XBF-2 is a transcriptional repressor that converts ectoderm into neural tissue

Development ◽  
1998 ◽  
Vol 125 (24) ◽  
pp. 5019-5031 ◽  
Author(s):  
F.V. Mariani ◽  
R.M. Harland
Keyword(s):  
Dna Binding ◽  
Neural Development ◽  
Ectopic Expression ◽  
Transcriptional Repressor ◽  
Neural Plate ◽  
Binding Domain ◽  
Expression Cloning ◽  
Dna Binding Domain ◽  
Neural Fate ◽  
Striking Contrast

We have identified Xenopus Brain Factor 2 (XBF-2) as a potent neuralizing activity in an expression cloning screen. In ectodermal explants, XBF-2 converts cells from an epidermal to a neural fate. Such explants contain neurons with distinct axonal profiles and express both anterior and posterior central nervous system (CNS) markers. In striking contrast to X-ngnR-1a or X-NeuroD, ectopic expression of XBF-2 in Xenopus embryos results in an expansion of the neural plate to the ventral midline. The enlarged neural plate consists predominantly of undifferentiated neurons. XBF-2 lies downstream of the BMP antagonists noggin, cerberus, and gremlin since ectodermal explants expressing these molecules exhibit strong expression of XBF-2. While XBF-2 does not upregulate the expression of secreted neural inducers, it downregulates the transcription of BMP-4, an epidermal inducer. We show that XBF-2 acts as a transcriptional repressor and that its effects can be phenocopied with either the engrailed or hairy repressor domain fused to the XBF-2 DNA-binding domain. A fusion of the DNA-binding domain to the activator domain of VP16 blocks the effects of XBF-2 and prevents neural plate development in the embryo. This provides evidence that a transcriptional repressor can affect both regional neural development and neurogenesis in vertebrates.

scholarly journals Functional Domains of c-myc Promoter Binding Protein 1 Involved in Transcriptional Repression and Cell Growth Regulation

1999 ◽  
Vol 19 (4) ◽  
pp. 2880-2886 ◽  
Author(s):  
Asish K. Ghosh ◽  
Robert Steele ◽  
Ratna B. Ray
Keyword(s):  
Amino Acids ◽  
Cell Growth ◽  
Dna Binding ◽  
Transcriptional Repression ◽  
Growth Regulation ◽  
Transcriptional Repressor ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Repressor Activity

ABSTRACT We initially identified c-myc promoter binding protein 1 (MBP-1), which negatively regulates c-myc promoter activity, from a human cervical carcinoma cell expression library. Subsequent studies on the biological role of MBP-1 demonstrated induction of cell death in fibroblasts and loss of anchorage-independent growth, reduced invasive ability, and tumorigenicity of human breast carcinoma cells. To investigate the potential role of MBP-1 as a transcriptional regulator, a chimeric protein containing MBP-1 fused to the DNA binding domain of the yeast transactivator factor GAL4 was constructed. This fusion protein exhibited repressor activity on the herpes simplex virus thymidine kinase promoter via upstream GAL4 DNA binding sites. Structure-function analysis of mutant MBP-1 in the context of the GAL4 DNA binding domain revealed that MBP-1 transcriptional repressor domains are located in the N terminus (amino acids 1 to 47) and C terminus (amino acids 232 to 338), whereas the activation domain lies in the middle (amino acids 140 to 244). The N-terminal domain exhibited stronger transcriptional repressor activity than the C-terminal region. When the N-terminal repressor domain was transferred to a potent activator, transcription was strongly inhibited. Both of the repressor domains contained hydrophobic regions and had an LXVXL motif in common. Site-directed mutagenesis in the repressor domains indicated that the leucine residues in the LXVXL motif are required for transcriptional repression. Mutation of the leucine residues in the common motif of MBP-1 also abrogated the repressor activity on the c-mycpromoter. In addition, the leucine mutant forms of MBP-1 failed to suppress cell growth in fibroblasts like wild-type MBP-1. Taken together, our results indicate that MBP-1 is a complex cellular factor containing multiple transcriptional regulatory domains that play an important role in cell growth regulation.

