All Tcf HMG box transcription factors interact with Groucho-related co-repressors

Tcf/Lef family transcription factors are the downstream effectors of the Wingless/Wnt signal transduction pathway. Upon Wingless/Wnt signalling, β-catenin translocates to the nucleus, interacts with Tcf (1–3) and thus activates transcription of target genes (4,5). Tcf factors also interact with members of the Groucho (Grg/TLE) family of transcriptional co-repressors (6). We have now tested all known mammalian Groucho family members for their ability to interact specifically with individual Tcf/Lef family members. Transcriptional activation by any Tcf could be repressed by Grg-1, Grg-2/TLE-2, Grg-3 and Grg-4 in a reporter assay. Specific interactions between Tcf and Grg proteins may be achieved in vivo by tissue- or cell type-limited expression. To address this, we determined the expression of all Tcf and Grg/TLE family members in a panel of cell lines. Within any cell line, several Tcfs and TLEs are co-expressed. Thus, redundancy in Tcf/Grg interactions appears to be the rule. The ‘long’ Groucho family members containing five domains are repressors of Tcf-mediated transactivation, whereas Grg-5, which only contains the first two domains, acts as a de-repressor. As previously shown for Drosophila Groucho, we show that long Grg proteins interact with histone deacetylase-1. Although Grg-5 contains the GP homology domain that mediates HDAC binding in long Grg proteins, Grg-5 fails to bind this co-repressor, explaining how it can de-repress transcription.

HMG box transcription factor gene Hbp1 is expressed in germ cells of the developing mouse testis

HMG box containing protein 1 (HBP1) is a high mobility group domain transcriptional repressor that regulates proliferation in differentiated tissues. We have found mouse Hbp1 to be expressed strongly in the embryonic mouse testis from approximately 12.5 days post coitum, compared with low levels of expression in the embryonic ovary. Expression of Hbp1 is maintained in the developing testis beyond the onset of spermatogenesis after birth. Whole-mount in situ hybridisation analysis showed that expression of Hbp1 in the XY gonad is localized within the developing testis cords, the precursors of the seminiferous tubules. Expression of Hbp1 is not apparent in testis cords of gonads from homozygous We mutant embryos, which lack germ cells. In situ hybridisation analysis on cryosectioned embryonic testis indicated that Hbp1 expression resembles that of the germ cell marker Oct4. We conclude that Hbp1 is up-regulated specifically in germ cells of the developing XY gonad. The expression of Hbp1 in XY germ cells appears to correlate with the onset of mitotic arrest in these cells. (C) 2004 Wiley-Liss, Inc.

Sox and Zfx genes in giant panda

By using PCR cloning techniques, the DNA sequences of the HMG box regions of six Sox genes (pSox) and the zinc finger domains of two Zfx genes (pZfx) in the giant panda were identified. The giant panda Sox genes fell into two subfamilies, SOX-S1 and SOX-S2. The pSox and pZfx genes of the giant panda were highly homologous to the corresponding genes in mammals and revealed close substitution rates to those in the primates.

Localization of Sry gene on Y chromosome of Muntjac munticus vaginalis

The chromosomes 1, Y-1, Y-2 of Muntjac munticus vaginalis were isolated by fluorescence activated chromosome sorting and amplified by degenerate oligonucleotide primed-polymerase chain reaction ( DOP-PCR). A primer pair within human Sry HMG box was design

Expression pattern of dmrt4 from olive flounder (Paralichthys olivaceus) in adult gonads and during embryogenesis

The dmrt (doublesex and mab-3 related transcription factor) gene family comprises several transcription factors that share a conserved DM domain. Dmrt1 is considered to be involved in sexual development, but the precise function of other family members is unclear. In this study, we isolated genomic DNA and cDNA sequences of dmrt4, a member of the dmrt gene family, from olive flounder, Paralichthys olivaceus, through genome walking and real-time reverse transcriptase (RT)-PCR. Sequence analysis indicated that its genomic DNA contains two exons and one intron. A transcriptional factor binding sites prediction program identified a sexual development-related protein, Sox9 (Sry-like HMG box containing 9) in its 5' promoter. Protein alignment and phylogenetic analysis suggested that flounder Dmrt4 is closely related to tilapia Dmo (DM domain gene in ovary). The expression of dmrt4 in adult flounder was sexually dimorphic, as shown by real-time RT-PCR analysis, with strong expression in the testis but very weak expression in the ovary. Its expression was also strong in the brain and gill, but there was only weak or no expression at all in some of the other tissues tested of both sexes. During embryogenesis, its expression was detected in most developmental stages, although the level of expression was distinctive of the various stages. Whole mount in situ hybridization revealed that the dmrt4 was expressed in the otic placodes, forebrain, telencephalon and olfactory placodes of embryos at different developmental stages. These results will improve our understanding of the possible role of flounder dmrt4 in the development of the gonads, nervous system and sense organs.

