126
|
Barrington R, Buhlmann J, Wang X, Bartlett A, Lim B, Smith W. CD275/ICOSL-independent germinal centers and autoantibody in autoimmune-prone RasGRP1-deficient mice (BA13P.125). THE JOURNAL OF IMMUNOLOGY 2014. [DOI: 10.4049/jimmunol.192.supp.177.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
Lymphopenia results in favorable microenvironments for the expansion and activation of autoreactive lymphocytes. Mice deficient in guanine nucleotide exchange factor Rasgrp1 (KO) are T lymphopenic early in life and develop a lymphoproliferative disorder with features of human SLE. Our previous work revealed that autoreactive B cells lacking RasGRP1 break tolerance early during development as well as during germinal center responses, suggesting both T cell-independent and -dependent mechanisms are responsible. To understand whether T cells are involved in the breach of tolerance in germinal centers, we examined T effector cells in KO mice. In addition to the expected increase in Th1 cells, the frequency and number of Th17 cells were also elevated in KO mice. Th17 cells were positive for CXCR5 and Bcl-6, localized to germinal centers and upregulated levels of CD278/ICOS coordinately with the appearance of germinal centers, all attributes of T follicular helper cells (Tfh17). To determine whether CD278-CD275 interactions were required for the development of Tfh17 cells and for autoantibody, we crossed KO and CD275-deficient mice. Interestingly, KO mice lacking CD275 formed germinal centers with an elevated frequency of Th17 cells and similar titers of autoantibodies. From these data, we suggest that CD278-CD275 interactions are not required for germinal centers and autoantibody production in mice lacking RasGRP1.
Collapse
|
127
|
Tan HK, Toh CXD, Ma D, Yang B, Liu TM, Lu J, Wong CW, Tan TK, Li H, Syn C, Tan EL, Lim B, Lim YP, Cook SA, Loh YH. Human finger-prick induced pluripotent stem cells facilitate the development of stem cell banking. Stem Cells Transl Med 2014; 3:586-98. [PMID: 24646489 DOI: 10.5966/sctm.2013-0195] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Induced pluripotent stem cells (iPSCs) derived from somatic cells of patients can be a good model for studying human diseases and for future therapeutic regenerative medicine. Current initiatives to establish human iPSC (hiPSC) banking face challenges in recruiting large numbers of donors with diverse diseased, genetic, and phenotypic representations. In this study, we describe the efficient derivation of transgene-free hiPSCs from human finger-prick blood. Finger-prick sample collection can be performed on a "do-it-yourself" basis by donors and sent to the hiPSC facility for reprogramming. We show that single-drop volumes of finger-prick samples are sufficient for performing cellular reprogramming, DNA sequencing, and blood serotyping in parallel. Our novel strategy has the potential to facilitate the development of large-scale hiPSC banking worldwide.
Collapse
|
128
|
Go MK, Zhang WC, Lim B, Yew WS. Glycine Decarboxylase Is an Unusual Amino Acid Decarboxylase Involved in Tumorigenesis. Biochemistry 2014; 53:947-56. [DOI: 10.1021/bi4014227] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
|
129
|
Loh KM, Ang LT, Zhang J, Kumar V, Ang J, Auyeong JQ, Lee KL, Choo SH, Lim CYY, Nichane M, Tan J, Noghabi MS, Azzola L, Ng ES, Durruthy-Durruthy J, Sebastiano V, Poellinger L, Elefanty AG, Stanley EG, Chen Q, Prabhakar S, Weissman IL, Lim B. Efficient endoderm induction from human pluripotent stem cells by logically directing signals controlling lineage bifurcations. Cell Stem Cell 2014; 14:237-52. [PMID: 24412311 DOI: 10.1016/j.stem.2013.12.007] [Citation(s) in RCA: 248] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 09/25/2013] [Accepted: 12/16/2013] [Indexed: 01/11/2023]
Abstract
Human pluripotent stem cell (hPSC) differentiation typically yields heterogeneous populations. Knowledge of signals controlling embryonic lineage bifurcations could efficiently yield desired cell types through exclusion of alternate fates. Therefore, we revisited signals driving induction and anterior-posterior patterning of definitive endoderm to generate a coherent roadmap for endoderm differentiation. With striking temporal dynamics, BMP and Wnt initially specified anterior primitive streak (progenitor to endoderm), yet, 24 hr later, suppressed endoderm and induced mesoderm. At lineage bifurcations, cross-repressive signals separated mutually exclusive fates; TGF-β and BMP/MAPK respectively induced pancreas versus liver from endoderm by suppressing the alternate lineage. We systematically blockaded alternate fates throughout multiple consecutive bifurcations, thereby efficiently differentiating multiple hPSC lines exclusively into endoderm and its derivatives. Comprehensive transcriptional and chromatin mapping of highly pure endodermal populations revealed that endodermal enhancers existed in a surprising diversity of "pre-enhancer" states before activation, reflecting the establishment of a permissive chromatin landscape as a prelude to differentiation.
