Histone Deacetylase 3 (HDAC3), a Component of N-CoR-TBL1/R1 Chromatin Remodeling Co-Repressor Complex, Is Recruited to the Target Gene Promoters by PML-RARα To Repress the Transcription In Vivo.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2750-2750
Author(s):  
Akihiro Tomita ◽  
Akihide Atsumi ◽  
Hitoshi Kiyoi ◽  
Tomoki Naoe
Keyword(s):  
Gene Expression ◽  
Retinoic Acid ◽  
Target Gene ◽  
Target Genes ◽  
Gene Promoters ◽  
Transcription Repression ◽  
Histone Deacetylase 3 ◽  
Repressor Complex ◽  
Endogenous Target

Abstract PML-RARα is a chimeric transcription factor deeply associated with acute promyelocytic leukemia (APL). PML-RARα plays an important role in the aberrant transcription repression on the target genes of wild type retinoic acid receptors (RARα). Pharmacological concentration of all-trans retinoic acid (ATRA) induces transcription de-repression on several target genes, and results in terminal differentiation of APL cells. However, the detailed mechanisms of transcription repression by PML-RARα in vivo are still unclear. Here we demonstrated that histone deacetylase 3 (HDAC3), one component of the N-CoR (nuclear receptor co-repressor)-TBL1/R1 (transducin beta-like protein 1/relating protein) transcription repressor protein complex, is a key regulator of the transcription repression by PML-RARα in vivo. Using immunoprecipitation (IP) assay, we first demonstrated that PML-RARα physically interacted with N-CoR/HDAC3 in vivo in the absence of ligand. The interaction was dissociated by adding ATRA in the dose dependent manner. Next we showed, using chromatin immunoprecipitation (ChIP) assay, that N-CoR/HDAC3 co-repressor complex was recruited to the endogenous target gene promoters (RARβ and CYP26) through PML-RARα. The neighboring histone H4 was de-acetylated and the gene expression was significantly repressed. When HDAC3 protein is knocked down by RNA interference in PML-RARα-presenting cells, the endogenous target gene expression was significantly activated. Almost the same results were also obtained when performing the luciferase reporter assay using RARβ and CYP26 promoter reporter vectors. Previously, we have shown that N-CoR-TBLR1 is recruited to the target gene promoter through PML-RARα in the absence of ligand, resulting in the transcription repression. Consistent with these data, it is strongly suggested that N-CoR/HDAC3/TBLR1 co-repressor complex is closely related to the aberrant transcription regulation by PML-RARα in APL cells. Furthermore, we also confirmed that PLZF-RARα, which is expressed in ATRA resistant APL cells, interacted with N-CoR/HDAC3/TBLR1 in ligand independent manner. These insights provide not only the basic mechanism of transcription repression by leukemia-related chimeric transcription factors, but also the new molecular targets for the transcription therapy for leukemia.

scholarly journals Differential transcriptional characteristics of small and large biliary epithelial cells derived from small and large bile ducts

2010 ◽  
Vol 299 (3) ◽  
pp. G769-G777 ◽  
Author(s):  
S. Glaser ◽  
M. Wang ◽  
Y. Ueno ◽  
J. Venter ◽  
K. Wang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Growth Hormone ◽  
Epithelial Cells ◽  
Target Gene ◽  
Target Genes ◽  
Biliary Epithelial Cells ◽  
Gene Response ◽  
Before And After ◽  
In Vivo Growth

