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Liu, R.

Publications and source records attributed to Liu, R..

At least 289 records · Page 16Linked to original sources

The lupus autoantigen La is an Xist-binding RNA chaperone involved in Xist folding and cloud formation

Using the programmable RNA-sequence binding domain of the Pumilio protein, we FLAG-tagged Xist (inactivated X chromosome specific transcript) in live cells. Affinity pulldown coupled to mass spectrometry was employed to identify a list of 138 candidate Xist-binding proteins, from which, the lupus autoantigen La (encoding gene Ssb) was validated as a protein functionally critical for X chromosome inactivation (XCI). Extensive XCI defects were detected in Ssb knockdown cells, including chromatin compaction, death of female ES cells during in vitro differentiation and chromosome-wide monoallelic gene expression pattern. Live-cell imaging of Xist RNA reveals the defining XCI defect: Xist cloud formation. La is a ubiquitous and versatile RNA-binding protein with RNA chaperone and RNA helicase activities. Functional dissection of La shows that the RNA chaperone domain and/or the ATP binding motif play critical roles in XCI. In mutant cells, Xist transcripts are unstable and misfolded. These results show that La is critically involved in XCI, possibly as a protein regulating the in-cell structure of Xist.

molecular biology↗

Tead1 reciprocally regulates adult β-cell proliferation and function

Proliferative quiescence in {beta}-cells is required to maintain functional competence. While this presents a significant hurdle in regenerative therapy for diabetes, the molecular underpinnings of this reciprocal relationship remain unclear. Here, we demonstrate that TEAD1, the transcription effector of the mammalian-Hippo pathway, drives developmental stage-specific {beta}-cell proliferative capacity in conjunction with its functional maturation. TEAD1 promotes adult {beta}-cell mature identity by direct transcriptional control of a network of critical {beta}-cell transcription factors, including, Pdx1, Nkx6.1, and MafA, while its regulation of Cdkn2a maintains proliferative quiescence. Consequently, mice with either constitutive or inducible genetic deletion of TEAD1 in {beta}-cells developed overt diabetes due to a severe loss of secretory function despite induction of proliferation. Furthermore, we show that TEAD1 has a similar regulatory role in human {beta}-cells. Consistent with this function in {beta}-cells, variants in TEAD1 have been associated with c-HOMA-B in American Indians. We propose that TEAD1 is an essential intrinsic molecular switch coordinating adult {beta}-cell proliferative quiescence with mature identity and its differential modulation may be necessary to overcome the challenge of inducing proliferation with functional competence in human beta cells.

molecular biology↗

Heimdallarchaeota harness light energy through photosynthesis

Photosynthesis is an ancient process that originated after the origin of life, and has only been found in the Bacterial and Eukaryotic kingdoms, but has never been reported in any member of the domain Archaea. Heimdallarchaeota, a member of Asgard archaea, are supposed as the most probable candidates (to date) for the archaeal protoeukaryote ancestor and might exist in light-exposed habitats during their evolutionary history. Here we describe the discovery that Heimdallarchaeota genomes are enriched for proteins formerly considered specific to photosynthetic apparatus and are suggestive performing oxygenic photosynthesis. Our results provide strong support for hypotheses in which Heimdallarchaeota harvest light by bacteriochlorophyll and/or carotenoid, then transport electron from photosystems to Calvin-Benson-Bassham cycle along with CO2 fixation and ATP biosynthesis, and release oxygen as a waste product. Given the possessing of phototrophic lifestyle together with other anaerobic and aerobic metabolic pathways, Heimdallarchaeota are firmly believed to be photomixotrophic and have a facultative aerobic metabolism. Our results expand our knowledge that archaea have played an important role in the molecular evolution of eukaryotic photosynthesis and raise the significant possibility that Heimdallarchaeota might be ancestor of eukaryotic photosynthetic organisms.

microbiology↗

Transcriptome analysis reveals the effects of transgenic expression of the Gal4 protein on normal gene expression in silkworm tissues

