scholarly journals Multiple Roles for the MyoD Basic Region in Transmission of Transcriptional Activation Signals and Interaction with MEF2

1998 ◽  
Vol 18 (1) ◽  
pp. 69-77 ◽  
Author(s):  
Brian L. Black ◽  
Jeffery D. Molkentin ◽  
Eric N. Olson
Keyword(s):  
Transcription Factors ◽  
Protein Interactions ◽  
Transcriptional Activation ◽  
Amino Acid Residues ◽  
Protein Protein Interactions ◽  
Activation Domain ◽  
Basic Domain ◽  
Helix Loop Helix ◽  
Bhlh Proteins ◽  
Basic Region

ABSTRACT Establishment of skeletal muscle lineages is controlled by the MyoD family of basic helix-loop-helix (bHLH) transcription factors. The ability of these factors to initiate myogenesis is dependent on two conserved amino acid residues, alanine and threonine, in the basic domains of these factors. It has been postulated that these two residues may be responsible for the initiation of myogenesis via interaction with an essential myogenic cofactor. The myogenic bHLH proteins cooperatively activate transcription and myogenesis through protein-protein interactions with members of the myocyte enhancer factor 2 (MEF2) family of MADS domain transcription factors. MyoD-E12 heterodimers interact with MEF2 proteins to synergistically activate myogenesis, while homodimers of E12, which lack the conserved alanine and threonine residues in the basic domain, do not interact with MEF2. We have examined whether the myogenic alanine and threonine in the MyoD basic region are required for interaction with MEF2. Here, we show that substitution of the MyoD basic domain with that of E12 does not prevent interaction with MEF2. Instead, the inability of alanine-threonine mutants of MyoD to initiate myogenesis is due to a failure to transmit transcriptional activation signals provided either from the MyoD or the MEF2 activation domain. This defect in transcriptional transmission can be overcome by substitution of the MyoD or the MEF2 activation domain with the VP16 activation domain. These results demonstrate that myogenic bHLH-MEF2 interaction can be uncoupled from transcriptional activation and support the idea that the myogenic residues in myogenic bHLH proteins are essential for transmission of a transcriptional activation signal.

scholarly journals Intramolecular Regulation of MyoD Activation Domain Conformation and Function

1998 ◽  
Vol 18 (9) ◽  
pp. 5478-5484 ◽  
Author(s):  
Jing Huang ◽  
Hal Weintraub ◽  
Larry Kedes
Keyword(s):  
Dna Binding ◽  
Transcriptional Activation ◽  
Activation Domain ◽  
Transcriptional Activation Domain ◽  
Helix Loop Helix ◽  
Dna Binding Specificity ◽  
E Box ◽  
And Function ◽  
Bhlh Proteins ◽  
Basic Region

ABSTRACT The MyoD family of basic helix-loop-helix (bHLH) proteins is required for myogenic determination and differentiation. The basic region carries the myogenic code and DNA binding specificity, while the N terminus contains a potent transcriptional activation domain. Myogenic activation is abolished when the basic region, bound to a myogenic E box, carries a mutation of Ala-114. It has been proposed that DNA binding of the MyoD basic region leads to recruitment of a recognition factor that unmasks the activation domain. Here we demonstrate that an A114N mutant exhibits an altered conformation in the basic region and that this local conformational difference can lead to a more global change affecting the conformation of the activation domain. This suggests that the deleterious effects of this class of mutations may result directly from defective conformation. Thus, the activation domain is unmasked only upon DNA binding by the correct basic region. Such a coupled conformational relationship may have evolved to restrict myogenic specificity to a small number of bHLH proteins among many with diverse functions yet with DNA binding specificities known to be similar.

scholarly journals A chimeric enhancer-of-split transcriptional activator drives neural development and achaete-scute expression.