Biliary epithelial cells (BEC) are morphologically and functionally heterogeneous. To investigate the molecular mechanism for their diversities, we test the hypothesis that large and small BEC have disparity in their target gene response to their transcriptional regulator, the biliary cell-enriched hepatocyte nuclear factor HNF6. The expression of the major HNF ( HNF6, OC2, HNF1b, HNF1a, HNF4a, C/EBPb, and Foxa2) and representative biliary transport target genes that are HNF dependent were compared between SV40-transformed BEC derived from large (SV40LG) and small (SV40SM) ducts, before and after treatment with recombinant adenoviral vectors expressing HNF6 (AdHNF6) or control LacZ cDNA (AdLacZ). Large and small BEC were isolated from mouse liver treated with growth hormone, a known transcriptional activator of HNF6, and the effects on selected target genes were examined. Constitutive Foxa2, HNF1a, and HNF4a gene expression were 2.3-, 12.4-, and 2.6-fold, respectively, higher in SV40SM cells. This was associated with 2.7- and 4-fold higher baseline expression of HNF1a- and HNF4a-regulated ntcp and oatp1 genes, respectively. Following AdHNF6 infection, HNF6 gene expression was 1.4-fold higher ( P = 0.02) in AdHNF6 SV40SM relative to AdHNF6 SV40LG cells, with a corresponding higher Foxa2 (4-fold), HNF1a (15-fold), and HNF4a (6-fold) gene expression in AdHNF6-SV40SM over AdHNF6-SV40LG. The net effects were upregulation of HNF6 target gene glucokinase and of Foxa2, HNF1a, and HNF4a target genes oatp1, ntcp, and mrp2 over AdLacZ control in both cells, but with higher levels in AdH6-SV40SM over AdH6-SV40LG of glucokinase, oatp1, ntcp, and mrp2 (by 1.8-, 3.4-, 2.4-, and 2.5-fold, respectively). In vivo, growth hormone-mediated increase in HNF6 expression was associated with similar higher upregulation of glucokinase and mrp2 in cholangiocytes from small vs. large BEC. Small and large BEC have a distinct profile of hepatocyte transcription factor and cognate target gene expression, as well as differential strength of response to transcriptional regulation, thus providing a potential molecular basis for their divergent function.

scholarly journals Enhancers with cooperative Notch binding sites are more resistant to regulation by the Hairless co-repressor

PLoS Genetics ◽  
2021 ◽  
Vol 17 (9) ◽  
pp. e1009039
Author(s):  
Yi Kuang ◽  
Anna Pyo ◽  
Natanel Eafergan ◽  
Brittany Cain ◽  
Lisa M. Gutzwiller ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Binding Sites ◽  
Target Gene ◽  
Gene Activation ◽  
Notch Intracellular Domain ◽  
Repressor Complex ◽  
Notch Activation

Notch signaling controls many developmental processes by regulating gene expression. Notch-dependent enhancers recruit activation complexes consisting of the Notch intracellular domain, the Cbf/Su(H)/Lag1 (CSL) transcription factor (TF), and the Mastermind co-factor via two types of DNA sites: monomeric CSL sites and cooperative dimer sites called Su(H) paired sites (SPS). Intriguingly, the CSL TF can also bind co-repressors to negatively regulate transcription via these same sites. Here, we tested how synthetic enhancers with monomeric CSL sites versus dimeric SPSs bind Drosophila Su(H) complexes in vitro and mediate transcriptional outcomes in vivo. Our findings reveal that while the Su(H)/Hairless co-repressor complex similarly binds SPS and CSL sites in an additive manner, the Notch activation complex binds SPSs, but not CSL sites, in a cooperative manner. Moreover, transgenic reporters with SPSs mediate stronger, more consistent transcription and are more resistant to increased Hairless co-repressor expression compared to reporters with the same number of CSL sites. These findings support a model in which SPS containing enhancers preferentially recruit cooperative Notch activation complexes over Hairless repression complexes to ensure consistent target gene activation.

scholarly journals The ING4 Tumor Suppressor Attenuates NF-κB Activity at the Promoters of Target Genes

2008 ◽  
Vol 28 (21) ◽  
pp. 6632-6645 ◽  
Author(s):  
Susan Nozell ◽  
Travis Laver ◽  
Dorothy Moseley ◽  
Lisa Nowoslawski ◽  
Marijke DeVos ◽  
...  
Keyword(s):  
Gene Expression ◽  
Tumor Suppressor ◽  
Target Gene ◽  
Target Genes ◽  
Nuclear Translocation ◽  
Inflammatory Responses ◽  
Gene Promoters ◽  
Protein Levels ◽  
Expression Of Genes ◽  
Regulated Gene Expression

