC
April 2021

Methylation quantitative trait locus analysis of chronic postsurgical pain uncovers epigenetic mediators of genetic risk.

Epigenomics 2021 Apr 6;13(8):613-630. Epub 2021 Apr 6.

Department of Anatomy, Physiology & Cell biology, California National Primate Research Center, University of California, Davis, CA 95616, USA.

Overlap of pathways enriched by single nucleotide polymorphisms and DNA-methylation underlying chronic postsurgical pain (CPSP), prompted pilot study of CPSP-associated methylation quantitative trait loci (meQTL). Children undergoing spine-fusion were recruited prospectively. Logistic-regression for genome- and epigenome-wide CPSP association and DNA-methylation-single nucleotide polymorphism association/mediation analyses to identify meQTLs were followed by functional genomics analyses. CPSP (n = 20/58) and non-CPSP groups differed in pain-measures. Of 2753 meQTLs, DNA-methylation at 127 cytosine-guanine dinucleotides mediated association of 470 meQTLs with CPSP (p < 0.05). At PARK16 locus, CPSP risk meQTLs were associated with decreased DNA-methylation at and increased DNA-methylation at Corresponding blood eQTLs (GTEx) and cytosine-guanine dinucleotide-loci enrichment for histone marks, transcription factor binding sites and ATAC-seq peaks suggest altered transcription factor-binding. CPSP-associated meQTLs indicate epigenetic mechanisms mediate genetic risk. Clinical trial registration: NCT01839461, NCT01731873 (ClinicalTrials.gov).
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http://dx.doi.org/10.2217/epi-2020-0424DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8173520PMC
April 2021

Fezf functions as a transcriptional repressor to direct layer-specific synaptic connectivity in the fly visual system.

Proc Natl Acad Sci U S A 2021 03;118(13)

Department of Neurobiology, Harvard Medical School, Boston, MA 02115;

The layered compartmentalization of synaptic connections, a common feature of nervous systems, underlies proper connectivity between neurons and enables parallel processing of neural information. However, the stepwise development of layered neuronal connections is not well understood. The medulla neuropil of the visual system, which comprises 10 discrete layers (M1 to M10), where neural computations underlying distinct visual features are processed, serves as a model system for understanding layered synaptic connectivity. The first step in establishing layer-specific connectivity in the outer medulla (M1 to M6) is the innervation by lamina (L) neurons of one of two broad, primordial domains that will subsequently expand and transform into discrete layers. We previously found that the transcription factor dFezf cell-autonomously directs L3 lamina neurons to their proper primordial broad domain before they form synapses within the developing M3 layer. Here, we show that dFezf controls L3 broad domain selection through temporally precise transcriptional repression of the transcription factor (sloppy paired 1). In wild-type L3 neurons, is transiently expressed at a low level during broad domain selection. When is deleted, expression is up-regulated, and ablation of fully rescues the defect of broad domain selection in -null L3 neurons. Although the early, transient expression of is expendable for broad domain selection, it is surprisingly necessary for the subsequent L3 innervation of the M3 layer. DFezf thus functions as a transcriptional repressor to coordinate the temporal dynamics of a transcriptional cascade that orchestrates sequential steps of layer-specific synapse formation.
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http://dx.doi.org/10.1073/pnas.2025530118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8020669PMC
March 2021

The genome of the stable fly, Stomoxys calcitrans, reveals potential mechanisms underlying reproduction, host interactions, and novel targets for pest control.

BMC Biol 2021 03 10;19(1):41. Epub 2021 Mar 10.

Department of Computer Science & Engineering, Department of Biochemistry & Biophysics, Texas A & M University, College Station, TX, USA.

Background: The stable fly, Stomoxys calcitrans, is a major blood-feeding pest of livestock that has near worldwide distribution, causing an annual cost of over $2 billion for control and product loss in the USA alone. Control of these flies has been limited to increased sanitary management practices and insecticide application for suppressing larval stages. Few genetic and molecular resources are available to help in developing novel methods for controlling stable flies.

Results: This study examines stable fly biology by utilizing a combination of high-quality genome sequencing and RNA-Seq analyses targeting multiple developmental stages and tissues. In conjunction, 1600 genes were manually curated to characterize genetic features related to stable fly reproduction, vector host interactions, host-microbe dynamics, and putative targets for control. Most notable was characterization of genes associated with reproduction and identification of expanded gene families with functional associations to vision, chemosensation, immunity, and metabolic detoxification pathways.

