Transcription regulator. Forms a sequence-specific DNA-binding protein complex with MYC or MAD which recognizes the core sequence 5'-CAC[GA]TG-3'. The MYC-MAX complex is a transcriptional activator, whereas the MAD-MAX complex is a repressor. May repress transcription via the recruitment of a chromatin remodeling complex containing H3 'Lys-9' histone methyltransferase activity.
Interacting selectively and non-covalently with any protein or protein complex (a complex of two or more proteins that may include other nonprotein molecules).
Evidence
1:
Inferred from Physical InteractionIntAct
The Myc oncoprotein family comprises transcription factors that control multiple cellular functions and are widely involved in oncogenesis. Here we report the identification of Myc-nick, a cytoplasmic form of Myc generated by calpain-dependent proteolysis at lysine 298 of full-length Myc. Myc-nick retains conserved Myc box regions but lacks nuclear localization signals and the bHLHZ domain essential for heterodimerization with Max and DNA binding. Myc-nick induces alpha-tubulin acetylation and altered cell morphology by recruiting histone acetyltransferase GCN5 to microtubules. During muscle differentiation, while the levels of full-length Myc diminish, Myc-nick and acetylated alpha-tubulin levels are increased. Ectopic expression of Myc-nick accelerates myoblast fusion, triggers the expression of myogenic markers, and permits Myc-deficient fibroblasts to transdifferentiate in response to MyoD. We propose that the cleavage of Myc by calpain abrogates the transcriptional inhibition of differentiation by full-length Myc and generates Myc-nick, a driver of cytoplasmic reorganization and differentiation.
Evidence
2:
Inferred from Physical InteractionIntAct
The c-Myc oncoprotein plays a central role in human cancer via its ability to either activate or repress the transcription of essential downstream targets. For many of the repressed target genes, down-regulation by c-Myc relies on its ability to bind and inactivate the transcription factor Miz-1. Although Miz-1 inactivation is suspected to be essential for at least some of the biological activities of c-Myc, it has been difficult to demonstrate this requirement experimentally. Using a combination of short hairpin RNA-mediated knockdown and a previously characterized mutant of c-Myc that is defective for Miz-1 inactivation, we examined whether this inactivation is critical for three of the most central biological functions of c-Myc, cell cycle progression, transformation, and apoptosis. The results of this analysis demonstrated that in the in vitro assays utilized here, Miz-1 inactivation is dispensable for c-Myc-induced cell cycle progression and transformation. In marked contrast, the ability of c-Myc to induce apoptosis in primary diploid human fibroblasts in response to growth factor withdrawal is entirely dependent on its ability to inactivate Miz-1. These data have a significant impact on our understanding of the biochemical mechanisms dictating how c-Myc mediates opposing biological functions, such as transformation and apoptosis, and demonstrate the first requirement for Miz-1 inactivation in any of the biological functions of c-Myc.
Evidence
3:
Inferred from Physical InteractionIntAct
The c-Myc oncoprotein plays critical roles in multiple biological processes by controlling cell proliferation, apoptosis, differentiation, and metabolism. Especially, c-Myc is frequently overexpressed in many human cancers and widely involved in tumorigenesis. However, how the post-translational modifications, especially acetylation of c-Myc, contribute to its activity in the leukemia cells remains largely unknown. Sirt1, a NAD-dependent class III histone deacetylase, has a paradoxical role in tumorigenesis by deacetylating several transcription factors, including p53, E2F1 and forkhead proteins. In this study, we show that Sirt1 interacts physically with the C-terminus of c-Myc and deacetylates c-Myc both in vitro and in vivo. Moreover, the deacetylation of c-Myc by Sirt1 promotes its association with Max, a partner essential for its activation, thereby facilitating c-Myc transactivation activity on hTERT promoter. Finally, inhibition of endogenous Sirt1 in K562 cells by either RNAi or its inhibitor NAM causes the overall decrease of c-Myc target genes expression, including hTERT, cyclinD2 and LDHA, which further suppress cell proliferation and arrest cell cycle at G1/S phase. Thus, our results demonstrate the positive effect of Sirt1 on c-Myc activity by efficiently enhancing c-Myc/Max association in human leukemia cell line K562, suggesting a potential role of Sirt1 in tumorigenesis.
Evidence
4:
Inferred from Physical InteractionIntAct
HIF-2alpha promotes von Hippel-Lindau (VHL)-deficient renal clear cell carcinoma (RCC) tumorigenesis, while HIF-1alpha inhibits RCC growth. As HIF-1alpha antagonizes c-Myc function, we hypothesized that HIF-2alpha might enhance c-Myc activity. We demonstrate here that HIF-2alpha promotes cell-cycle progression in hypoxic RCCs and multiple other cell lines. This correlates with enhanced c-Myc promoter binding, transcriptional effects on both activated and repressed target genes, and interactions with Sp1, Miz1, and Max. Finally, HIF-2alpha augments c-Myc transformation of primary mouse embryo fibroblasts (MEFs). Enhanced c-Myc activity likely contributes to HIF-2alpha-mediated neoplastic progression following loss of the VHL tumor suppressor and influences the behavior of hypoxic tumor cells.
