Publications by authors named "Xiaoying Tan"

20 Publications

  • Page 1 of 1

Self-Administration of Cotinine in Wistar Rats: Comparisons to Nicotine.

J Pharmacol Exp Ther 2021 03 23;376(3):338-347. Epub 2020 Dec 23.

Department of Anesthesiology and Perioperative Medicine, and Pharmacology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania (Z.-M.D., X.T.) and Department of Psychiatry, Indiana University School of Medicine, Indianapolis, Indiana (Y.G., A.S.).

Nicotine is the major addictive component in tobacco. Cotinine is the major metabolite of nicotine and a weak agonist for nicotinic acetylcholine receptors (nAChRs). Nicotine supports self-administration in rodents. However, it remains undetermined whether cotinine can be self-administered. This study aimed to characterize cotinine self-administration in rats, to compare effects of cotinine to those of nicotine, and to determine potential involvement of nAChRs in cotinine's effects. Adult Wistar rats were trained to self-administer cotinine or nicotine (0.0075, 0.015, 0.03, or 0.06 mg/kg per infusion) under fixed-ratio (FR) and progressive-ratio (PR) schedules. Blood nicotine and cotinine levels were determined after the last FR session. Effects of mecamylamine, a nonselective nAChR antagonist, and varenicline, a partial agonist for 42* nAChRs, on cotinine and nicotine self-administration were determined. Rats readily acquired cotinine self-administration, responded more on active lever, and increased motivation to self-administer cotinine when the reinforcement requirement increased. Blood cotinine levels ranged from 77 to 792 ng/ml. Nicotine induced more infusions at lower doses during FR schedules and greater breakpoints at higher doses during the PR schedule than cotinine. There was no difference in cotinine self-administration between male and female rats. Mecamylamine and varenicline attenuated nicotine but not cotinine self-administration. These results indicate that cotinine was self-administered by rats. These effects of cotinine were less robust than nicotine and exhibited no sex difference. nAChRs appeared to be differentially involved in self-administration of nicotine and cotinine. These results suggest cotinine may play a role in the development of nicotine use and misuse. SIGNIFICANCE STATEMENT: Nicotine addiction is a serious public health problem. Cotinine is the major metabolite of nicotine, but its involvement in nicotine reinforcement remains elusive. Our findings indicate that cotinine, at doses producing clinically relevant blood cotinine levels, supported intravenous self-administration in rats. Cotinine self-administration was less robust than nicotine. Mecamylamine and varenicline attenuated nicotine but not cotinine self-administration. These results suggest cotinine may play a role in the development of nicotine use and misuse.
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http://dx.doi.org/10.1124/jpet.120.000367DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7883011PMC
March 2021

CRISPR/Cas Derivatives as Novel Gene Modulating Tools: Possibilities and In Vivo Applications.

Int J Mol Sci 2020 Apr 25;21(9). Epub 2020 Apr 25.

Department of Cardiology and Pneumology, University Medical Center Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany.

The field of genome editing started with the discovery of meganucleases (e.g., the LAGLIDADG family of homing endonucleases) in yeast. After the discovery of transcription activator-like effector nucleases and zinc finger nucleases, the recently discovered clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated proteins (Cas) system has opened a new window of applications in the field of gene editing. Here, we review different Cas proteins and their corresponding features including advantages and disadvantages, and we provide an overview of the different endonuclease-deficient Cas protein (dCas) derivatives. These dCas derivatives consist of an endonuclease-deficient Cas9 which can be fused to different effector domains to perform distinct in vitro applications such as tracking, transcriptional activation and repression, as well as base editing. Finally, we review the in vivo applications of these dCas derivatives and discuss their potential to perform gene activation and repression in vivo, as well as their potential future use in human therapy.
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http://dx.doi.org/10.3390/ijms21093038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7246536PMC
April 2020

Serelaxin alleviates cardiac fibrosis through inhibiting endothelial-to-mesenchymal transition via RXFP1.

