| 1. |
- Zhao, Zhihu, et al.
(författare)
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Circular chromosome conformation capture (4C) uncovers extensive networks of epigenetically regulated intra- and interchromosomal interactions
- 2006
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 38:11, s. 1341-1347
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Tidskriftsartikel (refereegranskat)abstract
- Accumulating evidence converges on the possibility that chromosomes interact with each other to regulate transcription in trans. To systematically explore the epigenetic dimension of such interactions, we devised a strategy termed circular chromosome conformation capture (4C). This approach involves a circularization step that enables high-throughput screening of physical interactions between chromosomes without a preconceived idea of the interacting partners. Here we identify 114 unique sequences from all autosomes, several of which interact primarily with the maternally inherited H19 imprinting control region. Imprinted domains were strongly overrepresented in the library of 4C sequences, further highlighting the epigenetic nature of these interactions. Moreover, we found that the direct interaction between differentially methylated regions was linked to epigenetic regulation of transcription in trans. Finally, the patterns of interactions specific to the maternal H19 imprinting control region underwent reprogramming during in vitro maturation of embryonic stem cells. These observations shed new light on development, cancer epigenetics and the evolution of imprinting.
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| 2. |
- Agarwal, Prasoon, et al.
(författare)
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CGGBP1 mitigates cytosine methylation at repetitive DNA sequences
- 2015
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Background: CGGBP1 is a repetitive DNA-binding transcription regulator with target sites at CpG-rich sequences such as CGG repeats and Alu-SINEs and L1-LINEs. The role of CGGBP1 as a possible mediator of CpG methylation however remains unknown. At CpG-rich sequences cytosine methylation is a major mechanism of transcriptional repression. Concordantly, gene-rich regions typically carry lower levels of CpG methylation than the repetitive elements. It is well known that at interspersed repeats Alu-SINEs and L1-LINEs high levels of CpG methylation constitute a transcriptional silencing and retrotransposon inactivating mechanism. Results: Here, we have studied genome-wide CpG methylation with or without CGGBP1-depletion. By high throughput sequencing of bisulfite-treated genomic DNA we have identified CGGBP1 to be a negative regulator of CpG methylation at repetitive DNA sequences. In addition, we have studied CpG methylation alterations on Alu and L1 retrotransposons in CGGBP1-depleted cells using a novel bisulfite-treatment and high throughput sequencing approach. Conclusions: The results clearly show that CGGBP1 is a possible bidirectional regulator of CpG methylation at Alus, and acts as a repressor of methylation at L1 retrotransposons.
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| 3. |
- Agarwal, Prasoon, et al.
(författare)
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Genome-wide profiling of histone H3 lysine 27 and lysine 4 trimethylation in multiple myeloma reveals the importance of Polycomb gene targeting and highlights EZH2 as a potential therapeutic target.
- 2016
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Ingår i: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 7:6, s. 6809-6923
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Tidskriftsartikel (refereegranskat)abstract
- Multiple myeloma (MM) is a malignancy of the antibody-producing plasma cells. MM is a highly heterogeneous disease, which has hampered the identification of a common underlying mechanism for disease establishment as well as the development of targeted therapy. Here we present the first genome-wide profiling of histone H3 lysine 27 and lysine 4 trimethylation in MM patient samples, defining a common set of active H3K4me3-enriched genes and silent genes marked by H3K27me3 (H3K27me3 alone or bivalent) unique to primary MM cells, when compared to normal bone marrow plasma cells. Using this epigenome profile, we found increased silencing of H3K27me3 targets in MM patients at advanced stages of the disease, and the expression pattern of H3K27me3-marked genes correlated with poor patient survival. We also demonstrated that pharmacological inhibition of EZH2 had anti-myeloma effects in both MM cell lines and CD138+ MM patient cells. In addition, EZH2 inhibition decreased the global H3K27 methylation and induced apoptosis. Taken together, these data suggest an important role for the Polycomb repressive complex 2 (PRC2) in MM, and highlights the PRC2 component EZH2 as a potential therapeutic target in MM.
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| 4. |
- Agarwal, Prasoon, et al.