Evidence
5:
Inferred from Physical InteractionIntAct
Mammalian c-Myc is a member of a small family of three closely related transcription factors. The Myc family of proto-oncogenes are among the most potent activators of tumorigenesis, and are frequently overexpressed in diverse cancers. c-Myc has an unusually broad array of regulatory functions, which include, in addition to roles in the cell cycle and apoptosis, effects on a variety of metabolic functions, cell differentiation, senescence, and stem cell maintenance. A significant number of c-Myc interacting proteins have already been defined, but it is widely believed that the c-Myc interactome is vastly larger than currently documented. In addition to interactions with components of the transcription machinery, transcription independent nuclear interactions with the DNA replication and RNA processing pathways have been reported. Cytoplasmic roles of c-Myc have also been recently substantiated. Recent advances in proteomics have opened new possibilities for the isolation of protein complexes under native conditions and confidently identifying the components using ultrasensitive, high mass accuracy and high resolution mass spectrometry techniques. In this communication we report a new tandem affinity purification (TAP) c-Myc interaction screen that employed new cell lines with near-physiological levels of c-Myc expression with multi-dimensional protein identification techniques (MudPIT) for the detection and quantification of proteins. Both label-free and the recently developed stable isotope labeling with amino acids in cell culture (SILAC) methodologies were used. Combined data from multiple biological replicates provided a dataset of 418 non-redundant proteins, 389 of which are putative novel interactors. This new information should significantly advance our understanding of this interesting and important master regulator.
Evidence
6:
Inferred from Physical InteractionIntAct
Proteome-scale protein interaction maps are available for many organisms, ranging from bacteria, yeast, worms and flies to humans. These maps provide substantial new insights into systems biology, disease research and drug discovery. However, only a small fraction of the total number of human protein-protein interactions has been identified. In this study, we map the interactions of an unbiased selection of 5026 human liver expression proteins by yeast two-hybrid technology and establish a human liver protein interaction network (HLPN) composed of 3484 interactions among 2582 proteins. The data set has a validation rate of over 72% as determined by three independent biochemical or cellular assays. The network includes metabolic enzymes and liver-specific, liver-phenotype and liver-disease proteins that are individually critical for the maintenance of liver functions. The liver enriched proteins had significantly different topological properties and increased our understanding of the functional relationships among proteins in a liver-specific manner. Our data represent the first comprehensive description of a HLPN, which could be a valuable tool for understanding the functioning of the protein interaction network of the human liver.
Evidence
7:
Inferred from Physical InteractionIntAct
Large-scale data sets of protein-protein interactions (PPIs) are a valuable resource for mapping and analysis of the topological and dynamic features of interactome networks. The currently available large-scale PPI data sets only contain information on interaction partners. The data presented in this study also include the sequences involved in the interactions (i.e., the interacting regions, IRs) suggested to correspond to functional and structural domains. Here we present the first large-scale IR data set obtained using mRNA display for 50 human transcription factors (TFs), including 12 transcription-related proteins. The core data set (966 IRs; 943 PPIs) displays a verification rate of 70%. Analysis of the IR data set revealed the existence of IRs that interact with multiple partners. Furthermore, these IRs were preferentially associated with intrinsic disorder. This finding supports the hypothesis that intrinsically disordered regions play a major role in the dynamics and diversity of TF networks through their ability to structurally adapt to and bind with multiple partners. Accordingly, this domain-based interaction resource represents an important step in refining protein interactions and networks at the domain level and in associating network analysis with biological structure and function.
Evidence
8:
Inferred from Physical InteractionIntAct
Mitogen-activated protein kinase (MAPK) pathways form the backbone of signal transduction in the mammalian cell. Here we applied a systematic experimental and computational approach to map 2,269 interactions between human MAPK-related proteins and other cellular machinery and to assemble these data into functional modules. Multiple lines of evidence including conservation with yeast supported a core network of 641 interactions. Using small interfering RNA knockdowns, we observed that approximately one-third of MAPK-interacting proteins modulated MAPK-mediated signaling. We uncovered the Na-H exchanger NHE1 as a potential MAPK scaffold, found links between HSP90 chaperones and MAPK pathways and identified MUC12 as the human analog to the yeast signaling mucin Msb2. This study makes available a large resource of MAPK interactions and clone libraries, and it illustrates a methodology for probing signaling networks based on functional refinement of experimentally derived protein-interaction maps.
