cAMP-induced NF-κB (p50/relB) binding to a c-myb intronic enhancer correlates with c-myb up-regulation and inhibition of erythroleukemia cell differentiation

Suhasini, Modem; Reddy, C. Devendranath; Reddy, E. Premkumar; DiDonato, Joseph A.; Pilz, Renate B.

doi:10.1038/sj.onc.1201530

Cited by 40 publications

(46 citation statements)

References 38 publications

(82 reference statements)

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“…The activity of the rel proteins is also regulated through cytoplasmic retention by the inhibitors IkB-a, -b and -g which are phosphorylated and proteolytically degraded in response to various stimuli resulting in the release of active NF-kB dimers which translocate to the nucleus (Miyamoto and Verma, 1995). MEL cells express relatively low levels of NF-kB, but we found that cAMP-elevating agents or membrane-permeable cAMP analogs induced the expression and nuclear accumulation of NF-kB (p50/RelB) complexes which bound to the c-myb intronic NF-kB sites and transactivated a reporter construct containing one of these sites upstream of a minimal promoter (Suhasini et al, 1997). We also observed that cAMP analogs prevented the late down-regulation of c-myb mRNA by increasing transcriptional elongation during HMBA-induced di erentiation of MEL cells.…”

Section: Introductionmentioning

confidence: 87%

“…Whole cell extracts corresponding to 10 5 cells were analysed by Western blotting for the expression of p50 (upper panel), RelB (middle panel) and IkB-a (lower panel). The p50 blot also shows the endogenous precursor p105 which is up-regulated in cells overexpressing p50 (see text) as well as two endogenous p105-related proteins which cross-react with the p50 antibody (Suhasini et al, 1997). (b) Parental MEL cells were cultured for 3 days in the absence or presence of 1 mM 8-Br-cAMP (Wt, Wt+cAMP) and whole cell extracts corresponding to 10 5 cells were compared to extracts from equal numbers of P50/RelB-C5.7 cells hygromycin-resistant clones failed to express the transfected gene ( Figure 1a shows one such control clone, CC, as well as two representative clones expressing p50 or RelB, respectively).…”

Section: Generation Of Stably Transfected Mel Cells Expressing P50 Anmentioning

confidence: 99%

“…In HMBA-treated MEL cells, induction of NF-kB (p50/RelB) complexes by cAMP analogs was delayed and correlated with increased c-myb mRNA expression at 72 h (Suhasini et al, 1997). We, therefore, examined c-myb mRNA levels in the p50 and/or RelB-overexpressing MEL cell clones.…”

Section: E Ect Of P50 And/or Relb On C-myb Mrna Levelsmentioning

confidence: 99%

“…(b) Speci®city of binding was examined in competition experiments using nuclear extracts of clone P50/RelB-C5.7: complex formation with the labeled NF-kB/myb oligodNT probe (lane 2) was completely prevented by the addition of a 50-fold molar excess of unlabeled NF-kB/myb oligodNT (lane 3) or NF-kB/Igk (lane 4), whereas addition of the same amount of an unrelated oligodNT (SP-1) had no e ect (lane 5). Addition of unlabeled DNA fragments from c-myb intron I which include the two NF-kB binding sites¯anking the region of transcriptional attenuation (Toth et al, 1995;Suhasini et al, 1997) competed for protein binding to the radioactive probe (lanes 7 and 8), whereas addition of the same amount of adjacent restriction fragments from c-myb intron I had no e ect (lanes 6 and 9). Lane 1: free probe.…”

Section: E Ect Of P50 And/or Relb On C-myb Transcriptional Elongationmentioning

confidence: 99%

“…We also observed that cAMP analogs prevented the late down-regulation of c-myb mRNA by increasing transcriptional elongation during HMBA-induced di erentiation of MEL cells. The induction of NF-kB (p50/RelB) was delayed and correlated with the upregulation of c-myb mRNA by cAMP in HMBAtreated MEL cells (Suhasini et al, 1997). To determine whether NF-kB (p50/RelB) dimers regulate c-myb expression in intact cells, we stably transfected MEL cells with expression vectors encoding p50 and/or relB and selected clones overexpressing p50, RelB or both at levels similar to those induced by cAMP.…”

Section: Introductionmentioning

confidence: 99%

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Transcriptional elongation of c-myb is regulated by NF-κB (p50/RelB)

Suhasini

Pilz

1999

Oncogene

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High levels of c-myb expression are necessary for the proliferation of hematopoietic precursor cells whereas down-regulation of c-myb is required for terminal di erentiation; this down-regulation occurs through a conditional block to transcriptional elongation in intron I. We previously observed that cAMP analogs prevented the late down-regulation of c-myb during hexamethylene bisacetamide (HMBA)-induced di erentiation of murine erythroleukemia (MEL) cells and blocked di erentiation; this correlated with the induction of NF-kB (p50/RelB) complexes which were shown to bind to NF-kB recognition sites¯anking the transcriptional pause site of c-myb. We now selected stably-transfected MEL cells which overexpressed p50, RelB or both at levels similar to those induced by cAMP to determine whether these NF-kB proteins regulate c-myb expression in intact cells. We demonstrate that transcriptionally active NF-kB (p50/RelB) complexes, but not p50 or RelB alone, prevented the early and late down-regulation of c-myb mRNA and increased c-myb transcriptional elongation in HMBA-induced MEL cells. The increase in c-myb expression was su cient to block erythroid di erentiation and allow continuous proliferation of cells in the presence of HMBA. Steady-state c-myb mRNA levels in untreated cells were not a ected by overexpression of NF-kB, suggesting that p50/RelB speci®cally modulated the e ciency of transcriptional attenuation during MEL cell di erentiation.