1997 ◽  
Vol 17 (8) ◽  
pp. 4355-4362 ◽  
Author(s):  
G Jiménez ◽  
D Ish-Horowicz
Keyword(s):  
Neural Development ◽  
Transcriptional Activation ◽  
Target Genes ◽  
Wild Type ◽  
Activation Domain ◽  
Transcriptional Activation Domain ◽  
Helix Loop Helix ◽  
Inhibition Process ◽  
Bhlh Proteins ◽  
Enhancer Of Split

Drosophila melanogaster neurogenesis requires the opposing activities of two sets of basic helix-loop-helix (bHLH) proteins: proneural proteins, which confer on cells the ability to become neural precursors, and the Enhancer-of-split [E(spl)] proteins, which restrict such potential as part of the lateral inhibition process. Here, we test if E(spl) proteins function as promoter-bound repressors by examining the effects on neurogenesis of an E(spl) derivative containing a heterologous transcriptional activation domain [E(spl) m7Act (m7Act)]. In contrast to the wild-type E(spl) proteins, m7Act efficiently induces neural development, indicating that it binds to and activates target genes normally repressed by E(spl). Mutations in the basic domain disrupt m7Act activity, suggesting that its effects are mediated through direct DNA binding. m7Act causes ectopic transcription of the proneural achaete and scute genes. Our results support a model in which E(spl) proteins normally regulate neurogenesis by direct repression of genes at the top of the neural determination pathway.

scholarly journals Differential Regulation of Hand1 Homodimer and Hand1-E12 Heterodimer Activity by the Cofactor FHL2

2004 ◽  
Vol 24 (22) ◽  
pp. 9835-9847 ◽  
Author(s):  
Alison A. Hill ◽  
Paul R. Riley
Keyword(s):  
Protein Interactions ◽  
Differential Regulation ◽  
Protein Protein Interactions ◽  
Helix Loop Helix ◽  
Developing Heart ◽  
Unknown Protein ◽  
Class B ◽  
Bhlh Proteins

ABSTRACT The basic helix-loop-helix (bHLH) factor Hand1 plays an essential role in cardiac morphogenesis, and yet its precise function remains unknown. Protein-protein interactions involving Hand1 provide a means of determining how Hand1-induced gene expression in the developing heart might be regulated. Hand1 is known to form either heterodimers with near-ubiquitous E-factors and other lineage-restricted class B bHLH proteins or homodimers with itself in vitro. To date, there have been no reported Hand1 protein interactions involving non-bHLH proteins. Heterodimer-versus-homodimer choice is mediated by the phosphorylation status of Hand1; however, little is known about the in vivo function of these dimers or, importantly, how they are regulated. In an effort to understand how Hand1 activity in the heart might be regulated postdimerization, we have investigated tertiary Hand1-protein interactions with non-bHLH factors. We describe a novel interaction of Hand1 with the LIM domain protein FHL2, a known transcriptional coactivator and corepressor expressed in the developing cardiovascular system. FHL2 interacts with Hand1 via the bHLH domain and is able to repress Hand1/E12 heterodimer-induced transcription but has no effect on Hand1/Hand1 homodimer activity. This effect of FHL2 is not mediated either at the level of dimerization or via an effect of Hand1/E12 DNA binding. In summary, our data describe a novel differential regulation of Hand1 heterodimers versus homodimers by association of the cofactor FHL2 and provide insight into the potential for a tertiary level of control of Hand1 activity in the developing heart.

scholarly journals Cooperative Binding of Transcription Factors is a Hallmark of Active Enhancers

2020 ◽  
Author(s):  
Satyanarayan Rao ◽  
Kami Ahmad ◽  
Srinivas Ramachandran
Keyword(s):  
Transcription Factors ◽  
Single Molecule ◽  
Protein Interactions ◽  
Transcriptional Activation ◽  
Binding Sites ◽  
Gene Activation ◽  
Cooperative Binding ◽  
Protein Protein Interactions ◽  
Chromatin Profiling

