1
|
Hurd M, Pino J, Jang K, Allevato MM, Vorontchikhina M, Ichikawa W, Zhao Y, Gates R, Villalpando E, Hamilton MJ, Faiola F, Pan S, Qi Y, Hung YW, Girke T, Ann D, Seewaldt V, Martinez E. MYC acetylated lysine residues drive oncogenic cell transformation and regulate select genetic programs for cell adhesion-independent growth and survival. Genes Dev 2023; 37:865-882. [PMID: 37852796 PMCID: PMC10691474 DOI: 10.1101/gad.350736.123] [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: 04/19/2023] [Accepted: 10/02/2023] [Indexed: 10/20/2023]
Abstract
The MYC oncogenic transcription factor is acetylated by the p300 and GCN5 histone acetyltransferases. The significance of MYC acetylation and the functions of specific acetylated lysine (AcK) residues have remained unclear. Here, we show that the major p300-acetylated K148(149) and K157(158) sites in human (or mouse) MYC and the main GCN5-acetylated K323 residue are reversibly acetylated in various malignant and nonmalignant cells. Oncogenic overexpression of MYC enhances its acetylation and alters the regulation of site-specific acetylation by proteasome and deacetylase inhibitors. Acetylation of MYC at different K residues differentially affects its stability in a cell type-dependent manner. Lysine-to-arginine substitutions indicate that although none of the AcK residues is required for MYC stimulation of adherent cell proliferation, individual AcK sites have gene-specific functions controlling select MYC-regulated processes in cell adhesion, contact inhibition, apoptosis, and/or metabolism and are required for the malignant cell transformation activity of MYC. Each AcK site is required for anchorage-independent growth of MYC-overexpressing cells in vitro, and both the AcK148(149) and AcK157(158) residues are also important for the tumorigenic activity of MYC transformed cells in vivo. The MYC AcK site-specific signaling pathways identified may offer new avenues for selective therapeutic targeting of MYC oncogenic activities.
Collapse
Affiliation(s)
- Matthew Hurd
- Department of Biochemistry, University of California Riverside, Riverside, California 92521, USA
| | - Jeffrey Pino
- Department of Biochemistry, University of California Riverside, Riverside, California 92521, USA
| | - Kay Jang
- Department of Biochemistry, University of California Riverside, Riverside, California 92521, USA
| | - Michael M Allevato
- Department of Biochemistry, University of California Riverside, Riverside, California 92521, USA
| | - Marina Vorontchikhina
- Department of Biochemistry, University of California Riverside, Riverside, California 92521, USA
| | - Wataru Ichikawa
- Department of Biochemistry, University of California Riverside, Riverside, California 92521, USA
| | - Yifan Zhao
- Department of Biochemistry, University of California Riverside, Riverside, California 92521, USA
| | - Ryan Gates
- Department of Biochemistry, University of California Riverside, Riverside, California 92521, USA
| | - Emily Villalpando
- Department of Biochemistry, University of California Riverside, Riverside, California 92521, USA
| | - Michael J Hamilton
- Department of Biochemistry, University of California Riverside, Riverside, California 92521, USA
| | - Francesco Faiola
- Department of Biochemistry, University of California Riverside, Riverside, California 92521, USA
| | - Songqin Pan
- Institute for Integrative Genome Biology, University of California Riverside, Riverside, California 92521, USA
- Department of Botany and Plant Sciences, University of California Riverside, Riverside, California 92521, USA
| | - Yue Qi
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, Comprehensive Cancer Center, City of Hope, Duarte, California 91010, USA
| | - Yu-Wen Hung
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, Comprehensive Cancer Center, City of Hope, Duarte, California 91010, USA
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute, Comprehensive Cancer Center, City of Hope, Duarte, California 91010, USA
| | - Thomas Girke
- Institute for Integrative Genome Biology, University of California Riverside, Riverside, California 92521, USA
- Department of Botany and Plant Sciences, University of California Riverside, Riverside, California 92521, USA
| | - David Ann
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, Comprehensive Cancer Center, City of Hope, Duarte, California 91010, USA
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute, Comprehensive Cancer Center, City of Hope, Duarte, California 91010, USA
| | - Victoria Seewaldt
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute, Comprehensive Cancer Center, City of Hope, Duarte, California 91010, USA
- Department of Population Sciences, Beckman Research Institute, Comprehensive Cancer Center, City of Hope, Duarte, California 91010, USA
| | - Ernest Martinez
- Department of Biochemistry, University of California Riverside, Riverside, California 92521, USA;
- Institute for Integrative Genome Biology, University of California Riverside, Riverside, California 92521, USA
| |
Collapse
|
2
|
L- myc Gene Expression in Canine Fetal Fibroblasts Promotes Self-Renewal Capacity but Not Tumor Formation. Cells 2021; 10:cells10081980. [PMID: 34440750 PMCID: PMC8391401 DOI: 10.3390/cells10081980] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/23/2021] [Accepted: 07/28/2021] [Indexed: 12/26/2022] Open
Abstract
Canines are useful in mammalian preclinical studies because they are larger than rodents and share many diseases with humans. Canine fetal fibroblast cells (CFFs) are an easily accessible source of somatic cells. However, they are easily driven to senescence and become unusable with continuous in vitro culture. Therefore, to overcome these deficiencies, we investigated whether tetracycline-inducible L-myc gene expression promotes self-renewal activity and tumorigenicity in the production of induced conditional self-renewing fibroblast cells (iCSFCs). Here, we describe the characterization of a new iCSFC line immortalized by transduction with L-myc that displays in vitro self-renewal ability without tumorigenic capacity. We established conditionally inducible self-renewing fibroblast cells by transducing CFF-3 cells with L-myc under the tetracycline-inducible gene expression system. In the absence of doxycycline, the cells did not express L-myc or undergo self-renewal. The iCSFCs had a fibroblast-like morphology, normal chromosome pattern, and expressed fibroblast-specific genes and markers. However, the iCSFCs did not form tumors in a soft agar colony-forming assay. We observed higher expression of three ES modules (core pluripotency genes, polycomb repressive complex genes (PRC), and MYC-related genes) in the iCSFCs than in the CFF-3 cells; in particular, the core pluripotency genes (OCT4, SOX2, and NANOG) were markedly up-regulated compared with the PRC and MYC module genes. These results demonstrated that, in canine fetal fibroblasts, L-myc tetracycline-inducible promoter-driven gene expression induces self-renewal capacity but not tumor formation. This study suggests that L-myc gene-induced conditional self-renewing fibroblast cells can be used as an in vitro tool in a variety of biomedical studies related to drug screening.
Collapse
|
3
|
Prochownik EV. Reconciling the Biological and Transcriptional Variability of Hepatoblastoma with Its Mutational Uniformity. Cancers (Basel) 2021; 13:cancers13091996. [PMID: 33919162 PMCID: PMC8122429 DOI: 10.3390/cancers13091996] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 04/06/2021] [Accepted: 04/16/2021] [Indexed: 01/20/2023] Open
Abstract
Simple Summary Hepatoblastoma (HB), the most common form of childhood liver cancer, is associated with dual mutation and/or dysregulation of the Wnt/β-catenin and Hippo pathways in ~50% of cases. However, this mutational simplicity cannot explain HB’s biological and histologic diversity. This discussion focuses upon recent work showing that specific β-catenin mutants are key determinants of this HB variability as well as their metabolic and transcriptional signatures. Dysregulation of the anti-oxidant NFE2L2 pathway also contributes to tumorigenesis by being directly transforming in association with either of the other two factors. The transcriptional overlap of tumors generated by pairs of factors identifies crucial targets that likely mediate HB tumorigenesis, behavior and appearance. Abstract Hepatoblastoma (HB), the most common childhood liver cancer, is associated with seven distinct histologic subtypes and variable degrees of clinical aggressiveness and presentation. Yet it is among the least genomically altered tumors known, with about half of HBs showing mutation and/or dysregulation of the Wnt/β-catenin and Hippo pathways. This raises the question of how this mutational simplicity can generate such biological and histologic complexity. Recent work shows that the identity of the underlying β-catenin mutation is a major contributor. Mutation or over-expression of the NFE2L2/NRF2 transcription factor, previously thought only to promote anti-oxidant responses, has also recently been shown to accelerate the growth of HBs generated by mutations in the Wnt/β-catenin and Hippo pathways while imparting novel features such as the tumor-associated cysts and necrosis. Moreover, patient-associated NFE2L2 mutations are overtly transforming when co-expressed with either mutant β-catenin or a Hippo pathway effector. The finding that tumorigenesis can be driven by any two arms of the β-catenin/Hippo/NFE2L2 axis has permitted the identification of a small subset of coordinately regulated tumor-specific transcripts, some of whose levels correlate with inferior long-term outcomes in HB and other cancers. Collectively, these findings begin to provide for more refined and molecularly based classification, survival algorithms and design of chemotherapeutic regimens.
