Structure, function, evolution of transcription factor IIIA.
Explore the source record for details and available documents.
SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
Regulation of gene expression helps determine various phenotypes in most cellular life forms. It is orchestrated at different levels and at the point of transcription initiation by transcription factors (TFs). TFs bind to DNA through domains that are evolutionarily related, by shared membership of the same superfamilies (TF-SFs), to those found in other nucleic acid binding and protein-binding functions (nTFs for non-TFs). Here we ask how TF DNA binding sequence families in eukaryotes have evolved in relation to their nTF relatives. TF numbers scale by power law with the total number of protein-coding genes differently in different clades, with fungi usually showing sub-linear powers whereas chordates show super-linear scaling. The LECA probably encoded a complex regulatory machinery with both TFs and nTFs, but with an excess of nTFs when compared to the relative distribution of TFs and nTFs in extant organisms. Losses drive the evolution of TFs and nTFs, with the possible exception of TFs in animals for some tree topologies. TFs are highly dynamic in evolution, showing higher gain and loss rates than nTFs in some TF-SFs though both are conserved to similar extents. Gains of TFs and nTFs are driven by the appearance of a large number of new sequence clusters in a small number of nodes, which determine the presence of as many as a third of extant TFs and nTFs as well as the relative presence of TFs and nTFs. Whereas nodes showing explosion of TF numbers belong to multicellular clades, those for nTFs lie among the fungi and the protists.
Vertebrate erythroid cells contain a tissue-specific transcription factor referred to as Eryf 1 (ref. 1), GF-1 (ref. 2) or NF-E1 (ref. 3), for which binding sites are widely distributed in the promoters and enhancers of the globin gene family, and of other erythroid-specific genes. Aberrant binding of the human factor to a mutant site has been implicated in one form of hereditary persistence of fetal haemoglobin (HPFH; ref. 2). The complementary DNAs for both the chicken cEryf 1 (ref. 11) and mouse mEryf 1 (ref. 12) encoding genes have recently been cloned. We report here the cloning of the cDNA for the human Eryf 1 encoding gene. The central third of the hEryf 1 cDNA, containing two 'finger' motifs, is almost identical to that of chicken or mouse. The amino-and carboxy-terminal thirds of the human protein are similar to those of mouse, but are strikingly different from the corresponding domains in chicken. The evidence indicates that these erythroid regulatory factors evolved from a common precursor composed of two distinct kinds of repeated domains, which subsequently evolved at greatly different rates.
Pou domain transcription factor Pou4f2 is essential for the development of retinal ganglion cells (RGCs) in the vertebrate retina. A distant orthologue of Pou4f2 exists in the genome of the sea urchin (class Echinoidea) Strongylocentrotus purpuratus (SpPou4f1/2), yet the photosensory structure of sea urchins is strikingly different from that of the mammalian retina. Sea urchins have no obvious eyes, but have photoreceptors clustered around their tube feet disc. The mechanisms that are associated with the development and function of photoreception in sea urchins are largely unexplored. As an initial approach to better understand the sea urchin photosensory structure and relate it to the mammalian retina, we asked whether SpPou4f1/2 could support RGC development in the absence of Pou4f2. To answer this question, we replaced genomic Pou4f2 with an SpPou4f1/2 cDNA. In Pou4f2-null mice, retinas expressing SpPou4f1/2 were outwardly identical to those of wild-type mice. SpPou4f1/2 retinas exhibited dark-adapted electroretinogram scotopic threshold responses, indicating functionally active RGCs. During retinal development, SpPou4f1/2 activated RGC-specific genes and in S. purpuratus, SpPou4f2 was expressed in photoreceptor cells of tube feet in a pattern distinct from Opsin4 and Pax6. Our results suggest that SpPou4f1/2 and Pou4f2 share conserved components of a gene network for photosensory development and they maintain their conserved intrinsic functions despite vast morphological differences in mouse and sea urchin photosensory structures.