Theranostics 2020 4;10(9):3905-3924. Epub 2020 Mar 4.

Department of Cardiology and Pneumology, University Medical Center of Göttingen, Georg-August University, Göttingen, Germany.

: Cardiac fibrosis is an integral constituent of every form of chronic heart disease, and persistence of fibrosis reduces tissue compliance and accelerates the progression to heart failure. Relaxin-2 is a human hormone, which has various physiological functions such as mediating renal vasodilation in pregnancy. Its recombinant form Serelaxin has recently been tested in clinical trials as a therapy for acute heart failure but did not meet its primary endpoints. The aim of this study is to examine whether Serelaxin has an anti-fibrotic effect in the heart and therefore could be beneficial in chronic heart failure. : We utilized two different cardiac fibrosis mouse models (ascending aortic constriction (AAC) and Angiotensin II (ATII) administration via osmotic minipumps) to assess the anti-fibrotic potential of Serelaxin. Histological analysis, immunofluorescence staining and molecular analysis were performed to assess the fibrosis level and indicate endothelial cells which are undergoing EndMT. TGFβ1-induced endothelial-to-mesenchymal transition (EndMT) assays were performed in human coronary artery endothelial cells and mouse cardiac endothelial cells (MCECs) and were examined using molecular methods. Chromatin immunoprecipitation-qPCR assay was utilized to identify the Serelaxin effect on chromatin remodeling in the promoter region in MCECs. : Our results demonstrate a significant and dose-dependent anti-fibrotic effect of Serelaxin in the heart in both models. We further show that Serelaxin mediates this effect, at least in part, through inhibition of EndMT through the endothelial Relaxin family peptide receptor 1 (RXFP1). We further demonstrate that Serelaxin administration is able to increase its own receptor expression (RXFP1) through epigenetic regulation in form of histone modifications by attenuating TGFβ-pSMAD2/3 signaling in endothelial cells. : This study is the first to identify that Serelaxin increases the expression of its own receptor RXFP1 and that this mediates the inhibition of EndMT and cardiac fibrosis, suggesting that Serelaxin may have a beneficial effect as anti-fibrotic therapy in chronic heart failure.
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http://dx.doi.org/10.7150/thno.38640DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7086357PMC
March 2020

Effects of physical exercise on negative emotional susceptibility in young adult females: An event-related potential study.

Brain Res 2019 11 13;1722:146382. Epub 2019 Aug 13.

Key Laboratory of Exercise and Health Sciences, Ministry of Education, Shanghai University of Sport, Shanghai 200438, China. Electronic address:

The present study investigated whether habitual physical exercise can regulate susceptibility to negative emotions in young adult female participants. Female participants with and without long-term physical exercise habits were recruited and assigned to exercise and non-exercise groups, respectively. All participants performed a standard/deviant distinction task in which the emotional valence of the deviants could be highly negative (HN), moderately negative (MN), or neutral. Event-related potentials (ERPs) elicited by deviants were recorded and compared between the two groups. Regardless of the emotional valence of the deviants, the exercise group exhibited shorter reaction times (RTs) and greater parietal P3 responses to all deviants, compared to the non-exercise group, consistent with a superiority in detecting and responding to deviants. Importantly, whereas the non-exercise group showed greater frontal-central N2 responses to MN deviant stimuli than to neutral deviant stimuli, such a difference was not observed in the exercise group, indicating that the participants who exercised regularly had decreased attentional capture and allocation to MN deviants, and thus an apparent decreased negative emotional susceptibility selectively to moderately negative emotional stimuli. These results may indicate an effect of physical exercise on the processing of negative emotional information and support the promotion of physical exercise in the maintenance of mental health in females.
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http://dx.doi.org/10.1016/j.brainres.2019.146382DOI Listing
November 2019

Inhibitory and facilitatory connections from dorsolateral prefrontal to primary motor cortex in healthy humans at rest-An rTMS study.

Neurosci Lett 2018 11 19;687:82-87. Epub 2018 Sep 19.