(författare)
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Growth signals employ CGGBP1 to suppress transcription of Alu-SINEs
- 2016
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Ingår i: Cell Cycle. - : Informa UK Limited. - 1538-4101 .- 1551-4005. ; 15:12, s. 1558-1571
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Tidskriftsartikel (refereegranskat)abstract
- CGGBP1 (CGG triplet repeat-binding protein 1) regulates cell proliferation, stress response,cytokinesis, telomeric integrity and transcription. It could affect these processes by modulatingtarget gene expression under different conditions. Identification of CGGBP1-target genes andtheir regulation could reveal how a transcription regulator affects such diverse cellular processes.Here we describe the mechanisms of differential gene expression regulation by CGGBP1 inquiescent or growing cells. By studying global gene expression patterns and genome-wide DNAbindingpatterns of CGGBP1, we show that a possible mechanism through which it affects theexpression of RNA Pol II-transcribed genes in trans depends on Alu RNA. We also show that itregulates Alu transcription in cis by binding to Alu promoter. Our results also indicate thatpotential phosphorylation of CGGBP1 upon growth stimulation facilitates its nuclear retention,Alu-binding and dislodging of RNA Pol III therefrom. These findings provide insights into howAlu transcription is regulated in response to growth signals.
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| 5. |
- Põlajeva, Jelena, 1983-, et al.
(författare)
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miRNA-21 is developmentally regulated in mouse brain and is co-expressed with SOX2 in glioma
- 2012
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Ingår i: BMC Cancer. - : Springer Science and Business Media LLC. - 1471-2407 .- 1471-2407. ; 12, s. 378-
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundMicroRNAs (miRNAs) and their role during tumor development have been studied in greatdetail during the last decade, albeit their expression pattern and regulation during normaldevelopment are however not so well established. Previous studies have shown that miRNAsare differentially expressed in solid human tumors. Platelet-derived growth factor (PDGF)signaling is known to be involved in normal development of the brain as well as in malignantprimary brain tumors, gliomas, but the complete mechanism is still lacking. We decided toinvestigate the expression of the oncogenic miR-21 during normal mouse development andglioma, focusing on PDGF signaling as a potential regulator of miR-21.MethodsWe generated mouse glioma using the RCAS/tv-a system for driving PDGF-BB expression ina cell-specific manner. Expression of miR-21 in mouse cell cultures and mouse brain wereassessed using Northern blot analysis and in situ hybridization. Immunohistochemistry andWestern blot analysis were used to investigate SOX2 expression. LNA-modified siRNA wasused for irreversible depletion of miR-21. For inhibition of PDGF signaling Gleevec(imatinib mesylate), Rapamycin and U0126, as well as siRNA were used. Statisticalsignificance was calculated using double-sided unpaired Student´s t-test.ResultsWe identified miR-21 to be highly expressed during embryonic and newborn braindevelopment followed by a gradual decrease until undetectable at postnatal day 7 (P7), thiscorrelated with SOX2 expression. Furthermore, miR-21 and SOX2 showed up-regulation andoverlapping expression pattern in RCAS/tv-a generated mouse brain tumor specimens. Uponirreversible depletion of miR-21 the expression of SOX2 was strongly diminished in bothmouse primary glioma cultures and human glioma cell lines. Interestingly, in normalfibroblasts the expression of miR-21 was induced by PDGF-BB, and inhibition of PDGFsignaling in mouse glioma primary cultures resulted in suppression of miR-21 suggesting thatmiR-21 is indeed regulated by PDGF signaling.ConclusionsOur data show that miR-21 and SOX2 are tightly regulated already during embryogenesisand define a distinct population with putative tumor cell of origin characteristics. We believethat miR-21 is a mediator of PDGF-driven brain tumors, which suggests miR-21 as apromising target for treatment of glioma.
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| 6. |
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| 7. |
- Singh, Umashankar, et al.
(författare)
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A DNA sequence directed mutual transcription regulation of HSF1 and NFIX involves novel heat sensitive protein interactions
- 2009
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 4:4, s. e5050-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Though the Nuclear factor 1 family member NFIX has been strongly implicated in PDGFB-induced glioblastoma, its molecular mechanisms of action remain unknown. HSF1, a heat shock-related transcription factor is also a powerful modifier of carcinogenesis by several factors, including PDGFB. How HSF1 transcription is controlled has remained largely elusive. METHODOLOGY/PRINCIPAL FINDINGS: By combining microarray expression profiling and a yeast-two-hybrid screen, we identified that NFIX and its interactions with CGGBP1 and HMGN1 regulate expression of HSF1. We found that CGGBP1 organizes a bifunctional transcriptional complex at small CGG repeats in the HSF1 promoter. Under chronic heat shock, NFIX uses CGGBP1 and HMGN1 to get recruited to this promoter and in turn affects their binding to DNA. Results show that the interactions of NFIX with CGGBP1 and HMGN1 in the soluble fraction are heat shock sensitive due to preferential localization of CGGBP1 to heterochromatin after heat shock. HSF1 in turn was found to bind to the NFIX promoter and repress its expression in a heat shock sensitive manner. CONCLUSIONS/SIGNIFICANCE: NFIX and HSF1 exert a mutual transcriptional repressive effect on each other which requires CGG repeat in HSF1 promoter and HSF1 binding site in NFIX promoter. We unravel a unique mechanism of heat shock sensitive DNA sequence-directed reciprocal transcriptional regulation between NFIX and HSF1. Our findings provide new insights into mechanisms of transcription regulation under stress.