As important members of the ETS superfamily, the E74-like factor (ELF) transcription factor family regulates gene transcription through a conserved ETS domain and plays critical roles in immune regulation. However, the evolutionary characteristics and functions of this family in lampreys (Lethenteron reissneri) remain unclear. In this study, the ELF gene family of lampreys (Lr-ELF1, Lr-ELF2, Lr-ELF3, and Lr-ELF5) was systematically identified, and their molecular evolutionary features and immune response functions were investigated. Phylogenetic analysis revealed evolutionary characteristics reflecting the transition from jawless to jawed vertebrates. Domain architecture, gene structure, and three-dimensional structural analyses indicated that these genes appear to be conserved among vertebrates, with their three-dimensional structures showing high similarity to the core secondary structural elements of human homologous proteins. Synteny analysis demonstrated significant differences in the genomic neighborhoods of ELF genes between lampreys and jawed vertebrates. Quantitative real-time PCR (qRT-PCR) was performed with three biological and three technical replicates; relative expression levels were calculated using the ΔCt method, and statistical analysis was carried out with GraphPad Prism 9. Quantitative real-time PCR (qRT-PCR) results suggested that the ELF gene family may be involved in immune defense. This study not only enriches our understanding of the evolution of ELF genes but also provides new insights into the roles of lamprey ELFs in immune defense.
The DNA sequence motif ATTTGCAT (octamer) or its inverse complement has been identified as an evolutionarily conserved element in the promoter region of immunoglobulin genes. Two major DNA-binding proteins that bind in a sequence-specific manner to the octamer DNA sequence have been identified in mammalian species--a ubiquitously expressed protein (Oct-1) and a lymphoid-specific protein (Oct-2). During characterization of the promoter region of the chicken immunoglobulin light chain gene, we identified two homologous octamer-binding proteins in chicken B cells. When the cloning of the human gene for Oct-2 revealed it to be a member of a distinct family of homeobox genes, we sought to determine if the human Oct-2 cDNA could be used to identify homologous chicken homeobox genes. Using a human Oct-2 homeobox-specific DNA probe, we were able to identify 6-10 homeobox-containing genes in the chicken genome, demonstrating that the Oct-2-related subfamily of homeobox genes exists in avian species. Low-stringency screening of a chicken embryonic cDNA library allowed us to clone one of these genes. DNA sequence analysis revealed it to be the chicken homologue of the human Oct-1 gene. The predicted protein sequence of the chicken Oct-1 gene demonstrated that the gene for Oct-1 has been highly conserved during vertebrate evolution with an overall 96% amino acid sequence identity between the chicken and human proteins. The previously described POU domain (termed POU for its presence in the Pit-1, Oct-1/Oct-2, and Unc-86 genes) and homeobox domain are 100% conserved between the two protein products. Together, our data show that the POU-containing subfamily of homeobox genes have been highly conserved during vertebrate evolution, apparently as a result of selection for their DNA-binding and transcriptional regulatory properties.
Promoter-proximal pausing of RNA polymerase (Pol) II is a key regulatory step during transcription. Despite the central role of pausing in gene regulation, we do not understand the evolutionary processes that led to the emergence of Pol II pausing or its transition to a rate-limiting step actively controlled by transcription factors. Here, we analyzed transcription in species across the tree of life. Unicellular eukaryotes display an accumulation of Pol II near transcription start sites, which we propose transitioned to the longer-lived, focused pause observed in metazoans. This transition coincided with the evolution of new subunits in the negative elongation factor (NELF) and 7SK complexes. Depletion of NELF in mammals shifted the promoter-proximal buildup of Pol II from the pause site into the early gene body and compromised transcriptional activation for a set of heat-shock genes. Our work details the evolutionary history of Pol II pausing and sheds light on how new transcriptional regulatory mechanisms evolve.
The embryonal long terminal repeat-binding protein, ELP, is present in undifferentiated mouse embryonal carcinoma cells. It binds to and suppresses transcription of the Moloney leukemia virus long terminal repeat in undifferentiated murine embryonal carcinoma cells. We report here that ELP is a mouse homolog of Drosophila FTZ-F1, which positively regulates transcription of the fushi tarazu gene in blastoderm-stage embryos of the fly. As members of the steroid receptor superfamily, ELP and FTZ-F1 have both DNA binding and putative ligand binding domains which are well conserved between the two. ELP and FTZ-F1 function in cells in the extremely early stage of development. A high degree of conservation between the two transcription factors during the evolution of these species indicates the importance of their functions in early-stage embryogenesis. In addition, the sequence elements they recognize do not contain repeat units, in contrast to other steroid receptors, which usually bind to either palindromic or direct repeat sequences.