School of Physical Education and Coaching, Shanghai University of Sport, Shanghai, China. Electronic address:

Background: The human motor system consists of several divisions in the frontal lobes. The physiological function of projections from the dorsolateral prefrontal cortex (DLPFC) to the primary motor cortex (M1) remains elusive. Here, we introduce theta burst stimulation (TBS)-based protocols to target inhibitory and facilitatory connections in the DLPFC-M1 network.

Methods: Intermittent and continuous TBS with 600 pulses (iTBS600/cTBS600) were applied to the left DLPFC. Resting motor threshold (RMT), motor-evoked potential (MEP), and short-interval intracortical inhibition (SICI) were measured with transcranial magnetic stimulation to the ipsilateral M1.

Results: iTBS600 to the DLPFC decreased MEP amplitude in M1. Conversely, cTBS600 to the DLPFC increased MEP amplitude in M1. The peak decrease in MEP amplitude after iTBS600 was negatively correlated with the peak increase in MEP amplitude after cTBS600. There were no significant effects in the control group with the sham stimulation.

Discussion: These results provide insight into the regulation of inhibitory and facilitatory balance from the local DLPFC to M1. TBS modulation in one brain region will induce interactions within other remote cortical areas. Our results enable better understanding of how cognitive resources are allocated to achieve optimal control of motor output.
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http://dx.doi.org/10.1016/j.neulet.2018.09.032DOI Listing
November 2018

High-fidelity CRISPR/Cas9- based gene-specific hydroxymethylation rescues gene expression and attenuates renal fibrosis.

Nat Commun 2018 08 29;9(1):3509. Epub 2018 Aug 29.

German Center for Cardiovascular Research (DZHK) Partner Site, Göttingen, Germany.

While suppression of specific genes through aberrant promoter methylation contributes to different diseases including organ fibrosis, gene-specific reactivation technology is not yet available for therapy. TET enzymes catalyze hydroxymethylation of methylated DNA, reactivating gene expression. We here report generation of a high-fidelity CRISPR/Cas9-based gene-specific dioxygenase by fusing an endonuclease deactivated high-fidelity Cas9 (dHFCas9) to TET3 catalytic domain (TET3CD), targeted to specific genes by guiding RNAs (sgRNA). We demonstrate use of this technology in four different anti-fibrotic genes in different cell types in vitro, among them RASAL1 and Klotho, both hypermethylated in kidney fibrosis. Furthermore, in vivo lentiviral delivery of the Rasal1-targeted fusion protein to interstitial cells and of the Klotho-targeted fusion protein to tubular epithelial cells each results in specific gene reactivation and attenuation of fibrosis, providing gene-specific demethylating technology in a disease model.
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http://dx.doi.org/10.1038/s41467-018-05766-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6115451PMC
August 2018

Calculating osmotic pressure of glucose solutions according to ASOG model and measuring it with air humidity osmometry.

Pak J Pharm Sci 2016 Sep;29(5):1657-1600

Key Laboratory of Drug Targeting, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, PR China.

The osmotic pressure of glucose solution at a wide concentration range was calculated using ASOG model and experimentally determined by our newly reported air humidity osmometry. The measurements from air humidity osmometry were compared with the well-established freezing point osmometry and ASOG model calculations at low concentrations and with only ASOG model calculations at high concentrations where no standard experimental method could serve as a reference for comparison. Results indicate that air humidity osmometry measurements are comparable to ASOG model calculations at a wide concentration range, while at low concentrations freezing point osmometry measurements provide better comparability with ASOG model calculations.
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September 2016

Hypoxia-induced endothelial-mesenchymal transition is associated with RASAL1 promoter hypermethylation in human coronary endothelial cells.

FEBS Lett 2016 04 21;590(8):1222-33. Epub 2016 Apr 21.

Department of Cardiology and Pneumology, University Medical Center of Göttingen, Georg-August University, Göttingen, Germany.