Conclusions: The combined sequencing, assembly, and curation of the male stable fly genome followed by RNA-Seq and downstream analyses provide insights necessary to understand the biology of this important pest. These resources and new data will provide the groundwork for expanding the tools available to control stable fly infestations. The close relationship of Stomoxys to other blood-feeding (horn flies and Glossina) and non-blood-feeding flies (house flies, medflies, Drosophila) will facilitate understanding of the evolutionary processes associated with development of blood feeding among the Cyclorrhapha.
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http://dx.doi.org/10.1186/s12915-021-00975-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7944917PMC
March 2021

Global discovery of lupus genetic risk variant allelic enhancer activity.

Nat Commun 2021 03 12;12(1):1611. Epub 2021 Mar 12.

Center for Autoimmune Genomics and Etiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.

Genome-wide association studies of Systemic Lupus Erythematosus (SLE) nominate 3073 genetic variants at 91 risk loci. To systematically screen these variants for allelic transcriptional enhancer activity, we construct a massively parallel reporter assay (MPRA) library comprising 12,396 DNA oligonucleotides containing the genomic context around every allele of each SLE variant. Transfection into the Epstein-Barr virus-transformed B cell line GM12878 reveals 482 variants with enhancer activity, with 51 variants showing genotype-dependent (allelic) enhancer activity at 27 risk loci. Comparison of MPRA results in GM12878 and Jurkat T cell lines highlights shared and unique allelic transcriptional regulatory mechanisms at SLE risk loci. In-depth analysis of allelic transcription factor (TF) binding at and around allelic variants identifies one class of TFs whose DNA-binding motif tends to be directly altered by the risk variant and a second class of TFs that bind allelically without direct alteration of their motif by the variant. Collectively, our approach provides a blueprint for the discovery of allelic gene regulation at risk loci for any disease and offers insight into the transcriptional regulatory mechanisms underlying SLE.
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http://dx.doi.org/10.1038/s41467-021-21854-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7955039PMC
March 2021

Deciphering cis-regulatory grammar with deep learning.

Nat Genet 2021 03;53(3):266-268

Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.

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http://dx.doi.org/10.1038/s41588-021-00814-1DOI Listing
March 2021

Hyperuricemia causes kidney damage by promoting autophagy and NLRP3-mediated inflammation in rats with urate oxidase deficiency.

Dis Model Mech 2021 03 24;14(3). Epub 2021 Mar 24.

Department of Endocrinology and Metabolism, Shanghai 10th People's Hospital, Tongji University, Shanghai 200072, China

Epidemiological research has shown that elevated serum urate concentration is a risk factor for the development of kidney disease; however, the mechanisms underlying this process have not yet been elucidated. To examine the role of urate in the kidney, we used Wistar rats to functionally disrupt expression of urate oxidase (UOX) by using the CRISPR/Cas9 system. In comparison to wild-type (WT) rats, serum urate levels spontaneously and persistently increased in -KO rats, without showing a significant decrease in survival rate. Architecture and function of the kidneys in -KO rats were impaired. Injury to the kidney resulted in increased interstitial fibrosis, macrophage infiltration, increased expression of NLRP3 and IL-1β, and activation of multiple cell-signaling pathways associated with autophagy, such as AMPK, p38 MAPK, ERK and JNK pathways. Inhibition of autophagy with the PI3K inhibitor 3-MA abrogated the development of kidney damage and attenuated renal fibrosis, macrophage infiltration, and expression of NLRP3 and IL-1β in injured kidneys. In conclusion, the -KO rat is a great model to study hyperuricemia-related diseases. Hyperuricemia-induced autophagy and NLRP3-dependent inflammation are critically involved in the development of renal damage and, therefore, highlight the inhibition of autophagy and inflammation in search of therapeutic strategies to treat uric acid nephropathy.
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http://dx.doi.org/10.1242/dmm.048041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8015218PMC
March 2021

U2AF2 binds IL7R exon 6 ectopically and represses its inclusion.

RNA 2021 Feb 10. Epub 2021 Feb 10.

