Biology subjects

Liang, J.

Publications and source records attributed to Liang, J..

13 recordsLinked to original sources

bioRxiv2018

Induction of Sertoli cells from human fibroblasts by NR5A1 and GATA4

Sertoli cells are essential nurse cells in the testis that regulate the process of spermatogenesis and establish the immune-privileged environment of the blood-testis-barrier (BTB). The induction of human Sertoli cells from fibroblasts could provide cellular sources for fertility and transplantation treatments. Here, we report the in vitro reprogramming of human fibroblasts to Sertoli cells and characterize these human induced Sertoli cells (hiSCs). Initially, five transcriptional factors (NR5A1, GATA4, WT1, SOX9 and DMRT1) and a gene reporter carrying the AMH promoter were utilized to obtain the hiSCs. We further reduce the number of reprogramming factors to two, i.e., NR5A1 and GATA4, and show that these hiSCs have transcriptome profiles that are similar to those of primary human Sertoli cells. Consistent with the known cellular properties of Sertoli cells, hiSCs attract endothelial cells and exhibit high number of lipid droplets in the cytoplasm. More importantly, hiSCs can sustain the viability of spermatogonia cells harvested from mouse seminiferous tubules. In addition, hiSCs suppress the production of IL-2 and proliferation of human T lymphocytes. When hiSCs were cotransplanted with human embryonic kidney cells, these xenotransplanted human cells survived longer in mice with normal immune systems. hiSCs also allow us to determine a gene associated with Sertoli-only syndrome (SCO), CX43, is indeed important in regulating the maturation of Sertoli cells.

developmental biology↗

bioRxiv2018

PADI2-mediated citrullination is required for efficient oligodendrocyte differentiation and myelination

Citrullination, the deimination of arginine residues into citrulline, has been implicated in the aetiology of several diseases. In multiple sclerosis (MS), citrullination is thought to be a major driver of pathology, through hypercitrullination and destabilization of myelin. As such, inhibition of citrullination has been suggested as a therapeutic strategy for MS. Here, in contrast, we show citrullination by peptidylarginine deiminase 2 (PADI2) is required for normal oligodendrocyte differentiation, myelination and motor function. We identify several targets for PADI2, including myelin-related proteins and chromatin-associated proteins, implicating PADI2 in epigenetic regulation. Accordingly, we observe that PADI2 inhibition and its knockdown affect chromatin accessibility and prevent the upregulation of oligodendrocyte differentiation genes. Moreover, mice lacking PADI2, display motor dysfunction and decreased number of myelinated axons in the corpus callosum. We conclude that citrullination is required for oligodendrocyte lineage progression and myelination and suggest its targeted activation in the oligodendrocyte lineage might be beneficial in the context of remyelination.

neuroscience↗

bioRxiv2018

IL-11 is a therapeutic target in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) remains a progressive disease despite best medical management. We previously identified IL-11 as a critical factor for cardiovascular fibrosis and examine here its role in pulmonary fibrosis. IL-11 is consistently upregulated in IPF genomic datasets, which we confirmed by histology. Pulmonary fibroblasts stimulated with IL-11 transform into invasive myofibroblasts whereas fibroblasts from Il11ra deleted mice did not respond to pro-fibrotic stimuli. In the mouse, injection of recombinant Il-11 or fibroblast-specific expression of Il-11 caused pulmonary fibrosis. We then generated a neutralising IL-11 binding antibody that blocks lung fibroblast activation across species. In a mouse model of IPF, anti-IL-11 therapy attenuated lung fibrosis and specifically blocked Erk activation. These data prioritise IL-11 as an accessible drug target in IPF.\n\nOne Sentence SummaryNon-canonical IL-11 signalling is a central hallmark of idiopathic pulmonary fibrosis and represents a novel target for antibody therapies.

molecular biology↗

bioRxiv2018

Efficient differentiation of vascular endothelial cells from dermal-derived mesenchymal stem cells induced by endothelial cell lines conditioned medium

ObjectiveTo directionally-differentiate dermis-derived mesenchymal stem cells (DMSCs) into vascular endothelial cells (VECs) in vitro, providing an experimental basis for studies on the pathogenesis and treatment of vascular diseases.\n\nMethodsAfter separation by adherent culture, VEC line supernatant, vascular endothelial growth factor (VEGF), bone morphogenetic protein-4 and hypoxia were used for the differentiation of VECs from DMSCs. The cell type was authenticated by flow cytometry, matrigel angiogenesis assay in vitro, and immunofluorescent staining during differentiation. The VEGF concentration was investigated by enzyme-linked immunosorbent assay.\n\nResultsAfter 28 days of differentiation, the cell surface marker CD31 was significantly positive (80%-90%) by flow cytometry in the VEC line-conditioned culture, which was significantly higher than in the other groups. Differentiated DMSCs had the ability to ingest Dil-ac-LDL and vascularize in the conditioned culture, but not in the other groups. In the VEC line supernatant, the concentration of VEGF was very low. The VEGF concentration changed along with the differentiation into VECs in the medium of the conditioned culture group.\n\nConclusionVEC line supernatant can induce the differentiation of DMSCs into VECs, possibly through the pathway except VEGF.

