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Konagaya Y, Rosenthal D, Ratnayeke N, Fan Y, Meyer T. An intermediate Rb-E2F activity state safeguards proliferation commitment. Nature 2024; 631:424-431. [PMID: 38926571 PMCID: PMC11236703 DOI: 10.1038/s41586-024-07554-2] [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: 06/19/2022] [Accepted: 05/10/2024] [Indexed: 06/28/2024]
Abstract
Tissue repair, immune defence and cancer progression rely on a vital cellular decision between quiescence and proliferation1,2. Mammalian cells proliferate by triggering a positive feedback mechanism3,4. The transcription factor E2F activates cyclin-dependent kinase 2 (CDK2), which in turn phosphorylates and inactivates the E2F inhibitor protein retinoblastoma (Rb). This action further increases E2F activity to express genes needed for proliferation. Given that positive feedback can inadvertently amplify small signals, understanding how cells keep this positive feedback in check remains a puzzle. Here we measured E2F and CDK2 signal changes in single cells and found that the positive feedback mechanism engages only late in G1 phase. Cells spend variable and often extended times in a reversible state of intermediate E2F activity before committing to proliferate. This intermediate E2F activity is proportional to the amount of phosphorylation of a conserved T373 residue in Rb that is mediated by CDK2 or CDK4/CDK6. Such T373-phosphorylated Rb remains bound on chromatin but dissociates from it once Rb is hyperphosphorylated at many sites, which fully activates E2F. The preferential initial phosphorylation of T373 can be explained by its relatively slower rate of dephosphorylation. Together, our study identifies a primed state of intermediate E2F activation whereby cells sense external and internal signals and decide whether to reverse and exit to quiescence or trigger the positive feedback mechanism that initiates cell proliferation.
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Affiliation(s)
- Yumi Konagaya
- Department of Cell and Developmental Biology, Weill Cornell Medicine, New York, NY, USA.
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA.
- Laboratory for Quantitative Biology of Cell Fate Decision, RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo, Japan.
| | - David Rosenthal
- Department of Cell and Developmental Biology, Weill Cornell Medicine, New York, NY, USA
| | - Nalin Ratnayeke
- Department of Cell and Developmental Biology, Weill Cornell Medicine, New York, NY, USA
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Yilin Fan
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Pathology and Center for Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Tobias Meyer
- Department of Cell and Developmental Biology, Weill Cornell Medicine, New York, NY, USA.
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA.
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2
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Zhou L, Tong Y, Ho BM, Li J, Chan HYE, Zhang T, Du L, He JN, Chen LJ, Tham CC, Yam JC, Pang CP, Chu WK. Etiology including epigenetic defects of retinoblastoma. Asia Pac J Ophthalmol (Phila) 2024:100072. [PMID: 38789041 DOI: 10.1016/j.apjo.2024.100072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2024] [Revised: 04/09/2024] [Accepted: 05/02/2024] [Indexed: 05/26/2024] Open
Abstract
Retinoblastoma (RB), originating from the developing retina, is an aggressive intraocular malignant neoplasm in childhood. Biallelic loss of RB1 is conventionally considered a prerequisite for initiating RB development in most RB cases. Additional genetic mutations arising from genome instability following RB1 mutations are proposed to be required to promote RB development. Recent advancements in high throughput sequencing technologies allow a deeper and more comprehensive understanding of the etiology of RB that additional genetic alterations following RB1 biallelic loss are rare, yet epigenetic changes driven by RB1 loss emerge as a critical contributor promoting RB tumorigenesis. Multiple epigenetic regulators have been found to be dysregulated and to contribute to RB development, including noncoding RNAs, DNA methylations, RNA modifications, chromatin conformations, and histone modifications. A full understanding of the roles of genetic and epigenetic alterations in RB formation is crucial in facilitating the translation of these findings into effective treatment strategies for RB. In this review, we summarize current knowledge concerning genetic defects and epigenetic dysregulations in RB, aiming to help understand their links and roles in RB tumorigenesis.
