The bcl-2 major breakpoint region (mbr) possesses transcriptional regulatory function

In Saccharomyces cerevisiae, TRK1 and TRK2 encode the high- and low-affinity K+ transporters, respectively. In cells containing a deletion of TRK1, transcription levels of TRK2 are extremely low and are limiting for growth in media containing low levels of K+ (Trk- phenotype). Recessive mutations in RPD1 and RPD3 suppress the TRK2, conferring an approximately fourfold increase in transcription. rpd3 mutations confer pleiotropic phenotypes, including (i) mating defects, (ii) hypersensitivity to cycloheximide, (iii) inability to sporulate as homozygous diploids, and (iv) constitutive derepression of acid phosphatase. RPD3 was cloned and is predicted to encode a 48-kDa protein with no extensive similarity to proteins contained in current data bases. Deletion of RPD3 is not lethal but confers phenotypes identical to those caused by spontaneous mutations. RPD3 is required for both full repression and full activation of transcription of target genes including PHO5, STE6, and TY2. RPD3 is the second gene required for this function, since RPD1 is also required. The effects of mutations in RPD1 and RPD3 are not additive, suggesting that these genes are involved in the same transcriptional regulatory function or pathway.

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Modulated Binding of SATB1, a Matrix Attachment Region Protein, to the AT-Rich Sequence Flanking the Major Breakpoint Region of BCL2

Molecular and Cellular Biology ◽

10.1128/mcb.20.3.868-877.2000 ◽

2000 ◽

Vol 20 (3) ◽

pp. 868-877 ◽

Cited By ~ 26

Author(s):

Meera Ramakrishnan ◽

Wen-Man Liu ◽

Patricia A. DiCroce ◽

Aleza Posner ◽

Jian Zheng ◽

...

Keyword(s):

Cell Cycle ◽

Protein Interactions ◽

Specific Binding ◽

Chromosomal Translocation ◽

Breakpoint Region ◽

Matrix Attachment Region ◽

Regulatory Function ◽

Mobility Shift ◽

Attachment Region

ABSTRACT The t(14,18) chromosomal translocation that occurs in human follicular lymphoma constitutively activates the BCL2 gene and disrupts control of apoptosis. Interestingly, 70% of the t(14,18) translocations are confined to three 15-bp clusters positioned within a 150-bp region (major breakpoint region or [MBR]) in the untranslated portion of terminal exon 3. We analyzed DNA-protein interactions in the MBR, as these may play some role in targeting the translocation to this region. An 87-bp segment (87MBR) immediately 3′ to breakpoint cluster 3 was essential for DNA-protein interaction monitored with mobility shift assays. We further delineated a core binding region within 87MBR: a 33-bp, very AT-rich sequence highly conserved between the human and mouse BCL2 gene (37MBR). We have purified and identified one of the core factors as the matrix attachment region (MAR) binding protein, SATB1, which is known to bind to AT-rich sequences with a high propensity to unwind. Additional factors in nuclear extracts, which we have not yet characterized further, increased SATB1 affinity for the 37MBR target four- to fivefold. Specific binding activity within 37MBR displayed cell cycle regulation in Jurkat T cells, while levels of SATB1 remained constant throughout the cell cycle. Finally, we demonstrated in vivo binding of SATB1 to the MBR, strongly suggesting the BCL2 major breakpoint region is a MAR. We discuss the potential consequences of our observations for both MBR fragility and regulatory function.

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Spindle Assembly Checkpoint Protein Cdc20 Transcriptionally Activates Expression of Ubiquitin Carrier Protein UbcH10

Journal of Biological Chemistry ◽

10.1074/jbc.m110.160671 ◽

2011 ◽

Vol 286 (18) ◽

pp. 15666-15677 ◽

Cited By ~ 12

Author(s):

Somsubhra Nath ◽

Taraswi Banerjee ◽

Debrup Sen ◽

Tania Das ◽

Susanta Roychoudhury

Keyword(s):

Chromosomal Instability ◽

Spindle Assembly Checkpoint ◽

Spindle Assembly ◽

Regulatory Function ◽

Physical Interaction ◽

Anaphase Promoting Complex ◽

Transcriptional Regulatory ◽

Subsequent Degradation ◽

Ubiquitin Conjugating Enzyme ◽

Wd40 Domain

The spindle assembly checkpoint (SAC) ensures accurate segregation of chromosomes by monitoring kinetochore attachment of spindles during mitosis. Proper progression of mitosis depends on orderly ubiquitination and subsequent degradation of various mitotic inhibitors. At the molecular level, upon removal of SAC, Cdc20 activates E3 ubiquitin ligase anaphase-promoting complex/cyclosome that, along with E2 ubiquitin-conjugating enzyme UbcH10, executes this function. Both Cdc20 and UbcH10 are overexpressed in many cancer types and are associated with defective SAC function leading to chromosomal instability. The precise mechanism of correlated overexpression of these two proteins remains elusive. We show that Cdc20 transcriptionally up-regulates UbcH10 expression. The WD40 domain of Cdc20 is required for this activity. Physical interaction between Cdc20 and anaphase-promoting complex/cyclosome-CBP/p300 complex and its subsequent recruitment to the UBCH10 promoter are involved in this transactivation process. This transcriptional regulatory function of Cdc20 was observed to be cell cycle-specific. We hypothesize that this co-regulated overexpression of both proteins contributes to chromosomal instability.