Collapse
Affiliation(s)
- Edward V. Prochownik
- Division of Hematology/Oncology, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, PA 15224, USA;
- The Department of Microbiology and Molecular Genetics, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
- The University of Pittsburgh Hillman Cancer Center, Pittsburgh, PA 15232, USA
- The University of Pittsburgh Liver Research Center, Pittsburgh, PA 15213, USA
| |
Collapse
|
4
|
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.
Collapse
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
| |
Collapse
|
5
|
Zhang T, Li N, Sun C, Jin Y, Sheng X. MYC and the unfolded protein response in cancer: synthetic lethal partners in crime? EMBO Mol Med 2020; 12:e11845. [PMID: 32310340 PMCID: PMC7207169 DOI: 10.15252/emmm.201911845] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/07/2020] [Accepted: 03/10/2020] [Indexed: 12/15/2022] Open
Abstract
The transcription factors of the MYC family play pivotal roles in the initiation and progression of human cancers. High oncogenic level of MYC invades low‐affinity sites and enhancer sequences, which subsequently alters the transcriptome, causes metabolic imbalance, and induces stress response. The endoplasmic reticulum (ER) not only plays a central role in maintaining proteostasis, but also contributes to other key biological processes, including Ca2+ metabolism and the synthesis of lipids and glucose. Stress conditions, such as shortage in glucose or oxygen and disruption of Ca2+ homeostasis, may perturb proteostasis and induce the unfolded protein response (UPR), which either restores homeostasis or triggers cell death. Crucial roles of ER stress and UPR signaling have been implicated in various cancers, from oncogenesis to treatment response. Here, we summarize the current knowledge on the interaction between MYC and UPR signaling, and its contribution to cancer development. We also discuss the potential of targeting key UPR signaling nodes as novel synthetic lethal strategies in MYC‐driven cancers.
Collapse
Affiliation(s)
- Tingting Zhang
- Ministry of Education Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ningning Li
- The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen, China
| | - Chaoyang Sun
- Department of Obstetrics and Gynecology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yang Jin
- Institute for Cancer Genetics and Informatics, Oslo University Hospital, Oslo, Norway
| | - Xia Sheng
- Ministry of Education Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| |
Collapse
|
6
|
Massó-Vallés D, Beaulieu ME, Soucek L. MYC, MYCL, and MYCN as therapeutic targets in lung cancer. Expert Opin Ther Targets 2020; 24:101-114. [PMID: 32003251 DOI: 10.1080/14728222.2020.1723548] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Introduction: Lung cancer is the leading cause of cancer-related mortality globally. Despite recent advances with personalized therapies and immunotherapy, the prognosis remains dire and recurrence is frequent. Myc is an oncogene deregulated in human cancers, including lung cancer, where it supports tumorigenic processes and progression. Elevated Myc levels have also been associated with resistance to therapy.Areas covered: This article summarizes the genomic and transcriptomic studies that compile evidence for (i) MYC, MYCN, and MYCL amplification and overexpression in lung cancer patients, and (ii) their prognostic significance. We collected the most recent literature regarding the development of Myc inhibitors where the emphasis is on those inhibitors tested in lung cancer experimental models and their potential for future clinical application.Expert opinion: The targeting of Myc in lung cancer is potentially an unprecedented opportunity for inhibiting a key player in tumor progression and maintenance and therapeutic resistance. Myc inhibitory strategies are on the path to their clinical application but further work is necessary for the assessment of their use in combination with standard treatment approaches. Given the role of Myc in immune suppression, a significant opportunity may exist in the combination of Myc inhibitors with immunotherapies.
Collapse
Affiliation(s)
| | | | - Laura Soucek
- Peptomyc S.L., Edifici Cellex, Hospital Vall d'Hebron, Barcelona, Spain.,Edifici Cellex, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain.,Institució Catalana De Recerca I Estudis Avançats (ICREA), Barcelona, Spain.,Department of Biochemistry and Molecular Biology, Universitat Autònoma De Barcelona, Bellaterra, Spain
| |
Collapse
|
7
|
Guo J, Liu C, Wang P, Cheng Q, Sun L, Yang W, Shen H. The Aborted Microspores ( AMS)-Like Gene Is Required for Anther and Microspore Development in Pepper ( Capsicum annuum L.). Int J Mol Sci 2018; 19:ijms19051341. [PMID: 29724052 PMCID: PMC5983743 DOI: 10.3390/ijms19051341] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 04/27/2018] [Accepted: 04/30/2018] [Indexed: 12/01/2022] Open
Abstract
Pepper (Capsicum annuum L.) is an economically important vegetable crop worldwide. Although many genes associated with anther and pollen development have been identified, little is known about the mechanism of pollen abortion in pepper. Here, we identified and isolated two putative aborted microspore (AMS) isoforms from pepper flowers: CaAMS1 and CaAMS2. Sequence analysis showed that CaAMS2 was generated by retention of the fourth intron in CaAMS1 pre-mRNA. CaAMS1 encodes a putative protein with a basic helix-loop-helix (bHLH) domain belonging to the MYC subfamily of bHLH transcription factors, and it is localized to the nucleus. Truncated CaAMS2-1 and CaAMS2-2 are produced by alternative splicing. Quantitative real-time PCR analysis showed that CaAMS (referred to CaAMS1 and CaAMS2-2) was preferentially expressed in stamens and its expression level gradually decreases with flower development. RNA in situ hybridization analysis showed that CaAMS is strongly expressed in the tapetum at the tetrad and uninucleate stages. Downregulation of CaAMS led to partial shortened filaments, shriveled, indehiscent stamens and abortive pollens in pepper flowers. Several genes involved in pollen exine formation were downregulated in defective CaAMS-silenced anthers. Thus, CaAMS seems to play an important role in pepper tapetum and pollen development by regulating a complex genetic network.
Collapse
Affiliation(s)
- Jinju Guo
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing 100193, China.
| | - Chen Liu
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing 100193, China.
- Shandong Key Laboratory of Greenhouse Vegetable Biology, Institute of Vegetables and Flowers, Shandong Academy of Agricultural Sciences, Shandong Branch of National Vegetable Improvement Center, Jinan 250100, China.
| | - Peng Wang
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing 100193, China.
| | - Qing Cheng
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing 100193, China.
| | - Liang Sun
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing 100193, China.
| | - Wencai Yang
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing 100193, China.
| | - Huolin Shen
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing 100193, China.
| |
Collapse
|
8
|
Antimyeloma activity of bromodomain inhibitors on the human myeloma cell line U266 by downregulation of MYCL. Anticancer Drugs 2017; 27:756-65. [PMID: 27276402 PMCID: PMC4969056 DOI: 10.1097/cad.0000000000000389] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Supplemental Digital Content is available in the text. Bromodomain and extraterminal protein (BET) inhibitors suppress the expression of c-MYC. U266, a human myeloma cell line, expresses the MYCL gene, but not the c-MYC gene. Our aim was to analyse the antimyeloma activity of BET inhibitors on U266 cells. Two BET inhibitors, I-BET151 and JQ1, were tested. U266 cell proliferation decreased to 61.5 and 54.0% of the control after incubation with 500 nmol/l I-BET151 for 72 and 96 h and to 53.5 and 56.4% of control after incubation with 500 nmol/l JQ1 for 72 and 96 h by MTS tetrazolium, respectively. BET inhibitors induced cell cycle arrest at the G1 phase in U266 cells, but did not induce apoptosis by flow cytometry. According to Gene Set Enrichment Analysis, MYC-related genes were significantly downregulated in U266 cells treated with I-BET151 similar to KMS11 cells that expressed c-MYC. The MYCL1 was expressed in U266 cells, whereas c-MYC and MYCN were not by quantitative real-time reverse-transcription-PCR. Incubation with I-BET151 induced downregulation of MYCL1 in U266 cells. BET inhibitors decreased the cell proliferation in U266 cells with overexpression of MYCL less than those without overexpression of MYCL. BET inhibitors induce G1 arrest without apoptosis and interfere with the proliferation of U266 myeloma cells, which express MYCL, but not c-MYC. BET inhibitors might be active in cancers that express MYCL, but not c-MYC.