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Section: Introductionmentioning

confidence: 87%

Section: Generation Of Stably Transfected Mel Cells Expressing P50 Anmentioning

confidence: 99%

Section: E Ect Of P50 And/or Relb On C-myb Mrna Levelsmentioning

confidence: 99%

Section: E Ect Of P50 And/or Relb On C-myb Transcriptional Elongationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Transcriptional elongation of c-myb is regulated by NF-κB (p50/RelB)

Suhasini

Pilz

1999

Oncogene

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NF‐κB factors control the induction of NFATc1 in B lymphocytes

et al. 2014

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In peripheral lymphocytes, the transcription factors (TFs) NF-κB, NFAT, and AP-1 are the prime targets of signals that emerge from immune receptors. Upon activation, these TFs induce gene networks that orchestrate the growth, expansion, and effector function of peripheral lymphocytes. NFAT and NF-κB factors share several properties, such as a similar mode of induction and architecture in their DNA-binding domain, and there is a subgroup of κB-like DNA promoter motifs that are bound by both types of TFs. However, unlike NFAT and AP-1 factors that interact and collaborate in binding to DNA, NFAT, and NF-κB seem neither to interact nor to collaborate. We show here that NF-κB1/p50 and c-Rel, the most prominent NF-κB proteins in BCR-induced splenic B cells, control the induction of NFATc1/αA, a prominent short NFATc1 isoform. In part, this is mediated through two composite κB/NFAT-binding sites in the inducible Nfatc1 P1 promoter that directs the induction of NFATc1/αA by BCR signals. In concert with coreceptor signals that induce NF-κB factors, BCR signaling induces a persistent generation of NFATc1/αA. These data suggest a tight connection between NFATc1 and NF-κB induction in B lymphocytes contributing to the effector function of peripheral B cells. Keywords:Chromatin r Induction r Lymphocytes r Nfatc1 gene r NF-κB r Transcription Additional supporting information may be found in the online version of this article at the publisher's web-site IntroductionUpon Ag contact, the induction of resting peripheral lymphocytes leads to networks of signaling events that emerge from their Correspondence: Prof. Edgar Serfling e-mail: serfling.e@mail.uni-wuerzburg.de immune receptors. Primary targets of these signals are members of NF-κB, NFAT, and AP-1/ATF/CREB families of transcription factors (TFs). Upon activation they bind to the promoters, enhancers, and further regulatory elements of numerous genes, * These authors contributed equally to this work.C 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.eji-journal.eu Eur. J. Immunol. 2014. 44: 3392-3402 Molecular immunology 3393 control their expression and, thereby, orchestrate gene expression programs that control the growth, proliferation, and effector function of peripheral lymphocytes. One of the best-characterized lymphocyte-specific promoters is the promoter of human and murine Il2 genes. Within the Il2 promoter of approximately 300 bp, there are several noncanonical sequence motifs for the binding of NF-κB and AP-1/ATF/CREB factors, and composite NFAT + AP-1 sites to which both factors can bind with high affinity [1]. The distal NFAT-binding site from the Il2 promoter (the ARRE2 [2], or distal purine box, Pu-b d [3], that is often referred as the "prototypical" NFAT site), consists of the NFAT "core motif" 5 T / A GGAAAA 3 and a noncanonical TRE (TPA-responsive element), i.e. an AP-1/ATF-binding motif, located 10 bp downstream. Such composite NFAT + AP-1 sites are typical for the promoters/enhancers of many genes induced in peripheral T lymphocytes by immune rec...

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Mutations in the MYB intron I regulatory sequence increase transcription in colon cancers

Hugo

Cures

Suraweera

et al. 2006

Genes Chromosomes & Cancer

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Although MYB overexpression in colorectal cancer (CRC) is known to be a prognostic indicator for poor survival, the basis for this overexpression is unclear. Among multiple levels of MYB regulation, the most dynamic is the control of transcriptional elongation by sequences within intron 1. The authors have proposed that this regulatory sequence is transcribed into an RNA stem-loop and 19-residue polyuridine tract, and is subject to mutation in CRC. When this region was examined in colorectal and breast carcinoma cell lines and tissues, the authors found frequent mutations only in CRC. It was determined that these mutations allowed increased transcription compared with the wild type sequence. These data suggest that this MYB regulatory region within intron 1 is subject to mutations in CRC but not breast cancer, perhaps consistent with the mutagenic insult that occurs within the colon and not mammary tissue. In CRC, these mutations may contribute to MYB overexpression, highlighting the importance of noncoding sequences in the regulation of key cancer genes.

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cAMP-induced NF-κB (p50/relB) binding to a c-myb intronic enhancer correlates with c-myb up-regulation and inhibition of erythroleukemia cell differentiation

Cited by 40 publications

References 38 publications

Transcriptional elongation of c-myb is regulated by NF-κB (p50/RelB)

Transcriptional elongation of c-myb is regulated by NF-κB (p50/RelB)

NF‐κB factors control the induction of NFATc1 in B lymphocytes

Mutations in the MYB intron I regulatory sequence increase transcription in colon cancers

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