Germline mutations in GATA2 cause a syndromic inborn error of immunity characterized by cytopenia, infections, immune dysregulation, and a marked predisposition to myelodysplastic syndrome and acute myeloid leukemia. Initially defined by the DCML phenotype-dendritic cell, monocyte, B- and NK-cell deficiency-GATA2 deficiency is now recognized as a disorder of global immune-hematopoietic homeostasis. Recent multi-omics and experimental models reveal enhancer-driven inflammatory rewiring, IRF8-dependent lineage imbalance, and premature hematopoietic aging. In parallel, adaptive immune defects, including impaired B- and T-cell development and function, contribute to defective immune surveillance. These alterations not only explain susceptibility to infection but also shape clonal evolution and malignant transformation. Clinically, improved risk stratification and transplant outcomes underscore the importance of early recognition and monitoring of immune dysfunction. GATA2 deficiency thus represents a paradigm linking immune dysregulation, inflammatory stress, and cancer predisposition.
The heat shock response and the heat shock proteins have been conserved across evolution. In Escherichia coli, the heat shock response is positively regulated by the sigma 32 transcriptional factor and negatively regulated by a subset of the heat shock proteins themselves. In an effort to understand the regulation of the heat shock response, we have purified the sigma 32 polypeptide to homogeneity. During the purification procedure, we found that a large fraction of the overexpressed sigma 32 polypeptide copurified with the universally conserved DnaK heat shock protein (the prokaryotic equivalent of the 70-kDa heat shock protein, HSP70). Further experiments established that purified sigma 32 bound to DnaK and that this complex was disrupted in the presence of ATP. Consistent with the fact that dnaK756 mutant bacteria overexpress heat shock proteins at all temperatures, purified DnaK756 mutant protein did not appreciably bind to sigma 32.
We have characterized the structure of the human chromosomal gene for the 25 kilodalton insulin-like growth factor binding protein (BP-25) as a first step toward understanding both the factors which regulate BP-25 transcription and also the evolution of the insulin-like growth factor binding proteins. The BP-25 gene is present in the human genome as a single copy which spans 5.2 kilobases and contains four exons. Primer extension localizes the mRNA cap site 165 base pairs (bp) upstream of the ATG translational start codon. Preliminary analysis of the putative promoter region for BP-25 demonstrates characteristics consistent with those of many eukaryotic promoters; these include a consensus TATA box beginning 28 bp 5' to the cap site and a consensus CCAAT promoter element beginning 72 bp upstream from the cap site.
MCM1 and SRF bind to the same DNA sequence and form ternary complexes with STE12 and p62TCF, respectively. We show that in gel retardation assays, MCM1 recruits both ternary complex factors whereas SRF interacts only with p62TCF. A protein domain of 90 amino acids, shared by MCM1 and SRF, was found to be sufficient for ternary complex formation. The domain is also required for dimerization and DNA binding. Similar regions are found in other proteins, such as ARG80, Deficiens and Agamous. ARG80 and Agamous exhibit similar DNA binding specificities but do not interact with either STE12 or p62TCF. By exchanging three residues of ARG80 with those of corresponding positions in SRF (residues 198, 200 and 203), the ARG80 protein acquires the ability to recruit p62TCF into a ternary complex. Likewise, the substitution of four SRF amino acids by MCM1-derived residues (amino acids 73, 75, 77 and 78) confers on SRF the ability to interact with STE12. Thus, we have identified specific amino acids in MCM1 and SRF that are critical for ternary complex formation and which map to equivalent positions within the shared domains. Therefore, the structural basis for specific protein-protein interaction appears to be conserved in evolution between a class of transcription factors.
Gcm1 and Gcm2 are paralogous transcription factors in vertebrates that play key roles in the development of pharyngeal-derived epithelia, yet their deployment across vertebrate lineages remains incompletely understood. While Gcm2 shows deeply conserved pharyngeal expression across gnathostomes, Gcm1 has been mainly characterized in mammals, where it exhibits broader expression patterns. How Gcm1 is deployed in non-mammalian vertebrates has remained unexplored. Here, we performed a comparative analysis of Gcm1 expression in cartilaginous fishes, non-teleost actinopterygians, and amphibians. RNA in situ hybridization revealed conserved Gcm1 expression in gill epithelia across these taxa. Parallel analyses showed that Gcm2 is also expressed in gill epithelia, with overlapping but distinct spatial patterns. In addition, Gcm1 showed lineage-specific expression in bichir embryos, including strong expression in external gills and scattered epithelial cells in the yolk-sac membrane. In the external gills, Gcm1-positive cells possess vacuole-like cytoplasmic structures, suggesting a previously unrecognized epithelial cell population. Together, our findings indicate that Gcm1 and Gcm2 share ancestral expression in pharyngeal epithelia but have followed distinct evolutionary trajectories, with Gcm1 exhibiting greater lineage-specific diversification.
