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Harris EL, Roy V, Montagne M, Rose AMS, Livesey H, Reijnders MRF, Hobson E, Sansbury FH, Willemsen MH, Pfundt R, Warren D, Long V, Carr IM, Brunner HG, Sheridan EG, Firth HV, Lavigne P, Poulter JA. A recurrent de novo MAX p.Arg60Gln variant causes a syndromic overgrowth disorder through differential expression of c-Myc target genes. Am J Hum Genet 2024; 111:119-132. [PMID: 38141607 PMCID: PMC10806738 DOI: 10.1016/j.ajhg.2023.11.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 11/23/2023] [Accepted: 11/29/2023] [Indexed: 12/25/2023] Open
Abstract
Cyclin D2 (CCND2) stabilization underpins a range of macrocephaly-associated disorders through mutation of CCND2 or activating mutations in upstream genes encoding PI3K-AKT pathway components. Here, we describe three individuals with overlapping macrocephaly-associated phenotypes who carry the same recurrent de novo c.179G>A (p.Arg60Gln) variant in Myc-associated factor X (MAX). The mutation, located in the b-HLH-LZ domain, causes increased intracellular CCND2 through increased transcription but it does not cause stabilization of CCND2. We show that the purified b-HLH-LZ domain of MAXArg60Gln (Max∗Arg60Gln) binds its target E-box sequence with a lower apparent affinity. This leads to a more efficient heterodimerization with c-Myc resulting in an increase in transcriptional activity of c-Myc in individuals carrying this mutation. The recent development of Omomyc-CPP, a cell-penetrating b-HLH-LZ-domain c-Myc inhibitor, provides a possible therapeutic option for MAXArg60Gln individuals, and others carrying similar germline mutations resulting in dysregulated transcriptional c-Myc activity.
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Affiliation(s)
- Erica L Harris
- Division of Molecular Medicine, Leeds Institute of Medical Research, University of Leeds, Leeds, UK
| | - Vincent Roy
- Département de Biochimie et Génomique Fonctionnelle, PROTÉO et Institut de Pharmacologie de Sherbrooke. University of Sherbrooke, Sherbrooke, QC, Canada
| | - Martin Montagne
- Département de Biochimie et Génomique Fonctionnelle, PROTÉO et Institut de Pharmacologie de Sherbrooke. University of Sherbrooke, Sherbrooke, QC, Canada
| | - Ailsa M S Rose
- Division of Molecular Medicine, Leeds Institute of Medical Research, University of Leeds, Leeds, UK
| | - Helen Livesey
- Leeds Teaching Hospitals NHS Trust, Leeds, UK; All Wales Medical Genomics Service, NHS Wales Cardiff and Vale University Health Board, Cardiff, UK
| | - Margot R F Reijnders
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Emma Hobson
- Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - Francis H Sansbury
- All Wales Medical Genomics Service, NHS Wales Cardiff and Vale University Health Board, Cardiff, UK
| | - Marjolein H Willemsen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Rolph Pfundt
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | | | - Vernon Long
- Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - Ian M Carr
- Division of Molecular Medicine, Leeds Institute of Medical Research, University of Leeds, Leeds, UK
| | - Han G Brunner
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Eamonn G Sheridan
- Division of Molecular Medicine, Leeds Institute of Medical Research, University of Leeds, Leeds, UK; Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - Helen V Firth
- Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK; Wellcome Sanger Institute, Hinxton, Cambridge, UK
| | - Pierre Lavigne
- Département de Biochimie et Génomique Fonctionnelle, PROTÉO et Institut de Pharmacologie de Sherbrooke. University of Sherbrooke, Sherbrooke, QC, Canada.
| | - James A Poulter
- Division of Molecular Medicine, Leeds Institute of Medical Research, University of Leeds, Leeds, UK.