Collapse
|
9
|
Zhang Y, Dakic A, Chen R, Dai Y, Schlegel R, Liu X. Direct HPV E6/Myc interactions induce histone modifications, Pol II phosphorylation, and hTERT promoter activation. Oncotarget 2017; 8:96323-96339. [PMID: 29221209 PMCID: PMC5707103 DOI: 10.18632/oncotarget.22036] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Accepted: 09/15/2017] [Indexed: 11/25/2022] Open
Abstract
Human Papillomavirus Viruses (HPVs) are associated with the majority of human cervical and anal cancers and 10-30% of head and neck squamous carcinomas. E6 oncoprotein from high risk HPVs interacts with the p53 tumor suppressor protein to facilitate its degradation and increases telomerase activity for extending the life span of host cells. We published previously that the Myc cellular transcription factor associates with the high-risk HPV E6 protein in vivo and participates in the transactivation of the hTERT promoter. In the present study, we further analyzed the role of E6 and the Myc-Max-Mad network in regulating the hTERT promoter. We confirmed that E6 and Myc interact independently and that Max can also form a complex with E6. However, the E6/Max complex is observed only in the presence of Myc, suggesting that E6 associates with Myc/Max dimers. Consistent with the hypothesis that Myc is required for E6 induction of the hTERT promoter, Myc antagonists (Mad or Mnt) significantly blocked E6-mediated transactivation of the hTERT promoter. Analysis of Myc mutants demonstrated that both the transactivation domain and HLH domain of Myc protein were required for binding E6 and for the consequent transactivation of the hTERT promoter, by either Myc or E6. We also showed that E6 increased phosphorylation of Pol II on the hTERT promoter and induced epigenetic histone modifications of the hTERT promoter. More important, knockdown of Myc expression dramatically decreased engagement of acetyl-histones and Pol II at the hTERT promoter in E6-expressing cells. Thus, E6/Myc interaction triggers the transactivation of the hTERT promoter by modulating both histone modifications, Pol II phosphorylation and promoter engagement, suggesting a novel mechanism for telomerase activation and a new target for HPV- associated human cancer.
Collapse
Affiliation(s)
- Yiyu Zhang
- Department of Pathology, Center for Cell Reprogramming, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Aleksandra Dakic
- Department of Pathology, Center for Cell Reprogramming, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Renxiang Chen
- Department of Pathology, Center for Cell Reprogramming, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Yuhai Dai
- Department of Pathology, Center for Cell Reprogramming, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Richard Schlegel
- Department of Pathology, Center for Cell Reprogramming, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Xuefeng Liu
- Department of Pathology, Center for Cell Reprogramming, Georgetown University Medical Center, Washington, DC 20057, USA
| |
Collapse
|
10
|
Brägelmann J, Böhm S, Guthrie MR, Mollaoglu G, Oliver TG, Sos ML. Family matters: How MYC family oncogenes impact small cell lung cancer. Cell Cycle 2017; 16:1489-1498. [PMID: 28737478 DOI: 10.1080/15384101.2017.1339849] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Small cell lung cancer (SCLC) is one of the most deadly cancers and currently lacks effective targeted treatment options. Recent advances in the molecular characterization of SCLC has provided novel insight into the biology of this disease and raises hope for a paradigm shift in the treatment of SCLC. We and others have identified activation of MYC as a driver of susceptibility to Aurora kinase inhibition in SCLC cells and tumors that translates into a therapeutic option for the targeted treatment of MYC-driven SCLC. While MYC shares major features with its paralogs MYCN and MYCL, the sensitivity to Aurora kinase inhibitors is unique for MYC-driven SCLC. In this review, we will compare the distinct molecular features of the 3 MYC family members and address the potential implications for targeted therapy of SCLC.
Collapse
Affiliation(s)
- Johannes Brägelmann
- a Molecular Pathology, Institute of Pathology, University of Cologne , Cologne , Germany.,b Department of Translational Genomics , Medical Faculty, University of Cologne , Cologne , Germany
| | - Stefanie Böhm
- a Molecular Pathology, Institute of Pathology, University of Cologne , Cologne , Germany.,b Department of Translational Genomics , Medical Faculty, University of Cologne , Cologne , Germany
| | - Matthew R Guthrie
- c Department of Oncological Sciences , University of Utah, Huntsman Cancer Institute , Salt Lake City , UT , USA
| | - Gurkan Mollaoglu
- c Department of Oncological Sciences , University of Utah, Huntsman Cancer Institute , Salt Lake City , UT , USA
| | - Trudy G Oliver
- c Department of Oncological Sciences , University of Utah, Huntsman Cancer Institute , Salt Lake City , UT , USA
| | - Martin L Sos
- a Molecular Pathology, Institute of Pathology, University of Cologne , Cologne , Germany.,b Department of Translational Genomics , Medical Faculty, University of Cologne , Cologne , Germany.,d Center for Molecular Medicine Cologne , University of Cologne , Cologne , Germany
| |
Collapse
|
11
|
Kumari A, Folk WP, Sakamuro D. The Dual Roles of MYC in Genomic Instability and Cancer Chemoresistance. Genes (Basel) 2017; 8:genes8060158. [PMID: 28590415 PMCID: PMC5485522 DOI: 10.3390/genes8060158] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/31/2017] [Accepted: 06/01/2017] [Indexed: 12/18/2022] Open
Abstract
Cancer is associated with genomic instability and aging. Genomic instability stimulates tumorigenesis, whereas deregulation of oncogenes accelerates DNA replication and increases genomic instability. It is therefore reasonable to assume a positive feedback loop between genomic instability and oncogenic stress. Consistent with this premise, overexpression of the MYC transcription factor increases the phosphorylation of serine 139 in histone H2AX (member X of the core histone H2A family), which forms so-called γH2AX, the most widely recognized surrogate biomarker of double-stranded DNA breaks (DSBs). Paradoxically, oncogenic MYC can also promote the resistance of cancer cells to chemotherapeutic DNA-damaging agents such as cisplatin, clearly implying an antagonistic role of MYC in genomic instability. In this review, we summarize the underlying mechanisms of the conflicting functions of MYC in genomic instability and discuss when and how the oncoprotein exerts the contradictory roles in induction of DSBs and protection of cancer-cell genomes.
Collapse
Affiliation(s)
- Alpana Kumari
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
- Tumor Signaling and Angiogenesis Program, Georgia Cancer Center, Augusta University, Augusta, GA 30912, USA.
| | - Watson P Folk
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
- Tumor Signaling and Angiogenesis Program, Georgia Cancer Center, Augusta University, Augusta, GA 30912, USA.
- Biochemistry and Cancer Biology Program, The Graduate School, Augusta University, Augusta, GA 30912, USA.
| | - Daitoku Sakamuro
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
- Tumor Signaling and Angiogenesis Program, Georgia Cancer Center, Augusta University, Augusta, GA 30912, USA.