ABSTRACT The NF-κB family mediates immune and inflammatory responses. In many cancers, NF-κB is constitutively activated and induces the expression of genes that facilitate tumorigenesis. ING4 is a tumor suppressor that is absent or mutated in several cancers. Herein, we demonstrate that in human gliomas, NF-κB is constitutively activated, ING4 expression is negligible, and NF-κB-regulated gene expression is elevated. We demonstrate that an ING4 and NF-κB interaction exists but does not prevent NF-κB activation, nuclear translocation, or DNA binding. Instead, ING4 and NF-κB bind simultaneously at NF-κB-regulated promoters, and this binding correlates with reductions in p65 phosphorylation, p300, and the levels of acetylated histones and H3-Me3K4, while enhancing the levels of HDAC-1 at these promoters. Using a knockdown approach, we correlate reductions in ING4 protein levels with increased basal and inducible NF-κB target gene expression. Collectively, these data suggest that ING4 may specifically regulate the activity of NF-κB molecules that are bound to target gene promoters.

scholarly journals HDAC1 Cooperates with CBFβ-SMMHC in Regulating Gene Expression in Inversion 16 Acute Myeloid Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2690-2690
Author(s):  
Lisa Richter ◽  
Yiqian Wang ◽  
Michelle Becker ◽  
R. Katherine Hyde
Keyword(s):  
Gene Expression ◽  
Myeloid Leukemia ◽  
Target Gene ◽  
Target Genes ◽  
Hdac Inhibitors ◽  
Leukemia Cells ◽  
Gene Promoters ◽  
Promoter Regions ◽  
Mouse Leukemia ◽  
Primary Leukemia

Abstract The fusion of the genes for core binding factor beta and smooth muscle myosin heavy chain (CBFB-MYH11) is the recurrent mutation found in inversion 16 (inv(16)) acute myeloid leukemia (AML). The expressed fusion protein, CBFβ-SMMHC, binds to the transcriptional regulator RUNX1, and this interaction is required for leukemogenesis. Recent data shows CBFβ-SMMHC and RUNX1 are associated with promoters of both transcribed and repressed genes, implying that the CBFβ-SMMHC:RUNX1 complex directly regulates target gene expression. However, it is not known whether other transcriptional co-factors are also required for this activity. Histone deacetylase 1 (HDAC1) removes acetyl groups from histone tails to regulate the accessibility of chromatin to transcriptional machinery. It is recruited to chromatin by transcription factors, including RUNX1. HDAC1 also colocalizes with RUNX1 and CBFβ-SMMHC to promoter regions in ME-1 cells, a human inv(16) cell line. Based on this, we hypothesized that HDAC1 could bind to the RUNX1: CBFβ-SMMHC complex and plays a role in transcriptional regulation in inv(16). To test if CBFβ-SMMHC and HDAC1 form a complex, we transfected COS-7 cells with expression plasmids for HDAC1-FLAG and CBFβ-SMMHC and performed immunoprecipitations (IP) with nuclear extracts. IP with anti-MYH11 showed an interaction between HDAC1 and CBFβ-SMMHC, as did IP with anti-FLAG. Importantly, we found that HDAC1 and CBFβ-SMMHC co-immunoprecipitate in mouse leukemia cells from our knockin model which expresses CBFβ-SMMHC from the endogenous CBFβ promoter (CBFβ-SMMHC+). Confirming the specificity of this interaction, we found that IP with anti-MYH11 in ME-1 cells shows HDAC1 interaction, but the same IP in the t(8;21) AML cell line Kasumi-1 did not show HDAC1 interaction even though similar levels of HDAC1 are expressed. We next tested whether RUNX1 mediates the interaction between CBFβ-SMMHC and HDAC1. We performed IP experiments using a CBFβ-SMMHC mutant lacking RUNX1 binding (CBFβ-SMMHCN63K,N104K,Δ179-221). This mutant was co-immunoprecipitated with HDAC1, but not RUNX1, indicating that CBFβ-SMMHC's interaction with HDAC1 does not require RUNX1. We tested a construct lacking the c-terminal 95 amino acids, CBFβ-SMMHCΔC95, the domain known to interact with the related protein, HDAC8. We found that HDAC1 immunoprecipitated with CBFβ-SMMHCΔC95, suggesting that HDAC1 binds to a unique region of CBFβ-SMMHC. To test if HDAC1 plays a role in CBFβ-SMMHC-mediated gene expression, we performed chromatin immunoprecipitations on mouse CBFβ-SMMHC+ primary leukemia cells with antibodies against HDAC1, RUNX1, and MYH11, followed by real-time PCR for the promoter regions of three CBFβ-SMMHC target genes: MPO, CSF1R, and CEBPD. We observed all three proteins enriched on the target gene promoters as compared to immunoglobulin controls. This indicates that HDAC1 localizes with CBFβ-SMMHC and RUNX1 on target gene promoters in mouse primary leukemia cells. To test if HDAC1 is required for expression of these target genes, we used shRNA to knockdown Hdac1 expression. Mouse CBFβ-SMMHC+ leukemia cells were transduced with one of 2 different shRNAs against Hdac1 or with a control construct. We found that expression of all three genes was decreased with Hdac1knockdown, implying that HDAC1 is required for CBFβ-SMMHC induced changes in gene expression. These results also suggest that HDAC1 may have a role in transcriptional activation for certain genes, which is in contrast to its traditional role as a transcriptional repressor. These findings imply that HDAC1 activity is required for the maintenance of CBFβ-SMMHC expressing leukemia cells, and that HDAC1 inhibitors may be effective against inv(16) AML. To test this possibility we performed colony-forming assays using mouse leukemia cells grown in the presence of two different HDAC inhibitors, entinostat which is specific for HDAC1, and vorinostat, a nonspecific HDAC inhibitor. Our preliminary results indicate that both entinostat and vorinostat reduce the ability of primary CBFβ-SMMHC+ mouse leukemia cells to form colonies as compared to the vehicle control, while having minimal effects on growth of normal hematopoietic cells. In summary, we demonstrated that HDAC1 forms a complex with CBFβ-SMMHC and is required for its regulation of target gene expression, and that HDAC inhibitors may be effective for the treatment of inv(16) AML patients. Disclosures No relevant conflicts of interest to declare.