Duke University

Interleukin 7 receptor α-chain is crucial for the development and maintenance of T cells and is genetically associated with autoimmune disorders including multiple sclerosis (MS), a demyelinating disease of the CNS. Exon 6 of IL7R encodes for the transmembrane domain of the receptor and is regulated by alternative splicing: inclusion or skipping of IL7R exon 6 results in membrane-bound or soluble IL7R isoforms, respectively. We previously identified a SNP (rs6897932) in IL7R exon 6, strongly associated with MS risk and showed that the risk allele (C) increases skipping of the exon, resulting in elevated levels of sIL7R. This has important pathological consequences as elevated levels of sIL7R has been shown to exacerbate the disease in the experimental autoimmune encephalomyelitis mouse model of MS. Understanding the regulation of exon 6 splicing provides important mechanistic insights into the pathogenesis of MS. Here we report two mechanisms by which IL7R exon 6 is controlled. First, a competition between PTBP1 and U2AF2 at the polypyrimidine tract (PPT) of intron 5, and second, an unexpected U2AF2-mediated assembly of spicing factors in the exon. We noted the presence of a branchpoint sequence (BPS) (TACTAAT or TACTAAC) within exon 6, which is stronger with the C allele. We also noted that the BPS is followed by a PPT and conjectured that silencing could be mediated by the binding of U2AF2 to that tract. In support of this model, we show that evolutionary conservation of the exonic PPT correlates well with the degree of alternative splicing of exon 6 in two non-human primate species and that U2AF2 binding to this PPT recruits U2 snRNP components to the exon. These observations provide the first explanation for the stronger silencing of IL7R exon 6 with the disease associated C allele at rs6897932.
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http://dx.doi.org/10.1261/rna.078279.120DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8051268PMC
February 2021

The p53/miR-145a Axis Promotes Cellular Senescence and Inhibits Osteogenic Differentiation by Targeting Cbfb in Mesenchymal Stem Cells.

Front Endocrinol (Lausanne) 2020 11;11:609186. Epub 2021 Jan 11.

Department of Geriatrics, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.

The osteogenic differentiation capacity of senescent bone marrow mesenchymal stem cells (MSCs) is reduced. p53 not only regulates cellular senescence but also functions as a negative regulator in bone formation. However, the role of p53 in MSCs senescence and differentiation has not been extensively explored. In the present study, we investigated the molecular mechanism of p53 in MSCs senescence and osteogenic differentiation. We found that p53 was upregulated during cellular senescence and osteogenic differentiation of MSCs respectively induced by HO and BMP9. Similarly, the expression of p53-induced miR-145a was increased significantly. Furthermore, Overexpression of miR-145a in MSCs promoted cellular senescence and inhibited osteogenic differentiation. Then, we identified that p53-induced miR-145a inhibited osteogenic differentiation by targeting core binding factor beta (Cbfb), and the restoration of Cbfb expression rescued the inhibitory effects of miRNA-145a. In summary, our results indicate that p53/miR-145a axis exert its functions both in promoting senescence and inhibiting osteogenesis of MSCs, and the novel p53/miR-145a/Cbfb axis in osteogenic differentiation of MSCs may represent new targets in the treatment of osteoporosis.
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http://dx.doi.org/10.3389/fendo.2020.609186DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7829338PMC
May 2021

Conserved regulatory logic at accessible and inaccessible chromatin during the acute inflammatory response in mammals.

Nat Commun 2021 01 25;12(1):567. Epub 2021 Jan 25.

Hospital for Sick Children, Genetics and Genome Biology, Toronto, Canada.

The regulatory elements controlling gene expression during acute inflammation are not fully elucidated. Here we report the identification of a set of NF-κB-bound elements and common chromatin landscapes underlying the acute inflammatory response across cell-types and mammalian species. Using primary vascular endothelial cells (human/mouse/bovine) treated with the pro-inflammatory cytokine, Tumor Necrosis Factor-α, we identify extensive (~30%) conserved orthologous binding of NF-κB to accessible, as well as nucleosome-occluded chromatin. Regions with the highest NF-κB occupancy pre-stimulation show dramatic increases in NF-κB binding and chromatin accessibility post-stimulation. These 'pre-bound' regions are typically conserved (~56%), contain multiple NF-κB motifs, are utilized by diverse cell types, and overlap rare non-coding mutations and common genetic variation associated with both inflammatory and cardiovascular phenotypes. Genetic ablation of conserved, 'pre-bound' NF-κB regions within the super-enhancer associated with the chemokine-encoding CCL2 gene and elsewhere supports the functional relevance of these elements.
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http://dx.doi.org/10.1038/s41467-020-20765-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7835376PMC
January 2021

EF24 induces ferroptosis in osteosarcoma cells through HMOX1.