- Biochemistry and Cancer Biology Program, The Graduate School, Augusta University, Augusta, GA 30912, USA.
| |
Collapse
|
12
|
Zhang Q, West-Osterfield K, Spears E, Li Z, Panaccione A, Hann SR. MB0 and MBI Are Independent and Distinct Transactivation Domains in MYC that Are Essential for Transformation. Genes (Basel) 2017; 8:genes8050134. [PMID: 28481271 PMCID: PMC5448008 DOI: 10.3390/genes8050134] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 04/24/2017] [Accepted: 04/28/2017] [Indexed: 01/05/2023] Open
Abstract
MYC is a transcription factor that is essential for cellular proliferation and development. Deregulation or overexpression of MYC occurs in a variety of human cancers. Ectopic expression of MYC causes hyperproliferation and transformation of cells in culture and tumorigenesis in several transgenic mouse models. Deregulation of MYC can also induce apoptosis through activation of p53 and/or ARF tumor suppressors as a safeguard to prevent tumorigenesis. MYC binds to thousands of genomic sites and regulates hundreds of target genes in a context-dependent fashion to mediate these diverse biological roles. The N-terminal region of MYC contains several conserved domains or MYC Boxes (MB), which influence the different MYC transcriptional and biological activities to varying degrees. However, the specific domains that mediate the ability of MYC to activate transcription remain ill defined. In this report, we have identified a new conserved transactivation domain (TAD), MB0, which is essential for MYC transactivation and target gene induction. We demonstrate that MB0 and MBI represent two distinct and independent TADs within the N-terminal 62 amino acids of MYC. In addition, both MB0 and MBI are essential for MYC transformation of primary fibroblasts in cooperation with activated RAS, while MB0 is necessary for efficient MYC-induced p53-independent apoptosis.
Collapse
Affiliation(s)
- Qin Zhang
- Department of Cell and Developmental Biology, Vanderbilt University, School of Medicine, 1121 21st Ave., Nashville, TN 37232, USA.
| | - Kimberly West-Osterfield
- Department of Cell and Developmental Biology, Vanderbilt University, School of Medicine, 1121 21st Ave., Nashville, TN 37232, USA.
| | - Erick Spears
- Department of Cell and Developmental Biology, Vanderbilt University, School of Medicine, 1121 21st Ave., Nashville, TN 37232, USA.
| | - Zhaoliang Li
- Department of Cell and Developmental Biology, Vanderbilt University, School of Medicine, 1121 21st Ave., Nashville, TN 37232, USA.
| | - Alexander Panaccione
- Department of Cell and Developmental Biology, Vanderbilt University, School of Medicine, 1121 21st Ave., Nashville, TN 37232, USA.
| | - Stephen R Hann
- Department of Cell and Developmental Biology, Vanderbilt University, School of Medicine, 1121 21st Ave., Nashville, TN 37232, USA.
| |
Collapse
|
13
|
Kim DW, Wu N, Kim YC, Cheng PF, Basom R, Kim D, Dunn CT, Lee AY, Kim K, Lee CS, Singh A, Gazdar AF, Harris CR, Eisenman RN, Park KS, MacPherson D. Genetic requirement for Mycl and efficacy of RNA Pol I inhibition in mouse models of small cell lung cancer. Genes Dev 2017; 30:1289-99. [PMID: 27298335 PMCID: PMC4911928 DOI: 10.1101/gad.279307.116] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 05/05/2016] [Indexed: 12/17/2022]
Abstract
Kim et al. isolated preneoplastic neuroendocrine cells from a mouse model of small cell lung cancer (SCLC) and found that ectopic expression of L-Myc conferred tumor-forming capacity. An RNA polymerase I inhibitor used to target rRNA synthesis resulted in significant tumor inhibition in an autochthonous Rb/p53-deleted mouse SCLC model. Small cell lung cancer (SCLC) is a devastating neuroendocrine carcinoma. MYCL (L-Myc) is frequently amplified in human SCLC, but its roles in SCLC progression are poorly understood. We isolated preneoplastic neuroendocrine cells from a mouse model of SCLC and found that ectopic expression of L-Myc, c-Myc, or N-Myc conferred tumor-forming capacity. We focused on L-Myc, which promoted pre-rRNA synthesis and transcriptional programs associated with ribosomal biogenesis. Deletion of Mycl in two genetically engineered models of SCLC resulted in strong suppression of SCLC. The high degree of suppression suggested that L-Myc may constitute a therapeutic target for a broad subset of SCLC. We then used an RNA polymerase I inhibitor to target rRNA synthesis in an autochthonous Rb/p53-deleted mouse SCLC model and found significant tumor inhibition. These data reveal that activation of RNA polymerase I by L-Myc and other MYC family proteins provides an axis of vulnerability for this recalcitrant cancer.
Collapse
Affiliation(s)
- Dong-Wook Kim
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - Nan Wu
- Division of human Biology, Fred Hutchinson Cancer Research Center,Seattle,Washington 98109, USA; Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Young-Chul Kim
- Department of Biostatistics and Bioinformatics, Moffitt Cancer Center, Tampa, Florida 33612, USA
| | - Pei Feng Cheng
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Ryan Basom
- Genomics and Bioinformatics Shared Resource, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Dongkyoon Kim
- Stanford University Institute for Stem Cell Biology and Regenerative Medicine, Palo Alto, California 94305, USA
| | - Colin T Dunn
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - Anastasia Y Lee
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - Keebeom Kim
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - Chang Sup Lee
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - Andrew Singh
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - Adi F Gazdar
- Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA; Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA; Department of Pathology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Chris R Harris
- Raymond and Beverly Sackler Foundation, New Brunswick, New Jersey 08901, USA; Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08903, USA; Department of Pediatrics, Robert Wood Johnson Medical School, New Brunswick, New Jersey 08901, USA
| | - Robert N Eisenman
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Kwon-Sik Park
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - David MacPherson
- Division of human Biology, Fred Hutchinson Cancer Research Center,Seattle,Washington 98109, USA; Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| |
Collapse
|
14
|
Fagnocchi L, Zippo A. Multiple Roles of MYC in Integrating Regulatory Networks of Pluripotent Stem Cells. Front Cell Dev Biol 2017; 5:7. [PMID: 28217689 PMCID: PMC5289991 DOI: 10.3389/fcell.2017.00007] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 01/20/2017] [Indexed: 12/20/2022] Open
Abstract
Pluripotent stem cells (PSCs) are defined by their self-renewal potential, which permits their unlimited propagation, and their pluripotency, being able to generate cell of the three embryonic lineages. These properties render PSCs a valuable tool for both basic and medical research. To induce and stabilize the pluripotent state, complex circuitries involving signaling pathways, transcription regulators and epigenetic mechanisms converge on a core transcriptional regulatory network of PSCs, thus determining their cell identity. Among the transcription factors, MYC represents a central hub, which modulates and integrates multiple mechanisms involved both in the maintenance of pluripotency and in cell reprogramming. Indeed, it instructs the PSC-specific cell cycle, metabolism and epigenetic landscape, contributes to limit exit from pluripotency and modulates signaling cascades affecting the PSC identity. Moreover, MYC extends its regulation on pluripotency by controlling PSC-specific non-coding RNAs. In this report, we review the MYC-controlled networks, which support the pluripotent state and discuss how their perturbation could affect cell identity. We further discuss recent finding demonstrating a central role of MYC in triggering epigenetic memory in PSCs, which depends on the establishment of a WNT-centered self-reinforcing circuit. Finally, we comment on the therapeutic implications of the role of MYC in affecting PSCs. Indeed, PSCs are used for both disease and cancer modeling and to derive cells for regenerative medicine. For these reasons, unraveling the MYC-mediated mechanism in those cells is fundamental to exploit their full potential and to identify therapeutic targets.