Lithium Treatment Potentiates Both in Vitro and in Vivo Retinoic Acid Efficacy in APL.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2614-2614
Author(s):  
Fabien Zassadowski ◽  
Katka Pokorna ◽  
Nicolas Ferre ◽  
Laura Llopis ◽  
Oussama Chourbagi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Retinoic Acid ◽  
Mouse Model ◽  
Cell Line ◽  
Transcriptional Activation ◽  
Target Gene ◽  
Nb4 Cells ◽  
Target Gene Expression ◽  
Licl Treatment

Abstract Abstract 2614 We previously demonstrated that although retinoic acid (RA) has targeted efficacy in Acute Promyelocytic Leukemia (APL), heterogeneity exists leading to the appearance of un-targeted clones at the time of relapse. Characterization of these clones is not yet fully unraveled though we and others have previously highlighted the roles of RARα mutations, pharmacogenomics or APL miRNome. We recently identified that the ERK1/2 pathway synergized with RA to restore the transcriptional activity of RA in resistant APL cells, thus restoring RA induced differentiation (Cassinat et al. Mol Cell Biol 2011). These results suggest that targeting interconnected signaling pathways could optimize differentiation therapy efficacy. To this effect, we studied known signaling pathway activators or inhibitors that could potentiate with RA and identified Lithium chloride (LiCl). Treatment of the ATRA sensitive-APL NB4 cell line with LiCl (25mM) decreases proliferation and increases apoptosis (25% and 40% of Annexin V-positive cells at day 1 and 2 respectively) with evidence of caspase 3 cleavage at day 2. Because NB4 cells fully differentiated with RA alone we were unable to observe any synergy when combined with LiCl. Treatment of the RA-resistant APL UF-1 cell line with RA or LiCl alone does not induce differentiation. Combination of RA+LiCl restores differentiation after 3 days of culture (65% CD11b positive and 55% NBT test positive cells). Similar results were obtained with different GSK3 inhibitors, suggesting that the LiCL effects were in part linked to its well characterized GSK3 inhibitory activity. Interestingly, we noted that LiCl treatment induces rapid phosphorylation of ERK1/2 and pretreatment with the MEK/ERK1/2 inhibitor UO126 fully abolished the differentiation induced by the RA+LiCl combination. The combination restores in UF-1 the expression of RA target genes (such as RARα2) to the same levels obtained in NB4 cells treated by RA alone. The level of luciferase activity of an RA responsive element reporter gene was increased with the RA+LiCl combination compared to RA alone. Both target gene expression and luciferase activiy were abolished after inhibition of the MEK/ERK1/2 pathway. Thus, increase in differentiation of UF-1 cells by RA+LiCl is linked to increased RA transcriptional activation. Similar studies in fresh APL patient cells confirmed both the increase in differentiation and level of RA target gene expression and their inhibition by UO126. Finally, to translate these findings in vivo, we used the APL-transplantable mouse model. Plasma lithium levels in treated mice were measured between 0.6 and 1.05 mmol/l, levels reached in humans. When LiCl was combined with RA we repeatedly observed a pronounced survival advantage compared to mice treated by RA alone as evaluated by Kaplan Meier analysis. In this work we demonstrate that LiCl, a well tolerated agent in humans, has the potential, when combined with RA, to restore RA induced transcriptional activation and differentiation in RA resistant APL cells. Furthermore, this combination also increases RA efficacy in an in vivo APL mouse model. Disclosures: Off Label Use: Lithium is a mood modulator administered for bipolar disorders.

