Wu Qiang
Email Address
bchwq@nus.edu.sg
Organizational Units
BIOLOGY
dept
BIOCHEMISTRY
dept
SCIENCE
faculty
YONG LOO LIN SCH OF MEDICINE
faculty
14 results
Publication Search Results
Now showing 1 - 10 of 14
Publication The male seahorse synthesizes and secretes a novel C-type lectin into the brood pouch during early pregnancy(2005-03) Melamed, P.; Xue, Y.; Poon, J.F.D.; Wu, Q.; Xie, H.; Yeo, J.; FOO TET WEI,JOHN; Chua, H.K.; OFFICE OF LIFE SCIENCES; BIOLOGICAL SCIENCESThe male seahorse incubates its young in a manner resembling that of a mammalian pregnancy. After the female deposits her eggs into the male's brood pouch they are fertilized and the embryos develop and grow for several weeks until they are able to withstand the external environmental conditions independently, at which point they are irreversibly released. Although the precise function of the brood pouch is not clear, it is probably related to providing a suitable protective and osmotic environment for the young. The aim of this project was to construct and characterize a cDNA library made from the tissue lining the pouch, in order to help understand the molecular mechanisms regulating its development and function. The library profile indicates expression of genes encoding proteins involved in metabolism and transport, as well as structural proteins, gene regulatory proteins, and other proteins whose function is unknown. However, a large portion of the library contained genes encoding C-type lectins (CTLs), of which three full-length proteins were identified and found to contain a signal peptide and a single C-lectin domain, possessing all the conserved structural elements. We have produced recombinant protein for one of these and raised antisera; we have shown, using Western analysis and 2D electrophoresis, that this protein is secreted in significant quantities into the pouch fluid specifically during early pregnancy. Preliminary functional studies indicate that this CTL causes erythrocyte agglutination and may help to repress bacterial growth. © 2005 FEBS.Publication A genetic and developmental pathway from STAT3 to the OCT4-NANOG circuit is essential for maintenance of ICM lineages in vivo(2013-06-15) Do, D.V.; Ueda, J.; Messerschmidt, D.M.; Lorthongpanich, C.; Zhou, Y.; Feng, B.; Guo, G.; Lin, P.J.; Hossain, M.Z.; Zhang, W.; Moh, A.; Wu, Q.; Robson, P.; Ng, H.H.; Poellinger, L.; Knowles, B.B.; Solter, D.; Fu, X.-Y.; BIOCHEMISTRYAlthough it is known that OCT4-NANOG are required for maintenance of pluripotent cells in vitro, the upstream signals that regulate this circuit during early development in vivo have not been identified. Here we demonstrate, for the first time, signal transducers and activators of transcription 3 (STAT3)-dependent regulation of the OCT4- NANOG circuitry necessary to maintain the pluripotent inner cell mass (ICM), the source of in vitro-derived embryonic stem cells (ESCs). We show that STAT3 is highly expressed in mouse oocytes and becomes phosphorylated and translocates to the nucleus in the four-cell and later stage embryos. Using leukemia inhibitory factor (Lif)-null embryos, we found that STAT3 phosphorylation is dependent on LIF in four-cell stage embryos. In blastocysts, interleukin 6 (IL-6) acts in an autocrine fashion to ensure STAT3 phosphorylation, mediated by janus kinase 1 (JAK1), a LIF- and IL-6-dependent kinase. Using genetically engineered mouse strains to eliminate Stat3 in oocytes and embryos, we firmly establish that STAT3 is essential for maintenance of ICM lineages but not for ICM and trophectoderm formation. Indeed, STAT3 directly binds to the Oct4 and Nanog distal enhancers, modulating their expression to maintain pluripotency of mouse embryonic and induced pluripotent stem cells. These results provide a novel genetic model of cell fate determination operating through STAT3 in the preimplantation embryo and pluripotent stem cells in vivo. © 2013 by Cold Spring Harbor Laboratory Press.Publication Characterization of the interaction of wheat HMGa with linear and four-way junction DNAs(2003-06-03) Zhang, W.; Wu, Q.; Pwee, K.