Collapse
Affiliation(s)
- Luca Fagnocchi
- Department of Epigenetics, Fondazione Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi" (INGM)Milan, Italy; Division of Pathology, Fondazione IRCCS Ca' Granda, Ospedale Maggiore PoliclinicoMilan, Italy
| | - Alessio Zippo
- Department of Epigenetics, Fondazione Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi" (INGM)Milan, Italy; Division of Pathology, Fondazione IRCCS Ca' Granda, Ospedale Maggiore PoliclinicoMilan, Italy
| |
Collapse
|
15
|
The ubiquitin ligase Huwe1 regulates the maintenance and lymphoid commitment of hematopoietic stem cells. Nat Immunol 2016; 17:1312-1321. [PMID: 27668798 PMCID: PMC5117833 DOI: 10.1038/ni.3559] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 08/17/2016] [Indexed: 02/07/2023]
Abstract
Hematopoietic stem cells (HSCs) are dormant in the bone marrow and can be activated in response to diverse stresses to replenish all blood cell types. Here we identify the ubiquitin ligase Huwe1 as a crucial regulator of HSC functions via its post-translational control of N-myc. We found Huwe1 to be essential for HSC self-renewal, quiescence and lymphoid fate specification. Using a novel fluorescent fusion allele (MycnM), we observed that N-myc expression was restricted to the most immature, multipotent stem and progenitor populations. N-myc was upregulated in response to stress or upon loss of Huwe1, leading to increased proliferation and stem cell exhaustion. Mycn depletion reversed most of these phenotypes in vivo, suggesting that the attenuation of N-myc by Huwe1 is essential to reestablish homeostasis following stress.
Collapse
|
16
|
Lee CM. Transport of c-MYC by Kinesin-1 for proteasomal degradation in the cytoplasm. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2027-36. [PMID: 24821626 DOI: 10.1016/j.bbamcr.2014.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 04/30/2014] [Accepted: 05/02/2014] [Indexed: 10/25/2022]
Abstract
c-MYC is an oncogenic transcription factor that is degraded by the proteasome pathway. However, the mechanism that regulates delivery of c-MYC to the proteasome for degradation is not well characterized. Here, the results show that the motor protein complex Kinesin-1 transports c-MYC to the cytoplasm for proteasomal degradation. Inhibition of Kinesin-1 function enhanced ubiquitination of c-MYC and induced aggregation of c-MYC in the cytoplasm. Transport studies showed that the c-MYC aggregates moved from the nucleus to the cytoplasm and KIF5B is responsible for the transport in the cytoplasm. Furthermore, inhibition of the proteasomal degradation process also resulted in an accumulation of c-MYC aggregates in the cytoplasm. Moreover, Kinesin-1 was shown to interact with c-MYC and the proteasome subunit S6a. Inhibition of Kinesin-1 function also reduced c-MYC-dependent transformation activities. Taken together, the results strongly suggest that Kinesin-1 transports c-MYC for proteasomal degradation in the cytoplasm and the proper degradation of c-MYC mediated by Kinesin-1 transport is important for transformation activities of c-MYC. In addition, the results indicate that Kinesin-1 transport mechanism is important for degradation of a number of other proteins as well.
Collapse
Affiliation(s)
- Clement M Lee
- Icahn School of Medicine at Mount Sinai, Department of Oncological Sciences, One Gustave L. Levy Place, Box 1130, New York, NY 10029, USA.
| |
Collapse
|
17
|
Abstract
The MYC family of proteins is a group of basic-helix-loop-helix-leucine zipper transcription factors that feature prominently in cancer. Overexpression of MYC is observed in the vast majority of human malignancies and promotes an extraordinary set of changes that impact cell proliferation, growth, metabolism, DNA replication, cell cycle progression, cell adhesion, differentiation, and metastasis. The purpose of this review is to introduce the reader to the mammalian family of MYC proteins, highlight important functional properties that endow them with their potent oncogenic potential, describe their mechanisms of action and of deregulation in cancer cells, and discuss efforts to target the unique properties of MYC, and of MYC-driven tumors, to treat cancer.
Collapse
|
18
|
Pshenichnaya I, Schouwey K, Armaro M, Larue L, Knoepfler PS, Eisenman RN, Trumpp A, Delmas V, Beermann F. Constitutive gray hair in mice induced by melanocyte-specific deletion of c-Myc. Pigment Cell Melanoma Res 2012; 25:312-25. [PMID: 22420299 DOI: 10.1111/j.1755-148x.2012.00998.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
c-Myc is involved in the control of diverse cellular processes and implicated in the maintenance of different tissues including the neural crest. Here, we report that c-Myc is particularly important for pigment cell development and homeostasis. Targeting c-Myc specifically in the melanocyte lineage using the floxed allele of c-Myc and Tyr::Cre transgenic mice results in a congenital gray hair phenotype. The gray coat color is associated with a reduced number of functional melanocytes in the hair bulb and melanocyte stem cells in the hair bulge. Importantly, the gray phenotype does not progress with time, suggesting that maintenance of the melanocyte through the hair cycle does not involve c-Myc function. In embryos, at E13.5, c-Myc-deficient melanocyte precursors are affected in proliferation in concordance with a reduction in numbers, showing that c-Myc is required for the proper melanocyte development. Interestingly, melanocytes from c-Myc-deficient mice display elevated levels of the c-Myc paralog N-Myc. Double deletion of c-Myc and N-Myc results in nearly complete loss of the residual pigmentation, indicating that N-Myc is capable of compensating for c-Myc loss of function in melanocytes.
Collapse
Affiliation(s)
- Irina Pshenichnaya
- Swiss Institute for Experimental Cancer Research, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Smith K, Dalton S. Myc transcription factors: key regulators behind establishment and maintenance of pluripotency. Regen Med 2011; 5:947-59. [PMID: 21082893 DOI: 10.2217/rme.10.79] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The interplay between transcription factors, epigenetic modifiers, chromatin remodelers and miRNAs form the foundation of a complex regulatory network required for establishment and maintenance of the pluripotent state. Recent work indicates that Myc transcription factors are essential elements of this regulatory system. However, despite numerous studies, aspects of how Myc controls self-renewal and pluripotency remain obscure. This article reviews evidence supporting the placement of Myc as a central regulator of the pluripotent state and discusses possible mechanisms of action.
Collapse
Affiliation(s)
- Keriayn Smith
- Paul D Coverdell Center for Biomedical & Health Sciences, Department of Biochemistry & Molecular Biology, University of Georgia, 500 DW Brooks Drive, Athens, GA 30602, USA
| | | |
Collapse
|
20
|
He Z, Cho YY, Liu G, Ma WY, Bode AM, Dong Z. p38 Mitogen-activated protein kinase regulation of JB6 Cl41 cell transformation promoted by epidermal growth factor. J Biol Chem 2003; 278:26435-42. [PMID: 12748197 DOI: 10.1074/jbc.m303859200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The relationship between cell transformation and p38 MAP kinase, a major mitogen-activated protein (MAP) kinase pathway converting signals of various extracellular stimuli into expression of specific target genes through activation of transcription factors, still remains unclear. The aim of the present study was to investigate the role of the p38 MAP kinase pathway in epidermal growth factor (EGF)-induced cell transformation in JB6 cells. Our data show that a dominant negative mutant of p38 MAP (DN-p38) kinase inhibits EGF-promoted JB6 Cl41 cell transformation and that SB202190, an inhibitor of p38 MAP kinase, also inhibits JB6 Cl41 cell transformation in a dose-dependent manner. Moreover, our results show that DN-p38 MAP kinase inhibits the phosphorylation of EGF-stimulated activating transcription factor-2 (ATF-2) and signal transducer and activator of transcription 1 (STAT1). Additionally, DN-p38 MAP kinase inhibits EGF-induced phosphorylation of c-Myc (Thr58/Ser62). Gel shift assays indicate that DN-p38 MAP kinase inhibits EGF-induced activator protein-1 (AP-1) DNA binding in a dose-dependent manner. These results show that p38 MAP kinase plays a key role in the regulation of EGF-induced cell transformation in JB6 cells through regulation of phosphorylation of p38 MAP kinase and activation of its target genes in phosphorylation, c-Myc cell transformation-related genes, and AP-1 binding ability.
