Distribution Of Transcription Factors Research Articles

Genome-Wide Identification of Zn2Cys6 Class Fungal-Specific Transcription Factors (ZnFTFs) and Functional Analysis of UvZnFTF1 in Ustilaginoidea virens

Transcription factors (TFs) orchestrate the regulation of cellular gene expression and thereby determine cell functionality. In this study, we analyzed the distribution of TFs containing domains, which named as ZnFTFs, both in ascomycete and basidiomycete fungi. We found that ZnFTFs were widely distributed in these fungal species, but there was more expansion of the ZnFTF class in Ascomycota than Basidiomycota. We identified 40 ZnFTFs in Ustilaginoidea virens, and demonstrated the involvement of UvZnFTF1 in vegetative growth, conidiation, pigment biosynthesis and pathogenicity. RNA-Seq analysis suggested that UvZnFTF1 may regulate different nutrient metabolism pathways, the production of secondary metabolites, and the expression of pathogen-host interaction genes and secreted protein- encoding genes. Analysis of the distribution of different fungal TFs in U. virens further demonstrated that UvZnFTFs make up a large TF family and may play essential biological roles in U. virens.

Dynamical reorganization of the pluripotency transcription factors Oct4 and Sox2 during early differentiation of embryonic stem cells

Pluripotency maintenance requires transcription factors (TFs) that induce genes necessary to preserve the undifferentiated state and repress others involved in differentiation. Recent observations support that the heterogeneous distribution of TFs in the nucleus impacts on gene expression. Thus, it is essential to explore how TFs dynamically organize to fully understand their role in transcription regulation. Here, we examine the distribution of pluripotency TFs Oct4 and Sox2 in the nucleus of embryonic stem (ES) cells and inquire whether their organization changes during early differentiation stages preceding their downregulation. Using ES cells expressing Oct4-YPet or Sox2-YPet, we show that Oct4 and Sox2 partition between nucleoplasm and a few chromatin-dense foci which restructure after inducing differentiation by 2i/LIF withdrawal. Fluorescence correlation spectroscopy showed distinct changes in Oct4 and Sox2 dynamics after differentiation induction. Specifically, we detected an impairment of Oct4-chromatin interactions whereas Sox2 only showed slight variations in its short-lived, and probably more unspecific, interactions with chromatin. Our results reveal that differentiation cues trigger early changes of Oct4 and Sox2 nuclear distributions that also include modifications in TF-chromatin interactions. This dynamical reorganization precedes Oct4 and Sox2 downregulation and may contribute to modulate their function at early differentiation stages.

Genome-wide identification, classification, and expression analysis of TCP transcription factors in carrot

Carrot (Daucus carota L.) is a crop with rich nutritional value and is one of the most important economical horticulture crops worldwide. The TEOSINTE BRANCHED 1, CYCLOIDEA, PROLIFERATING CELL FACTORS (TCP) transcription factor (TF) family plays important roles in several physiological processes; However, TCP TFs in carrot are rarely reported. In this study, 36 D. carota TCP (DcTCP) TFs were identified from the carrot genome database. On the basis of phylogenetic relationship with TCP TFs in Arabidopsis, the DcTCP family was divided into two classes, namely class I and class II (including CIN and CYC/TB1 subclass). The number of DcTCP TFs in classes I and II were 22 and 14, respectively. Motif analysis and chromosome location of DcTCP TFs were also conducted. All of the DcTCP genes were distributed on nine chromosomes of carrot. The distribution of TCP TFs in different species indicates that the number of TCP TFs is consistent with plant evolution. Quantitative real-time PCR assay was performed to further understand the expression patterns of DcTCP genes during the development of carrot. The expression levels of DcTCP33 and DcTCP36 increased with the germination of carrot seed. The CIN subclass of DcTCPs (DcTCP1, DcTCP4, and DcTCP5) was primarily expressed in leaf blades, whereas the DcTCP26 gene was mainly expressed in roots. These results can provide potentially useful information about TCP TF identification and help explain the roles of TCP TFs in carrots.

Low-Affinity Binding Sites and the Transcription Factor Specificity Paradox in Eukaryotes.

Eukaryotic transcription factors (TFs) from the same structural family tend to bind similar DNA sequences, despite the ability of these TFs to execute distinct functions in vivo. The cell partly resolves this specificity paradox through combinatorial strategies and the use of low-affinity binding sites, which are better able to distinguish between similar TFs. However, because these sites have low affinity, it is challenging to understand how TFs recognize them in vivo. Here, we summarize recent findings and technological advancements that allow for the quantification and mechanistic interpretation of TF recognition across a wide range of affinities. We propose a model that integrates insights from the fields of genetics and cell biology to provide further conceptual understanding of TF binding specificity. We argue that in eukaryotes, target specificity is driven by an inhomogeneous 3D nuclear distribution of TFs and by variation in DNA binding affinity such that locally elevated TF concentration allows low-affinity binding sites to be functional.