-H.; Jois, S.D.S.; Kini, R.M.; BIOLOGICAL SCIENCES; PHARMACYWheat HMGa protein is a typical member of the plant HMGA family. It has four AT hooks and a histone H1-like region. A panel of deletion mutants of HMGa was generated to study the role of different regions of HMGa in its binding to 4H (a synthetic DNA that mimics the in vivo structure of intermediates of homologous recombination and DNA repair) and linear DNAs. Although the histone H1-like region of HMGa does not bind to 4H or linear DNAs, it does enhance the binding. Mutants with any two adjacent AT hooks show specific binding to both 4H and linear P268 (and P31) with different binding affinities, which is partly due to the flanking regions between AT hooks. Conformational studies indicate that the α-helical content of HMGa increases significantly when it binds to 4H compared to that after binding to P31, linear DNA. In contrast, linear DNA, but not 4H, undergoes substantial conformational change when it binds to HMGa, indicating that linear DNA is relatively more flexible than 4H. A more significant difference in the affinities of binding of the mutants of HMGa to 4H was observed compared to their affinities of binding to linear DNA, P31. These differences could be due to the rigidity of the DNA and the characters of the AT hook regions in the mutants.Publication Cross talk in hormonally regulated gene transcription through induction of estrogen receptor ubiquitylation(2005-08) Luo, M.; Koh, M.; Feng, J.; Wu, Q.; Melamed, P.; BIOLOGICAL SCIENCESEstrogen tightly regulates the levels of circulating gonadotropins, but a direct effect of estrogen receptor alpha (ERα) on the mammalian LHβ gene has remained poorly defined. We demonstrate here that ERα can associate with the LHβ promoter through interactions with Sf-1 and Pitx1 without requiring an estrogen response element (ERE). We show that gonadotropin-releasing hormone (GnRH) promotes ERα ubiquitylation and also degradation while stimulating expression of ubc4. GnRH also increases the association and lengthens the cycling time of ERα on the LHβ promoter. The ERα association and transactivation of the LHβ gene, as well as ERα degradation, are increased following ubc4 overexpression, while the effects of GnRH are abated following ubc4 knockdown. Our results indicate that ERα ubiquitylation and subsequent transactivation of the LHβ gene can be induced by increasing the levels of the E2 enzyme as a result of signaling by an extracellular hormone, thus providing a new form of cross talk in hormonally stimulated regulation of gene expression. Copyright © 2005, American Society for Microbiology. All Rights Reserved.Publication CARM1 is required in embryonic stem cells to maintain pluripotency and resist differentiation(2009) Wu, Q.; Bruce, A.W.; Jedrusik, A.; Zernicka-Goetz, M.; Ellis, P.D.; Andrews, R.M.; Langford, C.F.; Glover, D.M.; BIOCHEMISTRYPublication Interaction of wheat high-mobility-group proteins with four-way-junction DNA and characterization of the structure and expression of HMGA gene(2003-01-15) Zhang, W.; Wu, Q.; Pwee, K.-H.; Manjunatha Kini, R.; BIOLOGICAL SCIENCESPlant high-mobility-group (HMG) chromosomal proteins are the most abundant and ubiquitous nonhistone proteins found in the nuclei of higher eukaryotes. There are only two families of HMG proteins, namely, HMGA and HMGB in plants. The cDNA encoding wheat HMGa protein was isolated and characterized. Wheat HMGA cDNA encodes a protein of 189 amino acid residues. At its N terminus, there is a histone H1-like structure, which is a common feature of plant HMGA proteins, followed by four AT-hook motifs. Polymerase chain reaction results show that the gene contains a single intron of 134 bp. All four AT-hook motifs are encoded by the second exon. Northern blot results show that the expression of HMGA gene is much higher in organs undergoing active cell proliferation. Gel retardation analysis show that wheat HMGa, b, c and histone H1 bind to four-way-junction DNA with high binding affinity, but affinity is dramatically reduced with increasing Mg2+ and Na+ ion concentration. Competition binding studies show that proteins share overlapping binding sites on four-way-junction DNA. HMGd does not bind to four-way-junction DNA. © 2002 Elsevier Science (USA). All rights reserved.Publication Protein arginine methyltransferase 6 regulates embryonic stem cell identity(2012-09-20) Lee, Y.H.; Ma, H.; Tan, T.Z.; Ng, S.S.; Soong, R.; Mori, S.; Fu, X.