Evidence
9:
Inferred from Physical InteractionUniProtKB
The proto-oncoprotein c-Myc functions as a transcriptional regulator that controls different aspects of cell behavior, including proliferation, differentiation, and apoptosis. In addition, Myc proteins have the potential to transform cells and are deregulated in the majority of human cancers. Several Myc-interacting factors have been described that mediate part of Myc's functions in the control of cell behavior. Here, we describe the isolation of a novel 150 kDa protein, designated PARP-10, that interacts with Myc. PARP-10 possesses domains with homology to RNA recognition motifs and to poly(ADP-ribose) polymerases (PARP). Molecular modeling and biochemical analysis define a PARP domain that is capable of ADP-ribosylating PARP-10 itself and core histones, but neither Myc nor Max. PARP-10 is localized to the nuclear and cytoplasmic compartments that is controlled at least in part by a Leu-rich nuclear export sequence (NES). Functionally, PARP-10 inhibits c-Myc- and E1A-mediated cotransformation of rat embryo fibroblasts, a function that is independent of PARP activity but that depends on a functional NES. Together, our findings define a novel PARP enzyme involved in the control of cell proliferation.
Evidence
10:
Inferred from Physical InteractionIntAct
Using a yeast two-hybrid screen, we found that SNIP1 (Smad nuclear-interacting protein 1) associates with c-Myc, a key regulator of cell proliferation and transformation. We demonstrate that SNIP1 functions as an important regulator of c-Myc activity, binding the N terminus of c-Myc through its own C terminus, and that SNIP1 enhances the transcriptional activity of c-Myc both by stabilizing it against proteosomal degradation and by bridging the c-Myc/p300 complex. These effects of SNIP1 on c-Myc likely contribute to synergistic effects of SNIP1, c-Myc, and H-Ras in inducing formation of foci in an in vitro transformation assay and also in supporting anchorage-independent growth. The significant association of SNIP1 and c-Myc staining in a non-small cell lung cancer tissue array is further evidence that their activities might be linked and suggests that SNIP1 might be an important modulator of c-Myc activity in carcinogenesis.
Evidence
11:
Inferred from Physical InteractionIntAct
The c-MYC oncogene encodes a transcription factor, which is sufficient and necessary for the induction of cellular proliferation. However, the c-MYC protein is a relatively weak transactivator suggesting that it may have other functions. To identify protein interactors which may reveal new functions or represent regulators of c-MYC we systematically identified proteins associated with c-MYC in vivo using a proteomic approach. We combined tandem affinity purification (TAP) with the mass spectral multidimensional protein identification technology (MudPIT). Thereby, 221 c-MYC-associated proteins were identified. Among them were 17 previously known c-MYC-interactors. Selected new c-MYC-associated proteins (DBC-1, FBX29, KU70, MCM7, Mi2-beta/CHD4, RNA Pol II, RFC2, RFC3, SV40 Large T Antigen, TCP1alpha, U5-116kD, ZNF281) were confirmed independently. For association with MCM7, SV40 Large T Antigen and DBC-1 the functionally important MYC-box II region was required, whereas FBX29 and Mi2-beta interacted via MYC-box II and the BR-HLH-LZ motif. In addition, regulators of c-MYC activity were identified: ectopic expression of FBX29, an E3 ubiquitin ligase, decreased c-MYC protein levels and inhibited c-MYC transactivation, whereas knock-down of FBX29 elevated the concentration of c-MYC. Furthermore, sucrose gradient analysis demonstrated that c-MYC is present in numerous complexes with varying size and composition, which may accommodate the large number of new c-MYC-associated proteins identified here and mediate the diverse functions of c-MYC. Our results suggest that c-MYC, besides acting as a mitogenic transcription factor, regulates cellular proliferation by direct association with protein complexes involved in multiple synthetic processes required for cell division, as for example DNA-replication/repair and RNA-processing. Furthermore, this first comprehensive description of the c-MYC-associated sub-proteome will facilitate further studies aimed to elucidate the biology of c-MYC.
Interacting selectively and non-covalently with DNA of a specific nucleotide composition, e.g. GC-rich DNA binding, or with a specific sequence motif or type of DNA e.g. promotor binding or rDNA binding.
IEAOrtholog Compara
Sequence-specific DNA binding transcription factor activitydefinition[GO:0003700]‹silver
Interacting selectively and non-covalently with a specific DNA sequence in order to modulate transcription. The transcription factor may or may not also interact selectively with a protein or macromolecular complex.
Interacting selectively and non-covalently with a activating transcription factor and also with the basal transcription machinery in order to increase the frequency, rate or extent of transcription. Cofactors generally do not bind DNA, but rather mediate protein-protein interactions between activating transcription factors and the basal transcription machinery.