Cardiac fibrosis is integral in chronic heart disease, and one of the cellular processes contributing to cardiac fibrosis is endothelial-to-mesenchymal transition (EndMT). We recently found that hypoxia efficiently induces human coronary artery endothelial cells (HCAEC) to undergo EndMT through a hypoxia inducible factor-1α (HIF1α)-dependent pathway. Promoter hypermethylation of Ras-Gap-like protein 1 (RASAL1) has also been recently associated with EndMT progression and cardiac fibrosis. Our findings suggest that HIF1α and transforming growth factor (TGF)/SMAD signalling pathways synergistically regulate hypoxia-induced EndMT through both DNMT3a-mediated hypermethylation of RASAL1 promoter and direct SNAIL induction. The findings indicate that multiple cascades may be activated simultaneously to mediate hypoxia-induced EndMT.
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http://dx.doi.org/10.1002/1873-3468.12158DOI Listing
April 2016

DNMT1 and HDAC2 Cooperate to Facilitate Aberrant Promoter Methylation in Inorganic Phosphate-Induced Endothelial-Mesenchymal Transition.

PLoS One 2016 27;11(1):e0147816. Epub 2016 Jan 27.

Department of Cardiology and Pneumology, Göttingen University Medical Center, Georg August University, Göttingen, Germany.

While phosphorus in the form of inorganic or organic phosphate is critically involved in most cellular functions, high plasma levels of inorganic phosphate levels have emerged as independent risk factor for cardiac fibrosis, cardiovascular morbidity and decreased life-expectancy. While the link of high phosphate and cardiovascular disease is commonly explained by direct cellular effects of phospho-regulatory hormones, we here explored the possibility of inorganic phosphate directly eliciting biological responses in cells. We demonstrate that human coronary endothelial cells (HCAEC) undergo an endothelial-mesenchymal transition (EndMT) when exposed to high phosphate. We further demonstrate that such EndMT is initiated by recruitment of aberrantly phosphorylated DNMT1 to the RASAL1 CpG island promoter by HDAC2, causing aberrant promoter methylation and transcriptional suppression, ultimately leading to increased Ras-GTP activity and activation of common EndMT regulators Twist and Snail. Our studies provide a novel aspect for known adverse effects of high phosphate levels, as eukaryotic cells are commonly believed to have lost phosphate-sensing mechanisms of prokaryotes during evolution, rendering them insensitive to extracellular inorganic orthophosphate. In addition, our studies provide novel insights into the mechanisms underlying specific targeting of select genes in context of fibrogenesis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0147816PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4729486PMC
July 2016

High inorganic phosphate causes DNMT1 phosphorylation and subsequent fibrotic fibroblast activation.

Biochem Biophys Res Commun 2016 Apr 14;472(3):459-64. Epub 2016 Jan 14.

Department of Nephrology and Rheumatology, Göttingen University Medical Center, Georg August University, Göttingen, Germany; German Center for Cardiovascular Research (DZHK), Göttingen, Germany. Electronic address:

Phosphate is an essential constituent of critical cellular functions including energy metabolism, nucleic acid synthesis and phosphorylation-dependent cell signaling. Increased plasma phosphate levels are an independent risk factor for lowered life-expectancy as well as for heart and kidney failure. Nevertheless, direct cellular effects of elevated phosphate concentrations within the microenvironment are poorly understood and have been largely neglected in favor of phosphor-regulatory hormones. Because interstitial fibrosis is the common determinant of chronic progressive kidney disease, and because fibroblasts are major mediators of fibrogenesis, we here explored the effect of high extracellular phosphate levels on renal fibroblasts. We demonstrate that high inorganic phosphate directly induces fibrotic fibroblast activation associated with increased proliferative activity, increased expression of α-smooth muscle actin and increased synthesis of type I collagen. We further demonstrate that such fibroblast activation is dependent on phosphate influx, aberrant phosphorylation of DNA methyltransferase DNMT1 and aberrant CpG island promoter methylation. In summary, our studies demonstrate that elevated phosphate concentrations induce pro-fibrotic fibroblast activation independent of phospho-regulatory hormones.
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http://dx.doi.org/10.1016/j.bbrc.2016.01.077DOI Listing
April 2016

Snail Is a Direct Target of Hypoxia-inducible Factor 1α (HIF1α) in Hypoxia-induced Endothelial to Mesenchymal Transition of Human Coronary Endothelial Cells.