Collapse
Affiliation(s)
- Zhiwei He
- Hormel Institute, University of Minnesota, Austin, Minnesota 55912, USA
| | | | | | | | | | | |
Collapse
|
21
|
Schwering I, Bräuninger A, Distler V, Jesdinsky J, Diehl V, Hansmann ML, Rajewsky K, Küppers R. Profiling of Hodgkin’s Lymphoma Cell Line L1236 and Germinal Center B Cells: Identification of Hodgkin’s Lymphoma-specific Genes. Mol Med 2003. [DOI: 10.1007/bf03402041] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
|
22
|
Oster SK, Mao DYL, Kennedy J, Penn LZ. Functional analysis of the N-terminal domain of the Myc oncoprotein. Oncogene 2003; 22:1998-2010. [PMID: 12673205 DOI: 10.1038/sj.onc.1206228] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Myc is a multifunctional nuclear phosphoprotein that can drive cell cycle progression, apoptosis and cellular transformation. Myc orchestrates these activities at the molecular level by functioning as a regulator of gene transcription to activate or repress specific target genes. Previous studies have shown that both the Myc N-terminal domain (NTD) and the C-terminal domain (CTD) are essential for Myc functions. The role of the CTD is relatively well understood as it encodes a basic helix-loop-helix leucine zipper motif important for DNA binding and protein-protein interactions. By contrast, the role of the NTD and the specific domains responsible for different Myc activities are not as well defined. To investigate the regions of the NTD necessary for Myc function and to determine whether these activities are overlapping or independent of one another, we have conducted a detailed structure-function analysis of the Myc NTD. We assessed the ability of a number of deletion and point mutants within the highly conserved regions of the Myc NTD to induce cell cycle progression, apoptosis and transformation as well as repress and activate expression of endogenous target genes. Our analyses highlight the complexity of the Myc NTD and extend previous studies. For example, we show most Myc mutants that were compromised as repressors of gene transcription retained the ability to activate gene transcription, reinforcing the concept that these activities can be uncoupled. Repression of two different target genes could be distinguished by specific mutants, further supporting the notion of at least two different Myc repression mechanisms. Mutants disabled at both inducing and repressing gene transcription could not maximally drive the biological activities of Myc, indicating these functions are tightly linked. Indeed, a close association of Myc repression and apoptosis was also observed.
Collapse
Affiliation(s)
- Sara K Oster
- Ontario Cancer Institute, University of Toronto, Canada
| | | | | | | |
Collapse
|
23
|
Auvinen M, Järvinen K, Hotti A, Okkeri J, Laitinen J, Jänne OA, Coffino P, Bergman M, Andersson LC, Alitalo K, Hölttä E. Transcriptional regulation of the ornithine decarboxylase gene by c-Myc/Max/Mad network and retinoblastoma protein interacting with c-Myc. Int J Biochem Cell Biol 2003; 35:496-521. [PMID: 12565711 DOI: 10.1016/s1357-2725(02)00305-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
c-Myc is an oncogenic transcription factor involved in the regulation of cell proliferation, differentiation and apoptosis. The direct targets of c-Myc mediating these various processes are slowly being unravelled. This study indicates that the ornithine decarboxylase (ODC) gene is a physiological transcriptional target of c-Myc in association with induction of cell proliferation and transformation, but not with induction of apoptosis. In addition to the two conserved CACGTG c-Myc-binding sites in the first intron, the CATGTG motif in the 5'-flanking region of the murine odc is also shown to be a functional c-Myc response element. odc is thus a c-Myc target with three binding sites a distance apart. Transient transfection studies with different c-Myc, Max and Mad constructs in COS-7 cells showed that the balance between c-Myc/Max, Max/Max and Max/Mad complexes is crucial for the regulation, resulting in either transactivation or transrepression of an ODC-CAT reporter gene. Transcription of both ODC-CAT and endogenous odc was strongly induced in HeLa cells expressing tetracycline-regulated c-Myc, concomitant with c-Myc promoting the S-phase entry of the cells. Transformation of NIH3T3 cells by c-Ha-ras-(Val12) oncogene was reversed by expression of transcriptionally inactive c-Myc, which was associated with repression of ODC-CAT expression. Further, the c-Myc-induced transactivation of ODC-CAT in COS-7 cells was suppressed by co-expression of the retinoblastoma tumor suppresser pRb, evidently as a result of pRb directly or indirectly interacting with c-Myc. Importantly, the endogenous c-Myc and pRb proteins were also found to associate in Colo 320HSR cells under physiological conditions. These results suggest that c-Myc and pRb can interact in vivo, and may in part control some aspects of cell proliferation and transformation through modulation of odc expression.
Collapse
Affiliation(s)
- Merja Auvinen
- Department of Pathology, Haartman Institute and Helsinki University Central Hospital, University of Helsinki, P.O. Box 21, 00014, Helsinki, Finland
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Schwering I, Bräuninger A, Distler V, Jesdinsky J, Diehl V, Hansmann ML, Rajewsky K, Küppers R. Profiling of Hodgkin's lymphoma cell line L1236 and germinal center B cells: identification of Hodgkin's lymphoma-specific genes. Mol Med 2003; 9:85-95. [PMID: 12865944 PMCID: PMC1430727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023] Open
Abstract
The malignant cells of classical Hodgkin's lymphoma (cHL), Hodgkin and Reed-Sternberg (HRS) cells, appear to be derived from germinal center (GC) B cells in most cases of the disease. Apart from recent findings of constitutive activation of some transcription factors and autocrine stimulation by cytokine receptors, the mechanisms of malignant transformation in cHL still remain poorly understood. We performed a large scale gene expression study using serial analysis of gene expression (SAGE), comparing the cHL cell line L1236 and human GC B cells. Semiquantitative RT-PCR was used to confirm results from the SAGE and to analyze gene expression in 3 additional cHL cell lines. To investigate expression of some genes in cHL cases, we applied RT-PCR on microdissected HRS cells. In total, 464 genes showed a change in expression level of 5-fold or higher. For 12 genes (out of 177) identified as upregulated in L1236 cells, RT-PCR confirmed the SAGE results and also showed elevated expression in 3 other cHL cell lines. For 3 of the upregulated genes, expression by HRS cells in the tissue also was confirmed. Several of the differentially expressed genes may play a role in the pathogenesis of cHL because they represent potential oncogenes, such as rhoC, L-myc, and PTP4A, or transcription factors, such as ATF-5, ATBF1, and p21SNFT. The genes that showed significantly deregulated expression in HRS cells should be helpful not only for the identification of genes involved in the pathogenesis of cHL but also for discovering potential prognostic markers or therapeutic targets.
Collapse
Affiliation(s)
- Ines Schwering
- Institute for Genetics, University of Cologne, Cologne, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
25
|
Landay M, Oster SK, Khosravi F, Grove LE, Yin X, Sedivy J, Penn LZ, Prochownik EV. Promotion of growth and apoptosis in c-myc nullizygous fibroblasts by other members of the myc oncoprotein family. Cell Death Differ 2000; 7:697-705. [PMID: 10918443 DOI: 10.1038/sj.cdd.4400701] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
c-myc nullizygous fibroblasts (KO cells) were used to compare the abilities of c-myc, N-myc and L-myc oncoproteins to accelerate growth, promote apoptosis, revert morphology, and regulate the expression of previously described c-myc target genes. All three myc oncoproteins were expressed following retroviral transduction of KO cells. The proteins all enhanced the growth rate of KO cells and significantly shortened the cell cycle transition time. They also accelerated apoptosis following serum deprivation, reverted the abnormal KO cell morphology, and modulated the expression of previously described c-myc target genes. In most cases, L-myc was equivalent to c-myc and N-myc in restoring all of the c-myc-dependent activities. These findings contrast with the previously reported weak transforming and transactivating properties of L-myc. Myc oncoproteins may thus impart both highly similar as well as dissimilar signals to the cells in which they are expressed.