AbstractEnhancers harbor binding motifs that recruit transcription factors (TFs) for gene activation. While cooperative binding of TFs at enhancers is known to be critical for transcriptional activation of a handful of developmental enhancers, the extent TF cooperativity genome-wide is unknown. Here, we couple high-resolution nuclease footprinting with single-molecule methylation profiling to characterize TF cooperativity at active enhancers in the Drosophila genome. Enrichment of short MNase-protected DNA segments indicates that the majority of enhancers harbor two or more TF binding sites, and we uncover protected fragments that correspond to co-bound sites in thousands of enhancers. We integrate MNase-seq, methylation accessibility profiling, and CUT&RUN chromatin profiling as a comprehensive strategy to characterize co-binding of the Trithorax-like (TRL) DNA binding protein and multiple other TFs and identify states where an enhancer is bound by no TF, by either single factor, by multiple factors, or where binding sites are occluded by nucleosomes. From the analysis of co-binding, we find that cooperativity dominates TF binding in vivo at a majority of active enhancers. TF cooperativity can occur without apparent protein-protein interactions and provides a mechanism to effectively clear nucleosomes and promote enhancer function.

c-Fos-induced activation of a TATA-box-containing promoter involves direct contact with TATA-box-binding protein

1994 ◽  
Vol 14 (9) ◽  
pp. 6021-6029
Author(s):  
R Metz ◽  
A J Bannister ◽  
J A Sutherland ◽  
C Hagemeier ◽  
E C O'Rourke ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Transcriptional Activation ◽  
Binding Protein ◽  
Tata Box ◽  
Binding Motif ◽  
Protein Protein Interactions ◽  
High Concentrations ◽  
Tata Box Binding Protein

Transcriptional activation in eukaryotes involves protein-protein interactions between regulatory transcription factors and components of the basal transcription machinery. Here we show that c-Fos, but not a related protein, Fra-1, can bind the TATA-box-binding protein (TBP) both in vitro and in vivo and that c-Fos can also interact with the transcription factor IID complex. High-affinity binding to TBP requires c-Fos activation modules which cooperate to activate transcription. One of these activation modules contains a TBP-binding motif (TBM) which was identified through its homology to TBP-binding viral activators. This motif is required for transcriptional activation, as well as TBP binding. Domain swap experiments indicate that a domain containing the TBM can confer TBP binding on Fra-1 both in vitro and in vivo. In vivo activation experiments indicate that a GAL4-Fos fusion can activate a promoter bearing a GAL4 site linked to a TATA box but that this activity does not occur at high concentrations of GAL4-Fos. This inhibition (squelching) of c-Fos activity is relieved by the presence of excess TBP, indicating that TBP is a direct functional target of c-Fos. Removing the TBM from c-Fos severely abrogates activation of a promoter containing a TATA box but does not affect activation of a promoter driven only by an initiator element. Collectively, these results suggest that c-Fos is able to activate via two distinct mechanisms, only one of which requires contact with TBP. Since TBP binding is not exhibited by Fra-1, TBP-mediated activation may be one characteristic that discriminates the function of Fos-related proteins.

Single zinc-finger extension: enhancing transcriptional activity and specificity of three-zinc-finger proteins

2005 ◽  
Vol 386 (2) ◽  
pp. 95-99 ◽  
Author(s):  
Alexander E.F. Smith ◽  
Farzin Farzaneh ◽  
Kevin G. Ford
Keyword(s):  
Transcription Factors ◽  
Fusion Protein ◽  
Zinc Finger ◽  
Protein Interactions ◽  
Transcriptional Activation ◽  
Zinc Finger Protein ◽  
Zinc Finger Proteins ◽  
Finger Protein ◽  
Finger Extension ◽  
Vp16 Fusion