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Affiliation(s)
- Linbin Zhou
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China
| | - Yan Tong
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China
| | - Bo Man Ho
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China
| | - Jiahui Li
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China
| | - Hoi Ying Emily Chan
- Medicine Programme Global Physician-Leadership Stream, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China
| | - Tian Zhang
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China
| | - Lin Du
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China
| | - Jing Na He
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China
| | - Li Jia Chen
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China; Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China
| | - Clement C Tham
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China; Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China
| | - Jason C Yam
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China; Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China
| | - Chi Pui Pang
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China; Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China.
| | - Wai Kit Chu
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China; Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China.
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3
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Byroju VV, Nadukkandy AS, Cordani M, Kumar LD. Retinoblastoma: present scenario and future challenges. Cell Commun Signal 2023; 21:226. [PMID: 37667345 PMCID: PMC10478474 DOI: 10.1186/s12964-023-01223-z] [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: 03/24/2023] [Accepted: 07/12/2023] [Indexed: 09/06/2023] Open
Abstract
With an average incidence of 1 in every 18,000 live births, retinoblastoma is a rare type of intraocular tumour found to affect patients during their early childhood. It is curable if diagnosed at earlier stages but can become life-threateningly malignant if not treated timely. With no racial or gender predisposition, or even environmental factors known to have been involved in the incidence of the disease, retinoblastoma is often considered a clinical success story in pediatric oncology. The survival rate in highly developed countries is higher than 95% and they have achieved this because of the advancement in the development of diagnostics and treatment techniques. This includes developing the already existing techniques like chemotherapy and embarking on new strategies like enucleation, thermotherapy, cryotherapy, etc. Early diagnosis, studies on the etiopathogenesis and genetics of the disease are the need of the hour for improving the survival rates. According to the Knudson hypothesis, also known as the two hit hypothesis, two hits on the retinoblastoma susceptibility (RB) gene is often considered as the initiating event in the development of the disease. Studies on the molecular basis of the disease have also led to deciphering the downstream events and thus in the discovery of biomarkers and related targeted therapies. Furthermore, improvements in molecular biology techniques enhanced the development of efficient methods for early diagnosis, genetic counseling, and prevention of the disease. In this review, we discuss the genetic and molecular features of retinoblastoma with a special emphasis on the mutation leading to the dysregulation of key signaling pathways involved in cell proliferation, DNA repair, and cellular plasticity. Also, we describe the classification, clinical and epidemiological relevance of the disease, with an emphasis on both the traditional and innovative treatments to tackle retinoblastoma. Video Abstract.
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Affiliation(s)
- Vishnu Vardhan Byroju
- Department of Biochemistry, American International Medical University, Gros Islet, St. Lucia, USA
| | | | - Marco Cordani
- Department of Biochemistry and Molecular Biology, Complutense University of Madrid, and Instituto de Investigaciones Sanitarias San Carlos (IdISSC), Madrid, Spain.
| | - Lekha Dinesh Kumar
- CSIR-Centre for Cellular and Molecular Biology, Habsiguda, Uppal Road, Hyderabad, India.
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4
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Raicu AM, Castanheira P, Arnosti DN. Retinoblastoma protein activity revealed by CRISPRi study of divergent Rbf1 and Rbf2 paralogs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.19.541454. [PMID: 37293052 PMCID: PMC10245722 DOI: 10.1101/2023.05.19.541454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Retinoblastoma tumor suppressor proteins regulate the key transition from G1 to S phase of the cell cycle. The mammalian Rb family comprises Rb, p107, and p130, with overlapping and unique roles in gene regulation. Drosophila experienced an independent gene duplication event, leading to the Rbf1 and Rbf2 paralogs. To uncover the significance of paralogy in the Rb family, we used CRISPRi. We engineered dCas9 fusions to Rbf1 and Rbf2, and deployed them to gene promoters in developing Drosophila tissue to study their relative impacts on gene expression. On some genes, both Rbf1 and Rbf2 mediate potent repression, in a highly distance-dependent manner. In other cases, the two proteins have different effects on phenotype and gene expression, indicating different functional potential. In a direct comparison of Rb activity on endogenous genes and transiently transfected reporters, we found that only qualitative, but not key quantitative aspects of repression were conserved, indicating that the native chromatin environment generates context-specific effects of Rb activity. Our study uncovers the complexity of Rb-mediated transcriptional regulation in a living organism, which is clearly impacted by the different promoter landscapes and the evolution of the Rb proteins themselves.
