scholarly journals Wild-Type Circadian Rhythmicity Is Dependent on Closely Spaced E Boxes in the Drosophila timelessPromoter

2001 ◽  
Vol 21 (4) ◽  
pp. 1207-1217 ◽  
Author(s):  
Michael J. McDonald ◽  
Michael Rosbash ◽  
Patrick Emery
Keyword(s):  
Transcription Factor ◽  
Transcriptional Regulation ◽  
Locomotor Activity ◽  
Circadian Rhythms ◽  
High Amplitude ◽  
Wild Type ◽  
Activity Rhythms ◽  
E Box ◽  
E Boxes ◽  
Circadian Transcription

ABSTRACT Transcriptional regulation plays an important role inDrosophila melanogaster circadian rhythms. The period promoter has been well studied, but the timeless promoter has not been analyzed in detail. Mutagenesis of the canonical E box in the timelesspromoter reduces but does not eliminate timeless mRNA cycling or locomotor activity rhythms. This is because there are at least two other cis-acting elements close to the canonical E box, which can also be transactivated by the circadian transcription factor dCLOCK. These E-box-like sequences cooperate with the canonical E-box element to promote high-amplitude transcription, which is necessary for wild-type rhythmicity.

scholarly journals Role of mutation of the circadian clock gene Per2 in cardiovascular circadian rhythms

2010 ◽  
Vol 298 (3) ◽  
pp. R627-R634 ◽  
Author(s):  
Ana Vukolic ◽  
Vladan Antic ◽  
Bruce N. Van Vliet ◽  
Zhihong Yang ◽  
Urs Albrecht ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Locomotor Activity ◽  
Circadian Rhythms ◽  
Circadian Clock ◽  
Mutant Mice ◽  
Constant Darkness ◽  
Wild Type ◽  
Chi Square ◽  
Dark Light

Alterations in the circadian blood pressure pattern are frequently observed in hypertension and lead to increased cardiovascular morbidity. However, there are no studies that have investigated a possible implication of the Period2 gene, a key component of the molecular circadian clock, on the circadian rhythms of blood pressure and heart rate. To address this question, we monitored blood pressure, heart rate, and locomotor activity 24 h a day by telemetry in mice carrying a mutation in the Period2 gene and in wild-type control mice. Under a standard 12:12-h light-dark cycle, mutant mice showed a mild cardiovascular phenotype with an elevated 24-h heart rate, a decreased 24-h diastolic blood pressure, and an attenuation of the dark-light difference in blood pressure and heart rate. Locomotor activity was similar in both groups and did not appear to explain the observed hemodynamic differences. When mice were placed under constant darkness during eight consecutive days, wild-type mice maintained 24-h rhythms, whereas there was an apparent progressive loss of 24-h rhythm of blood pressure, heart rate, and locomotor activity in mutant mice. However, a chi square periodogram revealed that circadian rhythms were preserved under complete absence of any light cue, but with shorter periods by ∼40 min, leading to a cumulative phase shift toward earlier times of ∼5 h and 20 min by the end of the 8th day. When heart rate, mean arterial pressure, and activity were recalculated according to the endogenous circadian periods of each individual mouse, the amplitudes of the circadian rhythms (“subjective night”-“subjective day” differences) were maintained for all variables studied. Our data show that mutation of the Period2 gene results in an attenuated dipping of blood pressure and heart rate during both light-dark cycles and constant darkness, and in shorter circadian periods during constant darkness.

scholarly journals Do products of the myc proto-oncogene play a role in transcriptional regulation of the prothymosin alpha gene?