scholarly journals Developmental Effects of Ectopic Expression of the Glucocorticoid Receptor DNA Binding Domain Are Alleviated by an Amino Acid Substitution That Interferes with Homeodomain Binding

1999 ◽  
Vol 19 (10) ◽  
pp. 7106-7122 ◽  
Author(s):  
Jun Ming Wang ◽  
Gratien G. Préfontaine ◽  
Madeleine E. Lemieux ◽  
Louise Pope ◽  
Marie-Andrée Akimenko ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Heat Shock ◽  
Dna Binding ◽  
Glucocorticoid Receptor ◽  
Ectopic Expression ◽  
Binding Domain ◽  
Steroid Hormone Receptors ◽  
Dna Binding Domain ◽  
Homeodomain Proteins ◽  
Gene Markers

ABSTRACT Steroid hormone receptors are distinguished from other members of the nuclear hormone receptor family through their association with heat shock proteins and immunophilins in the absence of ligands. Heat shock protein association represses steroid receptor DNA binding and protein-protein interactions with other transcription factors and facilitates hormone binding. In this study, we investigated the hormone-dependent interaction between the DNA binding domain (DBD) of the glucocorticoid receptor (GR) and the POU domains of octamer transcription factors 1 and 2 (Oct-1 and Oct-2, respectively). Our results indicate that the GR DBD binds directly, not only to the homeodomains of Oct-1 and Oct-2 but also to the homeodomains of several other homeodomain proteins. As these results suggest that the determinants for binding to the GR DBD are conserved within the homeodomain, we examined whether the ectopic expression of GR DBD peptides affected early embryonic development. The expression of GR DBD peptides in one-cell-stage zebra fish embryos severely affected their development, beginning with a delay in the epibolic movement during the blastula stage and followed by defects in convergence-extension movements during gastrulation, as revealed by the abnormal patterns of expression of several dorsal gene markers. In contrast, embryos injected with mRNA encoding a GR peptide with a point mutation that disrupted homeodomain binding or with mRNA encoding the DBD of the closely related mineralocorticoid receptor, which does not bind octamer factors, developed normally. Moreover, coinjection of mRNA encoding the homeodomain of Oct-2 completely rescued embryos from the effects of the GR DBD. These results highlight the potential of DNA-independent effects of GR in a whole-animal model and suggest that at least some of these effects may result from direct interactions with homeodomain proteins.

scholarly journals Xbp1, a stress-induced transcriptional repressor of the Saccharomyces cerevisiae Swi4/Mbp1 family.

1997 ◽  
Vol 17 (11) ◽  
pp. 6491-6501 ◽  
Author(s):  
B Mai ◽  
L Breeden
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Dna Binding ◽  
Binding Site ◽  
Binding Sites ◽  
Binding Protein ◽  
Transcriptional Repressor ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
G1 Cyclin

We have identified Xbp1 (XhoI site-binding protein 1) as a new DNA-binding protein with homology to the DNA-binding domain of the Saccharomyces cerevisiae cell cycle regulating transcription factors Swi4 and Mbp1. The DNA recognition sequence was determined by random oligonucleotide selection and confirmed by gel retardation and footprint analyses. The consensus binding site of Xbp1, GcCTCGA(G/A)G(C/A)g(a/g), is a palindromic sequence, with an XhoI restriction enzyme recognition site at its center. This Xbpl binding site is similar to Swi4/Swi6 and Mbp1/Swi6 binding sites but shows a clear difference from these elements in one of the central core bases. There are binding sites for Xbp1 in the G1 cyclin promoter (CLN1), but they are distinct from the Swi4/Swi6 binding sites in CLN1, and Xbp1 will not bind to Swi4/Swi6 or Mbp1/Swi6 binding sites. The XBP1 promoter contains several stress-regulated elements, and its expression is induced by heat shock, high osmolarity, oxidative stress, DNA damage, and glucose starvation. When fused to the LexA DNA-binding domain, Xbp1 acts as transcriptional repressor, defining it as the first repressor in the Swi4/Mbp1 family and the first potential negative regulator of transcription induced by stress. Overexpression of XBP1 results in a slow-growth phenotype, lengthening of G1, an increase in cell volume, and a repression of G1 cyclin expression. These observations suggest that Xbp1 may contribute to the repression of specific transcripts and cause a transient cell cycle delay under stress conditions.