Collapse
|
130
|
Cao S, Han J, Wu J, Li Q, Liu S, Zhang W, Pei Y, Ruan X, Liu Z, Wang X, Lim B, Li N. Specific gene-regulation networks during the pre-implantation development of the pig embryo as revealed by deep sequencing. BMC Genomics 2014; 15:4. [PMID: 24383959 PMCID: PMC3925986 DOI: 10.1186/1471-2164-15-4] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Accepted: 12/26/2013] [Indexed: 12/29/2022] Open
Abstract
Background Because few studies exist to describe the unique molecular network regulation behind pig pre-implantation embryonic development (PED), genetic engineering in the pig embryo is limited. Also, this lack of research has hindered derivation and application of porcine embryonic stem cells and porcine induced pluripotent stem cells (iPSCs). Results We identified and analyzed the genome wide transcriptomes of pig in vivo-derived and somatic cell nuclear transferred (SCNT) as well as mouse in vivo-derived pre-implantation embryos at different stages using mRNA deep sequencing. Comparison of the pig embryonic transcriptomes with those of mouse and human pre-implantation embryos revealed unique gene expression patterns during pig PED. Pig zygotic genome activation was confirmed to occur at the 4-cell stage via genome-wide gene expression analysis. This activation was delayed to the 8-cell stage in SCNT embryos. Specific gene expression analysis of the putative inner cell mass (ICM) and the trophectoderm (TE) revealed that pig and mouse pre-implantation embryos share regulatory networks during the first lineage segregation and primitive endoderm differentiation, but not during ectoderm commitment. Also, fatty acid metabolism appears to be a unique characteristic of pig pre-implantation embryonic development. In addition, the global gene expression patterns in the pig SCNT embryos were different from those in in vivo-derived pig embryos. Conclusions Our results provide a resource for pluripotent stem cell engineering and for understanding pig development. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-4) contains supplementary material, which is available to authorized users.
Collapse
|
131
|
Lim B, Pasternak M, Meyer AJ, Cobbett CS. Restricting glutamylcysteine synthetase activity to the cytosol or glutathione biosynthesis to the plastid is sufficient for normal plant development and stress tolerance. PLANT BIOLOGY (STUTTGART, GERMANY) 2014; 16:58-67. [PMID: 23691990 DOI: 10.1111/plb.12033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Accepted: 03/04/2013] [Indexed: 05/08/2023]
Abstract
The tripeptide glutathione (GSH) is an important metabolite with a broad spectrum of functions, and its homeostasis is essential to maintain cellular redox poise and effective responses to stress in plants. In Arabidopsis GSH is synthesised in two successive enzymatic steps by γ-glutamylcysteine synthetase (GSH1), localised exclusively in plastids, forming the pathway intermediate γ-glutamylcysteine (γ-EC), and then by glutathione synthetase (GSH2), which is located in both plastids and cytosol. This suggests a mechanism for γ-EC export from the plastids and, because the majority of GSH2 transcripts (90%) encode the cytosolic isoform, it is speculated that the cytosol may be the main compartment for GSH biosynthesis. With the availability of knockout lethal mutants of GSH1 and GSH2 in Arabidopsis, we were able to manipulate the GSH biosynthetic pathway within cells through transgenic techniques. We successfully complemented the gsh1 and gsh2 null mutants with a cytosol-targeted bacterial EcGSHA and plastid-targeted Arabidopsis GSH2 protein, respectively, to wild-type phenotypes. These transgenics were little affected under heavy metal (cadmium) or oxidative stress (H2 O2 ) when compared to the wild type. Collectively, our data show that redirecting GSH1 activity exclusively to the cytosol or restricting GSH biosynthesis to the plastids has no significant impact on development or stress resistance, suggesting efficient exchange of γ-EC and GSH between the plastid and cytosol compartments within cells.