Molecular and morphological data support the existence of a sexual cycle in species of the genus Paracoccidioides

The genus Paracoccidioides includes the thermodimorphic species Paracoccidioides brasiliensis and P. lutzii, both of which are etiologic agents of paracoccidioidomycosis, a systemic mycosis that affects humans in Latin America. Despite the common occurrence of a sexual stage among closely related fungi, this has not been observed with Paracoccidioides species, which have thus been considered asexual. Molecular evolutionary studies revealed recombination events within isolated populations of the genus Paracoccidioides, suggesting the possible existence of a sexual cycle. Comparative genomic analysis of all dimorphic fungi and Saccharomyces cerevisiae demonstrated the presence of conserved genes involved in sexual reproduction, including those encoding mating regulators such as MAT, pheromone receptors, pheromone-processing enzymes, and mating signaling regulators. The expression of sex-related genes in the yeast and mycelial phases of both Paracoccidioides species was also detected by realtime PCR, with nearly all of these genes being expressed preferentially in the filamentous form of the pathogens. In addition, the expression of sex-related genes was responsive to the putative presence of pheromone in the supernatants obtained from previous cocultures of strains of two different mating types. In vitro crossing of isolates of different mating types, discriminated by phylogenetic analysis of the α-box (MAT1-1) and the high-mobility-group (HMG) domain (MAT1-2), led to the identification of the formation of young ascocarps with constricted coiled hyphae related to the initial stage of mating. These genomic and morphological analyses strongly support the existence of a sexual cycle in species of the genus Paracoccidioides. © 2013, American Society for Microbiology.

Improving chondrogenesis: potential and limitations of SOX9 gene transfer and mechanical stimulation for cartilage tissue engineering

Articular cartilage injuries and degeneration affect a large proportion of the population in developed countries world wide. Stem cells can be differentiated into chondrocytes by adding transforming growth factor-beta1 and dexamethasone to a pellet culture, which are unfeasible for tissue engineering purposes. We attempted to achieve stable chondrogenesis without any requirement for exogenous growth factors. Human mesenchymal stem cells were transduced with an adenoviral vector containing the SRY-related HMG-box gene 9 (SOX9), and were cultured in a three-dimensional (3D) hydrogel scaffold composite. As an additional treatment, mechanical stimulation was applied in a custom-made bioreactor. SOX9 increased the expression level of its known target genes, as well as its cofactors: the long form of SOX5 and SOX6. However, it was unable to increase the synthesis of sulfated glycosaminoglycans (GAGs). Mechanical stimulation slightly enhanced collagen type X and increased lubricin expression. The combination of SOX9 and mechanical load boosted GAG synthesis as shown by (35)S incorporation. GAG production rate corresponded well with the amount of (endogenous) transforming growth factor-beta1. Finally, cartilage oligomeric matrix protein expression was increased by both treatments. These findings provide insight into the mechanotransduction of mesenchymal stem cells and demonstrate the potential of a transcription factor in stem cell therapy.

Association of Smads with lymphoid enhancer binding factor 1/T cell-specific factor mediates cooperative signaling by the transforming growth factor-β and Wnt pathways

The transforming growth factor-β (TGFβ) and Wnt/wingless pathways play pivotal roles in tissue specification during development. Activation of Smads, the effectors of TGFβ superfamily signals, results in Smad translocation from the cytoplasm into the nucleus where they act as transcriptional comodulators to regulate target gene expression. Wnt/wingless signals are mediated by the DNA-binding HMG box transcription factors lymphoid enhancer binding factor 1/T cell-specific factor (LEF1/TCF) and their coactivator β-catenin. Herein, we show that Smad3 physically interacts with the HMG box domain of LEF1 and that TGFβ and Wnt pathways synergize to activate transcription of the Xenopus homeobox gene twin (Xtwn). Disruption of specific Smad and LEF1/TCF DNA-binding sites in the promoter abrogates synergistic activation of the promoter. Consistent with this observation, introduction of Smad sites into a TGFβ-insensitive LEF1/TCF target gene confers cooperative TGFβ and Wnt responsiveness to the promoter. Furthermore, we demonstrate that TGFβ-dependent activation of LEF1/TCF target genes can occur in the absence of β-catenin binding to LEF1/TCF and requires both Smad and LEF1/TCF DNA-binding sites in the Xtwn promoter. Thus, our results show that TGFβ and Wnt signaling pathways can independently or cooperatively regulate LEF1/TCF target genes and suggest a model for how these pathways can synergistically activate target genes.