scholarly journals A novel repressor, par-4, modulates transcription and growth suppression functions of the Wilms' tumor suppressor WT1.

1996 ◽  
Vol 16 (12) ◽  
pp. 6945-6956 ◽  
Author(s):  
R W Johnstone ◽  
R H See ◽  
S F Sells ◽  
J Wang ◽  
S Muthukkumar ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Dna Binding ◽  
Leucine Zipper ◽  
Wilms Tumor ◽  
Transcriptional Repressor ◽  
Growth Suppression ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Interacting Protein

The tumor suppressor WT1 represses and activates transcription. The loss and/or imbalance of the dual transcriptional activity of WT1 may contribute to Wilms' tumor. In this study, we identified par-4 (for prostate apoptosis response) as a WT1-interacting protein that itself functions as a transcriptional repressor. par-4 contains a putative leucine zipper domain and is specifically upregulated during apoptosis of prostate cells (S. F. Sells, D. P. Wood, Jr., S. S. Joshi-Barve, S. Muthukkumar, R. J. Jacob, S. A. Crist, S. Humphreys, and V. M. Rangnekar, Cell Growth Differ. 5:457-466, 1994). The leucine repeat domain of par-4 was shown to interact with the zinc finger DNA binding domain of WT1. Immunoprecipitation-Western blot (immunoblot) analyses demonstrated in vivo WT1-par-4 interactions. par-4 was ubiquitously expressed, and the protein was found in both the nucleus and the cytoplasm. Functionally, par-4 inhibited transcription activated by WT1, but not by the related protein EGR1. Inhibition of WT1-mediated transcription was dependent on the domain of par-4 that mediates its physical association with WT1. In addition, par-4 augmented WT1-mediated repression, possibly by contributing an additional repression domain. Consistent with these results, par-4 functioned as a transcriptional repressor when brought to a promoter via a heterologous DNA binding domain. Significantly, par-4, but not a mutant unable to interact with WT1, rescued growth suppression caused by WT1. Thus, we identified a novel repressor that modulates transcription as well as growth suppression functions of WT1.

NMR studies of the R2 repeat and related peptide fragments of the DNA binding domain of c-Myb. New light on the structure and folding of R2.

1999 ◽  
Vol 96 (9/10) ◽  
pp. 1580-1584 ◽  
Author(s):  
I. Ségalas ◽  
S. Desjardins ◽  
H. Oulyadi ◽  
Y. Prigent ◽  
S. Tribouillard ◽  
...  
Keyword(s):  
Dna Binding ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Peptide Fragments ◽  
Nmr Studies ◽  
Related Peptide

scholarly journals Primary structure of a glycosylated DNA-binding domain in human plasma fibronectin.

1985 ◽  
Vol 260 (4) ◽  
pp. 2301-2306
Author(s):  
H Pande ◽  
J Calaycay ◽  
D Hawke ◽  
C M Ben-Avram ◽  
J E Shively
Keyword(s):  
Dna Binding ◽  
Human Plasma ◽  
Primary Structure ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Plasma Fibronectin

scholarly journals Functional mechanisms of MYRF DNA-binding domain mutations implicated in birth defects

2021 ◽  
Vol 296 ◽  
pp. 100612
Author(s):  
Chuandong Fan ◽  
Hongjoo An ◽  
Mohamed Sharif ◽  
Dongkyeong Kim ◽  
Yungki Park
Keyword(s):  
Dna Binding ◽  
Birth Defects ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Functional Mechanisms
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