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Affiliation(s)
- Ana-Maria Raicu
- Cell and Molecular Biology Program, Michigan State University, East Lansing, MI
| | - Patricia Castanheira
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI
| | - David N Arnosti
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI
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Prostaglandin E2 prevents radiotherapy-induced alopecia by attenuating transit amplifying cell apoptosis through promoting G1 arrest. J Dermatol Sci 2023; 109:117-126. [PMID: 36872218 DOI: 10.1016/j.jdermsci.2023.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 01/15/2023] [Accepted: 02/16/2023] [Indexed: 02/22/2023]
Abstract
BACKGROUND Growing hair follicles (HFs) harbor actively dividing transit amplifying cells (TACs), rendering them highly sensitive to radiotherapy (RT). Clinically, there is still a lack of treatment options for radiotherapy-induced alopecia (RIA). OBJECTIVE Our present study aimed to investigated the effect and mechanism of local prostaglandin E2 (PGE2) treatment in RIA prevention. METHODS We compared the response of growing HFs to radiation with and without local PGE2 pretreatment in a mouse model in vivo. The effect of PGE2 on the cell cycle was determined in cultured HF cells from fluorescent ubiquitination-based cell cycle indicator mice. We also compared the protective effects of PGE2 and a cyclin-dependent kinases 4/6 (CDK4/6) inhibitor against RIA. RESULTS The local cutaneous PGE2 injection reduced RIA by enhancing HF self-repair. Mechanistically, PGE2 did not activate HF stem cells, but it preserved more TACs for regenerative attempts. Pretreatment of PGE2 lessened radiosensitivity of TACs by transiently arresting them in the G1 phase, thereby reducing TAC apoptosis and mitigating HF dystrophy. The preservation of more TACs accelerated HF self-repair and bypassed RT-induced premature termination of anagen. Promoting G1 arrest by systemic administration of palbociclib isethionate (PD0332991), a CDK4/6 inhibitor, offered a similar protective effect against RT. CONCLUSIONS Locally administered PGE2 protects HF TACs from RT by transiently inducing G1 arrest, and the regeneration of HF structures lost from RT is accelerated to resume anagen growth, thus bypassing the long downtime of hair loss. PGE2 has the potential to be repurposed as a local preventive treatment for RIA.
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6
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Pieroni S, Castelli M, Piobbico D, Ferracchiato S, Scopetti D, Di-Iacovo N, Della-Fazia MA, Servillo G. The Four Homeostasis Knights: In Balance upon Post-Translational Modifications. Int J Mol Sci 2022; 23:ijms232214480. [PMID: 36430960 PMCID: PMC9696182 DOI: 10.3390/ijms232214480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/14/2022] [Accepted: 11/17/2022] [Indexed: 11/23/2022] Open
Abstract
A cancer outcome is a multifactorial event that comes from both exogenous injuries and an endogenous predisposing background. The healthy state is guaranteed by the fine-tuning of genes controlling cell proliferation, differentiation, and development, whose alteration induces cellular behavioral changes finally leading to cancer. The function of proteins in cells and tissues is controlled at both the transcriptional and translational level, and the mechanism allowing them to carry out their functions is not only a matter of level. A major challenge to the cell is to guarantee that proteins are made, folded, assembled and delivered to function properly, like and even more than other proteins when referring to oncogenes and onco-suppressors products. Over genetic, epigenetic, transcriptional, and translational control, protein synthesis depends on additional steps of regulation. Post-translational modifications are reversible and dynamic processes that allow the cell to rapidly modulate protein amounts and function. Among them, ubiquitination and ubiquitin-like modifications modulate the stability and control the activity of most of the proteins that manage cell cycle, immune responses, apoptosis, and senescence. The crosstalk between ubiquitination and ubiquitin-like modifications and post-translational modifications is a keystone to quickly update the activation state of many proteins responsible for the orchestration of cell metabolism. In this light, the correct activity of post-translational machinery is essential to prevent the development of cancer. Here we summarize the main post-translational modifications engaged in controlling the activity of the principal oncogenes and tumor suppressors genes involved in the development of most human cancers.