scholarly journals Hottip Lncrna Reinforces CTCF Defined Chromatin Boundaries and Drives Wnt Target Gene Expression in AML Leukemogenesis

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 277-277
Author(s):  
Huacheng Luo ◽  
Ganqian Zhu ◽  
Tsz Kan Fung ◽  
Yi Qiu ◽  
Mingjiang Xu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Binding Sites ◽  
Triple Helix ◽  
Target Gene ◽  
Target Genes ◽  
Ctcf Binding ◽  
Target Gene Expression ◽  
Rna Immunoprecipitation

We reported recently that HOXA locus associated lncRNA, HOTTIP, is highly expressed in AML patients carrying MLL rearrangement and NPM1c+ mutations. The expression of HOTTIP positively correlates with posterior HOXA gene expression and poor patient survival. We further demonstrated that HOTTIP acts as an epigenetic regulator to define oncogenic HOXA topologically associated domain (TAD) and drive HOXA associated leukemic transcription program. However, it remains unclear whether and how HOTTIP lncRNA is involved in remodeling leukemic genome to facilitate AML leukemogenesis. Here, we showed that HOTTIP regulates a fraction of CTCF binding sites (CBSs) in the AML genome by directly interacting with CTCF and its binding motifs. We carried out CTCF ChIP-seq and HOTTIP ChIRP (chromatin isolation by RNA purification)-seq comparing WT and HOTTIP knockout (KO) MOLM13 cells. KO of HOTTIP in MLL-rearranged MOLM13 AML cells specifically impaired CTCF binding sites that were co-occupied by HOTTIP lncRNA, whereas loss of HOTTIP did not affect global CTCF binding. These target genes include posterior HOXA genes and Wnt target genes such as C-MYC, EVI1, AXIN, and TWIST1. Furthermore, we found that HOTTIP interacts with its putative target sites by formation of DNA: RNA hybridization structure triple helix and R-loop in vivo and in vitro. We then carried out DRIP (DNA-RNA immunoprecipitation)-seq and DRIPc(DNA-RNA immunoprecipitation followed by cDNA conversion)-Seq, which utilize a sequence independent but structure-specific S9.6 antibody for DRIP to capture global R-loops, by comparing WT and HOTTIP KO MOLM13 cells. The obtained DRIP-seq and DRIPc-seq data were then incorporated and integrated with the HOTTIP ChIRP-seq and CTCF ChIP-seq data to explore global collaboration between R-loop and HOTTIP associated CTCF binding sites. We found that HOTTIP interacts with CTCF binding motif that defines the TADs and the promoters of the HOTTIP target genes by formation of R-loop or triple helix structure. Loss of HOTTIP disrupted the R-loop formation at promoters and enhancers of the HOTTIP target genes to inhibit their expression. In MLL-rearranged AML genome, in addition to the HOXA locus, CTCF forms leukemic specific TADs that protect aberrant Wnt target genes. Depletion of HOTTIP lncRNA impaired CTCF defined TADs in the Wnt target gene loci and reduced Wnt target gene expression. In contrast, overexpression of Hottip lncRNA (Hottip-Tg) in the mice bone marrow hematopoietic compartment perturbs hematopoietic stem cell (HSC) self-renewal and differentiation leading to AML like disease by reinforcing CTCF defined TADs, enhancing chromatin accessibility within TADs, and upregulating gene transcription in the Wnt target loci. Finally, when we treated HOTTIP expressed primary patient AML cells carrying MLL-rearrangement and their derived PDX mouse model with a canonical Wnt inhibitor, ICG-001, ICG-001 inhibited AML LSC self-renewal in in vitro by LTC-IC assays and in vivo leukemogenesis in the PDX mouse models with an aberrant HOTTIP lncRNA expression, but not in HOTTIP negative/low non-MLL AML samples. Thus, HOTTIP lncRNA and CTCF cooperate to specifically reinforce CTCF defined WNT target locus TADs and drive Wnt target gene expression in the HOTTIP expressed AML. Disclosures No relevant conflicts of interest to declare.