J Biol Chem 2015 Jul 13;290(27):16653-64. Epub 2015 May 13.

From the Departments of Cardiology and Pneumology and DZHK (German Centre for Cardiovascular Research) partner site, 37075 Göttingen, Germany

Endothelial to mesenchymal transition (EndMT) was originally described in heart development where the endocardial endothelial cells that line the atrioventricular canal undergo an EndMT to form the endocardial mesenchymal cushion that later gives rise to the septum and mitral and tricuspid valves. In the postnatal heart specifically, endothelial cells that originate from the endocardium maintain increased susceptibility to undergo EndMT as remnants from their embryonic origin. Such EndMT involving adult coronary endothelial cells contributes to microvascular rarefaction and subsequent chronification of hypoxia in the injured heart, ultimately leading to cardiac fibrosis. Although in most endothelial beds hypoxia induces tip cell formation and sprouting angiogenesis, here we demonstrate that hypoxia is a stimulus for human coronary endothelial cells to undergo phenotypic changes reminiscent of EndMT via a mechanism involving hypoxia-inducible factor 1α-induced activation of the EndMT master regulatory transcription factor SNAIL. Our study adds further evidence for the unique susceptibility of endocardium-derived endothelial cells to undergo EndMT and provides novel insights into how hypoxia contributes to progression of cardiac fibrosis. Additional studies may be required to discriminate between distinct sprouting angiogenesis and EndMT responses of different endothelial cells populations.
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http://dx.doi.org/10.1074/jbc.M115.636944DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4505417PMC
July 2015

Epigenetic balance of aberrant Rasal1 promoter methylation and hydroxymethylation regulates cardiac fibrosis.

Cardiovasc Res 2015 Mar 23;105(3):279-91. Epub 2015 Jan 23.

Department of Cardiology and Pneumology, University Medical Center of Göttingen, Georg-August University, Robert-Koch-Str. 40, 37075 Göttingen, Germany German Center for Cardiovascular Research (DZHK), Partner Site Göttingen, Göttingen, Germany

Aims: Methylation of CpG island promoters is a prototypical epigenetic mechanism to stably control gene expression. The aim of this study was to elucidate the contribution of aberrant promoter DNA methylation in pathological endothelial to mesenchymal transition (EndMT) and subsequent cardiac fibrosis.

Methods And Results: In human coronary endothelial cells, TGFβ1 causes aberrant methylation of RASAL1 promoter, increased Ras-GTP activity, and EndMT. In end-stage failing vs. non-failing human myocardium, increased fibrosis was associated with significantly increased RASAL1 promoter methylation, decreased RASAL1 expression, increased Ras-GTP activity, and increased expression of markers of EndMT. In mice with pressure overload due to ascending aortic constriction, BMP7 significantly reduced RASAL1 promoter methylation, increased RASAL1 expression, and decreased EndMT markers as well as decreased cardiac fibrosis. The ten eleven translocation (TET) family enzyme TET3, which demethylates through hydroxymethylation, was significantly decreased in fibrotic mouse hearts, restored with BMP7, and BMP7 effects were absent in coronary endothelial cells with siRNA knockdown of TET3.

Conclusion: Our study provides proof-in-principle evidence that transcriptional suppression of RASAL1 through aberrant promoter methylation contributes to EndMT and ultimately to progression of cardiac fibrosis. Such aberrant methylation can be reversed through Tet3-mediated hydroxymethylation, which can be specifically induced by BMP7. This may reflect a new treatment strategy to stop cardiac fibrosis.
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http://dx.doi.org/10.1093/cvr/cvv015DOI Listing
March 2015

Dppa3 expression is critical for generation of fully reprogrammed iPS cells and maintenance of Dlk1-Dio3 imprinting.