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7
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Putta S, Alvarez L, Lüdtke S, Sehr P, Müller GA, Fernandez SM, Tripathi S, Lewis J, Gibson TJ, Chemes LB, Rubin SM. Structural basis for tunable affinity and specificity of LxCxE-dependent protein interactions with the retinoblastoma protein family. Structure 2022; 30:1340-1353.e3. [PMID: 35716663 PMCID: PMC9444907 DOI: 10.1016/j.str.2022.05.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 04/25/2022] [Accepted: 05/25/2022] [Indexed: 11/25/2022]
Abstract
The retinoblastoma protein (Rb) and its homologs p107 and p130 are critical regulators of gene expression during the cell cycle and are commonly inactivated in cancer. Rb proteins use their "pocket domain" to bind an LxCxE sequence motif in other proteins, many of which function with Rb proteins to co-regulate transcription. Here, we present binding data and crystal structures of the p107 pocket domain in complex with LxCxE peptides from the transcriptional co-repressor proteins HDAC1, ARID4A, and EID1. Our results explain why Rb and p107 have weaker affinity for cellular LxCxE proteins compared with the E7 protein from human papillomavirus, which has been used as the primary model for understanding LxCxE motif interactions. Our structural and mutagenesis data also identify and explain differences in Rb and p107 affinities for some LxCxE-containing sequences. Our study provides new insights into how Rb proteins bind their cell partners with varying affinity and specificity.
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Affiliation(s)
- Sivasankar Putta
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Lucia Alvarez
- Instituto de Investigaciones Biotecnológicas (IIBiO-CONICET), Escuela de Bio y Nanotecnologías (EByN), Universidad Nacional de San Martín, Av. 25 de Mayo y Francia, Buenos Aires CP1650, Argentina
| | - Stephan Lüdtke
- Belyntic GmbH, Richard-Willstätter-Str. 11, 12489 Berlin, Germany
| | - Peter Sehr
- Chemical Biology Core Facility, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Gerd A Müller
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Samantha M Fernandez
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Sarvind Tripathi
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Joe Lewis
- Chemical Biology Core Facility, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Toby J Gibson
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Lucia B Chemes
- Instituto de Investigaciones Biotecnológicas (IIBiO-CONICET), Escuela de Bio y Nanotecnologías (EByN), Universidad Nacional de San Martín, Av. 25 de Mayo y Francia, Buenos Aires CP1650, Argentina.
| | - Seth M Rubin
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA.
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8
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Field MG, Kuznetsoff JN, Zhang MG, Dollar JJ, Durante MA, Sayegh Y, Decatur CL, Kurtenbach S, Pelaez D, Harbour JW. RB1 loss triggers dependence on ESRRG in retinoblastoma. SCIENCE ADVANCES 2022; 8:eabm8466. [PMID: 35984874 PMCID: PMC9390996 DOI: 10.1126/sciadv.abm8466] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 07/08/2022] [Indexed: 05/10/2023]
Abstract
Retinoblastoma (Rb) is a deadly childhood eye cancer that is classically initiated by inactivation of the RB1 tumor suppressor. Clinical management continues to rely on nonspecific chemotherapeutic agents that are associated with treatment resistance and toxicity. Here, we analyzed 103 whole exomes, 20 whole transcriptomes, 5 single-cell transcriptomes, and 4 whole genomes from primary Rb tumors to identify previously unknown Rb dependencies. Several recurrent genomic aberrations implicate estrogen-related receptor gamma (ESRRG) in Rb pathogenesis. RB1 directly interacts with and inhibits ESRRG, and RB1 loss uncouples ESRRG from negative regulation. ESRRG regulates genes involved in retinogenesis and oxygen metabolism in Rb cells. ESRRG is preferentially expressed in hypoxic Rb cells in vivo. Depletion or inhibition of ESRRG causes marked Rb cell death, which is exacerbated in hypoxia. These findings reveal a previously unidentified dependency of Rb cells on ESRRG, and they implicate ESRRG as a potential therapeutic vulnerability in Rb.