scholarly journals Enhancers with cooperative Notch binding sites are more resistant to regulation by the Hairless co-repressor

2020 ◽  
Author(s):  
Yi Kuang ◽  
Anna Pyo ◽  
Natanel Eafergan ◽  
Brittany Cain ◽  
Lisa M. Gutzwiller ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Binding Sites ◽  
Target Gene ◽  
Gene Activation ◽  
Notch Intracellular Domain ◽  
Repressor Complex ◽  
Notch Activation

AbstractNotch signaling controls many developmental processes by regulating gene expression. Notch-dependent enhancers recruit activation complexes consisting of the Notch intracellular domain, the Cbf/Su(H)/Lag1 (CSL) transcription factor (TF), and the Mastermind co-factor via two types of DNA sites: monomeric CSL sites and cooperative dimer sites called Su(H) paired sites (SPS). Intriguingly, the CSL TF can also bind co-repressors to negatively regulate transcription via these same sites. Here, we tested how enhancers with monomeric CSL sites versus dimeric SPSs bind Drosophila Su(H) complexes in vitro and mediate transcriptional outcomes in vivo. Our findings reveal that while the Su(H)/Hairless co-repressor complex similarly binds SPS and CSL sites in an additive manner, the Notch activation complex binds SPSs, but not CSL sites, in a cooperative manner. Moreover, transgenic reporters with SPSs mediate stronger, more consistent transcription and are more resistant to increased Hairless co-repressor expression compared to reporters with the same number of CSL sites. These findings support a model in which SPS containing enhancers preferentially recruit cooperative Notch activation complexes over Hairless repression complexes to ensure consistent target gene activation.

scholarly journals Acetylation-Dependent Interaction of SATB1 and CtBP1 Mediates Transcriptional Repression by SATB1

2008 ◽  
Vol 29 (5) ◽  
pp. 1321-1337 ◽  
Author(s):  
Prabhat Kumar Purbey ◽  
Sunita Singh ◽  
Dimple Notani ◽  
P. Pavan Kumar ◽  
Amita S. Limaye ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcriptional Repression ◽  
Target Genes ◽  
Binding Protein ◽  
Interleukin 2 ◽  
Dependent Manner ◽  
Histone Deacetylase 1 ◽  
Repressor Complex