cell biology↗

bioRxiv2017

Endothelial Cell-Specific MCPIP Deletion Causes Endothelial Dysfunction and Impairs Post-ischemic Angiogenesis in Vivo

Vascular endothelial cells (ECs) play an important role in angiogenesis and inflammatory responses. MCPIP (also known as Zc3h12a or Regnase-1), a newly identified suppressor of cytokine signaling, is expressed in endothelial cells. To directly test the role of endothelium-derived MCPIP in cardiovascular pathophysiology, we specifically targeted deletion of the murine MCPIP gene in the endothelium by using the loxP/Cre system. A floxed MCPIP knock in mouse line was crossbred with VEcadherin5-Cre mice to generate offspring with deletion of the MCPIP gene in ECs (ECKO). Ablation of MCPIP in ECs resulted in systemic inflammation, anemia, splenomegaly, increased vessel permeability, muscle wasting, endothelial dysfunction, thrombus formation, impaired blood perfusion, and reduced lifespan in these mice. Serum levels of cytokines, chemokines, and biomarkers of EC dysfunction were significantly elevated in the ECKO mice, suggesting a hypercytokinemia. These mice also were more susceptible to lipopolysaccharide-induced death. When subjected to ischemia, these mice showed defective post-ischemic angiogenesis and impaired blood flow recovery in hind limb ischemia and stroke models, as well as in wound healing. This effect was associated with an increased cellular infiltration, cytokine expression, and decreased angiogenic factors. Moreover, MCPIP-deficient ECs displayed decreased vascular sprouting and tube elongation in ex vivo aortic ring assay. MCPIP-knockdown in cultured ECs enhanced NF-{kappa}B activity and dysregulated synthesis of microRNAs linked with elevated cytokines and biomarkers of EC dysfunction. These data show, for the first time, that constitutive expression of MCPIP in ECs is essential to maintain ECs in a quiescent state by serving as an important negative feedback regulator that keeps the inflammatory signaling suppressed.

pathology↗

bioRxiv2017

GeTFEP: a general transfer free energy profile for transmembrane proteins

Free energy of transferring amino acid side-chains from aqueous environment into lipid bilayers, known as transfer free energy (TFE), provides important information on the thermodynamic stability of membrane proteins. In this study, we derived a TFE profile named General Transfer Free Energy Profile (GeTFEP) based on computation of the TFEs of 58 {beta}-barrel membrane proteins ({beta}MPs). The GeTFEP agrees well with experimentally measured and computationally derived TFEs. Analysis based on the GeTFEP shows that residues in different regions of the TM segments of {beta}MPs have different roles during the membrane insertion process. Results further reveal the importance of the sequence pattern of transmembrane strands in stabilizing {beta}MPs in the membrane environment. In addition, we show that GeTFEP can be used to predict the positioning and the orientation of {beta}MPs in the membrane. We also show that GeTFEP can be used to identify structurally or functionally important amino acid residue sites of {beta}MPs. Furthermore, the TM segments of -helical membrane proteins can be accurately predicted with GeTFEP, suggesting that the GeTFEP captures fundamental thermodynamic properties of amino acid residues inside membrane, and is of general applicability in studying membrane protein.

biophysics↗

bioRxiv2017

Inhibition of mitochondrial fission preserves photoreceptors after retinal detachment

Photoreceptor degeneration is a leading cause of visual impairment worldwide. Separation of neurosensory retina from the underlying retinal pigment epithelium is a prominent feature preceding photoreceptor degeneration in a variety of retinal diseases. Although ophthalmic surgeries have been well developed to restore retinal structures, post-op patients usually experience progressive photoreceptor degeneration and irreversible vision loss that is incurable at present. Previous studies point to a critical role of mitochondria-mediated apoptotic pathway in photoreceptor degeneration, but the upstream triggers remain largely unexplored. In this study, we show that after experimental RD induction, photoreceptors activate dynamin-related protein 1 (Drp1)-dependent mitochondrial fission pathway and subsequent apoptotic cascades. Mechanistically, endogenous ROS is necessary for Drp1 activation in vivo and exogenous ROS insult is sufficient to activate Drp1-dependent mitochondrial fission in cultured photoreceptors. Accordingly, inhibition of Drp1 activity effectively preserves mitochondrial integrity and rescues photoreceptors. Collectively, our data delineates a ROS-Drp1-mitochondria axis that promotes photoreceptor degeneration in retinal diseased models.