-Y.; Zernicka-Goetz, M.; Wu, Q.; CANCER SCIENCE INSTITUTE OF SINGAPORE; BIOCHEMISTRYHistone arginine methylation has emerged as an important histone modification involved in gene regulation. Protein arginine methyltransferase (PRMT) 4 and 5 have been shown to play essential roles in early embryonic development and in embryonic stem (ES) cells. Recently, it has been reported that PRMT6-mediated di-methylation of histone H3 at arginine 2 (H3R2me2) can antagonize tri-methylation of histone H3 at lysine 4 (H3K4me3), which marks active genes. However, whether PRMT6 and PRMT6-mediated H3R2me2 play crucial roles in early embryonic development and ES cell identity remain unclear. Here, we have investigated their roles using gain and loss of function studies with mouse ES cells as a model system. We report that Prmt6 and histone H3R2 methylation levels increased when ES cells are induced to differentiate. Consistently, we find that differentiation of ES cells upon upregulation of Prmt6 is associated with decreased expression of pluripotency genes and increased expression of differentiation markers. We also observe that elevation of Prmt6 increases the methylation level of histone H3R2 and decreases H3K4me, Chd1, and Wdr5 levels at the promoter regions of Oct4 and Nanog. Surprisingly, knockdown of Prmt6 also leads to downregulation of pluripotency genes and induction of expression of differentiation markers suggesting that Prmt6 is important for ES cell pluripotency and self-renewal. Our results indicate that a critical level of Prmt6 and histone H3R2me must be maintained in mouse ES cells to sustain their pluripotency. © 2012 Mary Ann Liebert, Inc.Publication STAT3-Inducible mouse ESCs: A model to study the role of STAT3 in ESC maintenance and lineage differentiation(2018) Wong Y.Q.; Xu H.; Wu Q.; Liu X.; Lufei C.; Xu X.Q.; Fu X.-Y.; CANCER SCIENCE INSTITUTE OF SINGAPORE; BIOLOGICAL SCIENCES; BIOCHEMISTRYStudies have demonstrated that STAT3 is essential in maintaining self-renewal of embryonic stem cells (ESCs) and modulates ESC differentiation. However, there is still lack of direct evidence on STAT3 functions in ESCs and embryogenesis because constitutive STAT3 knockout (KO) mouse is embryonic lethal at E6.5-E7.5, prior to potential functional role in early development can be assessed. Therefore, in this study, two inducible STAT3 ESC lines were established, including the STAT3 knockout (InSTAT3 KO) and pSTAT3 overexpressed (InSTAT3 CA) using Tet-on inducible system in which STAT3 expression can be strictly controlled by doxycycline (Dox) stimulation. Through genotyping, deletion of STAT3 alleles was detected in InSTAT3 KO ESCs following 24 hours Dox stimulation. Western blot also showed that pSTAT3 and STAT3 protein levels were significantly reduced in InSTAT3 KO ESCs while dominantly elevated in InSTAT3 CA ECSs upon Dox stimulation. Likewise, it was found that STAT3-null ESCs would affect the differentiation of ESCs into mesoderm and cardiac lineage. Taken together, the findings of this study indicated that InSTAT3 KO and InSTAT3 CA ESCs could provide a new tool to clarify the direct targets of STAT3 and its role in ESC maintenance, which will facilitate the elaboration of the mechanisms whereby STAT3 maintains ESC pluripotency and regulates ESC differentiation during mammalian embryogenesis. © 2018 Yu Qian Wong et al.Publication Mark the transition: Chromatin modifications and cell fate decision(2011-10) Wu, Q.; Ng, H.-H.; BIOLOGICAL SCIENCES; BIOCHEMISTRYPublication Chromatin regulation landscape of embryonic stem cell identity(2011-04) Lee, Y.H.; Wu, Q.; BIOCHEMISTRYES cells (embryonic stem cells) derived from the ICM (inner cell mass) of blastocysts are pluripotent and are capable of giving rise to most cell types. The ES cell identity is mainly maintained by the Oct4 (octamer-binding transcription factor 4) and Nanog transcriptional networks. Recently, a tremendous amount of work has focused on deciphering how ES cell identity is regulated epigenetically. It has been shown that histone methylation/ demethylation, histone acetylation/deacetylation, histone variants and chromatin remodelling play crucial roles in ES cell maintenance and differentiation. Moreover, perturbation of those chromatin regulators results in loss of ES cell identity or aberrant differentiation. Therefore, it is important to fully understand the chromatin regulation landscape of ES cells. The knowledge gained will help us to harness the unique characteristics of ES cells for stem cell-related therapy and regenerative medicine. In the present review, we will discuss recent proceedings that provide novel insights into chromatin regulation of ES cell identity. ©The Authors Journal compilation ©2011 Biochemical Society.