Nat Commun 2015 Jan 23;6:6008. Epub 2015 Jan 23.

Institute of Human Genetics, University of Goettingen, Heinrich-Dueker-Weg 12, 37073 Goettingen, Germany.

Reprogramming of mouse somatic cells into induced pluripotent stem cells (iPSCs) often generates partially reprogrammed iPSCs (pre-iPSCs), low-grade chimera forming iPSCs (lg-iPSCs) and fully reprogrammed, high-grade chimera production competent iPSCs (hg-iPSCs). Lg-iPSC transcriptome analysis revealed misregulated Dlk1-Dio3 cluster gene expression and subsequently the imprinting defect at the Dlk1-Dio3 locus. Here, we show that germ-cell marker Dppa3 is present only in lg-iPSCs and hg-iPSCs, and that induction with exogenous Dppa3 enhances reprogramming kinetics, generating all hg-iPSCs, similar to vitamin C (Vc). Conversely, Dppa3-null fibroblasts show reprogramming block at pre-iPSCs state and Dlk1-Dio3 imprinting defect. At the molecular level, we show that Dppa3 is associated with Dlk1-Dio3 locus and identify that Dppa3 maintains imprinting by antagonizing Dnmt3a binding. Our results further show molecular parallels between Dppa3 and Vc in Dlk1-Dio3 imprinting maintenance and suggest that early activation of Dppa3 is one of the cascades through which Vc facilitates the generation of fully reprogrammed iPSCs.
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http://dx.doi.org/10.1038/ncomms7008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4354275PMC
January 2015

Calculating osmotic pressure of xylitol solutions from molality according to UNIFAC model and measuring it with air humidity osmometry.

Pharm Dev Technol 2014 Nov 13;19(7):853-5. Epub 2013 Sep 13.

Key Laboratory of Drug Targeting, West China School of Pharmacy, Sichuan University , Chengdu, Sichuan , PR China and.

The osmotic pressure of xylitol solution at a wide concentration range was calculated according to the UNIFAC model and experimentally determined by our newly reported air humidity osmometry. The measurements from air humidity osmometry were compared with UNIFAC model calculations from dilute to saturated solution. Results indicate that air humidity osmometry measurements are comparable to UNIFAC model calculations at a wide concentration range by two one-sided test and multiple testing corrections. The air humidity osmometry is applicable to measure the osmotic pressure and the osmotic pressure can be calculated from the concentration.
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http://dx.doi.org/10.3109/10837450.2013.836221DOI Listing
November 2014

Zfp819, a novel KRAB-zinc finger protein, interacts with KAP1 and functions in genomic integrity maintenance of mouse embryonic stem cells.

Stem Cell Res 2013 Nov 30;11(3):1045-59. Epub 2013 Jul 30.

Institute of Human Genetics, University of Goettingen, Heinrich-Dueker-Weg 12, 37073 Goettingen, Germany.

Pluripotency is maintained by both known and unknown transcriptional regulatory networks. In the present study, we have identified Zfp819, a KRAB-zinc finger protein, as a novel pluripotency-related factor and characterized its role in pluripotent stem cells. We show that Zfp819 is expressed highly in various types of pluripotent stem cells but not in their differentiated counterparts. We identified the presence of non-canonical nuclear localization signals in particular zinc finger motifs and identified them as responsible for the nuclear localization of Zfp819. Analysis of the Zfp819 promoter region revealed the presence of a transcriptionally active chromatin signature. Moreover, we confirmed the binding of pluripotency-related factors, Oct4, Sox2, and Nanog to the distal promoter region of Zfp819, indicating that the expression of this gene is regulated by a pluripotency transcription factor network. We found that the expression of endogenous retroviral elements (ERVs) such as Intracisternal A Particle (IAP) retrotransposons, Long Interspersed Nuclear Elements (LINE1), and Short Interspersed Nuclear Elements (SINE B1) is significantly upregulated in Zfp819-knockdown (Zfp819_KD) cells. In line with the activation of ERVs, we observed the occurrence of spontaneous DNA damage in Zfp819_KD cells. Furthermore, we tested whether Zfp819 can interact with KAP1, a KRAB-associated protein with a transcriptional repression function, and found the interaction between these two proteins in both in vitro and in vivo experiments. The challenging of Zfp819_KD cells with DNA damaging agent revealed that these cells are inefficient in repairing the damaged DNA, as cells showed presence of γH2A.X foci for a prolonged time. Collectively, our study identified Zfp819 as a novel pluripotency-related factor and unveiled its function in genomic integrity maintenance mechanisms of mouse embryonic stem cells.
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http://dx.doi.org/10.1016/j.scr.2013.07.006DOI Listing
November 2013