neuroscience↗

bioRxiv2017

Inhaled nicotine equivalent to cigarette smoking disrupts systemic and uterine hemodynamics and induces cardiac arrhythmia in pregnant rats

Maternal smoking with obligatory nicotine inhalation is associated with preterm delivery, low birth weight, fetal growth retardation and developmental defects. We tested the hypothesis that cigarette smoking-relevant nicotine inhalation during pregnancy impairs cardiovascular function and uterine hemodynamics with consequential fetal ischemia. Pregnant rats exposed to episodic inhaled nicotine via a novel lung alveolar region-targeted aerosol method produced nicotine pharmacokinetics resembling cigarette smoking in humans. This clinically relevant nicotine aerosol inhalation (NAI) induced transient reduction and irregular fluctuations in uterine artery blood flow associated with cardiac arrhythmia and high magnitude irregular fluctuations of systemic blood pressure. The arrhythmia included sinoatrial (SA) block, sinus arrest, 2o and 3o atrioventricular (A-V) block and supraventricular escape rhythm. These effects were blocked by the nicotinic receptor (nAChR) antagonist mecamylamine. Resection of the ovarian nerve, which innervates uterine blood vessels, counteracted the NAI-induced reduction in uterine blood flow. We suggest that the rapid rise pattern of arterial blood nicotine concentration stimulates and then desensitizes autonomic nAChRs leading to disruptions of cardiac function as well as systemic and uterine hemodynamics that reduces uteroplacental blood flow, a mechanism underlying maternal smoking-associated pregnancy complications and developmental disorders. These findings challenge the safety of pure nicotine inhalation, i.e., E-cigarettes.

pharmacology and toxicology↗

bioRxiv2017

Chronic intermittent nicotine delivery with lung alveolar region-targeted aerosol technology produces circadian blood pharmacokinetics in rats resembling human smokers

IntroductionCigarette smoke is an aerosol containing microparticles that carry nicotine into lung alveolar region where nicotine is rapidly absorbed into circulation. Nicotine exposure in smokers is a chronic intermittent process, with intake during wakefulness and abstinence during sleep resulting in circadian fluctuation of blood nicotine levels. Here we present a smoking-relevant nicotine exposure device and rodent model.\n\nMethodsWe developed a computer controlled integrated platform where freely moving rodents can be exposed to episodic nicotine aerosol on an investigator-designed schedule. Rats were exposed to nicotine aerosol once every half hr in the dark phase of 12/12-hr dark/light cycles for 10 days. Plasma nicotine and its metabolite cotinine levels were determined with a LC-MS/MS method.\n\nResultsWe characterized the aerosol in the breathing zone of the rodent exposure chamber. The droplet size distribution was within the respirable diameter range. The system can generate a wide range of nicotine concentrations in air that meet a variety of experimental needs. We optimized the parameters of aerosol generation and exposure: plasma nicotine and cotinine concentrations reached 30-35 ng/ml and 190-240 ng/ml, respectively. The nicotine levels and circadian patterns resembled the pharmacokinetic pattern of human smokers.\n\nConclusionsWe developed an aerosol system that can produce chronic intermittent nicotine exposure in unanesthetized and unrestrained rodents with route of administration and circadian blood pharmacokinetics resembling human smokers. This methodology is a novel tool for studies of behavior, pharmacology and toxicology of chronic nicotine exposure, nicotine addiction, tobacco-related diseases, teratogenicity, and for discovery of therapeutics.\n\nImplicationsWe developed a method and an alveolar region-targeted aerosol system that provides chronic intermittent nicotine exposure in rodents. The method produces clinically relevant animal models with the route of administration and circadian pharmacokinetics resembling human smokers. This method is a novel tool for understanding the health effects of chronic nicotine exposures such as with tobacco cigarettes, E-cigarettes and other tobacco products, for studies of pharmacology, toxicology, nicotine addiction, tobacco-related diseases, and for discovery of medications.