Biomed Pharmacother 2021 Apr 14;136:111202. Epub 2021 Jan 14.

Department of Orthopedic, The Third Affiliated Hospital of Southern Medical University, No. 183 Zhongshan Dadao West, 510630, Guangzhou, China. Electronic address:

Purpose: EF24, a synthetic analogue of curcumin, was developed as an anti-tumor compound to induce apoptosis, inhibit proliferation and metastasis in various cancers. However, whether EF24 induces ferroptosis in osteosarcoma cells or not, and its underlying mechanism remains largely elusive.

Methods: After EF24 combining with or without other compounds treatments, mRNA expression profiles were proceeded by RNA sequencing. Cytotoxicity was measured by cell counting kit-8 assay. Cell death was quantified by flow cytometer. Gene expression was quantified by real-time PCR. Protein level was detected by western blot. Malonydialdehyde (MDA) level was measured by lipid peroxidation MDA assay kit. Reactive oxygen species (ROS) level was measured by ROS Assay Kit. Ferric ion was measured by Iron Assay kit.

Results: EF24 significantly induced cell death in osteosarcoma cell lines, and this effect was significantly reversed by ferrostatin-1, but not Z-VAD(Ome)-FMK, MRT68921 or necrosulfonamide. EF24 significantly increased MDA level, ROS level and intracellular ferric ion level, these effects were significantly attenuated by ferrostatin-1. EF24 upregulated HMOX1 expression in a dose dependent manner, overexpression of HMOX1 facilitated EF24 to induce ferroptosis in osteosarcoma cell lines. HMOX1 knockdown attenuated EF24-induced cytotoxicity and attenuated EF24-induced inhibition of Glutathione Peroxidase 4 (GPX4) expression.

Conclusion: Our results showed that EF24 upregulated HMOX1 to suppress GPX4 expression to induce ferroptosis by increasing MDA level, ROS level and intracellular ferric ion level. Thus, EF24 might serve as a potential agent for the treatment of HMOX1-positive osteosarcoma patients.
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http://dx.doi.org/10.1016/j.biopha.2020.111202DOI Listing
April 2021

Comprehensive Review of Steroid-Sensitive Nephrotic Syndrome Genetic Risk Loci and Transcriptional Regulation as a Possible Mechanistic Link to Disease Risk.

Kidney Int Rep 2021 Jan 16;6(1):187-195. Epub 2020 Oct 16.

Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.

Introduction: The etiology of steroid-sensitive nephrotic syndrome (SSNS) is not well understood. Genetic studies have established common single nucleotide polymorphisms (SNPs) that are associated with increased SSNS disease risk. We review previous genetic association studies of SSNS and nominate particular transcriptional regulators and immune cells as potential key players in the etiology of this disease.

Methods: A list of SNPs associated with SSNS was compiled from published genome wide association and candidate gene studies. The Regulatory Element Locus Intersection (RELI) tool was used to calculate the enrichment of the overlap between disease risk SNPs and the genomic coordinates of data from a collection of >10,000 chromatin immunoprecipitation sequencing experiments.

Results: After linkage disequilibrium expansion of the previously reported tag associated SNPs, we identified 192 genetic variants at 8 independent risk loci. Using the Regulatory Element Locus Intersection algorithm, we identified transcriptional regulators with enriched binding at SSNS risk loci (10 <  < 10), including ZNF530, CIITA, CD74, RFX5, and ZNF425. Many of these regulators have well-described roles in the immune response. RNA polymerase II binding in B cells also demonstrated enriched binding at SSNS risk loci (10< <10).

Conclusion: SSNS is a complex disease, and immune dysregulation has been previously implicated as a potential underlying cause. This assessment of established SSNS risk loci and analysis of possible function implicates transcriptional dysregulation, and specifically particular transcriptional regulators with known roles in the immune response, as important in the genetic etiology of SSNS.
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http://dx.doi.org/10.1016/j.ekir.2020.09.048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7783560PMC
January 2021

Second-hand smoke and NFE2L2 genotype interaction increases paediatric asthma risk and severity.