Collapse
|
132
|
Lim B, Dolloff NG, Allen JE, Dicker DT, El-Deiry WS. Abstract P6-02-01: Elucidating the change of TRAIL sensitivity in basal like TNBC cell lines by lapatinib, and further therapeutic implication. Cancer Res 2013. [DOI: 10.1158/0008-5472.sabcs13-p6-02-01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Triple negative breast cancer (TNBC) comprises 15-20% of breast cancer, and carries a poor prognosis. Recently, efforts to understand this heterogeneous group of cancers have led to recognition of different subtypes of TNBC by Dr. Pietenpol et al based on genetic and functional signature. So far, the only targeting agent for TNBC still remains as androgen receptor inhibitor for LAR group. Thus, other strategies in therapeutic development for TNBCs are necessary. TRAIL (Tumor Necrosis Factor-related apoptosis inducing ligand), a member of the TNF-alpha family of death receptor ligands, induces apoptosis by binding death receptors (DR4 and DR5), could be a good strategy in therapeutic development in TNBC. Unfortunately, majority of breast cancer cell lines are resistant to TRAIL targeted therapy especially basal like group of cells, as previously shown in the work of Lipkowitz at the NCI. Lapatinib, a well known as erbB 1 and 2 inhibitor had been found to have off target activity inducing JNK, an important activator of nuclear transcription of death receptor, and mitochondrial mediated intrinsic apoptosis pathway. Interestingly, study of combination therapy with lapatinib and TRAIL not only confirmed baseline poor sensitivity to TRAIL induced apoptosis in “basal like” HCC 1937 and MDA-MB-468 cell lines, but also revealed an unexpected difference in sensitization to TRAIL induced apoptosis by Lapatinib pre-treatment between these two cell lines. When treated with 48hrs Lapatinib high–dose treatment, HCC 1937 showed increased sensitization whereas MDA-MB-468 did not. Both HCC 1937 and MDA-MB-468 are in the same basal like 1(BL1) group by Dr. Pietenpol's analysis, and their baseline sensitivity to TRAIL inducing apoptosis are the same. In terms of apoptosis - there are two big categories of cells. Type I cells are independent of mitochondria for the induction of Fas death receptor mediated apoptosis, where as type II cells are mitochrondria-dependent. Thus we hypothesized that this difference in lapatinib induced TRAIL sensitization between two cell lines is due to difference in one being type I vs the other being type II cell, and this type of apoptosis is not likely equal in same subgroup of TNBC. If this hypothesis is correct, targeting apoptosis pathway in TNBC should incorporate the recognition of apoptosis cell types rather than functional/genetic based subtypes. We will further elucidate our hypothesis by studying JNK, caspase 3 and 9 activity and downstream of both intrinsic, extrinsic apoptosis pathway.
Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-02-01.
Collapse
|
133
|
Tam WL, Lu H, Buikhuisen J, Soh BS, Lim E, Reinhardt F, Wu ZJ, Krall JA, Bierie B, Guo W, Chen X, Liu XS, Brown M, Lim B, Weinberg RA. Protein kinase C α is a central signaling node and therapeutic target for breast cancer stem cells. Cancer Cell 2013; 24:347-64. [PMID: 24029232 PMCID: PMC4001722 DOI: 10.1016/j.ccr.2013.08.005] [Citation(s) in RCA: 255] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Revised: 05/03/2013] [Accepted: 08/06/2013] [Indexed: 02/06/2023]
Abstract
The epithelial-mesenchymal transition program becomes activated during malignant progression and can enrich for cancer stem cells (CSCs). We report that inhibition of protein kinase C α (PKCα) specifically targets CSCs but has little effect on non-CSCs. The formation of CSCs from non-stem cells involves a shift from EGFR to PDGFR signaling and results in the PKCα-dependent activation of FRA1. We identified an AP-1 molecular switch in which c-FOS and FRA1 are preferentially utilized in non-CSCs and CSCs, respectively. PKCα and FRA1 expression is associated with the aggressive triple-negative breast cancers, and the depletion of FRA1 results in a mesenchymal-epithelial transition. Hence, identifying molecular features that shift between cell states can be exploited to target signaling components critical to CSCs.