The Gal4/upstream activating sequence(UAS) system, a well-known genetic tool, has been widely used to analyze gene function in many organisms, including the silkworm (Bombyx mori), a model lepidopteran insect. Several studies have suggested that Gal4 protein activation in tissues can negatively affect transgenic individuals; however, whether and to what extent the Gal4 protein affects normal endogenous gene expression have rarely been studied. Here, we analyzed the transcriptomes of transgenic silkworms expressing the Gal4 protein at high levels in both the wing disc (WD) and epidermis (EP) and investigated gene expression changes in both tissues. Overall, 24,593 genes were identified in the WD and EP libraries, and 2,025 and 2,488 were identified as significant differentially expressed genes(DEGs) in the WD and EP between the transgenic and control groups, respectively. These DEGs were further annotated by gene function classification and pathway assessment using public databases. In addition, 506 DEGs were shared (common) between both tissues. Of these, 97 genes were commonly upregulated, and 234 were commonly downregulated; many of them were annotated to be involved in metabolic processes such as "fat digestion and absorption", "glycine, serine and threonine metabolism" and "glutathione metabolism" and in signal transduction pathways such as the "Rap1 signaling pathway", "MAPK signaling pathway" and "Hippo signaling pathway". Overall, this work enhances understanding of the effects of transgenic Gal4 protein expression on normal gene expression in silkworm tissues and suggests that researchers should pay attention to unexpected effects when using the Gal4/UAS system to study gene function.

genomics↗

Poecivirus is present in individuals with beak deformities in seven species of North American birds

Avian keratin disorder (AKD), a disease characterized by debilitating beak overgrowth but with unknown etiology, has increasingly affected wild bird populations since the 1990s. We previously showed that a novel picornavirus, Poecivirus, is closely correlated with disease status in Black-capped Chickadees (Poecile atricapillus) in Alaska. However, our knowledge of the relationship between Poecivirus and beak deformities in other species and other geographic areas remains limited. The growing geographic scope and number of species affected by AKD-like beak deformities require a better understanding of the causative agent to evaluate the population-level impacts of this epizootic. Here, we tested eight individuals from six avian species with AKD-consistent deformities for the presence of Poecivirus: Mew Gull (Larus canus), Hairy Woodpecker (Picoides villosus), Black-billed Magpie (Pica hudsonia), Northwestern Crow (Corvus caurinus), Red-breasted Nuthatch (Sitta canadensis), and Blackpoll Warbler (Setophaga striata); individuals were sampled in Alaska and Maine (1999-2016). We used targeted PCR followed by Sanger sequencing to test for the presence of Poecivirus in each specimen, and to obtain viral genome sequence from virus-positive host individuals. We detected Poecivirus in all individuals tested, but not in negative controls. Furthermore, we used unbiased metagenomic sequencing to test for the presence of other pathogens in six of these specimens (Hairy Woodpecker, two Northwestern Crows, two Red-breasted Nuthatches, Blackpoll Warbler). This analysis yielded additional viral sequence from several specimens, including the complete coding region of Poecivirus from one Red-breasted Nuthatch, which we confirmed via targeted PCR followed by Sanger sequencing. This study demonstrates that Poecivirus is present in individuals with AKD-consistent deformities from six avian species other than Black-capped Chickadee. While further investigation will be required to explore whether there exists a causal link between this virus and AKD, this study demonstrates that Poecivirus is not geographically restricted to Alaska, but rather occurs elsewhere in North America.

microbiology↗

Schisandrin B for treatment of male infertility

The decline of male fertility and its consequences on human populations are important public-health issues. However, there are limited choices for treatment of male infertility. In an attempt to identify a compound that could promote male fertility, we identified and characterized a library of small molecules from an ancient formulation Wuzi Yanzong-Pill, which was used as a folk medicine since the Tang dynasty of China. We found that SB enabled evident repairs in oligoasthenospermia-associated testicular tissue abnormality and in spermatogenesis disruption, resulting in significant improvements of sperm count, mobility, and reproductive ability in oligoasthenospermia mice. Furthermore, SB could alter substantial testicular genes (2033), among which, upregulation of Fst while downregulation of Inhba involved in reproductive signaling pathway could explain its role in enhancing spermatogenesis. The encouraging preclinical data with pharmacokinetics warranted a rapid development of this new class of therapeutic agent. Our finding provides a strong potent drug for treatment of male infertility.

pharmacology and toxicology↗

Competition between kinesin-1 and myosin-V define Drosophila posterior determination