Clin Exp Allergy 2021 06 13;51(6):801-810. Epub 2021 Feb 13.

Division of Asthma Research, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.

Background: Second-hand smoke (SHS) exposure is associated with paediatric asthma, and oxidative stress is believed to play a role in mediating this association. The nuclear factor (erythroid-derived 2)-like 2 (NFE2L2) is important for the defence against oxidative stress.

Objective: To explore interactions between NFE2L2 genotype and SHS exposure in paediatric asthma risk.

Methods: We used a genotyped subset of patients of European ancestry (N = 669, median age at enrolment = 6.8 years) enrolled in the clinical cohort Greater Cincinnati Pediatric Clinic Repository as the study population, and a population-based paediatric cohort (N = 791) to replicate our findings. History of asthma diagnosis was obtained from medical records, and SHS exposure was obtained from questionnaires. Four NFE2L2 tagging SNPs were included in the analysis, and interactions between SHS and NFE2L2 genotype were evaluated using logistic regression.

Results: Three of the analysed SNPs, rs10183914, rs1806649 and rs2886161, interacted significantly with SHS exposure to increase asthma risk (p ≤ .02). The interaction was replicated in an independent cohort for rs10183914 (p = .04). Interactions between SHS exposure and NFE2L2 genotype were also associated with an increased risk of hospitalization (p = .016). In stratified analyses, NFE2L2 genotype was associated with daily asthma symptoms in children with SHS exposure (OR = 3.1; p = .048). No association was found in children without SHS exposure. Examination of publicly available chromatin immunoprecipitation followed by sequencing (ChIP-seq) data sets confirmed the presence of active histone marks and binding sites for particular transcription factors overlapping the coordinates for the significantly associated SNPs.

Conclusions And Clinical Relevance: Our study provides evidence that NFE2L2 genotype interacts with SHS exposure to affect both asthma risk and severity in children and identifies a population of children at increased risk of asthma development.
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http://dx.doi.org/10.1111/cea.13815DOI Listing
June 2021

Single-nucleus RNA-seq identifies transcriptional heterogeneity in multinucleated skeletal myofibers.

Nat Commun 2020 12 11;11(1):6374. Epub 2020 Dec 11.

Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.

While the majority of cells contain a single nucleus, cell types such as trophoblasts, osteoclasts, and skeletal myofibers require multinucleation. One advantage of multinucleation can be the assignment of distinct functions to different nuclei, but comprehensive interrogation of transcriptional heterogeneity within multinucleated tissues has been challenging due to the presence of a shared cytoplasm. Here, we utilized single-nucleus RNA-sequencing (snRNA-seq) to determine the extent of transcriptional diversity within multinucleated skeletal myofibers. Nuclei from mouse skeletal muscle were profiled across the lifespan, which revealed the presence of distinct myonuclear populations emerging in postnatal development as well as aging muscle. Our datasets also provided a platform for discovery of genes associated with rare specialized regions of the muscle cell, including markers of the myotendinous junction and functionally validated factors expressed at the neuromuscular junction. These findings reveal that myonuclei within syncytial muscle fibers possess distinct transcriptional profiles that regulate muscle biology.
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http://dx.doi.org/10.1038/s41467-020-20063-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7733460PMC
December 2020

Meta-analysis of 208370 East Asians identifies 113 susceptibility loci for systemic lupus erythematosus.

Ann Rheum Dis 2021 05 3;80(5):632-640. Epub 2020 Dec 3.

Department of Dermatology, First Affiliated Hospital, Anhui Medical University, Hefei, Anhui, China.

Objective: Systemic lupus erythematosus (SLE), an autoimmune disorder, has been associated with nearly 100 susceptibility loci. Nevertheless, these loci only partially explain SLE heritability and their putative causal variants are rarely prioritised, which make challenging to elucidate disease biology. To detect new SLE loci and causal variants, we performed the largest genome-wide meta-analysis for SLE in East Asian populations.

Methods: We newly genotyped 10 029 SLE cases and 180 167 controls and subsequently meta-analysed them jointly with 3348 SLE cases and 14 826 controls from published studies in East Asians. We further applied a Bayesian statistical approach to localise the putative causal variants for SLE associations.