Collapse
Affiliation(s)
- M Landay
- Section of Hematology/Oncology, Department of Pediatrics, Children's Hospital of Pittsburgh, Pittsburgh, PA 15213, USA
| | | | | | | | | | | | | | | |
Collapse
|
26
|
Malynn BA, de Alboran IM, O'Hagan RC, Bronson R, Davidson L, DePinho RA, Alt FW. N-myc can functionally replace c-myc in murine development, cellular growth, and differentiation. Genes Dev 2000; 14:1390-9. [PMID: 10837031 PMCID: PMC316670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Members of the myc family of cellular oncogenes have been implicated as transcriptional regulators in pathways that govern cellular proliferation and death. In addition, N-myc and c-myc are essential for completion of murine embryonic development. However, the basis for the evolutionary conservation of myc gene family has remained unclear. To elucidate this issue, we have generated mice in which the endogenous c-myc coding sequences have been replaced with N-myc coding sequences. Strikingly, mice homozygous for this replacement mutation can survive into adulthood and reproduce. Moreover, when expressed from the c-myc locus, N-myc is similarly regulated and functionally complementary to c-myc in the context of various cellular growth and differentiation processes. Therefore, the myc gene family must have evolved, to a large extent, to facilitate differential patterns of expression.
Collapse
Affiliation(s)
- B A Malynn
- The Center for Blood Research, Boston, Massachusetts 02115 USA
| | | | | | | | | | | | | |
Collapse
|
27
|
Yin XY, Gupta K, Han WP, Levitan ES, Prochownik EV. Mmip-2, a novel RING finger protein that interacts with mad members of the Myc oncoprotein network. Oncogene 1999; 18:6621-34. [PMID: 10597267 DOI: 10.1038/sj.onc.1203097] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mad proteins are basic-helix-loop-helix-leucine zipper (bHLH-ZIP)-containing members of the myc oncoprotein network. They interact with the bHLH-ZIP protein max, compete for the same DNA binding sites as myc-max heterodimers and down-regulate myc-responsive genes. Using the bHLH-ZIP domain of mad1 as a yeast two-hybrid 'bait', we identified Mmip-2, a novel RING finger protein that interacts with all mad members, but weakly or not at all with c-myc, max or unrelated bHLH or bZIP proteins. The mad1-Mmip-2 interaction is mediated by the ZIP domain in the former protein and by at least two regions in the latter which do not include the RING finger. Mmip-2 can disrupt max-mad DNA binding and can reverse the suppressive effects of mad proteins on c-myc-responsive target genes and on c-myc + ras-mediated focus formation in fibroblasts. Tagging with spectral variants of green fluorescent protein showed that Mmip-2 and mad proteins reside in separate cytoplasmic and nuclear compartments, respectively. When co-expressed, however, the proteins interact and translocate to the cellular compartment occupied by the more abundant protein. These observations suggest a novel way by which Mmip-2 can modulate the transcriptional activity of myc oncoproteins.
Collapse
Affiliation(s)
- X Y Yin
- Section of Hematology/Oncology, Children's Hospital of Pittsburgh, University of Pittsburgh Cancer Institute, PA 15213, USA
| | | | | | | | | |
Collapse
|
28
|
Cole MD, McMahon SB. The Myc oncoprotein: a critical evaluation of transactivation and target gene regulation. Oncogene 1999; 18:2916-24. [PMID: 10378688 DOI: 10.1038/sj.onc.1202748] [Citation(s) in RCA: 233] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mutations which disrupt the regulation or expression level of the c-myc gene are among the most common found in human and animal cancers (reviewed in ref. Cole, 1986; Henriksson and Luscher, 1996; Marcu et al., 1992). Ectopic expression studies define numerous biological activities of the c-myc gene, including transformation, immortalization, blockage of cell differentiation and induction of apoptosis (Askew et al., 1991; Cole, 1986; Evan and Littlewood, 1993; Freytag et al., 1990; Henriksson and Luscher, 1996; Marcu et al., 1992). Furthermore, c-myc is required for efficient progression through the cell cycle (Goruppi et al., 1994; Prochownik et al., 1988; Yokoyama and Imamoto, 1987), although recent studies indicate that it is not absolutely essential (Mateyak et al., 1997). This fascinating array of biological activities makes the c-myc gene one of the most intriguing oncogenes and presents the challenging question of how a single gene can manifest so many different effects. The c-Myc protein exhibits sequence-specific DNA binding when dimerized with its partner Max, and DNA binding is mediated through the basic region, which recognizes the core sequence CACGTG (Berberich et al., 1992; Blackwell et al., 1993; Blackwood and Eisenman, 1991; Prendergast and Ziff, 1991; Prendergast et al., 1991), but exhibits somewhat higher affinity for the more extended sequence ACCACGTGGT (Berberich et al., 1992; Blackwell et al., 1993; Halazonetis and Kandil, 1991). There are three closely related Myc family proteins (c-Myc, N-Myc and L-Myc), each with documented oncogenic potential (Birrer et al., 1988; Schwab et al., 1985; Yancopoulos et al., 1985) and similar DNA binding properties (Mukherjee et al., 1992). For simplicity, we will use the term Myc to refer to all three proteins, but delineate any distinct activities where they apply. The goal of this review is to discuss Myc as a transcriptional activator and critically evaluate the evidence for the transactivation of specific target genes as direct downstream effectors. Since excellent comprehensive reviews on Myc have been published recently (Facchini and Penn, 1998; Henriksson and Luscher, 1996), we will focus on the latest observations that offer mechanistic insight into transactivation and oncogenic transformation.
Collapse
Affiliation(s)
- M D Cole
- Department of Molecular Biology, Princeton University, New Jersey 08544-1014, USA
| | | |
Collapse
|
29
|
Abstract
c-myc, N-myc and L-myc are the three members of the myc oncoprotein family whose role in the pathogenesis of many human neoplastic diseases has received wide empirical support. In this review, we first summarize data, derived mainly from non-clinical studies, indicating that these oncoproteins actually serve quite different roles in vivo. This concept necessarily lies at the heart of the basis for the observation that the deregulated expression of each MYC gene is reproducibly associated with only certain naturally occurring malignancies in humans and that these genes are not interchangeable with respect to their aberrant functional consequences. We also review evidence implicating each of the above MYC genes in specific neoplastic diseases and have attempted to identify unresolved questions which deserve further basic or clinical investigation. We have made every attempt to review those diseases for which significant and confirmatory evidence, based on studies with primary tumor material, exists to implicate MYC members in their causation and/or progression.
Collapse
Affiliation(s)
- C E Nesbit
- Department of Pediatrics, Children's Hospital of Pittsburgh, Pennsylvania 15213, USA
| | | | | |
Collapse
|
30
|
Yin XY, Grove L, Datta NS, Long MW, Prochownik EV. C-myc overexpression and p53 loss cooperate to promote genomic instability. Oncogene 1999; 18:1177-84. [PMID: 10022123 DOI: 10.1038/sj.onc.1202410] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
p53 monitors genomic integrity at the G1 and G2/M cell cycle checkpoints. Cells lacking p53 may show gene amplification as well as the polyploidy or aneuploidy typical of many tumors. The pathways through which this develops, however, are not well defined. We demonstrate here that the combination of p53 inactivation and c-myc overexpression in diploid cells markedly accelerates the spontaneous development of tetraploidy. This is not seen with either N-myc or L-myc. Tetraploidy is accompanied by significantly higher levels of cyclin B and its associated cdc2 kinase activity. Mitotic spindle poisons accelerate the appearance of tetraploidy in cells either lacking functional p53 or overexpressing c-myc whereas the combination is additive. Restoration of p53 function in cells overexpressing c-myc causing rapid apoptosis, indicating that cells yet to become tetraploid have nonetheless suffered irreversible genomic and/or mitotic spindle damage. In the face of normal p53 function, such damage would either be repaired or trigger apoptotis. We propose that loss of p53 and overexpression of c-myc permits the emergence and survival of cells with increasingly severe damage and the eventual development of tetraploidy.