Collapse
|
134
|
Bartlett A, Buhlmann JE, Stone J, Lim B, Barrington RA. Multiple checkpoint breach of B cell tolerance in Rasgrp1-deficient mice. THE JOURNAL OF IMMUNOLOGY 2013; 191:3605-13. [PMID: 23997211 DOI: 10.4049/jimmunol.1202892] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Lymphopenic hosts offer propitious microenvironments for expansion of autoreactive B and T cells. Despite this, many lymphopenic hosts do not develop autoimmune disease, suggesting that additional factors are required for breaching self-tolerance in the setting of lymphopenia. Mice deficient in guanine nucleotide exchange factor Rasgrp1 develop a lymphoproliferative disorder with features of human systemic lupus erythematosus. Early in life, Rasgrp1-deficient mice have normal B cell numbers but are T lymphopenic, leading to defective homeostatic expansion of CD4 T cells. To investigate whether B cell-intrinsic mechanisms also contribute to autoimmunity, Rasgrp1-deficient mice were bred to mice containing a knockin autoreactive BCR transgene (564Igi), thereby allowing the fate of autoreactive B cells to be assessed. During B cell development, the frequency of receptor-edited 564Igi B cells was reduced in Rasrp1-deficient mice compared with Rasgrp1-sufficient littermate control mice, suggesting that tolerance was impaired. In addition, the number of 564Igi transitional B cells was increased in Rasgrp1-deficient mice compared with control mice. Immature 564Igi B cells in bone marrow and spleen lacking RasGRP1 expressed lower levels of Bim mRNA and protein, suggesting that autoreactive B cells elude clonal deletion during development. Concomitant with increased serum autoantibodies, Rasgrp1-deficient mice developed spontaneous germinal centers at 8-10 wk of age. The frequency and number of 564Igi B cells within these germinal centers were significantly increased in Rasgrp1-deficient mice relative to control mice. Taken together, these studies suggest that autoreactive B cells lacking Rasgrp1 break central and peripheral tolerance through both T cell-independent and -dependent mechanisms.
Collapse
|
135
|
Li Y, Chen Q, Zheng D, Yin L, Chionh YH, Wong LH, Tan SQ, Tan TC, Chan JKY, Alonso S, Dedon PC, Lim B, Chen J. Induction of functional human macrophages from bone marrow promonocytes by M-CSF in humanized mice. THE JOURNAL OF IMMUNOLOGY 2013; 191:3192-9. [PMID: 23935193 DOI: 10.4049/jimmunol.1300742] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Engraftment of human CD34⁺ hematopoietic stem/progenitor cells into immunodeficient mice leads to robust reconstitution of human T and B cells but not monocytes and macrophages. To identify the cause underlying the poor monocyte and macrophage reconstitution, we analyzed human myeloid cell development in humanized mice and found that it was blocked at the promonocyte stage in the bone marrow. Expression of human M-CSF or GM-CSF by hydrodynamic injection of cytokine-encoding plasmid completely abolished the accumulation of promonocytes in the bone marrow. M-CSF promoted the development of mature monocytes and tissue-resident macrophages whereas GM-CSF did not. Moreover, correlating with an increased human macrophages at the sites of infection, M-CSF-treated humanized mice exhibited an enhanced protection against influenza virus and Mycobacterium infection. Our study identifies the precise stage at which human monocyte/macrophage development is blocked in humanized mice and reveals overlapping and distinct functions of M-CSF and GM-CSF in human monocyte and macrophage development. The improved reconstitution and functionality of monocytes/macrophages in the humanized mice following M-CSF expression provide a superior in vivo system to investigate the role of macrophages in physiological and pathological processes.