AbstractIn order to demonstrate that an existing zinc-finger protein can be simply modified to enhance DNA binding and sequence discrimination in both episomal and chromatin contexts using existing zinc-finger DNA recognition code data, and without recourse to phage display and selection strategies, we have examined the consequences of a single zinc-finger extension to a synthetic three-zinc-finger VP16 fusion protein, on transcriptional activation from model target promoters harbouring the zinc-finger binding sequences. We report a nearly 10-fold enhanced transcriptional activation by the four-zinc-finger VP16 fusion protein relative to the progenitor three-finger VP16 protein in transient assays and a greater than five-fold enhancement in stable reporter-gene expression assays. A marked decrease in transcriptional activation was evident for the four-zinc-finger derivative from mutated regulatory regions compared to the progenitor protein, as a result of recognition site-size extension. This discriminatory effect was shown to be protein concentration-dependent. These observations suggest that four-zinc-finger proteins are stable functional motifs that can be a significant improvement over the progenitor three-zinc-finger protein, both in terms of specificity and the ability to target transcriptional function to promoters, and that single zinc-finger extension can therefore have a significant impact on DNA zinc-finger protein interactions. This is a simple route for modifying or enhancing the binding properties of existing synthetic zinc-finger-based transcription factors and may be particularly suited for the modification of endogenous zinc-finger transcription factors for promoter biasing applications.

scholarly journals Functional analysis of Met4, a yeast transcriptional activator responsive to S-adenosylmethionine.

1995 ◽  
Vol 15 (1) ◽  
pp. 208-216 ◽  
Author(s):  
L Kuras ◽  
D Thomas
Keyword(s):  
Transcriptional Activation ◽  
Leucine Zipper ◽  
Transcriptional Activator ◽  
Activation Function ◽  
Functional Domain ◽  
Distinct Region ◽  
Activation Domain ◽  
Inhibitory Region ◽  
Leucine Zipper Protein ◽  
Basic Region

Transcription of the genes necessary for sulfur amino acid biosynthesis in Saccharomyces cerevisiae is dependent on Met4, a transcriptional activator that belongs to the basic region-leucine zipper protein family. In this report, we show that one mechanism permitting the repression of the sulfur network by S-adenosylmethionine (AdoMet) involves inhibition of the transcriptional activation function of Met4. Using a wide array of deleted LexA-Met4 fusion proteins as well as various Gal4-Met4 hybrids, we identify the functional domains of Met4 and characterize their relationship. Met4 appears to contain only one activation domain, located in its N-terminal part. We demonstrate that this activation domain functions in a constitutive manner and that AdoMet responsiveness requires a distinct region of Met4. Furthermore, we show that when fused to a heterologous activation domain, this inhibitory region confers inhibition by AdoMet. Met4 contains another distinct functional domain that appears to function as an antagonist of the inhibitory region when intracellular AdoMet is low. On the basis of the presented results, a model for intramolecular regulation of Met4 is proposed.

scholarly journals Atoh8 in Development and Disease

Biology ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 136
Author(s):  
Satya Srirama Karthik Divvela ◽  
Darius Saberi ◽  
Beate Brand-Saberi
Keyword(s):  
Transcription Factors ◽  
Embryonic Development ◽  
Subcellular Location ◽  
Transcriptional Regulators ◽  
Special Group ◽  
Helix Loop Helix ◽  
Wide Range ◽  
Disease Initiation ◽  
Bhlh Transcription Factors ◽  
Bhlh Proteins

Atoh8 belongs to a large superfamily of transcriptional regulators called basic helix-loop-helix (bHLH) proteins. bHLH proteins have been identified in a wide range of organisms from yeast to humans. The members of this special group of transcription factors were found to be involved not only in embryonic development but also in disease initiation and its progression. Given their importance in several fundamental processes, the translation, subcellular location and turnover of bHLH proteins is tightly regulated. Alterations in the expression of bHLH proteins have been associated with multiple diseases also in context with Atoh8 which seems to unfold its functions as both transcriptional activator and repressor. Like many other bHLH transcription factors, so far, Atoh8 has also been observed to be involved in both embryonic development and carcinogenesis where it mainly acts as tumor suppressor. This review summarizes our current understanding of Atoh8 structure, function and regulation and its complex and partially controversial involvement in development and disease.

