Home About us Contact
|
Home About us Contact | ||
|
|
||
Homeodomain Protein (homeodomain + protein)
Selected AbstractsAn endoderm-specific transcriptional enhancer from the mouse Gata4 gene requires GATA and homeodomain protein,binding sites for function in vivoDEVELOPMENTAL DYNAMICS, Issue 10 2009Anabel Rojas Abstract Several transcription factors function in the specification and differentiation of the endoderm, including the zinc finger transcription factor GATA4. Despite its essential role in endoderm development, the transcriptional control of the Gata4 gene in the developing endoderm and its derivatives remains incompletely understood. Here, we identify a distal enhancer from the Gata4 gene, which directs expression exclusively to the visceral and definitive endoderm of transgenic mouse embryos. The activity of this enhancer is initially broad within the definitive endoderm but later restricts to developing endoderm-derived tissues, including pancreas, glandular stomach, and duodenum. The activity of this enhancer in vivo is dependent on evolutionarily-conserved HOX- and GATA-binding sites, which are bound by PDX-1 and GATA4, respectively. These studies establish Gata4 as a direct transcriptional target of homeodomain and GATA transcription factors in the endoderm and support a model in which GATA4 functions in the transcriptional network for pancreas formation. Developmental Dynamics 238:2588,2598, 2009. © 2009 Wiley-Liss, Inc. [source] Expression and functional analysis of Tgif during mouse midline developmentDEVELOPMENTAL DYNAMICS, Issue 2 2006Jiu-Zhen Jin Abstract The Tgif gene encodes a homeodomain protein that functions as a transforming growth factor beta (TGF-,) repressor by binding to Smad2. Mutations in the TGIF gene are associated with human holoprosencephaly, a common birth defect caused by the failure of anterior ventral midline formation. However, Smad2-mediated TGF-, signaling in the axial mesendoderm has been demonstrated to be essential for ventral midline formation, and loss of a Smad2 antagonist should in principle promote rather than inhibit ventral midline formation. This suggests a more complex mechanism for the function of TGIF in controlling ventral midline formation. To explore the role of TGIF in ventral forebrain formation and patterning, we investigated Tgif expression and function during mouse development by in situ hybridization and gene targeting. We found that Tgif is highly expressed in the anterior neural plate, consistent with the proposed neural differentiation model in which TGF-, suppression is required for normal neural differentiation. This result suggests a possible role for Tgif in anterior neural differentiation and patterning. However, targeted disruption of the Tgif gene during mouse development does not cause any detectable defects in development and growth. Both histological examination and gene expression analysis showed that Tgif,/, embryos have a normal ventral specification in the central nervous system, including the forebrain region. One interpretation of these results is that the loss of TGIF function is compensated by other TGF-, antagonists such as c-Ski and SnoN during vertebrate anterior neural development. Developmental Dynamics 235:547,553, 2006. © 2005 Wiley-Liss, Inc. [source] A novel synthetic mammalian promoter derived from an internal ribosome entry siteBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2006Shizuka Hartenbach Abstract Introduction of specific mutations into a synthetic internal ribosome entry site (IRESGTX) derived from the GTX homeodomain protein revealed additional transcriptional activity. This novel synthetic PGTX promoter exhibited consensus core promoter modules such as the initiator (Inr) and the partial downstream promoter elements (DPE) and mediated high-level expression of a variety of transgenes including the human vascular endothelial growth factor 121 (VEGF121), the human placental secreted alkaline phosphatase (SEAP), and the Bacillus stearothermophilus -derived secreted ,-amylase (SAMY) in Chinese hamster ovary cells (CHO-K1) and a variety of other mammalian and human cell lines. The spacing between Inr and DPE modules was found to be critical for promoter performance since introduction of a single nucleotide (resulting in PGTX2) doubled the SEAP expression levels in CHO-K1. PGTX2 reached near 70% of PSV40 -driven expression levels and outperformed constitutive phosphoglycerate kinase (PPGK) and human ubiquitin C (PhUBC) promoters in CHO-K1. Also, PGTX2 was successfully engineered for macrolide-inducible transgene expression. Owing to its size of only 182 bp, PGTX2 is one of the smallest eukaryotic promoters. Although PGTX2 was found to be a potent promoter, it retained its IRESGTX -specific translation-initiation capacity. Synthetic DNAs, which combine multiple activities in a most compact sequence format may foster advances in therapeutic engineering of mammalian cells. © 2006 Wiley Periodicals, Inc. [source] Arm,domain interactions can provide high binding cooperativityPROTEIN SCIENCE, Issue 10 2004Robert Schleif Abstract Peptidyl arms extending from one protein domain to another protein domain mediate many important interactions in biology. A well-studied example of this type of protein,protein interaction occurs between the yeast homeodomain proteins, MAT ,2 and MAT a1, which form a high-affinity heterodimer on DNA. The carboxyl-terminal arm extending from MAT ,2 to MAT a1 has been proposed to produce an allosteric conformational change in the a1 protein that generates a very large increase in the DNA binding affinity of a1. Although early studies lent some support to this model, a more recent crystal structure determination of the free a1 protein argues against any allosteric change. This note presents a thermodynamic argument that accounts for the proteins' binding behavior, so that allosteric conformational changes are not required to explain the large affinity increase. The analysis presented here should be useful in analyzing binding behavior in other systems involving arm interactions. [source] | ||||||||||