Results: We identified 113 genetic regions including 46 novel loci at genome-wide significance (p<5×10). Conditional analysis detected 233 association signals within these loci, which suggest widespread allelic heterogeneity. We detected genome-wide associations at six new missense variants. Bayesian statistical fine-mapping analysis prioritised the putative causal variants to a small set of variants (95% credible set size ≤10) for 28 association signals. We identified 110 putative causal variants with posterior probabilities ≥0.1 for 57 SLE loci, among which we prioritised 10 most likely putative causal variants (posterior probability ≥0.8). Linkage disequilibrium score regression detected genetic correlations for SLE with albumin/globulin ratio (r=-0.242) and non-albumin protein (r=0.238).

Conclusion: This study reiterates the power of large-scale genome-wide meta-analysis for novel genetic discovery. These findings shed light on genetic and biological understandings of SLE.
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http://dx.doi.org/10.1136/annrheumdis-2020-219209DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8053352PMC
May 2021

Construction of cerium oxide nanoparticles immobilized on the surface of zinc vanadate nanoflowers for accelerated photocatalytic degradation of tetracycline under visible light irradiation.

J Colloid Interface Sci 2021 Apr 13;587:831-844. Epub 2020 Nov 13.

School of Chemistry and Chemical Engineering, Research Center for Clean Energy Materials Chemical Engineering Technology of Guangdong, Key Laboratory of Clean Energy Materials Chemistry of Guangdong Higher Education Institutes, Lingnan Normal University, Zhanjiang 524048, China. Electronic address:

Construction of Z-scheme heterojunction has been deemed to be an effective and promising approach to boost the photocatalytic activity on account of accelerating the separation efficiency of the photogenerated carriers and maintaining the strong redox ability. Herein, an attractive CeO/ZnVO Z-scheme heterojunction photocatalyst was rationally constructed by zero-dimensional (0D) CeO nanoparticles immobilized on the surface of three-dimensional (3D) ZnVO nanoflowers using a simple mixing method, and applied to the photocatalytic degradation of tetracycline (TC) under visible light irradiation. As expected, it was observed that the prepared CeO/ZnVO hybrid illustrated significantly boosted the photocatalytic activity for the elimination of TC compared to pure ZnVO. More importantly, the optimized CeO(40 wt%)/ZnVO hybrid owned the largest elimination rate of TC with 1.13 × 10 min, which was around 8.1 and 3.8 times as high as single CeO (0.14 × 10 min) and ZnVO (0.30 × 10 min), respectively. The appreciable performance improvement was mainly ascribed to the formation of Z-scheme heterojunction between CeO and ZnVO, facilitating the transfer rate of photogenerated carriers and remaining the high reducibility of photoexcited electrons in CeO and strong oxidizability of photoinduced holes in ZnVO. Active species capture experiments and electron spin resonance spectra showed that superoxide radicals and holes were the main active species for TC degradation. Besides, the possible degradation pathways of TC were speculated by identifying degradation intermediates, and the reasonable degradation mechanism including migration and transport behaviors of charge carriers and generation processes of reactive species were revealed in depth. This investigation enriches ZnVO-based Z-scheme heterojunction photocatalytic system and offers a new inspiration for the construction and fabrication of high-efficiency Z-scheme heterojunction photocatalysts to remove the antibiotics from wastewater.
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http://dx.doi.org/10.1016/j.jcis.2020.11.044DOI Listing
April 2021

Multi-level analysis of reproduction in an Antarctic midge identifies female and male accessory gland products that are altered by larval stress and impact progeny viability.

Sci Rep 2020 11 13;10(1):19791. Epub 2020 Nov 13.

Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, USA.

The Antarctic midge, Belgica antarctica, is a wingless, non-biting midge endemic to Antarctica. Larval development requires at least 2 years, but adults live only 2 weeks. The nonfeeding adults mate in swarms and females die shortly after oviposition. Eggs are suspended in a gel of unknown composition that is expressed from the female accessory gland. This project characterizes molecular mechanisms underlying reproduction in this midge by examining differential gene expression in whole males, females, and larvae, as well as in male and female accessory glands. Functional studies were used to assess the role of the gel encasing the eggs, as well as the impact of stress on reproductive biology. RNA-seq analyses revealed sex- and development-specific gene sets along with those associated with the accessory glands. Proteomic analyses were used to define the composition of the egg-containing gel, which is generated during multiple developmental stages and derived from both the accessory gland and other female organs. Functional studies indicate the gel provides a larval food source as well as a buffer for thermal and dehydration stress. All of these function are critical to juvenile survival. Larval dehydration stress directly reduces production of storage proteins and key accessory gland components, a feature that impacts adult reproductive success. Modeling reveals that bouts of dehydration may have a significant impact on population growth. This work lays a foundation for further examination of reproduction in midges and provides new information related to general reproduction in dipterans. A key aspect of this work is that reproduction and stress dynamics, currently understudied in polar organisms, are likely to prove critical in determining how climate change will alter their survivability.
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http://dx.doi.org/10.1038/s41598-020-76139-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7666147PMC
November 2020