pharmacology and toxicology↗

bioRxiv2017

Feedback regulation of steady-state epithelial turnover and organ size

Epithelial organs undergo steady-state turnover throughout adult life, with old cells being continually replaced by the progeny of stem cell divisions1. To avoid hyperplasia or atrophy, organ turnover demands strict equilibration of cell production and loss2-4. However, the mechanistic basis of this equilibrium is unknown. Using the adult Drosophila intestine5, we find that robustly precise turnover arises through a coupling mechanism in which enterocyte apoptosis breaks feedback inhibition of stem cell divisions. Healthy enterocytes inhibit stem cell division through E-cadherin, which prevents secretion of mitogenic EGFs by repressing transcription of the EGF maturation factor rhomboid. Individual apoptotic enterocytes promote divisions by loss of E-cadherin, which releases cadherin-associated {beta}-catenin/Armadillo and p120-catenin to induce rhomboid. Induction of rhomboid in the dying enterocyte triggers EGFR activation in stem cells within a discrete radius. When we block apoptosis, E-cadherin-controlled feedback suppresses divisions, and the organ retains the same number of cells. When we disrupt feedback, apoptosis and divisions are uncoupled, and the organ develops either hyperplasia or atrophy. Altogether, our work demonstrates that robust cellular balance hinges on the obligate coupling of divisions to apoptosis, which limits the proliferative potential of a stem cell to the precise time and place that a replacement cell is needed. In this manner, localized cell-cell communication gives rise to tissue-level homeostatic equilibrium and constant organ size.

developmental biology↗

bioRxiv2017

SUMO E3 ligase Mms21 prevents spontaneous DNA damage induced genome rearrangements

Mms21, a subunit of the Smc5/6 complex, possesses an E3 ligase activity for the Small Ubiquitin-like MOdifier (SUMO), which has a major, but poorly understood role in genome maintenance. Here we show mutations that inactivate the E3 ligase activity of Mms21 cause Rad52- and Pol32-dependent break-induced replication (BIR), which specifically requires the Rrm3 DNA helicase. Interestingly, mutations affecting both Mms21 and the Sgs1 helicase, but not sumoylation of Sgs1, cause further accumulation of genome rearrangements, indicating the distinct roles of Mms21 and Sgs1 in suppressing genome rearrangements. Whole genome sequencing further revealed that the Mre11 endonuclease prevents microhomology-mediated translocations and hairpin-mediated inverted duplications in the mms21 mutant. Consistent with the accumulation of endogenous DNA lesions, mms21 cells accumulate spontaneous Ddc2 foci and display a hyper-activated DNA damage checkpoint. Together, these findings support a new paradigm that Mms21 prevents the accumulation of spontaneous DNA lesions that cause diverse genome rearrangements.

genetics↗

bioRxiv2017

Interactome INSIDER: A Multi-Scale Structural Interactome Browser For Genomic Studies

Protein interactions underlie nearly all known cellular function, making knowledge of their binding conformations paramount to understanding the physical workings of the cell. Studying binding conformations has allowed scientists to explore some of the mechanistic underpinnings of disease caused by disruption of protein interactions. However, since experimentally determined interaction structures are only available for a small fraction of the known interactome such inquiry has largely excluded functional genomic studies of the human interactome and broad observations of the inner workings of disease. Here we present Interactome INSIDER, an information center for genomic studies using the first full-interactome map of human interaction interfaces. We applied a new, unified framework to predict protein interaction interfaces for 184,605 protein interactions with previously unresolved interfaces in human and 7 model organisms, including the entire experimentally determined human binary interactome. We find that predicted interfaces share several known functional properties of interfaces, including an enrichment for disease mutations and recurrent cancer mutations, suggesting their applicability to functional genomic studies. We also performed 2,164 de novo mutagenesis experiments and show that mutations of predicted interface residues disrupt interactions at a similar rate to known interface residues and at a much higher rate than mutations outside of predicted interfaces. To spur functional genomic studies in the human interactome, Interactome INSIDER (http://interactomeinsider.yulab.org) allows users to explore known population variants, disease mutations, and somatic cancer mutations, or upload their own set of mutations to find enrichment at the level of protein domains, residues, and 3D atomic clustering in known and predicted interaction interfaces.

genomics↗

bioRxiv2016

Genome-wide association analyses of sleep disturbance traits identify new loci and highlight shared genetics with neuropsychiatric and metabolic traits

Chronic sleep disturbances, associated with cardio-metabolic diseases, psychiatric disorders and all-cause mortality1,2, affect 25-30% of adults worldwide3. While environmental factors contribute importantly to self-reported habitual sleep duration and disruption, these traits are heritable4-9, and gene identification should improve our understanding of sleep function, mechanisms linking sleep to disease, and development of novel therapies. We report single and multi-trait genome-wide association analyses (GWAS) of self-reported sleep duration, insomnia symptoms including difficulty initiating and/or maintaining sleep, and excessive daytime sleepiness in the UK Biobank (n=112,586), with discovery of loci for insomnia symptoms (near MEIS1, TMEM132E, CYCL1, TGFBI in females and WDR27 in males), excessive daytime sleepiness (near AR/OPHN1) and a composite sleep trait (near INADL and HCRTR2), as well as replication of a locus for sleep duration (at PAX-8). Genetic correlation was observed between longer sleep duration and schizophrenia (rG=0.29, p=1.90x10-13) and between increased excessive daytime sleepiness and increased adiposity traits (BMI rG=0.20, p=3.12x10-09; waist circumference rG=0.20, p=2.12x10-07).

genetics↗