Local accumulation of oskar (osk) mRNA in the Drosophila oocyte determines the posterior pole of the future embryo. Two major cytoskeletal components, microtubules and actin filaments, together with a microtubule motor, kinesin-1, and an actin motor, myosin-V, are essential for osk mRNA posterior localization. In this study, we use Staufen, an RNA-binding protein that colocalizes with osk mRNA, as a proxy for posterior determination. We demonstrate that posterior localization of osk/Staufen is determined by competition between kinesin-1 and myosin-V. While kinesin-1 removes osk/Staufen from the cortex along microtubules, myosin-V anchors osk/Staufen at the cortex. Myosin-V wins over kinesin-1 at the posterior pole due to low microtubule density at this site, while kinesin-1 wins it at anterior and lateral positions because they have high density of cortically-anchored microtubules. As a result, posterior determinants are removed from the anterior and lateral cortex but retained at the posterior pole. Thus, posterior determination of Drosophila oocyte is defined by kinesin-myosin competition, whose outcome is primarily determined by cortical microtubule density.

cell biology↗

ACPT gene is inactivated in mammalian lineages that lack enamel and teeth

Loss of tooth or enamel is widespread in multiple mammal lineages. Although several studies have been reported, the evolutionary mechanisms of tooth / enamel loss are still unclear. Most previous studies have found that some tooth-related genes have been inactivated in toothless and / or enamel-less mammals, such as ENAM, ODAM, C4orf26, AMBN, AMTN, DSPP, etc. Here, we conducted evolutionary analyses on ACPT plays a key role in amelogenesis, to interrogate the mechanisms. We obtained the ACPT sequences from 116 species, including edentulous and enamel-less mammals, then evolutionary analyses were implemented. The results showed that variant ORF-disrupting mutations have been detected in ACPT coding region among nine edentulous baleen whales and three enamel-less taxa (pygmy sperm whale, aardvark, nine-banded armadillo). Furtherly, selective pressure uncovered that the selective constraints have been relaxed among all toothless and enamel-less lineages. Moreover, our results support the hypothesis that mineralized teeth were lost or degenerated in the common ancestor of crown Mysticeti through two shared single-base sites deletion in exon 4 and 5 of ACPT among all living baleen whales. DN / dS values on transitional branches were used to estimate ACPT inactivation times. In the case of aardvark, inactivation of ACPT was estimated at ~23.60-28.32 Ma, which is earlier than the oldest pangolin fossil time (Orycteropus minutus, ~19Ma), suggesting that ACPT inactivation may result in degeneration or loss of enamel. Conversely, the inactivation time of ACPT estimated in armadillo (~10.18-11.30 Ma) is later than the oldest fossil time, suggesting that inactivation of ACPT may result from degeneration or loss of enamel in these mammals. Our findings suggested that different mechanisms of degeneration of tooth / enamel might exist among toothless and enamel-less lineages during evolution. Our study further considered that ACPT is a novel gene for studying tooth evolution.

evolutionary biology↗

SPOP Promotes Ubiquitination and Degradation of MyD88 to Suppress the Innate Immune Response

As a canonical adaptor for Toll-like receptor (TLR) family, MyD88 has crucial roles in host defence against infection of microbial pathogens and its dysregulation might induce autoimmune diseases. Here we demonstrate that the Cullin 3-based ubiquitin ligase adaptor SPOP recognizes the intermediate domain and degrades chMyD88 through the proteasome pathway. Knockdown or genetic ablation of chSPOP leads to aberrant elevation of the chMyD88 protein. Consequently, ChSPOP negatively regulates the activity of NF-{kappa}B pathway and thus the production of IL-1{beta} and IL-8 upon LPS challenge. Furthermore, SPOP deficiency mice are more susceptible to infection of Salmonella typhimurium. Collectively, these findings demonstrate chMyD88 as a bona fide substrate of chSPOP and uncover a mechanism by which chSPOP suppresses the innate immune signaling.\n\nAuthor SummaryMyD88 is a central adaptor mediating the initiate of innate immune response and production of proinflammatory cytokines that restrain pathogens and activate adaptive immunity. Although MyD88 is crucial for the host to prevent pathogenic infection, misregulation of MyD88 abundance might lead to autoimmune diseases. Thus, degradation of MyD88 is a canonical mechanism to terminate cytokines production. Here we characterized a novel E3 ligase SPOP that target MyD88 for degradation. SPOP attenuated IL1{beta} and IL8 production through K48-linked polyubiquitination and degradation of MyD88 and thus impaired immune responses. SPOP deficient mice show more susceptibility to infection by Salmonella typhimurium. These findings demonstrate that SPOP is a negative regulator of MyD88-dependent pathway activation triggered by LPS and Salmonella typhimurium, which helps the host to maintain immune homeostasis.