1995 ◽  
Vol 15 (12) ◽  
pp. 6999-7009 ◽  
Author(s):  
P C Mol ◽  
R H Wang ◽  
D W Batey ◽  
L A Lee ◽  
C V Dang ◽  
...  
Keyword(s):  
Transcriptional Start Site ◽  
Dominant Negative ◽  
Wild Type ◽  
Enhancer Element ◽  
Prothymosin Alpha ◽  
L Cells ◽  
Intron 1 ◽  
E Box ◽  
Alpha Gene ◽  
E Boxes

The Myc protein has been reported to activate transcription of the rat prothymosin alpha gene by binding to an enhancer element or E box (CACGTG) located in the first intron (S. Gaubatz et al., Mol. Cell. Biol. 14:3853-3862, 1994). The human prothymosin alpha gene contains two such motifs: in the promoter region at kb -1.2 and in intron 1, approximately 2 kb downstream of the transcriptional start site in a region which otherwise bears little homology to the rat gene. Using chloramphenicol acetyltransferase (CAT) reporter constructs driven either by the 5-kb human prothymosin alpha promoter or by a series of truncated promoters, we showed that removal of the E-box sequence had no effect on transient expression of CAT activity in mouse L cells. When intron 1 of the prothymosin alpha gene was inserted into the most extensive promoter construct downstream of the CAT coding region, a diminution in transcription, which remained virtually unchanged upon disruption of the E boxes, was observed. CAT constructs driven by the native prothymosin alpha promoter or the native promoter and intron were indifferent to Myc; equivalent CAT activity was observed in the presence of ectopic normal or mutant Myc genes. Similarly, expression of a transiently transfected wild-type prothymosin alpha gene as the reporter was not affected by a repertoire of myc-derived genes, including myc itself and dominant or recessive negative myc mutants. In COS-1 cells, equivalent amounts of the protein were produced from transfected prothymosin alpha genes regardless of whether genomic E boxes were disrupted, intron 1 was removed, or a repertoire of myc-derived genes was included in the transfection cocktail. More importantly, cotransfection of a dominant negative Max gene failed to reduce transcription of the endogenous prothymosin alpha gene in COS cells or the wild-type transfected gene in COS or L cells. Taken together, the data do not support the idea that Myc activates transcription of the intact human prothymosin alpha gene or reporter constructs that mimic its structure. Rather, they suggest that the human prothymosin alpha promoter and downstream elements are buffered so as to respond poorly, if at all, to transient fluctuations in transcription factors which regulate other genes.

scholarly journals takeout, a Novel DrosophilaGene under Circadian Clock Transcriptional Regulation

2000 ◽  
Vol 20 (18) ◽  
pp. 6935-6944 ◽  
Author(s):  
W. Venus So ◽  
Lea Sarov-Blat ◽  
Carolyn K. Kotarski ◽  
Michael J. McDonald ◽  
Ravi Allada ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcriptional Regulation ◽  
Transcription Factors ◽  
Gene Family ◽  
Wild Type ◽  
Circadian Control ◽  
Its Gene ◽  
E Box ◽  
Identification And Characterization

ABSTRACT We report the identification and characterization of a newDrosophila clock-regulated gene, takeout(to). to is a member of a novel gene family and is implicated in circadian control of feeding behavior. Its gene expression is down-regulated in all of the clock mutants tested. In wild-type flies, to mRNA exhibits daily cycling expression but with a novel phase, delayed relative to those of the better-characterized clock mRNAs, period andtimeless. The E-box-containing sequence in theto promoter shows impressive similarities with those ofperiod and timeless. However, our results suggest that the E box is not involved in the amplitude and phase of the transcriptional cycling of to. The circadian delayed transcriptional phase is therefore most likely the result of indirect regulation through unknown transcription factors.

scholarly journals The MNT transcription factor autoregulates its expression and supports proliferation in MYC-associated factor X (MAX)-deficient cells

2020 ◽  
Vol 295 (7) ◽  
pp. 2001-2017 ◽  
Author(s):  
M. Carmen Lafita-Navarro ◽  
Judit Liaño-Pons ◽  
Andrea Quintanilla ◽  
Ignacio Varela ◽  
Rosa Blanco ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Transcription Factor ◽  
Transcriptional Regulator ◽  
Bhlh Transcription Factor ◽  
Factor X ◽  
Associated Factor ◽  
Helix Loop Helix ◽  
E Box ◽  
E Boxes ◽  
Cycle Regulation