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| 8. |
- Singh, Umashankar, et al.
(författare)
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Carboxypeptidase E in the mouse placenta
- 2006
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Ingår i: Differentiation. - : Elsevier BV. - 0301-4681 .- 1432-0436. ; 74:9-10, s. 648-660
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Tidskriftsartikel (refereegranskat)abstract
- Carboxypeptidase E (CPE) has important functions in processing of endocrine pro-peptides, such as pro-insulin, pro-opiomelanocortin, or pro-gonadotropin-releasing hormone, as evidenced by the hyperpro-insulinemia, obesity, and sterility of Cpe mutant mice. Down-regulation of Cpe in enlarged placentas of interspecific hybrid (interspecies hybrid placental dysplasia (IHPD)) and cloned mice suggested that reduced CPE enzyme and receptor activity could underlie abnormal placental phenotypes. In this study, we have explored the role of Cpe in murine placentation by determining its expression at various stages of gestation, and by phenotypic analysis of Cpe mutant placentas. Our results show that Cpe and Carboxypeptidase D (Cpd), another carboxypeptidase with a very similar function, are strictly co-localized in the mouse placenta from late mid-gestation to term. We also show that absence of CPE causes a sporadic but striking placental phenotype characterized by an increase in giant and glycogen cell numbers and giant cell hypertrophy. Microarray-based transcriptional pro. ling of Cpe mutant placentas identified only a very small number of genes with altered expression, including Dtprp, which belongs to the prolactin gene family. Concordant deregulation of Cpe and Cpd in abnormal placentas of interspecies hybrids before the onset of IHPD phenotype and recapitulation of some phenotypes of IHPD hyperplastic placentas in Cpe mutant placentas suggests that these two genes are causally involved in IHPD and may function as speciation genes in the genus Mus.
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| 9. |
- Singh, Umashankar, et al.
(författare)
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CGGBP1-an indispensable protein with ubiquitous cytoprotective functions
- 2015
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Ingår i: Upsala Journal of Medical Sciences. - : Uppsala Medical Society. - 0300-9734 .- 2000-1967. ; 120:4, s. 219-232
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Forskningsöversikt (refereegranskat)abstract
- The human genome contains multiple stretches of CGG trinucleotide repeats, which act as transcription- and translation-regulatory elements but at the same time form secondary structures that impede replication and give rise to sites of chromosome fragility. Proteins binding to such DNA elements may be involved in divergent cellular processes such as transcription, DNA damage, and epigenetic state of the chromatin. We review here the work done on CGG repeats and associated proteins with special focus on a factor called CGGBP1. CGGBP1 presents with an interesting example of factors that do not have any single dedicated function, but participate indispensably in multiple processes. Both experimental results and data from cancer genome sequencing have revealed that any alteration in CGGBP1 that compromises its function is not tolerated by normal or cancer cells alike. Based upon a large amount of published data, information from databases, and unpublished results, we decipher in this review how CGGBP1 is a classic example of the one factor, divergent functions' paradigm of cytoprotection. By taking cues from the studies on CGGBP1, more such factors can be discovered for a better understanding of the evolution of mechanisms of cellular survival.
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| 10. |
- Singh, Umashankar, et al.
(författare)
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CGGBP1 is a nuclear and midbody protein regulating abscission
- 2011
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Ingår i: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 317:2, s. 143-150
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Tidskriftsartikel (refereegranskat)abstract
- Abscission marks the completion of cell division and its failure is associated with delayed cytokinesis and even tetraploidization. Aberrant abscission and consequential ploidy changes can underlie various diseases including cancer. Midbody, a transient structure formed in the intercellular bridge during telophase, contains several proteins including Aurora kinase B (AURKB), which participate in abscission. We report here an unexpected expression pattern and function of the transcription repressor protein CGG triplet repeat-binding protein 1 (CGGBP1), in normal human fibroblasts. We show that CGGBP1, a chromatin-associated protein, trans-localizes to spindle midzone and midbodies in a manner similar to that of AURKB. CGGBP1 depletion resulted in a cell cycle block at G2, characterized by failure of cells to undergo mitosis and also reduced entry into S phase. Consistent with its presence in the midbodies, live microscopy showed that CGGBP1 deficiency caused mitotic failure at abscission resulting in tetraploidy, which could be rescued by CGGBP1 overexpression. These results show that CGGBP1 is a bona fide midbody protein required for normal abscission and mitosis in general.
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