immunology↗

Enzalutamide-induced PTH1R-mediated TGFBR2 decrease in osteoblasts contributes to resistance in bone-metastatic prostate cancer

Over 80% of prostate cancer (PCa) patients in the United States die with bone metastases. Second-line hormonal therapies, such as enzalutamide, improve overall survival in about 50% of patients with bone metastases, but almost all responsive patients eventually develop enzalutamide resistance. Our study showed that although enzalutamide significantly inhibited the tumor growth of subcutaneously or orthotopically grafted PCa C4-2B cells, it had no effect on the bone lesion development when C4-2B tumors were grafted in the bone, suggesting a crucial role of the microenvironment in enzalutamide resistance in PCa bone metastasis. We found that enzalutamide significantly decreased the amount of the TGFBR2 (TGF-{beta} type II receptor) in osteoblasts, both in vitro and in patient samples. The osteoblast-specific knockout of Tgfbr2 significantly induced bone metastasis. We showed that the enzalutamide-induced TGFBR2 decrease in osteoblasts was mediated by increased PTH1R (parathyroid hormone/parathyroid hormone-related peptide receptor), which resulted in TGFBR2 degradation, and that blocking PTH1R rescued the TGFBR2 decrease. Furthermore, we found that PTH1R up-regulation by enzalutamide was correlated with increased Pth1r promoter occupancy by transcription factor NR2F1. Our findings highlight a potential enzalutamide-resistance mechanism through TGFBR2 decrease in osteoblasts, thus suggesting future PTH1R-blocking approaches to overcome enzalutamide resistance in PCa bone metastasis.

cancer biology↗

Towards Staining Independent Segmentation of Glomerulus from Histopathological Images of Kidney

This paper introduces a detection-based framework to segment glomeruli from digital scanning image of light microscopic slide of renal biopsy specimens. The proposed method aims to better use the precise localization ability of Faster R-CNN and powerful segmentation ability of U-Net. We use a detector to localize the glomeruli from whole slide image to make the segmentation only focus on the most relevant area of the image. We explored the effectiveness of the network depth on its localization and segmentation ability in glomerular classification, and then propose to use the classification network with enhanced ability of localization and segmentation to construct and initialize a segmentation network. We also propose a weakly supervised training strategy to train the segmentation network by taking advantage of the unique morphology of the glomerulus. Both strong initialization and weakly supervised training are used to resolve the problem of insufficient and inaccurate data annotations and enhance the adaptability of the segmentation network. Experimental results demonstrate that the proposed framework is effective and robust.

pathology↗

Junction-skipping regulation in complex disease

Multiple mRNA isoforms can be generated from a single gene locus through alternative splicing. Abnormality in alternative splicing has been linked to many human disorders. Here using RNA-seq data from 48 tissues from GTEx v7 release and summary statistics from GWAS of complex diseases and traits, we present a study to identify genomic variants regulating junction-skipping with the goal to understand their contribution to complex diseases and traits. For each tissue, we found 48 - 575 junction-skipping events regulated by genomic variants. We performed fine-mapping on both the junction-skipping association and 23 complex disease and trait associations and mapped them to 95% credible sets. We found 13 - 279 junction-skipping regulations were mapped to a credible set with [≤]5 variants. On the genome-wide scale, we noted a clear disease-tissue specificity. Results from this approach provided critical insights into the functional mechanism of the genetic disease associations and contributed to our understanding of the genetic architecture of human complex disorders.