The MAX network transcriptional repressor (MNT) is an MXD family transcription factor of the basic helix-loop-helix (bHLH) family. MNT dimerizes with another transcriptional regulator, MYC-associated factor X (MAX), and down-regulates genes by binding to E-boxes. MAX also dimerizes with MYC, an oncogenic bHLH transcription factor. Upon E-box binding, the MYC–MAX dimer activates gene expression. MNT also binds to the MAX dimerization protein MLX (MLX), and MNT–MLX and MNT–MAX dimers co-exist. However, all MNT functions have been attributed to MNT–MAX dimers, and no functions of the MNT–MLX dimer have been described. MNT's biological role has been linked to its function as a MYC oncogene modulator, but little is known about its regulation. We show here that MNT localizes to the nucleus of MAX-expressing cells and that MNT–MAX dimers bind and repress the MNT promoter, an effect that depends on one of the two E-boxes on this promoter. In MAX-deficient cells, MNT was overexpressed and redistributed to the cytoplasm. Interestingly, MNT was required for cell proliferation even in the absence of MAX. We show that in MAX-deficient cells, MNT binds to MLX, but also forms homodimers. RNA-sequencing experiments revealed that MNT regulates the expression of several genes even in the absence of MAX, with many of these genes being involved in cell cycle regulation and DNA repair. Of note, MNT–MNT homodimers regulated the transcription of some genes involved in cell proliferation. The tight regulation of MNT and its functionality even without MAX suggest a major role for MNT in cell proliferation.

Transcription factor AP-4 is a ligand for immunoglobulin-κ promoter E-box elements

2001 ◽  
Vol 354 (2) ◽  
pp. 431-438 ◽  
Author(s):  
Alaitz ARANBURU ◽  
Robert CARLSSON ◽  
Christine PERSSON ◽  
Tomas LEANDERSON
Keyword(s):  
Transcription Factor ◽  
Gene Families ◽  
Sequence Motifs ◽  
Mobility Shift ◽  
Conserved Sequence ◽  
Nuclear Extracts ◽  
E Box ◽  
Variable Gene ◽  
E Boxes ◽  
Electrophoretic Mobility Shift Assays

Immunoglobulin (Ig)-κ promoters from humans and mice share conserved sequences. The octamer element is common to all Ig promoters and pivotal for their function. However, other conserved sequence motifs, that differ between Ig variable gene families, are required for normal promoter function. These conserved motifs do not stimulate transcription in the absence of an octamer. One example is an E-box of the E47/E12 type (5′-CAGCTG-3′), which is found in all promoters of the human and murine Ig-κ gene subgroups/families, with the exception of subgroups II and VI and their related murine families. In the present study we show that the ubiquitously expressed transcription factor AP-4, and not E47, interacts specifically with the κ promoter E-boxes when tested in electrophoretic mobility-shift assays using nuclear extracts derived from human and murine B-cell lines. Furthermore, AP-4, unlike E47, did not act as a transactivator, which is in agreement with previous studies on intact κ promoters, showing that transcription is absent when the octamer element has been mutated. Based on these data, and the conservation of the 5′-CAGCTG-3′ motif among human and murine κ promoters, we propose that AP-4 is the major ligand for Ig-κ promoter E-boxes.