ABSTRACT Special AT-rich binding protein 1 (SATB1) acts as a global regulator of gene expression by recruiting various corepressor or coactivator complexes, thereby establishing a unique chromatin structure at its genomic targets in a context-dependent manner. Although SATB1 acts predominantly as a repressor via recruitment of histone deacetylase 1 (HDAC1) complexes, the precise mechanism of global repression is not clear. Here we report that SATB1 and C-terminal binding protein 1 (CtBP1) form a repressor complex in vivo. The interaction occurs via the CtBP1 interaction consensus motif PVPLS within the PDZ-like domain of SATB1. The acetylation of SATB1 upon LiCl and ionomycin treatments disrupts its association with CtBP1, resulting in enhanced target gene expression. Chromatin immunoprecipitation analysis indicated that the occupancy of CtBP1 and HDAC1 is gradually decreased and the occupancy of PCAF is elevated at the SATB1 binding sites within the human interleukin-2 and mouse c-Myc promoters. Moreover, gene expression profiling studies using cells in which expression of SATB1 and CtBP1 was silenced indicated commonly targeted genes that may be coordinately repressed by the SATB1-CtBP1 complex. Collectively, these results provide a mechanistic insight into the role of SATB1-CtBP1 interaction in the repression and derepression of SATB1 target genes during Wnt signaling in T cells.

scholarly journals Differential Inhibition of Target Gene Expression by Human microRNAs

Cells ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 791 ◽  
Author(s):  
Peng Li ◽  
Yi Chen ◽  
Conslata Awino Juma ◽  
Chengyong Yang ◽  
Jinfeng Huang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Large Scale ◽  
Mirna Target ◽  
Target Gene ◽  
Target Genes ◽  
Success Rates ◽  
Endogenous Gene ◽  
Reporter Assays ◽  
Differential Gene

microRNAs (miRNAs) exert their functions by repressing the expression of their target genes, but most miRNA target genes are unknown, and the degree to which a miRNA differentially inhibits the expression of its targets is underappreciated. We selected human miR-1, miR-122, and miR-124 as representatives to investigate the reliability of miRNA target predictions and examine how miRNAs suppress their targets. We constructed miRNA target gene reporter libraries based on prediction programs TargetScan, miRanda, and PicTar, and performed large-scale reporter assays to directly evaluate whether and how strongly a predicted target gene is repressed by its miRNA. We then performed statistical analyses to examine parameters that contributed to the miRNA inhibition of target genes. We found that the three programs have approximately 72–85% success rates in predicting genuine targets and that the miRNA inhibition of different targets varies in extent. We also identified parameters that could predict the degrees of miRNA repression, and further showed that differential miR-124 repression might contribute to differential gene expression in vivo. Our studies systematically investigated hundreds of miRNA target genes, shed light on factors influencing miRNA functions, and suggested a new mechanism by which differential target repression by miRNAs regulates endogenous gene expression.

scholarly journals Chromatin Remodeling Complex Interacts with ADD1/SREBP1c To Mediate Insulin-Dependent Regulation of Gene Expression

2006 ◽  
Vol 27 (2) ◽  
pp. 438-452 ◽  
Author(s):  
Yun Sok Lee ◽  
Dong Hyun Sohn ◽  
Daehee Han ◽  
Han-Woong Lee ◽  
Rho Hyun Seong ◽  
...  
Keyword(s):  
Gene Expression ◽  
Insulin Sensitivity ◽  
Chromatin Remodeling ◽  
Target Gene ◽  
Regulation Of Gene Expression ◽  
Whole Body ◽  
Gene Promoters ◽  
Proteolytic Activation ◽  
Insulin Dependent

ABSTRACT Insulin plays a critical role in whole-body energy homeostasis by regulating lipid and glucose metabolism. In fat and liver tissues, ADD1/SREBP1c is a key transcription factor to mediate insulin-dependent regulation of gene expression. Although transcriptional and proteolytic activation of ADD1/SREBP1c has been studied intensively, the mechanism by which insulin regulates expression of its target genes with ADD1/SREBP1c at the chromatin level is unclear. Here, we reveal that SWI/SNF chromatin remodeling factors interact with the ADD1/SREBP1c and actively regulate insulin-dependent gene expression. Insulin enhanced recruitment of SWI/SNF chromatin remodeling factors to its target gene promoters with concomitant changes in the chromatin structures as well as gene expression. Furthermore, in vivo overexpression of BAF155/SRG3, a component of the SWI/SNF complex, substantially promoted insulin target gene expression and insulin sensitivity. Taken together, our results suggest that the SWI/SNF chromatin remodeling complexes confer not only insulin-dependent gene expression but also insulin sensitivity in vivo via interaction with ADD1/SREBP1c.

Sign in / Sign up

Export Citation Format

Share Document