Identification of a 42-bp heart-specific enhancer of the notch1b gene in zebrafish embryos.

NOTCH1 plays a key role in the differentiation of ventricles, and mutations are strongly associated with both sporadic and familial bicuspid aortic valves. However, few heart-specific enhancers have been identified to date. In this study, we investigated evolutionary conserved regions (ECRs) that might act as potential enhancers within the region approximately 150-kb upstream and downstream of the NOTCH1 gene. Functional validation revealed that one 127-bp ECR located ~85-kb downstream of the NOTCH1 gene drives green fluorescent protein expression in the zebrafish embryo heart. Transcription factor (TF) prediction and core TF distribution analyses were performed to identify the core region. Dissection of ECR3 was performed to identify the 42-bp sequence, which is sufficient for heart-specific expression. In situ hybridization experiments showed that notch1b is expressed in the heart. Overexpression experiments in cells indicated that NKX2-5 is critical for enhancer activity. Mutation of the NKX-5 binding site significantly decreased reporter gene expression. Next, compared with the commonly used myocardium-labeled zebrafish transgenic strain Tg(cmlc2: mCherry), this 42-bp enhancer-labeled stable line mediated a similar expression pattern but with a smaller core region. This study identified a 42-bp heart-specific enhancer near the NOTCH1 gene and further verified its functional targeting by NKX2-5.

Genetic Mapping and Comparative Expression Analysis of Transcription Factors in Cotton

Transcription factors (TFs) play an important role in the regulation of plant growth and development. The study of the structure and function of TFs represents a research frontier in plant molecular biology. The findings of these studies will provide significant information regarding genetic improvement traits in crops. Currently, a large number of TFs have been cloned, and their function has been verified. However, relatively few studies that genetically map TFs in cotton are available. To genetically map TFs in cotton in this study, specific primers were designed for TF genes that were published in the Plant Transcription Factor Database. A total of 977 TF primers were obtained, and 31 TF polymorphic loci were mapped on 15 cotton chromosomes. These polymorphic loci were clearly preferentially distributed on chromosomes 5, 11, 19 and 20; and TFs from the same family mapped to homologous cotton chromosomes. In-silico mapping verified that many mapped TFs were mapped on their corresponding chromosomes or their homologous chromosomes’ corresponding chromosomes in the diploid genomes. QTL mapping for fiber quality revealed that TF-Ghi005602-2 mapped on Chr19 was associated with fiber length. Eighty-five TF genes were selected for RT-PCR analysis, and 4 TFs were selected for qRT-PCR analysis, revealing unique expression patterns across different stages of fiber development between the mapping parents. Our data offer an overview of the chromosomal distribution of TFs in cotton, and the comparative expression analysis between Gossypium hirsutum and G. barbadense provides a rough understanding of the regulation of TFs during cotton fiber development.

Are clustered genes in the genomes of Arabidopsis and Drosophila regulated differently?

In the eukaryotic genome, genes with similar functions tend to co-localize in close proximity. Such gene clusters together with non-clustered genes constitute a chromatin domain which is a higher order regulatory unit. On a lower level co-expressed genes are regulated by differential activity of transcription factors (TF). We compared genome-wide distributions of TF in gene clusters in the genomes of Drosophila melanogaster and Arabidopsis thaliana. This revealed a significant excess of TF genes in gene clusters of the Arabidopsis genome, whereas in the genome of Drosophila distribution of TF in gene clusters did not differ from stochastic. We speculate that these alternatives could lead to different pathways of regulation of clustered genes in two species and to evolutionary-progressive changes in architecture of regulatory networks, governing the activity of clustered genes in the animal kingdom.

FTFD: an informatics pipeline supporting phylogenomic analysis of fungal transcription factors

Genomes of more than 60 fungal species have been sequenced to date, yet there has been no systematic approach to analyze fungal transcription factors (TFs) kingdom widely. We developed a standardized pipeline for annotating TFs in fungal genomes. Resulting data have been archived in a new database termed the Fungal Transcription Factor Database (FTFD). In FTFD, 31,832 putative fungal TFs, identified from 62 fungal and 3 Oomycete species, were classified into 61 families and phylogenetically analyzed. The FTFD will serve as a community resource supporting comparative analyses of the distribution and domain structure of TFs within and across species. All data described in this study can be browsed through the FTFD web site at http://ftfd.snu.ac.kr/.