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ESR2 regulates indian hedgehog signaling in neonatal rat ovary

10.1101/2021.12.01.470808 ◽

2021 ◽

Author(s):

Iman Dilower ◽

Veera Raghavulu Praveen Chakravarthi ◽

Eun B Lee ◽

Subhra Ghosh ◽

Shaon Borosha ◽

...

Keyword(s):

Estrogen Receptor ◽

Hedgehog Signaling ◽

Primordial Follicle ◽

Neonatal Rat ◽

Regulatory Function ◽

Indian Hedgehog ◽

Rna Seq ◽

Transcriptional Regulatory ◽

Primordial Follicle Activation ◽

Rat Ovary

The transcriptional regulatory function of estrogen receptor β (ESR2) is essential for the regulation of primordial follicle activation (PFA). Increased PFA due to the loss of ESR2 becomes evident as early as postnatal day 8 (PND8). To identify the ESR2-regulated genes that control PFA, we performed RNA-seq analyses of wildtype, and Esr2 knockout (Esr2KO) neonatal rat ovaries collected on PND4, PND6, and PND8. Among the differentially expressed genes in Esr2KO ovaries, indian hedgehog (Ihh) displayed the highest downregulation among the ovary enriched genes. IHH regulated genes including Hhip as well as the steroidogenic enzymes were also downregulated in Esr2KO rat ovaries. Remarkably, the expression of Ihh in Esr2KO ovaries was not upregulated despite the high levels of Gdf9 and Bmp15, which are known regulators of Ihh expression in granulosa cells. Our findings suggest that indian hedgehog signaling in the neonatal rat ovary is dependent on ESR2.

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The Alternative Breakpoint Region (ABR) of BCL6 Is An Active Transcribed Region in Germinal Center B Cells and May Serve as An Enhancer

Blood ◽

10.1182/blood.v112.11.4465.4465 ◽

2008 ◽

Vol 112 (11) ◽

pp. 4465-4465

Author(s):

Yulei Shen ◽

Himabindu Ramachandrareddy ◽

Wing C. Chan ◽

Timothy McKeithan

Keyword(s):

B Cells ◽

B Cell ◽

Germinal Center ◽

Regulatory Elements ◽

Breakpoint Region ◽

Luciferase Reporter ◽

Regulatory Function ◽

B Cell Differentiation ◽

B Cell Lymphomas ◽

Bcl6 Expression

Abstract Chromosomal translocations at 3q27 involving BCL6 occur in two different regions. Rearrangements with breaks within the major breakpoint region (MBR), comprising the first exon and part of the first intron of BCL6, are among the most common genetic abnormalities in of B-cell non-Hodgkin lymphoma, whereas breaks within an alternative breakpoint region (ABR), located between 245 and 285 kb 5′ to BCL6, have also been reported in follicular lymphoma grade and a small group (6.4%) of diffuse large B-cell lymphomas (DLBCLs). As a result of the MBR translocation, BCL6 expression is deregulated by promoter substitution with either immunoglobulin (Ig) genes or non-Ig genes as partners. A role for deregulated BCL6 expression in the pathogenesis of DLBCL has previously been confirmed in a mouse model. However, the biological role of the more distant ABR region is still not known. Using real-time PCR, we identified in the ABR region an evolutionarily conserved DNase I hypersensitive site (named Far5) which contains a conserved composite binding site for transcription factors PU.1 and IRF4, both of which play important roles in B-cell differentation. Further studies demonstrated that chromatin in the Far5 region, 190kb upstream of BCL6 promoter, has an open configuration in DHL6, Granta 519 and U266 cell lines. Far5 DNA showed enhancer activity by a luciferase reporter assay. PU.1 binds to Far5 in vivo (DHL16 cell line) by a chromatin immunoprecipitation (ChIP) assay, and PU.1 binds in vitro to the conserved PU.1/IRF composite site in Far5 synergistically with either IRF4 or IRF8. ChIP-on-chip assays showed Far5 histone H3K4 monomethylation, a chromatin modification associated with gene enhancers and other regulatory elements. In addition, we identified a transcript upstream of the Far5 region that is specifically expressed in germinal center (GC) B cells, but not at other stages of B-cell differentation. These results indicated that Far5 may play a role in selective expression of intergenic transcripts in GC B-cells. In other genes, intergenic transcription plays a role in looping between distal regulatory regions and the promoter. Our data showed that ABR region is constitutively active in GC B-cells and may play an important role in increasing BCL6 transcription when naïve B cells differentiate into GC B-cells. Further investigation of interactions between the ABR and the BCL6 promoter will uncover the regulatory function of the BCL6 ABR in B-cell differentiation and B-cell lymphomas.

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