The myc protooncogene family has been implicated in cell proliferation, differentiation, and neoplasia, but its mechanism of function at the molecular level is unknown. The carboxyl terminus of Myc family proteins contains a basic region helix-loop-helix leucine zipper motif (bHLH-Zip), which has DNA-binding activity and has been predicted to mediate protein-protein interactions. The bHLH-Zip region of c-Myc was used to screen a complementary DNA (cDNA) expression library, and a bHLH-Zip protein, termed Max, was identified. Max specifically associated with c-Myc, N-Myc, and L-Myc proteins, but not with a number of other bHLH, bZip, or bHLH-Zip proteins. The interaction between Max and c-Myc was dependent on the integrity of the c-Myc HLH-Zip domain, but not on the basic region or other sequences outside the domain. Furthermore, the Myc-Max complex bound to DNA in a sequence-specific manner under conditions where neither Max nor Myc exhibited appreciable binding. The DNA-binding activity of the complex was dependent on both the dimerization domain and the basic region of c-Myc. These results suggest that Myc family proteins undergo a restricted set of interactions in the cell and may belong to the more general class of eukaryotic DNA-binding transcription factors.
Interacting selectively and non-covalently with a regulatory transcription factor and also with the basal transcription machinery in order to modulate transcription. Cofactors generally do not bind DNA, but rather mediate protein-protein interactions between regulatory transcription factors and the basal transcription machinery.
Myc family proteins appear to function through heterodimerization with the stable, constitutively expressed bHLH-Zip protein, Max. To determine whether Max mediates the function of regulatory proteins other than Myc, we screened a lambda gt11 expression library with radiolabeled Max protein. One cDNA identified encodes a new member of the bHLH-Zip protein family, Mad. Human Mad protein homodimerizes poorly but binds Max in vitro, forming a sequence-specific DNA binding complex with properties very similar to those of Myc-Max. Both Myc-Max and Mad-Max heterocomplexes are favored over Max homodimers, and, unlike Max homodimers, the DNA binding activity of the heterodimers is unaffected by CKII phosphorylation. Mad does not associate with Myc or with representative bHLH, bZip, or bHLH-Zip proteins. In vivo transactivation assays suggest that Myc-Max and Mad-Max complexes have opposing functions in transcription and that Max plays a central role in this network of transcription factors.
Any process that results in a change in state or activity of a cell (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a peptide hormone stimulus. A peptide hormone is any of a class of peptides that are secreted into the blood stream and have endocrine functions in living animals.
Any process that results in a change in state or activity of a cell (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of deprivation of nourishment.
Any process that decreases the frequency, rate or extent of gene expression. Gene expression is the process in which a gene's coding sequence is converted into a mature gene product or products (proteins or RNA). This includes the production of an RNA transcript as well as any processing to produce a mature RNA product or an mRNA (for protein-coding genes) and the translation of that mRNA into protein. Some protein processing events may be included when they are required to form an active form of a product from an inactive precursor form.
Any apoptotic process in a neuron, the basic cellular unit of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the nervous system.
Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of an axon injury stimulus.
Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of an insulin stimulus. Insulin is a polypeptide hormone produced by the islets of Langerhans of the pancreas in mammals, and by the homologous organs of other organisms.
The process whose specific outcome is the progression of the retina over time, from its formation to the mature structure. The retina is the innermost layer or coating at the back of the eyeball, which is sensitive to light and in which the optic nerve terminates.
The synthesis of RNA from a DNA template by RNA polymerase II, originating at an RNA polymerase II promoter. Includes transcription of messenger RNA (mRNA) and certain small nuclear RNAs (snRNAs).
Myc family proteins appear to function through heterodimerization with the stable, constitutively expressed bHLH-Zip protein, Max. To determine whether Max mediates the function of regulatory proteins other than Myc, we screened a lambda gt11 expression library with radiolabeled Max protein. One cDNA identified encodes a new member of the bHLH-Zip protein family, Mad. Human Mad protein homodimerizes poorly but binds Max in vitro, forming a sequence-specific DNA binding complex with properties very similar to those of Myc-Max. Both Myc-Max and Mad-Max heterocomplexes are favored over Max homodimers, and, unlike Max homodimers, the DNA binding activity of the heterodimers is unaffected by CKII phosphorylation. Mad does not associate with Myc or with representative bHLH, bZip, or bHLH-Zip proteins. In vivo transactivation assays suggest that Myc-Max and Mad-Max complexes have opposing functions in transcription and that Max plays a central role in this network of transcription factors.
Protein involved in the transfer of genetic information from DNA to messenger RNA (mRNA) by DNA-directed RNA polymerase. In the case of some RNA viruses, protein involved in the transfer of genetic information from RNA to messenger RNA (mRNA) by RNA-directed RNA polymerase.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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