Collapse
Affiliation(s)
- X Y Yin
- Department of Pediatrics, Children's Hospital of Pittsburgh Pennsylvania, USA
| | | | | | | | | |
Collapse
|
31
|
Smith-Sørensen B, Hijmans EM, Beijersbergen RL, Bernards R. Functional analysis of Burkitt's lymphoma mutant c-Myc proteins. J Biol Chem 1996; 271:5513-8. [PMID: 8621409 DOI: 10.1074/jbc.271.10.5513] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The c-myc gene encodes a sequence-specific DNA binding protein that activates transcription of cellular genes. Transcription activation by Myc proteins is regulated by phosphorylation of serine and threonine residues within the transactivation domain and by complex formation with the retinoblastoma-related protein p107. In Burkitt's lymphoma, missense mutations within the c-Myc transactivation domain have been found with high frequency. It has been reported that mutant c-Myc proteins derived from Burkitt's lymphoma cell lines are resistant to inhibition by p107, thus providing a rationale for the increased oncogenic activity of these mutant c-Myc proteins. It has been suggested that these mutant c-Myc proteins resist down-modulation by p107 because they lack cyclin A-cdk2-dependent phosphorylation. Here, we have examined three different Burkitt's lymphoma mutant c-Myc proteins found in primary Burkitt's lymphomas and one mutant c-Myc protein detected in a Burkitt's lymphoma cell line. All four have an unaltered ability to activate transcription and are sensitive to inhibition of transactivation by p107. Furthermore, we provide evidence that down-modulation of c-Myc transactivation by p107 does not require phosphorylation of the c-Myc transactivation domain by cyclin A-cdk2. Our data indicate that escape from p107-induced suppression is not a general consequence of all Burkitt's lymphoma-associated c-Myc mutations, suggesting that other mechanisms exist to deregulate c-Myc function.
Collapse
Affiliation(s)
- B Smith-Sørensen
- Division of Molecular Carcinogenesis, The Netherlands Cancer Institute, 121 Plesmanlaan, 1066 CX Amsterdam, The Netherlands
| | | | | | | |
Collapse
|
32
|
Henriksson M, Lüscher B. Proteins of the Myc network: essential regulators of cell growth and differentiation. Adv Cancer Res 1996; 68:109-82. [PMID: 8712067 DOI: 10.1016/s0065-230x(08)60353-x] [Citation(s) in RCA: 583] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- M Henriksson
- Institute for Molecular Biology, Hannover Medical School, Germany
| | | |
Collapse
|
33
|
Amati B, Land H. Myc-Max-Mad: a transcription factor network controlling cell cycle progression, differentiation and death. Curr Opin Genet Dev 1994; 4:102-8. [PMID: 8193530 DOI: 10.1016/0959-437x(94)90098-1] [Citation(s) in RCA: 264] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The Myc oncoprotein dimerizes with its partner, Max, to bind DNA, activate transcription, and promote cell proliferation, as well as programmed cell death. Max also forms homodimers or heterodimers with its alternative partners, Mad and Mxi-1. These complexes behave as antagonists of Myc/Max through competition for common DNA targets, and perhaps permit cellular differentiation.
Collapse
Affiliation(s)
- B Amati
- Imperial Cancer Research Fund, London, UK
| | | |
Collapse
|
34
|
Moens CB, Stanton BR, Parada LF, Rossant J. Defects in heart and lung development in compound heterozygotes for two different targeted mutations at the N-myc locus. Development 1993; 119:485-99. [PMID: 8287798 DOI: 10.1242/dev.119.2.485] [Citation(s) in RCA: 123] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Two types of mutant allele, one leaky and one null, have been generated by gene targeting at the N-myc locus in embryonic stem cells and the phenotypes of mice homozygous for these mutations have been described. These mutations have shown that N-myc has a number of functions during development, including a role in branching morphogenesis in the lung, which manifests itself at birth in mice homozygous for the leaky allele, and roles in the development of the mesonephric tubules, the neuroepithelium, the sensory ganglia, the gut and the heart, which become evident at midgestation in embryos homozygous for the null allele. In an attempt to define roles for N-myc at other stages of development, we have combined the two types of N-myc mutant allele in a compound heterozygote that as a result contains approximately 15% of normal levels of N-Myc protein. Compound heterozygotes died during gestation at a time intermediate to the times of death of embryos homozygous for either mutation individually, and their death appeared to result from cardiac failure stemming from hypoplasia of the compact subepicardial layer of the myocardium. Investigation of the expression pattern of N-myc and various markers of differentiation in wild-type and compound heterozygote mutant hearts has suggested that N-myc may function in maintaining the proliferation and/or preventing the differentiation of compact layer myocytes. This study illustrates the importance of generating different mutations at a given locus to elucidate fully the function of a particular gene during development.
Collapse
Affiliation(s)
- C B Moens
- Division of Molecular and Developmental Biology, Samuel Lunenfeld Research Institute, Toronto, Ontario, Canada
| | | | | | | |
Collapse
|
35
|
Hirvonen H, Hukkanen V, Salmi TT, Pelliniemi TT, Alitalo R. L-myc and N-myc in hematopoietic malignancies. Leuk Lymphoma 1993; 11:197-205. [PMID: 8260894 DOI: 10.3109/10428199309086996] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The myc proto-oncogenes encode nuclear DNA-binding phosphoproteins which regulate cell proliferation and differentiation. The c-myc gene is implicated in hematopoietic malignancies on the basis of its frequent deregulation in naturally occurring leukemias and lymphomas. Recent evidence suggests that also the N-myc and L-myc genes may have a role in normal and malignant hematopoiesis. N-myc and to a certain degree L-myc can substitute for c-myc in transformation assays in vitro, and their overexpression can block the differentiation of leukemia cell lines. Immunoglobulin heavy chain enhancer (IgH) -driven overexpression of N-myc or L-myc genes cause lymphatic and myeloid tumors, respectively, in transgenic mice. Furthermore, the L-myc and N-myc genes are expressed in several human leukemias and leukemia cell lines, L-myc predominantly in myeloid and N-myc both in myeloid and in some lymphoid leukemias. All N/L-myc positive leukemias and leukemia cell lines coexpress the c-myc gene, thus exemplifying a lack of negative cross-regulation between the different myc genes in leukemia cells. Taken together, these data suggest that L-myc and N-myc may participate in the growth regulation of hematopoietic cells.
Collapse
Affiliation(s)
- H Hirvonen
- Department of Medical Biochemistry, University of Turku, Finland
| | | | | | | | | |
Collapse
|
36
|
Zervos AS, Gyuris J, Brent R. Mxi1, a protein that specifically interacts with Max to bind Myc-Max recognition sites. Cell 1993; 72:223-32. [PMID: 8425219 DOI: 10.1016/0092-8674(93)90662-a] [Citation(s) in RCA: 615] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We used the interaction trap to isolate a novel human protein that specifically interacts with Max. This protein, Mxi1 (for Max interactor 1), contains a bHLH-Zip motif that is similar to that found in Myc family proteins. Mxi1 interacts specifically with Max to form heterodimers that efficiently bind to the Myc-Max consensus recognition site. When bound to DNA by a LexA moiety in yeast, Mxi1 does not stimulate transcription. mxi1 mRNA is expressed in many tissues, and its expression is elevated in U-937 myeloid leukemia cells that have been stimulated to differentiate. These facts are consistent with a model in which Mxi1-Max heterodimers indirectly inhibit Myc function in two ways: first, by sequestering Max, thus preventing the formation of Myc-Max heterodimers, and second, by competing with Myc-Max heterodimers for binding to target sites.
Collapse
MESH Headings
- Amino Acid Sequence
- Bacterial Proteins/metabolism
- Base Sequence
- Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
- Basic Helix-Loop-Helix Transcription Factors
- Basic-Leucine Zipper Transcription Factors
- Binding Sites
- Cell Differentiation/physiology
- Cloning, Molecular
- DNA, Neoplasm/genetics
- DNA, Neoplasm/isolation & purification
- DNA-Binding Proteins/chemistry
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Escherichia coli/genetics
- Gene Library
- Genes, myc
- HeLa Cells
- Humans
- Leucine Zippers/genetics
- Leucine Zippers/physiology
- Macromolecular Substances
- Molecular Sequence Data
- Oligodeoxyribonucleotides
- Open Reading Frames
- Plasmids
- Protein Structure, Secondary
- Proto-Oncogene Proteins c-myc/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Sequence Homology, Amino Acid
- Serine Endopeptidases
- Transcription Factors
- Transcription, Genetic
- Tumor Cells, Cultured
- Tumor Suppressor Proteins
- beta-Galactosidase/metabolism
Collapse
Affiliation(s)
- A S Zervos
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02114
| | | | | |
Collapse
|