The ubiquitous octamer-binding protein Oct-1 contains a POU domain with a homeo box subdomain.

Sturm, Richard A.; Das, Gautam; Herr, Winship

doi:10.1101/gad.2.12a.1582

Cited by 656 publications

(357 citation statements)

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“…Studies on the expression of OCT.1 have demonstrated a high-level expression in pre-B cell lines. 12,13 On the other hand, OCT.2 expression is restricted to B cells and neuronal cells, 14 and plays an important role in Ig promoter transactivation, as has been demonstrated by transfection experiments. 15 They both participate in the control of important B-specific genes involved in proliferation and differentiation, [16][17][18][19][20] such as Ig genes, CD20, CD79a and J chain.…”

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confidence: 86%

Analysis of transcription factor OCT.1, OCT.2 and BOB.1 expression using tissue arrays in classical Hodgkin's lymphoma

et al. 2004

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Hodgkin's lymphoma can be considered in most cases a B-cell lymphoma due to the presence of potentially functional immunoglobulin (Ig) gene rearrangements in the neoplastic cells. In contrast to lymphocytepredominant Hodgkin's lymphoma, Hodgkin/Reed-Sternberg (HRS) cells from classical Hodgkin's lymphoma have low frequency of B-cell marker expression and lack Ig light and Ig heavy messenger RNA. Recent studies have shown transcription machinery deficiency in Hodgkin's lymphoma caused by an absence of the transcription factors OCT.1, OCT.2 and/or BOB.1. By using the tissue microarray technique, we have performed an immunohistochemical study of OCT.1, OCT.2 and BOB.1 in 325 classical Hodgkin's lymphoma cases. The results have been correlated with the expression of the B-cell markers CD20, CD79a, B-cell-specific activator protein (BSAP) and MUM.1, the presence of Epstein-Barr virus and the histological subtype. The percentage of CD20 and CD79a positivity was low (18 and 18%, respectively), whereas MUM.1 and BSAP were positive in the majority of cases. Considering the positive cases with independence of the intensity of staining, 62% of them expressed OCT.2, 59% OCT.1 and 37% BOB.1. Nevertheless, when we considered only the strongly positive cases, the results were similar to those previously described by others. No statistical association was found between the transcription factor expression, histological subtype and Epstein-Barr virus presence. To our knowledge, this is the largest series of classical Hodgkin's lymphoma cases in which the expression of transcription factors has been studied. We have found a notorious percentage of cases displaying weak positivity for OCT.2 and BOB.1 factors in HRS cells. We propose that other mechanisms different from the absence of transcription factors OCT.2 and BOB.1 might be involved in the control of Ig transcription and B lineage in classical Hodgkin's lymphoma.

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confidence: 86%

Analysis of transcription factor OCT.1, OCT.2 and BOB.1 expression using tissue arrays in classical Hodgkin's lymphoma

et al. 2004

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“…The sequence of MBP-1 does not contain any known DNA-binding motifs such as a zinc finger structure (25,43), leucine zipper (32), POU-specific regions (11,15,(64)(65)(66), or homeoboxes (33,40,42 Several groups have investigated the sequence requirement for initiation at the P1 and P2 start sites of the human c-myc gene (10,19,37,48,59). Sequences between -60 and -37 relative to the human c-myc P1 start site are essential for its activity in microinjected Xenopus laevis oocytes (48).…”

Section: Tcccctgtaccgccacatcgcgtacttggctggcaacttcgaagtcatcctgccagtcccmentioning

confidence: 99%

Cloning and characterization of a human c-myc promoter-binding protein.

Ray¹,

Miller²

1991

Mol. Cell. Biol.

107

128

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A human cDNA clone encoding a c-myc promoter-binding protein was detected by screening a HeLa cell k phage expression cDNA library. The library was screened by using an XhoI-NaeI human c-myc P2 promoter fragment as a probe. The recombinant phage encoded a fusion protein, myc-binding protein 1 (MBP-1), which had an apparent molecular size of 40 kDa. A corresponding protein with a molecular size of 35 kDa was present in a HeLa cell extract. Sequence analysis of the cloned gene reveals an open reading frame of 1,038 bp with a 3' untranslated region of 378 bp. The predicted protein sequence contains a proline-rich region in the amino terminus but does not demonstrate a known DNA-binding domain. DNase I footprint analysis demonstrates that MBP-1 binds to the sequence just 5' of the TATA box sequence of the human c-myc P2 promoter. MBP-1 cDNA hybridizes to a 1.4-kb mRNA from HeLa and HL-60 cells, indicating that the cDNA insert (1,416 bp) is a full-length clone. Coexpression of the MBP-1 protein represses transcription from the human c-myc promoter, suggesting that MBP-1 may act as a negative regulatory factor for the human c-myc gene.