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Affiliation(s)
- Matthew G. Field
- Bascom Palmer Eye Institute, Sylvester Comprehensive Cancer Center, and Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - Jeffim N. Kuznetsoff
- Bascom Palmer Eye Institute, Sylvester Comprehensive Cancer Center, and Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Michelle G. Zhang
- Bascom Palmer Eye Institute, Sylvester Comprehensive Cancer Center, and Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - James J. Dollar
- Bascom Palmer Eye Institute, Sylvester Comprehensive Cancer Center, and Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Michael A. Durante
- Bascom Palmer Eye Institute, Sylvester Comprehensive Cancer Center, and Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Yoseph Sayegh
- Bascom Palmer Eye Institute, Sylvester Comprehensive Cancer Center, and Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Christina L. Decatur
- Bascom Palmer Eye Institute, Sylvester Comprehensive Cancer Center, and Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Stefan Kurtenbach
- Bascom Palmer Eye Institute, Sylvester Comprehensive Cancer Center, and Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Daniel Pelaez
- Bascom Palmer Eye Institute, Sylvester Comprehensive Cancer Center, and Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - J. William Harbour
- Bascom Palmer Eye Institute, Sylvester Comprehensive Cancer Center, and Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA
- Department of Ophthalmology and Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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9
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Zhou L, Ng DSC, Yam JC, Chen LJ, Tham CC, Pang CP, Chu WK. Post-translational modifications on the retinoblastoma protein. J Biomed Sci 2022; 29:33. [PMID: 35650644 PMCID: PMC9161509 DOI: 10.1186/s12929-022-00818-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 05/26/2022] [Indexed: 11/21/2022] Open
Abstract
The retinoblastoma protein (pRb) functions as a cell cycle regulator controlling G1 to S phase transition and plays critical roles in tumour suppression. It is frequently inactivated in various tumours. The functions of pRb are tightly regulated, where post-translational modifications (PTMs) play crucial roles, including phosphorylation, ubiquitination, SUMOylation, acetylation and methylation. Most PTMs on pRb are reversible and can be detected in non-cancerous cells, playing an important role in cell cycle regulation, cell survival and differentiation. Conversely, altered PTMs on pRb can give rise to anomalies in cell proliferation and tumourigenesis. In this review, we first summarize recent findings pertinent to how individual PTMs impinge on pRb functions. As many of these PTMs on pRb were published as individual articles, we also provide insights on the coordination, either collaborations and/or competitions, of the same or different types of PTMs on pRb. Having a better understanding of how pRb is post-translationally modulated should pave the way for developing novel and specific therapeutic strategies to treat various human diseases.
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Affiliation(s)
- Linbin Zhou
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Danny Siu-Chun Ng
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Jason C Yam
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
- Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong, China
| | - Li Jia Chen
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
- Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong, China
| | - Clement C Tham
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
- Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong, China
| | - Chi Pui Pang
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
- Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong, China
| | - Wai Kit Chu
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.
- Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong, China.
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Eye Hospital, 147K Argyle Street, Kowloon, Hong Kong, China.
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10
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Flores M, Goodrich DW. Retinoblastoma Protein Paralogs and Tumor Suppression. Front Genet 2022; 13:818719. [PMID: 35368709 PMCID: PMC8971665 DOI: 10.3389/fgene.2022.818719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 02/25/2022] [Indexed: 01/01/2023] Open
Abstract
The retinoblastoma susceptibility gene (RB1) is the first tumor suppressor gene discovered and a prototype for understanding regulatory networks that function in opposition to oncogenic stimuli. More than 3 decades of research has firmly established a widespread and prominent role for RB1 in human cancer. Yet, this gene encodes but one of three structurally and functionally related proteins that comprise the pocket protein family. A central question in the field is whether the additional genes in this family, RBL1 and RBL2, are important tumor suppressor genes. If so, how does their tumor suppressor activity overlap or differ from RB1. Here we revisit these questions by reviewing relevant data from human cancer genome sequencing studies that have been rapidly accumulating in recent years as well as pertinent functional studies in genetically engineered mice. We conclude that RBL1 and RBL2 do have important tumor suppressor activity in some contexts, but RB1 remains the dominant tumor suppressor in the family. Given their similarities, we speculate on why RB1 tumor suppressor activity is unique.