genetics↗

Radiologic Evaluation of the Influence of Cleft Type on Nasal Dorsum Growth

PurposeThe study was designed to evaluate whether intrinsic morphological characteristics of the nasal dorsum are affected by cleft type, specifically cleft lip only (CL) and cleft lip with cleft palate(CL/P).\n\nMethods576 cleft patients (278 CL only, 298 CL/P), and 333 individuals without orofacial clefts were retrospectively enrolled. Lateral cephalometric radiographs of all individuals were taken to evaluate the nasal length and nasal dorsum height. Dunns test was used to analyze the difference (p < 0.001).\n\nResultsIn CL and control, the angulation of the nasal bone and nasal dorsum increase by age similarly (5y-18y, p>0.05). In CL, the total dorsal length is significantly shorter (5y-18y, p<0.001). Although the upper nasal dorsum is similar (except in 5y-6y), the lower nasal dorsum is shorter (5y-18y, p<0.001).\n\nIn CLP, there is no significant difference in the nasal bone angle compared with controls between 5y-7y. However, it develops insufficiently as children grow (8y-18y, p<0.001). The nasal dorsum angle is notably smaller (5y-18y, p<0.001). Nasal bone length is not significantly different from control at all stages except during ages 11y-13y (p<0.05). Total nasal dorsal length is similar to the control at skeletal maturity (17y-18y, p>0.05), although it is shorter during 8y to 16y (p<0.05). The upper nasal dorsum is overdeveloped (14y-18y, p<0.05), whereas the lower nasal dorsum is underdeveloped (5y-18y, p<0.001).\n\nConclusionCL inhibits the growth of nasal dorsum length, leading to short nose deformity. CL/P patients are prone to saddle-nose deformity because of the diminished nasal height (decreased nasal angle).

developmental biology↗

Lesions of canine prostate underwent laser ablation, radiofrequency ablation, and microwave ablation: Lesions shapes and clinical significances

ObjectiveTo explore the shapes and clinical significances of the lesions of canine prostate underwent laser ablation (LA), radiofrequency ablation (RFA), and microwave ablation (MWA).\n\nMethodsHere, 6 male Beagle dogs were randomly assigned to LA, RFA, and MWA groups, respectively. The ablations were conducted with the doses commonly applied in clinical practice (LA: 3 W/1200 J; RFA and MWA: 30 W/120 s) for one region in the left and right lobes of the prostate, which totally resulted in 12 lesions. An energy transmitter was inserted via the perineum under the guidance of transrectal ultrasound (TRUS) and the ablation process was observed dynamically. After ablation, the efficacy was assessed by contrast-enhanced ultrasonography (CEUS), and transverse diameter (TRD), anteroposterior diameter (APD), and longitudinal diameter (TRD) were measured. Then, the volume (V) was calculated according to the following formulae, V = 1/6 x {pi} x (MLD x APD x LD), and ratio (R) R =[(MLD + APD)/2 x LD], which was used to show the shape of the lesion (The closer R is to 1, the more spherical it is).\n\nResultsThe shapes and sizes of the lesions underwent the three techniques varied under the clinically commonly used doses. The R values, reflecting the changes in shapes of lesions, were 0.89{+/-}0.02, 0.72{+/-}0.01, and 0.65{+/-}0.03 for RFA, MWA, and LA, respectively, which were significantly different (P =0.027). The volumes of the lesions underwent the three ablation techniques significantly varied as well (P=0.001), which were 2.17{+/-}0.10, 1.51{+/-}0.20, and 0.79{+/-}0.07 ml for MWA, LA, and RFA, respectively. Conclusion: The above-mentioned three techniques could be used for ablation of prostate cancer using the clinically commonly used doses. The shapes of the lesions underwent the three ablation techniques varied evidently, with the lesions received RFA and LA were more spherical and oval, respectively, while the shapes of lesions underwent MWA were between spherical and oval. The lesions received MWA and RFA had the largest and smallest sizes, respectively, while sizes of lesions underwent LA were in the middle. These findings may assist physicians to select an appropriate therapeutic method for treatment of prostate disease.

cancer biology↗

A cell-free platform based on nisin biosynthesis for discovering novel lanthipeptides and guiding their overproduction in vivo