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“…We were given the following cDNAs: E12 and E47 (11), deletions and point mutants of E47 generated by PCR (13), and mouse c-Myc (32). We cloned the following cDNAs by reverse transcriptase PCR and confirmed their sequences: rat Id3 (33): rat Max (34), human OCT-1 (35), and rat c-Jun (36). Mathias Treier (European Molecular Biology Laboratory, Heidelberg, Germany) provided the ubiquitin construct pCMVHA-Ub (22).…”

Section: Methodsmentioning

confidence: 99%

“…Spun samples were then cleared with normal mouse serum and protein G-agarose (Pierce) for 1 h at 4°C. 35 S incorporation in the total protein pool was determined by trichloroacetic acid precipitation. Lysate volumes were adjusted so that each extract contained equivalent amounts of radioactivity (trichloroacetic acid-precipitable counts/min).…”

Section: Methodsmentioning

confidence: 99%

“…35 S-Labeled proteins were generated by using the TNT T7-coupled reticulocyte lysate system (Promega) with the Id3 or UbcE2A expression construct in pCite4 (Novagen). 35 S-Labeled protein (3 l) was incubated with the beads (25 l) in 50 mM NaCl and bovine serum albumin (1 mg/ml) at 4°C for 1 h (43). The beads were then washed four times with 0.1% Nonidet P-40 in PBS.…”

Section: Methodsmentioning

confidence: 99%

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Degradation of E2A Proteins through a Ubiquitin-conjugating Enzyme, UbcE2A

Kho

Huggins

Endege³

et al. 1997

Journal of Biological Chemistry

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The helix-loop-helix E2A proteins (E12 and E47) govern cellular growth and differentiation. To identify binding partners that regulate the function of these ubiquitous transcription factors, we screened for proteins that interacted with the C terminus of E12 by the yeast interaction trap. UbcE2A, a rat enzyme that is highly homologous to and functionally complements the yeast ubiquitin-conjugating enzyme UBC9, was identified and cloned. UbcE2A appears to be an E2A-selective ubiquitin-conjugating enzyme because it interacts specifically with a 54-amino acid region in E47-(477-530) distinct from the helix-loop-helix domain. In contrast, most of the UbcE2A protein is required for interaction with an E2A protein. The E2A proteins appear to be degraded by the ubiquitin-proteasome pathway because the E12 half-life of 60 min is extended by the proteasome inhibitor MG132, and E12 is multi-ubiquitinated in vivo. Finally, antisense UbcE2A reduces E12 degradation. By participating in the degradation of the E2A proteins, UbcE2A may regulate cell growth and differentiation.By alternative splicing, the E2A gene encodes two proteins, E12 and E47, through two adjacent exons encoding a basic helix-loop-helix (HLH) 1 motif (1). These proteins belong to a family of eukaryotic transcription regulators distinguished by the highly conserved HLH motif, which mediates dimerization, and by the adjacent basic region, which mediates site-specific DNA binding (2, 3). The ubiquitous E2A proteins form heterodimers with tissue-specific HLH proteins that then bind to DNA and up-regulate the transcription of target genes. Tissuespecific HLH proteins include the MyoD family involved in skeletal muscle differentiation (4), the achaete-scute family involved in neuronal differentiation (5), and SCL/TAL, which is involved in hematopoiesis (6). The E2A proteins also form homodimers that are linked by intermolecular disulfide bonds in B cells but not muscle cells (7). These homodimers are thought to be the predominant DNA-binding species in B cells (8). In mice carrying a null mutation in E2A, immunoglobulin gene segments do not rearrange and the animals lack mature B lymphocytes (9, 10).In addition to its role in cellular differentiation, the E2A gene is the breakpoint of two translocations associated with childhood lymphoid leukemia. A truncated E2A gene fuses to the PBX1 homeobox gene (11) and to the HLF basic leucine zipper gene (12). Because the E2A portion is required for transformation in both instances, E2A proteins appear to play a role in growth control. Peverali et al. (13) have shown that overexpression of E12 or E47 inhibits cell proliferation and mediates arrest of growth a few hours before the G 1 -S transition of the cell cycle. The level of E2A proteins at different stages of the cell cycle could also determine whether cells proliferate or differentiate.Certain transcription factors and cell cycle regulators are degraded rapidly in vivo (14). For example, c-Fos and c-Jun, which have half-lives of about 30 and 90 min, respectively, ca...

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The ubiquitous octamer-binding protein Oct-1 contains a POU domain with a homeo box subdomain.

Cited by 656 publications

References 77 publications

Analysis of transcription factor OCT.1, OCT.2 and BOB.1 expression using tissue arrays in classical Hodgkin's lymphoma

Analysis of transcription factor OCT.1, OCT.2 and BOB.1 expression using tissue arrays in classical Hodgkin's lymphoma

Cloning and characterization of a human c-myc promoter-binding protein.

Degradation of E2A Proteins through a Ubiquitin-conjugating Enzyme, UbcE2A

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