scholarly journals Group I Metabotropic Glutamate Receptors and Interacting Partners: An Update

2022 ◽  
Vol 23 (2) ◽  
pp. 840
Author(s):  
Li-Min Mao ◽  
Alaya Bodepudi ◽  
Xiang-Ping Chu ◽  
John Q. Wang
Keyword(s):  
Synaptic Plasticity ◽  
Protein Interactions ◽  
Metabotropic Glutamate Receptors ◽  
Adaptor Proteins ◽  
Mammalian Brain ◽  
Amino Acid Residues ◽  
Protein Protein Interactions ◽  
Metabotropic Glutamate ◽  
Group I ◽  
Associated Proteins

Group I metabotropic glutamate (mGlu) receptors (mGlu1/5 subtypes) are G protein-coupled receptors and are broadly expressed in the mammalian brain. These receptors play key roles in the modulation of normal glutamatergic transmission and synaptic plasticity, and abnormal mGlu1/5 signaling is linked to the pathogenesis and symptomatology of various mental and neurological disorders. Group I mGlu receptors are noticeably regulated via a mechanism involving dynamic protein–protein interactions. Several synaptic protein kinases were recently found to directly bind to the intracellular domains of mGlu1/5 receptors and phosphorylate the receptors at distinct amino acid residues. A variety of scaffolding and adaptor proteins also interact with mGlu1/5. Constitutive or activity-dependent interactions between mGlu1/5 and their interacting partners modulate trafficking, anchoring, and expression of the receptors. The mGlu1/5-associated proteins also finetune the efficacy of mGlu1/5 postreceptor signaling and mGlu1/5-mediated synaptic plasticity. This review analyzes the data from recent studies and provides an update on the biochemical and physiological properties of a set of proteins or molecules that interact with and thus regulate mGlu1/5 receptors.

scholarly journals Characterization of COMMD protein–protein interactions in NF-κB signalling

2006 ◽  
Vol 398 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Prim de Bie ◽  
Bart van de Sluis ◽  
Ezra Burstein ◽  
Karen J. Duran ◽  
Ruud Berger ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Copper Metabolism ◽  
Nuclear Factor Κb ◽  
Inhibitory Effect ◽  
Protein Family ◽  
Amino Acid Residues ◽  
Protein Protein Interactions ◽  
Necrosis Factor

COMMD [copper metabolism gene MURR1 (mouse U2af1-rs1 region 1) domain] proteins constitute a recently identified family of NF-κB (nuclear factor κB)-inhibiting proteins, characterized by the presence of the COMM domain. In the present paper, we report detailed investigation of the role of this protein family, and specifically the role of the COMM domain, in NF-κB signalling through characterization of protein–protein interactions involving COMMD proteins. The small ubiquitously expressed COMMD6 consists primarily of the COMM domain. Therefore COMMD1 and COMMD6 were analysed further as prototype members of the COMMD protein family. Using specific antisera, interaction between endogenous COMMD1 and COMMD6 is described. This interaction was verified by independent techniques, appeared to be direct and could be detected throughout the whole cell, including the nucleus. Both proteins inhibit TNF (tumour necrosis factor)-induced NF-κB activation in a non-synergistic manner. Mutation of the amino acid residues Trp24 and Pro41 in the COMM domain of COMMD6 completely abolished the inhibitory effect of COMMD6 on TNF-induced NF-κB activation, but this was not accompanied by loss of interaction with COMMD1, COMMD6 or the NF-κB subunit RelA. In contrast with COMMD1, COMMD6 does not bind to IκBα (inhibitory κBα), indicating that both proteins inhibit NF-κB in an overlapping, but not completely similar, manner. Taken together, these data support the significance of COMMD protein–protein interactions and provide new mechanistic insight into the function of this protein family in NF-κB signalling.

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