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2
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Pellanda P, Dalsass M, Filipuzzi M, Loffreda A, Verrecchia A, Castillo Cano V, Thabussot H, Doni M, Morelli MJ, Soucek L, Kress T, Mazza D, Mapelli M, Beaulieu ME, Amati B, Sabò A. Integrated requirement of non-specific and sequence-specific DNA binding in Myc-driven transcription. EMBO J 2021; 40:e105464. [PMID: 33792944 DOI: 10.15252/embj.2020105464] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 02/15/2021] [Accepted: 02/24/2021] [Indexed: 12/17/2022] Open
Abstract
Eukaryotic transcription factors recognize specific DNA sequence motifs, but are also endowed with generic, non-specific DNA-binding activity. How these binding modes are integrated to determine select transcriptional outputs remains unresolved. We addressed this question by site-directed mutagenesis of the Myc transcription factor. Impairment of non-specific DNA backbone contacts caused pervasive loss of genome interactions and gene regulation, associated with increased intra-nuclear mobility of the Myc protein in murine cells. In contrast, a mutant lacking base-specific contacts retained DNA-binding and mobility profiles comparable to those of the wild-type protein, but failed to recognize its consensus binding motif (E-box) and could not activate Myc-target genes. Incidentally, this mutant gained weak affinity for an alternative motif, driving aberrant activation of different genes. Altogether, our data show that non-specific DNA binding is required to engage onto genomic regulatory regions; sequence recognition in turn contributes to transcriptional activation, acting at distinct levels: stabilization and positioning of Myc onto DNA, and-unexpectedly-promotion of its transcriptional activity. Hence, seemingly pervasive genome interaction profiles, as detected by ChIP-seq, actually encompass diverse DNA-binding modalities, driving defined, sequence-dependent transcriptional responses.
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Affiliation(s)
- Paola Pellanda
- European Institute of Oncology (IEO) - IRCCS, Milan, Italy.,Center for Genomic Science of IIT@SEMM, Fondazione Istituto Italiano di Tecnologia (IIT), Milan, Italy
| | - Mattia Dalsass
- European Institute of Oncology (IEO) - IRCCS, Milan, Italy
| | | | - Alessia Loffreda
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | | | - Virginia Castillo Cano
- Peptomyc S.L., Barcelona, Spain.,Vall d'Hebron Institute of Oncology (VHIO), Edifici Cellex, Barcelona, Spain
| | | | - Mirko Doni
- European Institute of Oncology (IEO) - IRCCS, Milan, Italy
| | - Marco J Morelli
- Center for Genomic Science of IIT@SEMM, Fondazione Istituto Italiano di Tecnologia (IIT), Milan, Italy
| | - Laura Soucek
- Peptomyc S.L., Barcelona, Spain.,Vall d'Hebron Institute of Oncology (VHIO), Edifici Cellex, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.,Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Theresia Kress
- Center for Genomic Science of IIT@SEMM, Fondazione Istituto Italiano di Tecnologia (IIT), Milan, Italy
| | - Davide Mazza
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Marina Mapelli
- European Institute of Oncology (IEO) - IRCCS, Milan, Italy
| | | | - Bruno Amati
- European Institute of Oncology (IEO) - IRCCS, Milan, Italy
| | - Arianna Sabò
- European Institute of Oncology (IEO) - IRCCS, Milan, Italy
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3
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Beaulieu ME, Castillo F, Soucek L. Structural and Biophysical Insights into the Function of the Intrinsically Disordered Myc Oncoprotein. Cells 2020; 9:E1038. [PMID: 32331235 PMCID: PMC7226237 DOI: 10.3390/cells9041038] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/16/2020] [Accepted: 04/17/2020] [Indexed: 12/13/2022] Open
Abstract
Myc is a transcription factor driving growth and proliferation of cells and involved in the majority of human tumors. Despite a huge body of literature on this critical oncogene, our understanding of the exact molecular determinants and mechanisms that underlie its function is still surprisingly limited. Indubitably though, its crucial and non-redundant role in cancer biology makes it an attractive target. However, achieving successful clinical Myc inhibition has proven challenging so far, as this nuclear protein is an intrinsically disordered polypeptide devoid of any classical ligand binding pockets. Indeed, Myc only adopts a (partially) folded structure in some contexts and upon interacting with some protein partners, for instance when dimerizing with MAX to bind DNA. Here, we review the cumulative knowledge on Myc structure and biophysics and discuss the implications for its biological function and the development of improved Myc inhibitors. We focus this biophysical walkthrough mainly on the basic region helix-loop-helix leucine zipper motif (bHLHLZ), as it has been the principal target for inhibitory approaches so far.
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Affiliation(s)
| | | | - Laura Soucek
- Peptomyc S.L., Edifici Cellex, 08035 Barcelona, Spain; (F.C.); (L.S.)