Collapse
|
136
|
|
137
|
Zhang L, Prak L, Rayon-Estrada V, Thiru P, Flygare J, Lim B, Lodish HF. ZFP36L2 is required for self-renewal of early burst-forming unit erythroid progenitors. Nature 2013; 499:92-6. [PMID: 23748442 PMCID: PMC3702661 DOI: 10.1038/nature12215] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 04/23/2013] [Indexed: 11/09/2022]
Abstract
Stem cells and progenitors in many lineages undergo self- renewing divisions, but the extracellular and intracellular proteins that regulate this process are largely unknown. Glucocorticoids stimulate red cell formation by promoting self-renewal of early erythroid burst forming unit-erythrocyte (BFU-E) progenitors1-4. Here we show that the RNA binding protein Zfp36l2 is a transcriptional target of the glucocorticoid receptor (GR) in BFU-Es and is required for BFU-E self-renewal. Zfp36l2 is normally downregulated during erythroid differentiation from the BFU-E stage but its expression is maintained by all tested GR agonists that stimulate BFU-E self-renewal, and the GR binds to several potential enhancer regions of Zfp36l2. Knockdown of Zfp36l2 in cultured BFU-E cells did not affect the rate of cell division but disrupted glucocorticoid-induced BFU-E self-renewal, and knockdown of Zfp36l2 in transplanted erythroid progenitors prevented expansion of erythroid lineage progenitors normally seen following induction of anemia by phenylhydrazine treatment. Zfp36l2 preferentially binds to mRNAs that are induced or maintained at high expression levels during terminal erythroid differentiation and negatively regulates their expression levels. Thus Zfp36l2 functions as part of molecular switch promoting BFU-E self-renewal and thus a subsequent increase in the total numbers of CFU-E progenitors and erythroid cells that are generated.
Collapse
|
138
|
Arya SK, Lim B, Rahman ARA. Enrichment, detection and clinical significance of circulating tumor cells. LAB ON A CHIP 2013; 13:1995-2027. [PMID: 23625167 DOI: 10.1039/c3lc00009e] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Circulating Tumor Cells (CTCs) are shed from primary or secondary tumors into blood circulation. Accessing and analyzing these cells provides a non-invasive alternative to tissue biopsy. CTCs are estimated to be as few as 1 cell among a few million WBCs and few billion RBCs in 1 ml of patient blood and are rarely found in healthy individuals. CTCs are FDA approved for prognosis of the major cancers, namely, Breast, Colon and Prostate. Currently, more than 400 clinical trials are ongoing to establish their clinical significance beyond prognosis, such as, therapy selection and companion diagnostics. Understanding the clinical relevance of CTCs typically involves isolation, detection and molecular characterization of cells, ideally at single cell level. The need for highly reliable, standardized and robust methodologies for isolating and analyzing CTCs has been widely expressed by clinical thought leaders. In the last decade, numerous academic and commercial technology platforms for isolation and analysis of CTCs have been reported. A recent market report highlighted the presence of more than 100 companies offering products and services related to CTCs. This review aims to capture the state of the art and examines the technical merits and limitations of contemporary technologies for clinical use.
Collapse
|
139
|
Oh MH, Yu T, Yu SH, Lim B, Ko KT, Willinger MG, Seo DH, Kim BH, Cho MG, Park JH, Kang K, Sung YE, Pinna N, Hyeon T. Galvanic Replacement Reactions in Metal Oxide Nanocrystals. Science 2013; 340:964-8. [DOI: 10.1126/science.1234751] [Citation(s) in RCA: 426] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
|
140
|
Levantini E, Basseres DS, Zhang WC, Welner RS, Alberich-Jorda' M, Yong KJ, Thakkar BM, Zhang J, Battelli C, Hetherington CJ, Ye M, O'Brien K, Magli MC, Loh M, Nga ME, Pang YH, Borczuk AC, Varticovski L, Kocher O, Zhang P, Soo RA, Lim B, Halmos B, Tenen DG. Abstract LB-46: C/EBPα acts as tumor suppressor in lung cancer by inhibiting the proto-oncogene Bmi-1. Cancer Res 2013. [DOI: 10.1158/1538-7445.am2013-lb-46] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
C/EBPα gene expression is frequently lost in non-small cell lung cancer, suggesting it acts as a tumor suppressor. Here, we generated an inducible lung-specific mouse model of C/EBPα deletion (C/EBPαLung-Δ mice) that develops lung adenocarcinomas. We observed that C/EBPα excision results in upregulation of Bmi-1, and that tumor initiation strictly depends on Bmi-1 gene dosage, as C/EBPαLung-Δ mice carrying only one functional Bmi-1 allele escape tumorigenesis. Accordingly, C/EBPα negative human adenocarcinomas show elevated Bmi-1 expression, in line with our observation that C/EBPα acts as tumor suppressor in lung cells by directly inhibiting Bmi-1 transcription. Furthermore, pharmacological inhibition of Bmi-1 impairs the ability of C/EBPα null adenocarcinoma cells to form tumors in xenografts. Overall, we have identified Bmi-1 as a critical therapeutic target in those patients carrying abnormal C/EBPα function.