Circadian rhythms in the absence of the clock gene Bmal1

Science ◽  
2020 ◽  
Vol 367 (6479) ◽  
pp. 800-806 ◽  
Author(s):  
Sandipan Ray ◽  
Utham K. Valekunja ◽  
Alessandra Stangherlin ◽  
Steven A. Howell ◽  
Ambrosius P. Snijders ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Transcriptional Regulation ◽  
Transcription Factors ◽  
Circadian Rhythms ◽  
Molecular Clock ◽  
Knockout Mice ◽  
Clock Gene ◽  
Skin Fibroblasts ◽  
Temperature Cycles ◽  
Ets Family

Circadian (~24 hour) clocks have a fundamental role in regulating daily physiology. The transcription factor BMAL1 is a principal driver of a molecular clock in mammals. Bmal1 deletion abolishes 24-hour activity patterning, one measure of clock output. We determined whether Bmal1 function is necessary for daily molecular oscillations in skin fibroblasts and liver slices. Unexpectedly, in Bmal1 knockout mice, both tissues exhibited 24-hour oscillations of the transcriptome, proteome, and phosphoproteome over 2 to 3 days in the absence of any exogenous drivers such as daily light or temperature cycles. This demonstrates a competent 24-hour molecular pacemaker in Bmal1 knockouts. We suggest that such oscillations might be underpinned by transcriptional regulation by the recruitment of ETS family transcription factors, and nontranscriptionally by co-opting redox oscillations.

scholarly journals Dissecting transcriptional amplification by MYC

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Zuqin Nie ◽  
Chunhua Guo ◽  
Subhendu K Das ◽  
Carson C Chow ◽  
Eric Batchelor ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Large Scale ◽  
Statistical Parameter ◽  
Genome Wide ◽  
E Box ◽  
Amplifier Gain ◽  
Series Of Experiments ◽  
E Boxes ◽  
Transcriptional Amplification ◽  
Theory And Experiments

Supraphysiological MYC levels are oncogenic. Originally considered a typical transcription factor recruited to E-boxes (CACGTG), another theory posits MYC a global amplifier increasing output at all active promoters. Both models rest on large-scale genome-wide ”-omics’. Because the assumptions, statistical parameter and model choice dictates the ‘-omic’ results, whether MYC is a general or specific transcription factor remains controversial. Therefore, an orthogonal series of experiments interrogated MYC’s effect on the expression of synthetic reporters. Dose-dependently, MYC increased output at minimal promoters with or without an E-box. Driving minimal promoters with exogenous (glucocorticoid receptor) or synthetic transcription factors made expression more MYC-responsive, effectively increasing MYC-amplifier gain. Mutations of conserved MYC-Box regions I and II impaired amplification, whereas MYC-box III mutations delivered higher reporter output indicating that MBIII limits over-amplification. Kinetic theory and experiments indicate that MYC activates at least two steps in the transcription-cycle to explain the non-linear amplification of transcription that is essential for global, supraphysiological transcription in cancer.

scholarly journals CLOCK, an essential pacemaker component, controls expression of the circadian transcription factor DBP

2000 ◽  
Vol 14 (6) ◽  
pp. 679-689 ◽  
Author(s):  
Jürgen A. Ripperger ◽  
Lauren P. Shearman ◽  
Steven M. Reppert ◽  
Ueli Schibler
Keyword(s):  
Transcription Factor ◽  
Leucine Zipper ◽  
Molecular Mechanisms ◽  
Clock Genes ◽  
Promoter Sequence ◽  
Peripheral Tissues ◽  
Helix Loop Helix ◽  
E Box ◽  
Liver Gene ◽  
Circadian Transcription

DBP, the founding member of the PAR leucine zipper transcription factor family, is expressed according to a robust daily rhythm in the suprachiasmatic nucleus and several peripheral tissues. Previous studies with mice deleted for the Dbp gene have established that DBP participates in the regulation of several clock outputs, including locomotor activity, sleep distribution, and liver gene expression. Here we present evidence that circadian Dbptranscription requires the basic helix–loop–helix–PAS protein CLOCK, an essential component of the negative-feedback circuitry generating circadian oscillations in mammals and fruit flies. Genetic and biochemical experiments suggest that CLOCK regulates Dbpexpression by binding to E-box motifs within putative enhancer regions located in the first and second introns. Similar E-box motifs have been found previously in the promoter sequence of the murine clock genemPeriod1. Hence, the same molecular mechanisms generating circadian oscillations in the expression of clock genes may directly control the rhythmic transcription of clock output regulators such asDbp.

scholarly journals A circadian enhancer mediates PER-dependent mRNA cycling in Drosophila melanogaster.