- Vall d’Hebron Institute of Oncology (VHIO), Edifici Cellex, 08035 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08035 Barcelona, Spain
- Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, 08035 Bellaterra, Spain
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Calo-Lapido R, Penas C, Jiménez-Balsa A, Vázquez ME, Mascareñas JL. A chemical approach for the synthesis of the DNA-binding domain of the oncoprotein MYC. Org Biomol Chem 2020; 17:6748-6752. [PMID: 31166361 DOI: 10.1039/c9ob01209e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We describe the first chemical synthesis of a functional mutant of the DNA binding domain of the oncoprotein MYC, using two alternative strategies which involve either one or two Native Chemical Ligations (NCLs). Both routes allowed the efficient synthesis of a miniprotein which is capable of heterodimerizing with MAX, and replicate the DNA binding of the native protein. The versatility of the reported synthetic approach enabled the straightforward preparation of MYC and Omomyc analogues, as well as fluorescently labeled derivatives.
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Affiliation(s)
- Renata Calo-Lapido
- Departamento de Química Orgánica and Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS). Universidade de Santiago de Compostela. 15782 Santiago de Compostela, Spain.
| | - Cristina Penas
- Departamento de Química Orgánica and Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS). Universidade de Santiago de Compostela. 15782 Santiago de Compostela, Spain.
| | - Adrián Jiménez-Balsa
- Departamento de Química Orgánica and Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS). Universidade de Santiago de Compostela. 15782 Santiago de Compostela, Spain.
| | - M Eugenio Vázquez
- Departamento de Química Orgánica and Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS). Universidade de Santiago de Compostela. 15782 Santiago de Compostela, Spain.
| | - José L Mascareñas
- Departamento de Química Orgánica and Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS). Universidade de Santiago de Compostela. 15782 Santiago de Compostela, Spain.
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5
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Panova S, Cliff MJ, Macek P, Blackledge M, Jensen MR, Nissink JWM, Embrey KJ, Davies R, Waltho JP. Mapping Hidden Residual Structure within the Myc bHLH-LZ Domain Using Chemical Denaturant Titration. Structure 2019; 27:1537-1546.e4. [DOI: 10.1016/j.str.2019.07.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 05/05/2019] [Accepted: 07/17/2019] [Indexed: 12/25/2022]
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Inhibiting MYC binding to the E-box DNA motif by ME47 decreases tumour xenograft growth. Oncogene 2017; 36:6830-6837. [PMID: 28806396 DOI: 10.1038/onc.2017.275] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Revised: 04/21/2017] [Accepted: 05/27/2017] [Indexed: 02/07/2023]
Abstract
Developing therapeutics to effectively inhibit the MYC oncoprotein would mark a key advance towards cancer patient care as MYC is deregulated in over 50% of human cancers. MYC deregulation is correlated with aggressive disease and poor patient outcome. Despite strong evidence in mouse models that inhibiting MYC would significantly impact tumour cell growth and patient survival, traditional approaches have not yet yielded the urgently needed therapeutic agents that directly target MYC. MYC functions through its interaction with MAX to regulate gene transcription by binding to E-box DNA response elements of MYC target genes. Here we used a structure-based strategy to design ME47, a small minimalist hybrid protein (MHP) able to disrupt the MAX:E-box interaction/binding and block transcriptional MYC activity. We show that inducing ME47 expression in established tumour xenografts inhibits tumour growth and decreases cellular proliferation. Mechanistically, we show by chromatin immunoprecipitation that ME47 binds to E-box binding sites of MYC target genes. Moreover, ME47 occupancy decreases MYC:DNA interaction at its cognate E-box binding sites. Taken together, ME47 is a prototypic MHP inhibitor that antagonizes tumour cell growth in vitro and in vivo and inhibits the interaction of MYC with DNA E-box elements. These results support ME47's role as a MYC inhibitor and suggest that MHPs provide an alternative therapeutic targeting system that can be used to target transcription factors important in human diseases, including cancer.