Citation Format: Elena Levantini, Daniela S. Basseres, Wen Cai Zhang, Robert S. Welner, Meritxell Alberich-Jorda’, Kol Jia Yong, Bhavin M. Thakkar, Junyan Zhang, Chiara Battelli, Christopher J. Hetherington, Min Ye, Karen O'Brien, Maria Cristina Magli, Marie Loh, Min En Nga, Yin Huei Pang, Alain C. Borczuk, Lyuba Varticovski, Olivier Kocher, Pu Zhang, Ross A. Soo, Bing Lim, Balazs Halmos, Daniel G. Tenen. C/EBPα acts as tumor suppressor in lung cancer by inhibiting the proto-oncogene Bmi-1. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-46. doi:10.1158/1538-7445.AM2013-LB-46
Collapse
|
141
|
Ramulu T, Venu R, Sinha B, Lim B, Jeon S, Yoon S, Kim C. Nanowires array modified electrode for enhanced electrochemical detection of nucleic acid. Biosens Bioelectron 2013; 40:258-64. [DOI: 10.1016/j.bios.2012.07.034] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 07/19/2012] [Accepted: 07/20/2012] [Indexed: 11/28/2022]
|
142
|
Kothari D, Lim B. O373 OUTCOMES OF DIABETES IN PREGNANCY AT AN AUSTRALIAN TEACHING HOSPITAL. Int J Gynaecol Obstet 2012. [DOI: 10.1016/s0020-7292(12)60803-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
143
|
Liu TM, Ng WM, Tan HS, Vinitha D, Yang Z, Fan JB, Zou Y, Hui JH, Lee EH, Lim B. Molecular basis of immortalization of human mesenchymal stem cells by combination of p53 knockdown and human telomerase reverse transcriptase overexpression. Stem Cells Dev 2012; 22:268-78. [PMID: 22765508 DOI: 10.1089/scd.2012.0222] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mesenchymal stem cells (MSCs) represent one of the most promising stem cells for a number of degenerative conditions due to their multipotency, immunoprivileged properties, and easy expansion in vitro. However, the limited life span of primary MSCs during in vitro expansion greatly hampers their use in clinical applications and basic research. Immortalization of MSCs will overcome this problem and may provide a very useful tool with which to study MSC biology. Here we showed that silencing p53 expression with lentivirus-mediated small interfering RNA delayed the senescence by extended passage number, but was not sufficient to immortalize primary MSCs. However, combination of p53 knockdown and human telomerase reverse transcriptase (hTERT) overexpression was sufficient to immortalize MSCs. The effects of p53 knockdown and hTERT overexpression on MSCs, including proliferation, colony formation, and differentiation, were determined. The resultant immortal MSCs displayed similar surface antigen profile to primary MSCs and retained MSC differentiation potential. Gene expression profile showed high similarity between immortalized MSCs and primary MSCs. In addition, immortalization-associated genes were also identified. Our data suggested immortalization of MSCs related to upregulation of cell cycle regulator and DNA repair genes enabling them to bypass cell crisis and complete mitosis. This study provides a new cellular model for basic studies of MSCs and understanding of the molecular basis of MSC immortalization.