1997 ◽  
Vol 17 (7) ◽  
pp. 3687-3693 ◽  
Author(s):  
H Hao ◽  
D L Allen ◽  
P E Hardin
Keyword(s):  
Drosophila Melanogaster ◽  
High Amplitude ◽  
Transcriptional Enhancer ◽  
Rhythmic Expression ◽  
E Box ◽  
Dna Fragment ◽  
High Level ◽  
Circadian Transcription ◽  
Per Gene ◽  
Constant Dark

Genes expressed under circadian-clock control are found in organisms ranging from prokaryotes to humans. In Drosophila melanogaster, the period (per) gene, which is required for clock function, is transcribed in a circadian manner. We have identified a circadian transcriptional enhancer within a 69-bp DNA fragment upstream of the per gene. This enhancer drives high-amplitude mRNA cycling under light-dark-cycling or constant-dark conditions, and this activity is per protein (PER) dependent. An E-box sequence within this 69-bp fragment is necessary for high-level expression, but not for rhythmic expression, indicating that PER mediates circadian transcription through other sequences in this fragment.

scholarly journals Evaluation of Myc E-Box Phylogenetic Footprints in Glycolytic Genes by Chromatin Immunoprecipitation Assays

2004 ◽  
Vol 24 (13) ◽  
pp. 5923-5936 ◽  
Author(s):  
Jung-whan Kim ◽  
Karen I. Zeller ◽  
Yunyue Wang ◽  
Anil G. Jegga ◽  
Bruce J. Aronow ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Chromatin Immunoprecipitation ◽  
Binding Sites ◽  
Phylogenetic Footprinting ◽  
Regulatory Sequences ◽  
Full Spectrum ◽  
E Box ◽  
Important Regulator ◽  
E Boxes ◽  
Genomic Regions

ABSTRACT Prediction of gene regulatory sequences using phylogenetic footprinting has advanced considerably but lacks experimental validation. Here, we report whether transcription factor binding sites predicted by dot plotting or web-based Trafac analysis could be validated by chromatin immunoprecipitation assays. MYC overexpression enhances glycolysis without hypoxia and hence may contribute to altered tumor metabolism. Because the full spectrum of glycolytic genes directly regulated by Myc is not known, we chose Myc as a model transcription factor to determine whether it binds target glycolytic genes that have conserved canonical Myc binding sites or E boxes (5′-CACGTG-3′). Conserved canonical E boxes in ENO1, HK2, and LDHA occur in 31- to 111-bp islands with high interspecies sequence identity (>65%). Trafac analysis revealed another region in ENO1 that corresponds to a murine region with a noncanonical E box. Myc bound all these conserved regions well in the human P493-6 B lymphocytes. We also determined whether Myc could bind nonconserved canonical E boxes found in the remaining human glycolytic genes. Myc bound PFKM, but it did not significantly bind GPI, PGK1, and PKM2. Binding to BPGM, PGAM2, and PKLR was not detected. Both GAPD and TPI1 do not have conserved E boxes but are induced and bound by Myc through regions with noncanonical E boxes. Our results indicate that Myc binds well to conserved canonical E boxes, but not nonconserved E boxes. However, the binding of Myc to unpredicted genomic regions with noncanonical E boxes reveals a limitation of phylogenetic footprinting. In aggregate, these observations indicate that Myc is an important regulator of glycolytic genes, suggesting that MYC plays a key role in a switch to glycolytic metabolism during cell proliferation or tumorigenesis.

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