ABSTRACT: Recombinant adenovirus vectors were used to express wild type or domain swap mutants of A-Myb and c-Myb transcription factors in MCF-7 cells or pimary lung epithelial cells or fibroblasts. The results show that Myb proteins have extreme context specificity and identify sub-domains responsible for the activation of specific sets of target genes. Keywords = Myb proteins Keywords = oncogenes Keywords = transcription Keywords = gene activation Keywords: ordered
Project description:Recombinant adenovirus vectors were used to express wild type or domain swap mutants of A-Myb and c-Myb transcription factors in MCF-7 cells or pimary lung epithelial cells or fibroblasts. The results show that Myb proteins have extreme context specificity and identify sub-domains responsible for the activation of specific sets of target genes.
Project description:The transcriptional activities of c-Myb and its oncogenic variant v-Myb were compared by expressing them in primary human monocytes using recombinant adenovirus vectors. All the samples were compared to cells infected with a control adenovirus expressing only GFP. The results showed that v-Myb, which differs from c-Myb only by N- and C-terminal deletions and eleven amino acid substitutions, has a qualitatively different transcriptional activity. Experiment Overall Design: 2 replicates of each type were analyzed. Replicates were performed independently, more than a week apart.
Project description:The transcriptional activities of c-Myb and its oncogenic variant v-Myb were compared by expressing them in human MCF7 cells using recombinant adenovirus vectors. A hybrid construct, 3Mutc, which is a variant of c-Myb harboring three v-Myb-derived DNA binding domain mutations was also analyzed. All the samples were compared to cells infected with a control adenovirus. The results showed that v-Myb, which differs from c-Myb only by N- and C-terminal deletions and eleven amino acid substitutions, has a qualitatively different transcriptional activity. Experiment Overall Design: 2 replicates of each type were analyzed. Replicates were performed independently, more than a week apart.
Project description:Earlier we have shown important roles of MYB in pancreatic tumor pathobiology. To better understand the role of MYB in the tumor microenvironment and identify MYB-associated secreted biomarker proteins, we conducted mass spectrometry analysis of the secretome from MYB-modulated and control pancreatic cancer cell lines. We also performed in silico analyses to determine MYB-associated biofunctions, gene networks and altered biological pathways. We further investigated the secreted proteins for their potential biomarker properties.
Project description:Most E2F-binding sites repress transcription through the recruitment of Retinoblasoma (RB) family members until the end of the G1 cell-cycle phase. Although the MYB promoter contains an E2F-binding site, its transcription is activated shortly after the exit from quiescence, before RB family members inactivation, by unknown mechanisms. We had previously uncovered a nuclear factor distinct from E2F, Myb-sp, whose DNA-binding site overlapped the E2F element and had hypothesized that this factor might overcome the transcriptional repression of MYB by E2F-RB family members. We have purified Myb-sp and discovered that Myc-associated zinc finger proteins (MAZ) are major components. We show that various MAZ isoforms are present in Myb-sp and activate transcription via the MYB-E2F element. Moreover, while forced RB or p130 expression repressed the activity of a luciferase reporter driven by the MYB-E2F element, co-expression of MAZ proteins not only reverted repression, but also activated transcription. Finally, we show that MAZ binds the MYB promoter in vivo, that its binding site is critical for MYB transactivation, and that MAZ knockdown inhibits MYB expression during the exit from quiescence. Together, these data indicate that MAZ is essential to bypass MYB promoter repression by RB family members and to induce MYB expression.
Project description:Myb-MuvB (MMB)/dREAM is a nine subunit complex first described in Drosophila as a repressor of transcription, dependent upon E2F2 and the RBFs. Myb, an integral member of MMB, curiously plays no role in the silencing of the test genes previously analyzed. Moreover, Myb plays an activating role in DNA replication in Drosophila egg chamber follicle cells. The essential functions for Myb are executed as part of MMB. This duality of function lead to the hypothesis that MMB, which contains both known activator and repressor proteins, might function as part of a switching mechanism that is dependent upon DNA sites and developmental context. Keywords: Drosophila Myb-MuvB/dREAM, ChIP-chip
Project description:The transcriptional activities of c-Myb and its oncogenic variant v-Myb were compared by expressing them in primary human monocytes using recombinant adenovirus vectors. All the samples were compared to cells infected with a control adenovirus expressing only GFP. The results showed that v-Myb, which differs from c-Myb only by N- and C-terminal deletions and eleven amino acid substitutions, has a qualitatively different transcriptional activity. Keywords: repeat
Project description:The transcriptional activities of c-Myb and its oncogenic variant v-Myb were compared by expressing them in human MCF7 cells using recombinant adenovirus vectors. A hybrid construct, 3Mutc, which is a variant of c-Myb harboring three v-Myb-derived DNA binding domain mutations was also analyzed. All the samples were compared to cells infected with a control adenovirus. The results showed that v-Myb, which differs from c-Myb only by N- and C-terminal deletions and eleven amino acid substitutions, has a qualitatively different transcriptional activity. Keywords: repeat
Project description:A-MYB (MYBL1) is a transcription factor with a role in meiosis in spermatocytes. The related B-MYB protein is a key proto-oncogene and a master regulator activating late cell cycle genes. To activate genes, B-MYB forms a complex with MuvB and is recruited indirectly to cell cycle genes homology region (CHR) promoter sites of target genes. Activation through the B-MYB-MuvB (MMB) complex is essential for successful mitosis. Here, we discover that A-MYB has a function in transcriptional regulation of the mitotic cell cycle and can substitute for B-MYB. Knockdown experiments in cells not related to spermatogenesis show that B-MYB loss alone only delays cell cycle progression. Only dual knockdown of B-MYB and A-MYB causes cell cycle arrest. A-MYB can substitute for B-MYB in binding to MuvB. The resulting A-MYB-MuvB complex activates genes through CHR sites. We find that A-MYB activates the same target genes as B-MYB. Many of the corresponding proteins are central regulators of the cell division cycle. In summary, we demonstrate that A-MYB is an activator of the mitotic cell cycle by activating late cell cycle genes.
Project description:Myb-MuvB (MMB)/dREAM is a nine subunit complex first described in Drosophila as a repressor of transcription, dependent upon E2F2 and the RBFs. Myb, an integral member of MMB, curiously plays no role in the silencing of the test genes previously analyzed. Moreover, Myb plays an activating role in DNA replication in Drosophila egg chamber follicle cells. The essential functions for Myb are executed as part of MMB. This duality of function lead to the hypothesis that MMB, which contains both known activator and repressor proteins, might function as part of a switching mechanism that is dependent upon DNA sites and developmental context. Here, we used proliferating Drosophila Kc tissue culture cells to explore both the network of genes regulated by MMB (employing RNAi and micro-array expression analysis) and the genomic locations of MMB following chromatin immunoprecipitation (ChIP) and tiling array analysis. MMB occupies thousands of chromosomal sites where a substantial number are proximal to repressed genes that are normally expressed in a wide range of developmental pathways. At many of these sites, E2F2 was critical for repression whereas at other non-overlapping sites, Myb was critical for repression. These data highlight that the MMB factors are utilized in a combinatorial way for targeting gene regulation. We also found sites where MMB was a positive regulator of transcript levels that included genes required for mitotic functions (G2/M), which may explain some of the chromosome instability phenotypes attributed to loss of Myb function in myb mutants. Keywords: Drosophila Myb-MuvB/dREAM, RNAi, ChIP-chip