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Affiliation(s)
| | - David W. Goodrich
- Roswell Park Comprehensive Cancer Center, Department of Pharmacology and Therapeutics, Buffalo, NY, United States
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11
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Janostiak R, Torres-Sanchez A, Posas F, de Nadal E. Understanding Retinoblastoma Post-Translational Regulation for the Design of Targeted Cancer Therapies. Cancers (Basel) 2022; 14:cancers14051265. [PMID: 35267571 PMCID: PMC8909233 DOI: 10.3390/cancers14051265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 02/22/2022] [Accepted: 02/25/2022] [Indexed: 01/05/2023] Open
Abstract
Simple Summary Rb1 is a regulator of cell cycle progression and genomic stability. This review focuses on post-translational modifications, their effect on Rb1 interactors, and their role in intracellular signaling in the context of cancer development. Finally, we highlight potential approaches to harness these post-translational modifications to design novel effective anticancer therapies. Abstract The retinoblastoma protein (Rb1) is a prototypical tumor suppressor protein whose role was described more than 40 years ago. Together with p107 (also known as RBL1) and p130 (also known as RBL2), the Rb1 belongs to a family of structurally and functionally similar proteins that inhibits cell cycle progression. Given the central role of Rb1 in regulating proliferation, its expression or function is altered in most types of cancer. One of the mechanisms underlying Rb-mediated cell cycle inhibition is the binding and repression of E2F transcription factors, and these processes are dependent on Rb1 phosphorylation status. However, recent work shows that Rb1 is a convergent point of many pathways and thus the regulation of its function through post-translational modifications is more complex than initially expected. Moreover, depending on the context, downstream signaling can be both E2F-dependent and -independent. This review seeks to summarize the most recent research on Rb1 function and regulation and discuss potential avenues for the design of novel cancer therapies.
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Affiliation(s)
- Radoslav Janostiak
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, 08028 Barcelona, Spain; (R.J.); (A.T.-S.)
- Department of Medicine and Life Sciences (MELIS), Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
| | - Ariadna Torres-Sanchez
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, 08028 Barcelona, Spain; (R.J.); (A.T.-S.)
- Department of Medicine and Life Sciences (MELIS), Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
| | - Francesc Posas
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, 08028 Barcelona, Spain; (R.J.); (A.T.-S.)
- Department of Medicine and Life Sciences (MELIS), Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
- Correspondence: (F.P.); (E.d.N.); Tel.: +34-93-403-4810 (F.P.); +34-93-403-9895 (E.d.N.)
| | - Eulàlia de Nadal
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, 08028 Barcelona, Spain; (R.J.); (A.T.-S.)
- Department of Medicine and Life Sciences (MELIS), Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
- Correspondence: (F.P.); (E.d.N.); Tel.: +34-93-403-4810 (F.P.); +34-93-403-9895 (E.d.N.)
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Wei T, Grace M, Uberoi A, Romero-Masters JC, Lee D, Lambert PF, Munger K. The Mus musculus Papillomavirus Type 1 E7 Protein Binds to the Retinoblastoma Tumor Suppressor: Implications for Viral Pathogenesis. mBio 2021; 12:e0227721. [PMID: 34465025 PMCID: PMC8406179 DOI: 10.1128/mbio.02277-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 08/05/2021] [Indexed: 12/17/2022] Open
Abstract
The species specificity of papillomaviruses has been a significant roadblock for performing in vivo pathogenesis studies in common model organisms. The Mus musculus papillomavirus type 1 (MmuPV1) causes cutaneous papillomas that can progress to squamous cell carcinomas in laboratory mice. The papillomavirus E6 and E7 genes encode proteins that establish and maintain a cellular milieu that allows for viral genome synthesis and viral progeny synthesis in growth-arrested, terminally differentiated keratinocytes. The E6 and E7 proteins provide this activity by binding to and functionally reprogramming key cellular regulatory proteins. The MmuPV1 E7 protein lacks the canonical LXCXE motif that mediates the binding of multiple viral oncoproteins to the cellular retinoblastoma tumor suppressor protein, RB1. Our proteomic experiments, however, revealed that MmuPV1 E7 still interacts with RB1. We show that MmuPV1 E7 interacts through its C terminus with the C-terminal domain of RB1. Binding of MmuPV1 E7 to RB1 did not cause significant activation of E2F-regulated cellular genes. MmuPV1 E7 expression was shown to be essential for papilloma formation. Experimental infection of mice with MmuPV1 expressing an E7 mutant that is defective for binding to RB1 caused delayed onset, lower incidence, and smaller sizes of papillomas. Our results demonstrate that the MmuPV1 E7 gene is essential and that targeting noncanonical