Calculating osmotic pressure according to nonelectrolyte Wilson nonrandom factor model.

Drug Dev Ind Pharm 2014 Aug 5;40(8):1044-6. Epub 2013 Jun 5.

Key Laboratory of Drug Targeting, West China School of Pharmacy, Sichuan University , Chengdu, Sichuan , P. R. China and.

Abstract The osmotic pressure of NaCl solutions was determined by the air humidity in equilibrium (AHE) method. The relationship between the osmotic pressure and the concentration was explored theoretically, and the osmotic pressure was calculated according to the nonelectrolyte Wilson nonrandom factor (N-Wilson-NRF) model from the concentration. The results indicate that the calculated osmotic pressure is comparable to the measured one.
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http://dx.doi.org/10.3109/03639045.2013.801985DOI Listing
August 2014

Mouse Dazl and its novel splice variant functions in translational repression of target mRNAs in embryonic stem cells.

Biochim Biophys Acta 2013 May 6;1829(5):425-35. Epub 2013 Jan 6.

University of Goettingen, Goettingen, Germany.

Dazl (deleted in azoospermia-like) is an RNA binding protein that is important for germ cell differentiation in vertebrates. In the present study, we report the identification of a novel Dazl isoform (Dazl_Δ8) that results from alternative splicing of exon8 of mouse Dazl. We observed the expression of Dazl_Δ8 in various pluripotent cell types, but not in somatic cells. Furthermore, the Dazl_Δ8 splice variant was expressed along with the full-length isoform of Dazl (Dazl_FL) throughout male germ-cell development and in the ovary. Sub-cellular localization studies of Dazl_Δ8 revealed a diffused cytoplasmic and large granular pattern, which is similar to the localization patterns of Dazl_FL protein. In contrast to the well documented translation stimulation function in germ cells, overexpression and downregulation studies of Dazl isoforms (Dazl_FL and Dazl_Δ8) revealed a role for Dazl in the negative translational regulation of Mvh, a known target of Dazl, as well as Oct3/4 and Sox2 in embryonic stem cells (ESCs). In line with these observations, a luciferase reporter assay with the 3'UTRs of Oct3/4 and Mvh confirmed the translational repressive role of Dazl isoforms in ESCs but not in germ cells derived cell line GC-1. Further, we identified several putative target mRNAs of Dazl_FL and Dazl_Δ8 in ESCs through RNA-binding immunoprecipitation followed by whole genome transcriptome analysis. Collectively, our results show a translation repression function of Dazl in pluripotent stem cells.
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http://dx.doi.org/10.1016/j.bbagrm.2012.12.010DOI Listing
May 2013

[Correlation analysis between serum interleukin-6 and central nervous injury in septic patients].

Nan Fang Yi Ke Da Xue Xue Bao 2012 Oct;32(10):1451-3

Department of ICU, Southern Medical University, Guangzhou, China.

Objective: To explore the relationship between interleukin-6 (IL-6) production and central nervous injury in septic patients.

Methods: Twenty-two septic patients without central nervous system diseases were examined for serum IL-6 and neuron-specific enolase (NSE) levels, and the serum NSE levels and APACHEII scores were compared between patients with low, moderate, and high serum IL-6 levels. The correlations between NSE, APACHEII and serum IL-6 were analyzed.