Origin and diversity of the Sox transcription factor gene family: genome-wide analysis in Fugu rubripes

The SOX family of transcription factors are found throughout the animal kingdom and are important in a variety of developmental contexts. Genome analysis has identified 20 Sox genes in human and mouse, which can be subdivided into 8 groups, based on sequence comparison and intron-exon structure. Most of the SOX groups identified in mammals are represented by a single SOX sequence in invertebrate model organisms, suggesting a duplication and divergence mechanism has operated during vertebrate evolution. We have now analysed the Sox gene complement in the pufferfish, Fugu rubripes, in order to shed further light on the diversity and origins of the Sox gene family. Major differences were found between the Sox family in Fugu and those in humans and mice. In particular, Fugu does not have orthologues of Sry, Sox,15 and Sox30, which appear to be specific to mammals, while Sox19, found in Fugu and zebrafish but absent in mammals, seems to be specific to fishes. Six mammalian Sox genes are represented by two copies each in Fugu, indicating a large-scale gene duplication in the fish lineage. These findings point to recent Sox gene loss, duplication and divergence occurring during the evolution of tetrapod and teleost lineages, and provide further evidence for large-scale segmental or a whole-genome duplication occurring early in the radiation of teleosts. (C) 2004 Elsevier B.V. All rights reserved.

Redundant roles of Sox17 and Sox18 in postnatal angiogenesis in mice

Sox7, Sox17 and Sox18 constitute group F of the Sox family of HMG box transcription factor genes. Dominant-negative mutations in Sox18 underlie the cardiovascular defects observed in ragged mutant mice. By contrast, Sox18(-/-) mice are viable and fertile, and display no appreciable anomaly in their vasculature, suggesting functional compensation by the two other SoxF genes. Here, we provide direct evidence for redundant function of Sox17 and Sox18 in postnatal neovascularization by generating Sox17(+/-)-Sox18(-/-) double mutant mice. Whereas Sox18(-/-) and Sox17(+/-)-Sox18(+/)-mice showed no vascular defects, approximately half of the Sox17(+/-)-Sox18(-/-) pups died before postnatal day 21 (P21). They showed reduced neovascularization in the liver sinusoids and kidney outer medulla vasa recta at P7, which most likely caused the ischemic necrosis observed by P14 in hepatocytes and renal tubular epithelia. Those that survived to adulthood showed similar, but milder, vascular anomalies in both liver and kidney, and females were infertile with varying degrees of vascular abnormalities in the reproductive organs. These anomalies corresponded with sites of expression of Sox7 and Sox17 in the developing postnatal vasculature. In vitro angiogenesis assays, using primary endothelial cells isolated from the P7 livers, showed that the Sox17(+/-)-Sox18(-/-)endothelial cells were defective in endothelial sprouting and remodeling of the vasculature in a phenotype-dependent manner. Therefore, our findings indicate that Sox17 and Sox18, and possibly all three SoxF genes, are cooperatively involved in mammalian vascular development.

Sound radiation characteristics of a box-type structure

The finite element and boundary element methods are employed in this study to investigate the sound radiation characteristics of a box-type structure. It has been shown [T.R. Lin, J. Pan, Vibration characteristics of a box-type structure, Journal of Vibration and Acoustics, Transactions of ASME 131 (2009) 031004-1–031004-9] that modes of natural vibration of a box-type structure can be classified into six groups according to the symmetry properties of the three panel pairs forming the box. In this paper, we demonstrate that such properties also reveal information about sound radiation effectiveness of each group of modes. The changes of radiation efficiencies and directivity patterns with the wavenumber ratio (the ratio between the acoustic and the plate bending wavenumbers) are examined for typical modes from each group. Similar characteristics of modal radiation efficiencies between a box structure and a corresponding simply supported panel are observed. The change of sound radiation patterns as a function of the wavenumber ratio is also illustrated. It is found that the sound radiation directivity of each box mode can be correlated to that of elementary sound sources (monopole, dipole, etc.) at frequencies well below the critical frequency of the plates of the box. The sound radiation pattern on the box surface also closely related to the vibration amplitude distribution of the box structure at frequencies above the critical frequency. In the medium frequency range, the radiated sound field is dominated by the edge vibration pattern of the box. The radiation efficiency of all box modes reaches a peak at frequencies above the critical frequency, and gradually approaches unity at higher frequencies.

Mobiles In-a-Box : Reflections on Developing a Toolkit with Grassroots Human Rights Advocates

In 2008 Tactical Tech published 'Mobiles in-a-box': a toolkit designed to help human rights organisations and advocates use mobile technology in their work in Africa. This chapter reflects on the participatory development process used to develop the toolkit.

Investigating international accounting standard setting : the black box of IFRS 6

This paper examines the role of powerful entities and coalitions in shaping international accounting standards. Specifically, the focus is on the process by which the International Accounting Standards Board (IASB) developed IFRS 6, Exploration for and Evaluation of Mineral Resources. In its Issues Paper, the IASB recommended that the successful efforts method be mandated for pre-production costs, eliminating the choice previously available between full cost and successful efforts methods. In spite of the endorsement of this view by a majority of the constituents who responded to the Issues Paper, the final outcome changed nothing, with choice being retained. A compelling explanation of this disparity between the visible inputs and outputs of the standard setting process is the existence of a “black box”, in which powerful extractive industries entities and coalitions covertly influenced the IASB to secure their own ends and ensure that the status quo was maintained