Sex determination in vertebrates exhibits remarkable evolutionary plasticity, with diverse mechanisms and master sex-determining (MSD) genes arising independently across lineages. Among these, dmrt1, a dosage-sensitive gene, has repeatedly been recruited as an MSD gene through gene duplication or allelic diversification. However, the biochemical basis of such evolutionary transitions, particularly those driven by allelic diversification, remains largely unexplored. Here, we generated haplotype-resolved genome assemblies for both XX and XY black carp (Mylopharyngodon piceus) and identified a ∼40-kb region on chromosome 4, containing only dmrt1, as the candidate sex-determining locus. We discovered two Y-specific insertions in the dmrt1 promoter: a 13.4-kb highly repetitive element and an 11-bp motif. Functional assays revealed that these insertions act as enhancer and a promoter element, respectively, driving early, allele-specific upregulation of dmrt1 prior to gonadal differentiation. Notably, the 13.4-kb insertion contains transposable elements (TEs) functioning as cis-regulatory modules with transcription factor binding sites that mediate Y-specific activation. Our findings reveal a TE-mediated regulatory innovation that promoted dmrt1's evolution as a male-determining gene via allelic diversification, providing new insights into how mobile genetic elements drive the origin and diversification of sex-determining systems in vertebrates.
Sequence specific binding of protein extracts from 13 different yeast species to three oligonucleotide probes and two points mutants derived from Saccharomyces cerevisiae DNA binding proteins were tested using mobility shift assays. The probes were high affinity binding sites for GRF1/RAP1/ABF1 and CP1/CPF1. Most yeasts in the genus Saccharomyces showed specific binding to all three probes and also displayed similar sequence requirements when challenged by molar excesses of mutant probes. The affinities for the probes varied amongst the other yeasts tested, but in general, CPF1 binding activity was the most widespread, while the other two were more limited.
A post-transcriptional regulatory protein, termed iron regulatory factor (IRF), that binds specifically to the iron-responsive elements of ferritin and transferrin receptor mRNA, has recently been identified in the cytoplasm of human and mouse cells. Activation of this factor by low intracellular iron levels leads to inhibition of ferritin translation and an increase of TR mRNA stability. To investigate whether these feedback regulatory mechanisms are conserved during evolution, we analysed cytoplasmic extracts from 12 different species for a specific IRE-binding activity. We found mRNA-binding proteins in chicken, frog, fish and fly, which are equivalent to human and mouse IRF in gel-retardation assays with radiolabeled RNA transcripts. Competition experiments, molecular weight determinations, and modulation of the mRNA-binding activity in response to intracellular iron levels or reduction by beta-mercaptoethanol indicate that IRF has similar structural and functional properties in these different species.
Haematological malignancies arise as a consequence of clonal evolution driven by an accumulation of somatic mutations. Many haematological malignancies are associated with chromosome translocations that have provided powerful tools for the identification of proto-oncogenes implicated in the pathogenesis of leukaemia/lymphoma. The recent characterisation of several translocation breakpoints associated with human haematological tumours has demonstrated that genes encoding transcription factors are frequently involved. Direct alteration of transcription factor activity by somatic mutation may represent a particularly powerful leukaemogenic event.
Transcriptional promoters of mitochondrial DNA have diverged extensively in the course of mammalian evolution. Nevertheless, the transcriptional machinery and the overall mechanisms of transcriptional control and regulation seem to be conserved. We have compared the human and murine homologs of the major DNA-binding transcriptional activator, mitochondrial transcription factor 1 (mtTF1), with unexpected results. Both proteins have similar chromatographic and transcriptional properties and are the same size. Both recognize and bind sequences between -12 and -39 within their respective homologous promoters. However, the sequences that they recognize are markedly divergent; although the base pairs they contact are situated similarly or identically with respect to the transcriptional start site, sequence identity between the two species' contact points is less than 50%. Interestingly, the two proteins are functionally interchangeable; each can bind to the heterologous light-strand promoter and can activate transcription by the heterologous mitochondrial RNA polymerase. Thus, the RNA polymerase or some as yet undetected transcription factor, rather than mTF1, may determine the strict species specificity of mitochondrial transcription. Flexible DNA sequence recognition by mtTF1, on the other hand, may be a principal facilitating mechanism for rapid control sequence evolution.