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Maltais L, Montagne M, Bédard M, Tremblay C, Soucek L, Lavigne P. Biophysical characterization of the b-HLH-LZ of ΔMax, an alternatively spliced isoform of Max found in tumor cells: Towards the validation of a tumor suppressor role for the Max homodimers. PLoS One 2017; 12:e0174413. [PMID: 28350847 PMCID: PMC5370111 DOI: 10.1371/journal.pone.0174413] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 03/08/2017] [Indexed: 11/19/2022] Open
Abstract
It is classically recognized that the physiological and oncogenic functions of Myc proteins depend on specific DNA binding enabled by the dimerization of its C-terminal basic-region-Helix-Loop-Helix-Leucine Zipper (b-HLH-LZ) domain with that of Max. However, a new paradigm is emerging, where the binding of the c-Myc/Max heterodimer to non-specific sequences in enhancers and promoters drives the transcription of genes involved in diverse oncogenic programs. Importantly, Max can form a stable homodimer even in the presence of c-Myc and bind DNA (specific and non-specific) with comparable affinity to the c-Myc/Max heterodimer. Intriguingly, alterations in the Max gene by germline and somatic mutations or changes in the gene product by alternative splicing (e.g. ΔMax) were recently associated with pheochromocytoma and glioblastoma, respectively. This has led to the proposition that Max is, by itself, a tumor suppressor. However, the actual mechanism through which it exerts such an activity remains to be elucidated. Here, we show that contrary to the WT motif, the b-HLH-LZ of ΔMax does not homodimerize in the absence of DNA. In addition, although ΔMax can still bind the E-box sequence as a homodimer, it cannot bind non-specific DNA in that form, while it can heterodimerize with c-Myc and bind E-box and non-specific DNA as a heterodimer with high affinity. Taken together, our results suggest that the WT Max homodimer is important for attenuating the binding of c-Myc to specific and non-specific DNA, whereas ΔMax is unable to do so. Conversely, the splicing of Max into ΔMax could provoke an increase in overall chromatin bound c-Myc. According to the new emerging paradigm, the splicing event and the stark reduction in homodimer stability and DNA binding should promote tumorigenesis impairing the tumor suppressor activity of the WT homodimer of Max.
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Affiliation(s)
- Loïka Maltais
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
- PROTÉO; Regroupement Stratégique sur la Fonction, la Structure et l'Ingénierie des Protéines, Université Laval, Québec, Canada
| | - Martin Montagne
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
- PROTÉO; Regroupement Stratégique sur la Fonction, la Structure et l'Ingénierie des Protéines, Université Laval, Québec, Canada
| | - Mikaël Bédard
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
- PROTÉO; Regroupement Stratégique sur la Fonction, la Structure et l'Ingénierie des Protéines, Université Laval, Québec, Canada
| | - Cynthia Tremblay
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
- PROTÉO; Regroupement Stratégique sur la Fonction, la Structure et l'Ingénierie des Protéines, Université Laval, Québec, Canada
| | - Laura Soucek
- Vall d’Hebron Institute of Oncology (VHIO), Hospital Vall d’Hebron, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
- Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Pierre Lavigne
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
- PROTÉO; Regroupement Stratégique sur la Fonction, la Structure et l'Ingénierie des Protéines, Université Laval, Québec, Canada
- * E-mail:
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Comino-Méndez I, Leandro-García LJ, Montoya G, Inglada-Pérez L, de Cubas AA, Currás-Freixes M, Tysoe C, Izatt L, Letón R, Gómez-Graña Á, Mancikova V, Apellániz-Ruiz M, Mannelli M, Schiavi F, Favier J, Gimenez-Roqueplo AP, Timmers HJLM, Roncador G, Garcia JF, Rodríguez-Antona C, Robledo M, Cascón A. Functional and in silico assessment of MAX variants of unknown significance. J Mol Med (Berl) 2015; 93:1247-55. [DOI: 10.1007/s00109-015-1306-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 05/27/2015] [Accepted: 06/02/2015] [Indexed: 12/25/2022]
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Abstract
In this chapter, we discuss in detail two essential methods used to evaluate the interaction of Myc with another protein of interest: co-immunoprecipitation (Co-IP) and in vitro pull-down assays. Co-IP is a method that, by immunoaffinity, allows the identification of protein-protein interactions within cells. We provide methods to conduct Co-IPs from whole-cell extracts as well as cytoplasmic and nuclear-enriched fractions. By contrast, the pull-down assay evaluates whether a bait protein that is bound to a solid support can specifically interact with a prey protein that is in solution. We provide methods to conduct in vitro pull-downs and further detail how to use this assay to distinguish whether a protein-protein interaction is direct or indirect. We also discuss methods used to screen for Myc interactors and provide an in silico strategy to help prioritize hits for further validation using the described Co-IP and in vitro pull-down assays.