Results: In patients with low, moderate, and high serum IL-6 levels, the serum levels of NSE were 10.29∓4.05, 16.06∓5.84 and 23.97∓3.28 µg/L, respectively, showing a significant difference between the 3 groups (P<0.001). The APACHEII scores also differed significantly between the 3 groups (14.17∓4.67, 16.40∓4.84, and 24.00∓6.26, respectively, P=0.009). Correlation analysis showed significant positive correlations of IL-6 with NSE (r=0.788, P<0.001) and with APACHEII scores (r=0.733, P<0.001).

Conclusion: In septic patients, serum IL-6 level is significantly correlated with the severity of sepsis and brain injury, and can be used as a marker to monitor brain injury in septic patients.
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October 2012

Generation and characterization of yeast two-hybrid cDNA libraries derived from two distinct mouse pluripotent cell types.

Mol Biotechnol 2013 Jun;54(2):228-37

Institute of Human Genetics, University of Goettingen, Goettingen, Germany.

Pluripotent stem cells have the therapeutic potential in future regenerative medicine applications. Therefore, it is highly important to understand the molecular mechanisms governing the pluripotency and differentiation potential of these cells. Our current knowledge of pluripotent cells is largely limited owing to the candidate gene/protein approach rather than studying the complex interactions of the proteins. Experimentally, yeast two-hybrid system (Y2H) is by far the most useful and widely used method to detect the protein-protein interactions in high-throughput screenings. Unfortunately, currently there is no GAL4-based pluripotent stem cell-specific cDNA library available for screening the interaction proteins impeding the large-scale studies. In this study, we report the construction of Y2H cDNA libraries derived from mouse pluripotent embryonic stem cells (ESCs) and multipotent adult germ-line stem cells (maGSCs) in GAL4-based Y2H vector system with very high transformation efficiency. Furthermore, we have constructed two different baits and screened for interaction partners in an effort to characterize the libraries and also as a part of our ongoing studies. Consequently, many putative interaction proteins were identified in both cases and their interaction was further validated by direct-Y2H. The observed interactions between bait proteins and their respective analyzed putative interaction proteins were further confirmed using two independent approaches in mammalian cells, thus highlighting the biological significance of the identified interactor (s). Finally, we would like to make these cDNA libraries as a resource that can be distributed to the research community.
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http://dx.doi.org/10.1007/s12033-012-9561-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3636440PMC
June 2013

Stage-specific germ-cell marker genes are expressed in all mouse pluripotent cell types and emerge early during induced pluripotency.

PLoS One 2011 25;6(7):e22413. Epub 2011 Jul 25.

Institute of Human Genetics, University of Goettingen, Goettingen, Germany.

Embryonic stem cells (ESCs) generated from the in-vitro culture of blastocyst stage embryos are known as equivalent to blastocyst inner cell mass (ICM) in-vivo. Though several reports have shown the expression of germ cell/pre-meiotic (GC/PrM) markers in ESCs, their functional relevance for the pluripotency and germ line commitment are largely unknown. In the present study, we used mouse as a model system and systematically analyzed the RNA and protein expression of GC/PrM markers in ESCs and found them to be comparable to the expression of cultured pluripotent cells originated from the germ line. Further, siRNA knockdown experiments have demonstrated the parallel maintenance and independence of pluripotent and GC/PrM networks in ESCs. Through chromatin immunoprecipitation experiments, we observed that pluripotent cells exhibit active chromatin states at GC marker genes and a bivalent chromatin structure at PrM marker genes. Moreover, gene expression analysis during the time course of iPS cells generation revealed that the expression of GC markers precedes pluripotency markers. Collectively, through our observations we hypothesize that the chromatin state and the expression of GC/PrM markers might indicate molecular parallels between in-vivo germ cell specification and pluripotent stem cell generation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0022413PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143132PMC
December 2011