Nasal DNA methylation differentiates severe from non-severe asthma in African-American children.

Allergy 2021 06 25;76(6):1836-1845. Epub 2020 Nov 25.

California National Primate Research Center, Davis, CA, USA.

Background: Asthma is highly heterogeneous, and severity evaluation is key to asthma management. DNA methylation (DNAm) contributes to asthma pathogenesis. This study aimed to identify nasal epithelial DNAm differences between severe and nonsevere asthmatic children and evaluate the impact of environmental exposures.

Methods: Thirty-three nonsevere and 22 severe asthmatic African American children were included in an epigenome-wide association study. Genome-wide nasal epithelial DNAm and gene expression were measured. CpG sites associated with asthma severity and environmental exposures and predictive of severe asthma were identified. DNAm was correlated with gene expression. Enrichment for transcription factor (TF) binding sites or histone modifications surrounding DNAm differences were determined.

Results: We identified 816 differentially methylated CpG positions (DMPs) and 10 differentially methylated regions (DMRs) associated with asthma severity. Three DMPs exhibited discriminatory ability for severe asthma. Intriguingly, six DMPs were simultaneously associated with asthma, allergic asthma, total IgE, environmental IgE, and FeNO in an independent cohort of children. Twenty-seven DMPs were associated with traffic-related air pollution or secondhand smoke. DNAm at 22 DMPs was altered by diesel particles or allergen in human bronchial epithelial cells. DNAm levels at 39 DMPs were correlated with mRNA expression. Proximal to 816 DMPs, three histone marks and several TFs involved in asthma pathogenesis were enriched.

Conclusions: Significant differences in nasal epithelial DNAm were observed between nonsevere and severe asthma in African American children, a subset of which may be useful to predict disease severity. These CpG sites are subjected to the influences of environmental exposures and may regulate gene expression.
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http://dx.doi.org/10.1111/all.14655DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8110596PMC
June 2021

Structure-based discovery and redesign of TGF-β1 Elbow epitope recognition by its type-II receptor in hypertrophic scarring biotherapy.

J Mol Recognit 2021 04 2;34(4):e2881. Epub 2020 Nov 2.

Department of Plastic Surgery, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai, China.

Transforming growth factor-β1 (TGF-β1) signaling pathway has been implicated in the fibroblast activation of hypertrophic scarring (HS). Previously, we proposed a new biotherapeutic strategy to combat HS by disrupting the intermolecular interaction of TGF-β1 with its cognate type-II receptor (TβR-II). Here, we further demonstrate that the binding site of TGF-β1 to TβR-II is not overlapped with the conformational wrist epitope and linear knuckle epitope that are traditionally recognized as the functional binding sites of bone morphogenetic protein-2 (BMP-2) to its type-II receptor (BMPR-II), which can thus be regarded as a new functional site we called elbow epitope. Structural, energetic, and dynamic investigations reveal that the elbow epitope consists of two sequentially discontinuous, spatially vicinal segments Loop and Turn ; they cannot work effectively to independently interact with TβR-II. Rational redesign of the epitope is performed using an integrated in silio-in vitro method based on crystal and modeled structure data. In the procedure, the two epitope segments are split from the interface of TGF-β1-TβR-II complex and then connected with each other in a head-to-tail manner by adding a flexible poly-(Gly)n linker between them, thus resulting in a series of combined peptides. We found that the peptide affinity reaches maximum at n = 2, which shares a consistent binding mode with the elbow epitope at native complex interface. The linker of either too long (n > 2) or too short (n < 2) cannot properly place the gap space between the two segments, thus impairing the binding compatibility of designed peptides with TβR-II active site.
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http://dx.doi.org/10.1002/jmr.2881DOI Listing
April 2021
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