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Hussain I, Husain Q, Baredes S, Eloy JA, Jyung RW, Liu JK. Molecular genetics of paragangliomas of the skull base and head and neck region: implications for medical and surgical management. J Neurosurg 2014; 120:321-30. [DOI: 10.3171/2013.10.jns13659] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Paragangliomas are rare, slow-growing tumors that frequently arise in the head and neck, with the carotid bodies and temporal bone of the skull base being the most common sites. These neoplasms are histologically similar to pheochromocytomas that form in the adrenal medulla and are divided into sympathetic and parasympathetic subtypes based on functionality. Skull base and head and neck region paragangliomas (SHN-PGs) are almost always derived from parasympathetic tissue and rarely secrete catecholamines. However, they can cause significant morbidity by mass effect on various cranial nerves and major blood vessels. While surgery for SHN-PG can be curative, postoperative deficits and recurrences make these lesions challenging to manage. Multiple familial syndromes predisposing individuals to development of paragangliomas have been identified, all involving mutations in the succinate dehydrogenase complex of mitochondria. Mutations in this enzyme lead to a state of “pseudohypoxia” that upregulates various angiogenic, survival, and proliferation factors. Moreover, familial paraganglioma syndromes are among the rare inherited diseases in which genomic imprinting occurs. Recent advances in gene arrays and transcriptome/exome sequencing have identified an alternate mutation in sporadic SHN-PG, which regulates proto-oncogenic pathways independent of pseudohypoxia-induced factors. Collectively these findings demonstrate that paragangliomas of the skull base and head and neck region have a distinct genetic signature from sympathetic-based paragangliomas occurring below the neck, such as pheochromocytomas. Paragangliomas serve as a unique model of primarily surgically treated neoplasms whose future will be altered by the elucidation of their genomic complexities. In this review, the authors present an analysis of the molecular genetics of SHN-PG and provide future directions in patient care and the development of novel therapies.
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Affiliation(s)
| | | | - Soly Baredes
- 2Otolaryngology–Head and Neck Surgery, and
- 3Center for Skull Base and Pituitary Surgery, Neurological Institute of New Jersey, Rutgers New Jersey Medical School, Newark, New Jersey
| | - Jean Anderson Eloy
- 1Departments of Neurological Surgery and
- 2Otolaryngology–Head and Neck Surgery, and
- 3Center for Skull Base and Pituitary Surgery, Neurological Institute of New Jersey, Rutgers New Jersey Medical School, Newark, New Jersey
| | - Robert W. Jyung
- 2Otolaryngology–Head and Neck Surgery, and
- 3Center for Skull Base and Pituitary Surgery, Neurological Institute of New Jersey, Rutgers New Jersey Medical School, Newark, New Jersey
| | - James K. Liu
- 1Departments of Neurological Surgery and
- 2Otolaryngology–Head and Neck Surgery, and
- 3Center for Skull Base and Pituitary Surgery, Neurological Institute of New Jersey, Rutgers New Jersey Medical School, Newark, New Jersey
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Beaulieu ME, McDuff FO, Bédard M, Montagne M, Lavigne P. Methods for the expression, purification, preparation, and biophysical characterization of constructs of the c-Myc and Max b-HLH-LZs. Methods Mol Biol 2013; 1012:7-20. [PMID: 24006055 DOI: 10.1007/978-1-62703-429-6_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Specific heterodimerization and DNA binding by the b-HLH-LZ transcription factors c-Myc and Max is central to the activation and repression activities of c-Myc that lead to cell growth, proliferation, and tumorigenesis (Adhikary and Eilers, Nat Rev Mol Cell Biol 6:635-645, 2005; Eilers and Eisenman, Genes Dev 22:2755-2766, 2008; Grandori et al., Annu Rev Cell Dev Biol 16:653-699, 2000; Whitfield and Soucek, Cell Mol Life Sci 69:931-934, 2011). Although many c-Myc-interacting partner proteins are known to interact through their HLH domain (Adhikary and Eilers, Nat Rev Mol Cell Biol 6:635-645, 2005), current knowledge regarding the structure and the determinants of molecular recognition of these complexes is still very limited. Moreover, recent advances in the development and use of b-HLH-LZ dominant negatives (Soucek et al., Nature 455:679-683, 2008) and inhibitors of c-Myc interaction with its protein partners (Bidwell et al., J Control Release 135:2-10, 2009; Mustata et al., J Med Chem 52:1247-1250, 2009; Prochownik and Vogt, Genes Cancer 1:650-659, 2010) or DNA highlight the importance of efficient protocols to prepare such constructs and variants. Here, we provide methods to produce and purify high quantities of pure and untagged b-HLH-LZ constructs of c-Myc and Max as well as specific c-Myc/Max heterodimers for their biophysical and structural characterization by CD, NMR, or crystallography. Moreover, biochemical methods to analyze the homodimers and heterodimers as well as DNA binding of these constructs by native electrophoresis are presented. In addition to enable the investigation of the c-Myc/Max b-HLH-LZ complexes, the protocols described herein can be applied to the biochemical characterization of various mutants of either partner, as well as to ternary complexes with other partner proteins.
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Affiliation(s)
- Marie-Eve Beaulieu
- Département de Pharmacologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
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