Collapse
|
144
|
Ryu J, Yun Y, Lim B. P04.63. The consciousness of medical doctors about collaborative practice of Western medicine and traditional Korean medicine. Altern Ther Health Med 2012. [PMCID: PMC3373801 DOI: 10.1186/1472-6882-12-s1-p333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
145
|
Choi B, Han G, Lim B, Cho H. P04.18. Current status of the dual medical license holders in Korea. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2012. [PMCID: PMC3373385 DOI: 10.1186/1472-6882-12-s1-p288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
|
146
|
Choi B, Lim B, Han D. P04.53. Factors related to use of both western medicine and complementary and alternative medicine among patients with chronic diseases in South Korea. Altern Ther Health Med 2012. [PMCID: PMC3373811 DOI: 10.1186/1472-6882-12-s1-p323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
147
|
Orlov Y, Xu H, Afonnikov D, Lim B, Heng JC, Yuan P, Chen M, Yan J, Clarke N, Orlova N, Huss M, Gunbin K, Podkolodnyy N, Ng HH. Computer and Statistical Analysis of Transcription Factor Binding and Chromatin Modifications by ChIP-seq data in Embryonic Stem Cell. J Integr Bioinform 2012. [DOI: 10.1515/jib-2012-211] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Summary Advances in high throughput sequencing technology have enabled the identification of transcription factor (TF) binding sites in genome scale. TF binding studies are important for medical applications and stem cell research. Somatic cells can be reprogrammed to a pluripotent state by the combined introduction of factors such as Oct4, Sox2, c-Myc, Klf4. These reprogrammed cells share many characteristics with embryonic stem cells (ESCs) and are known as induced pluripotent stem cells (iPSCs). The signaling requirements for maintenance of human and murine embryonic stem cells (ESCs) differ considerably. Genome wide ChIP-seq TF binding maps in mouse stem cells include Oct4, Sox2, Nanog, Tbx3, Smad2 as well as group of other factors. ChIP-seq allows study of new candidate transcription factors for reprogramming. It was shown that Nr5a2 could replace Oct4 for reprogramming. Epigenetic modifications play important role in regulation of gene expression adding additional complexity to transcription network functioning. We have studied associations between different histone modification using published data together with RNA Pol II sites. We found strong associations between activation marks and TF binding sites and present it qualitatively. To meet issues of statistical analysis of genome ChIP-sequencing maps we developed computer program to filter out noise signals and find significant association between binding site affinity and number of sequence reads. The data provide new insights into the function of chromatin organization and regulation in stem cells.
Collapse
|
148
|
Layer K, Lin G, Nencion A, Hu W, Schmucker A, Antov A, Li X, Takamatsu S, Chevassut T, Dower N, Stang S, Beier D, Buhlmann J, Bronson R, Elkon K, Stone J, Van Parijs L, Lim B. Autoimmunity as the Consequence of a Spontaneous Mutation in Rasgrp1. Immunity 2012; 36:886. [DOI: 10.1016/j.immuni.2012.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
149
|
Finlay MC, Lim B, McCready J, Ahsan S, Gopalmurugan AB, Xu L, Segal O, Lowe M, Lambiase PD. 051 Organisational index is the best assessment of fractionation in persistent atrial fibrillation: analytic comparisons and ablation results: Abstract 051 Figure 1. BRITISH HEART JOURNAL 2012. [DOI: 10.1136/heartjnl-2012-301877b.51] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
150
|
Kumar PA, Hu Y, Yamamoto Y, Hoe NB, Wei TS, Mu D, Sun Y, Joo LS, Dagher R, Zielonka EM, Wang DY, Lim B, Chow VT, Crum CP, Xian W, McKeon F. Distal airway stem cells yield alveoli in vitro and during lung regeneration following H1N1 influenza infection. Cell 2011; 147:525-38. [PMID: 22036562 DOI: 10.1016/j.cell.2011.10.001] [Citation(s) in RCA: 417] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2011] [Revised: 08/28/2011] [Accepted: 10/04/2011] [Indexed: 11/19/2022]
Abstract
The extent of lung regeneration following catastrophic damage and the potential role of adult stem cells in such a process remains obscure. Sublethal infection of mice with an H1N1 influenza virus related to that of the 1918 pandemic triggers massive airway damage followed by apparent regeneration. We show here that p63-expressing stem cells in the bronchiolar epithelium undergo rapid proliferation after infection and radiate to interbronchiolar regions of alveolar ablation. Once there, these cells assemble into discrete, Krt5+ pods and initiate expression of markers typical of alveoli. Gene expression profiles of these pods suggest that they are intermediates in the reconstitution of the alveolar-capillary network eradicated by viral infection. The dynamics of this p63-expressing stem cell in lung regeneration mirrors our parallel finding that defined pedigrees of human distal airway stem cells assemble alveoli-like structures in vitro and suggests new therapeutic avenues to acute and chronic airway disease.
Collapse
|