Lanthipeptides have extensive therapeutic and industrial applications; however, since many are bactericidal, traditional in vivo platforms are limited in their capacity to discover and mass produce novel lanthipeptides as bacterial organisms are often critical components in these systems. We developed a cell-free protein synthesis (CFPS) platform that enables rapid genome mining, screening and guiding overproduction of lanthipeptides in vivo. For proof-of-concept studies, the type I lanthipeptide, nisin, was selected. Four novel lanthipeptides with anti-bacterial activity were identified among all nisin analogs in the NCBI database in a single day. Further, we coupled the CFPS platform with a screening assay for gram-negative bacterial growth and identified a potent nisin mutant, M5. The titer of nisin and nisin analogs significantly improved with CFPS platform guidance. Owing to the similarities in biosynthesis, our CFPS platform is broadly applicable to other lanthipeptides, provides a universal method for lanthipeptides discovery and overproduction.

synthetic biology↗

Geomagnetic field intensity may be a cue for the regulation of insect migration

Geomagnetic field (GMF) intensity can be used by some animals to determine their direction and position during migration. However, its role, if any, in mediating other migration-related phenotypes remains largely unknown. Here, we simulated variation in GMF intensity between two locations along the migration route of a nocturnal insect migrant, the brown planthopper Nilaparvata lugens, that varied by [~]5 T (GMF50T vs. GMF45T) in field intensity. After one generation of exposure, we tested for changes in key morphological, behavioural and physiological traits related to migratory performance including wing dimorphism, flight capacity and positive phototaxis. Our results showed that all three morphological and behavioural phenotypes responded to a small difference in magnetic field intensity between the simulated northern vs. southern locations in ways expected along the migratory route. Consistent magnetic responses in the expression of the phototaxis-related Drosophila-like cryptochrome 1 (Cry1) gene and levels of two primary energy substrates used during flight, triglyceride and trehalose, were also found. Our findings indicate GMF intensity can be a cue that regulates the expression of phenotypes critical for insect migration and highlight the unique role of magnetoreception as a trait that can help migratory insects express potentially beneficial phenotypes in geographically variable environments.

animal behavior and cognition↗

Structural insights into the mechanism of the human soluble guanylate cyclase

Soluble guanylate cyclase (sGC) is the primary nitric oxide (NO) sensor. It plays a central role in NO signaling and is implicated in many essential physiological processes and disease conditions. The binding of NO leads to a significant boost in sGC enzymatic activity. However, the mechanism of NO activation remains incompletely understood. Here, we report the cryo-electron microscopy structures of the human sGC 1{beta}1 heterodimer in different functional states. These structures revealed that the transducer module bridges the NO sensor module and the catalytic module. NO binding to the {beta}1 H-NOX domain triggers the structural rearrangement of the sensor module and the bending-straightening conformational switch of the transducer module. The resulting movement of the N-termini of the catalytic domains drives the structural changes within the catalytic module, which in turn boost sGC enzymatic activity. These observations indicate the structural framework for the mechanism of sGC activation induced by NO binding.

biochemistry↗

Supervised-learning is an accurate method for network-based gene classification

BackgroundAssigning every human gene to specific functions, diseases, and traits is a grand challenge in modern genetics. Key to addressing this challenge are computational methods such as supervised-learning and label-propagation that can leverage molecular interaction networks to predict gene attributes. In spite of being a popular machine learning technique across fields, supervised-learning has been applied only in a few network-based studies for predicting pathway-, phenotype-, or disease-associated genes. It is unknown how supervised-learning broadly performs across different networks and diverse gene classification tasks, and how it compares to label-propagation, the widely-benchmarked canonical approach for this problem.\n\nResultsIn this study, we present a comprehensive benchmarking of supervised-learning for network-based gene classification, evaluating this approach and a state-of-the-art label-propagation technique on hundreds of diverse prediction tasks and multiple networks using stringent evaluation schemes. We demonstrate that supervised-learning on a genes full network connectivity outperforms label-propagation and achieves high prediction accuracy by efficiently capturing local network properties, rivaling label-propagations appeal for naturally using network topology. We further show that supervised-learning on the full network is also superior to learning on node-embeddings (derived using node2vec), an increasingly popular approach for concisely representing network connectivity.\n\nConclusionThese results show that supervised-learning is an accurate approach for prioritizing genes associated with diverse functions, diseases, and traits and should be considered a staple of network-based gene classification workflows. The datasets and the code used to reproduce the results and add new gene classification methods have been made freely available.\n\nContactarjun@msu.edu

bioinformatics↗