activities of RB1, which are independent of RB1's ability to modulate the expression of E2F-regulated genes, contribute to papillomavirus-mediated pathogenesis. IMPORTANCE Papillomavirus infections cause a variety of epithelial hyperplastic lesions, or warts. While most warts are benign, some papillomaviruses cause lesions that can progress to squamous cell carcinomas, and approximately 5% of all human cancers are caused by human papillomavirus (HPV) infections. The papillomavirus E6 and E7 proteins are thought to function to reprogram host epithelial cells to enable viral genome replication in terminally differentiated, normally growth-arrested cells. E6 and E7 lack enzymatic activities and function by interacting and functionally altering host cell regulatory proteins. Many cellular proteins that can interact with E6 and E7 have been identified, but the biological relevance of these interactions for viral pathogenesis has not been determined. This is because papillomaviruses are species specific and do not infect heterologous hosts. Here, we use a recently established mouse papillomavirus (MmuPV1) model to investigate the role of the E7 protein in viral pathogenesis. We show that MmuPV1 E7 is necessary for papilloma formation. The retinoblastoma tumor suppressor protein (RB1) is targeted by many papillomaviral E7 proteins, including cancer-associated HPVs. We show that MmuPV1 E7 can bind RB1 and that infection with a mutant MmuPV1 virus that expresses an RB1 binding-defective E7 mutant caused smaller and fewer papillomas that arise with delayed kinetics.
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Affiliation(s)
- Tao Wei
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Miranda Grace
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Aayushi Uberoi
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - James C. Romero-Masters
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Denis Lee
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Paul F. Lambert
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Karl Munger
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, USA
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Koliopoulos MG, Alfieri C. Cell cycle regulation by complex nanomachines. FEBS J 2021; 289:5100-5120. [PMID: 34143558 DOI: 10.1111/febs.16082] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 05/05/2021] [Accepted: 05/17/2021] [Indexed: 12/13/2022]
Abstract
The cell cycle is the essential biological process where one cell replicates its genome and segregates the resulting two copies into the daughter cells during mitosis. Several aspects of this process have fascinated humans since the nineteenth century. Today, the cell cycle is exhaustively investigated because of its profound connections with human diseases and cancer. At the heart of the molecular network controlling the cell cycle, we find the cyclin-dependent kinases (CDKs) acting as an oscillator to impose an orderly and highly regulated progression through the different cell cycle phases. This oscillator integrates both internal and external signals via a multitude of signalling pathways involving posttranslational modifications including phosphorylation, protein ubiquitination and mechanisms of transcriptional regulation. These tasks are specifically performed by multi-subunit complexes, which are intensively studied both biochemically and structurally with the aim to unveil mechanistic insights into their molecular function. The scope of this review is to summarise the structural biology of the cell cycle machinery, with specific focus on the core cell cycle machinery involving the CDK-cyclin oscillator. We highlight the contribution of cryo-electron microscopy, which has started to revolutionise our understanding of the molecular function and dynamics of the key players of the cell cycle.
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Affiliation(s)
- Marios G Koliopoulos
- Chester Beatty Laboratories, Structural Biology Division, Institute of Cancer Research, London, UK
| | - Claudio Alfieri
- Chester Beatty Laboratories, Structural Biology Division, Institute of Cancer Research, London, UK
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14
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Martínez-Sánchez M, Hernandez-Monge J, Rangel M, Olivares-Illana V. Retinoblastoma: from discovery to clinical management. FEBS J 2021; 289:4371-4382. [PMID: 34042282 DOI: 10.1111/febs.16035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 05/13/2021] [Accepted: 05/24/2021] [Indexed: 01/02/2023]
Abstract
The retinoblastoma gene (RB1) was the first tumour suppressor cloned; the role of its protein product (RB) as the principal driver of the G1 checkpoint in cell cycle control has been extensively studied. However, many other RB functions are continuously reported. Its role in senescence, DNA repair and apoptosis, among others, is indications of the significance of RB in a vast network of cellular interactions, explaining why RB loss or its malfunction is one of the leading causes of a large number of paediatric and adult cancers. RB was first reported in retinoblastoma, a common intraocular malignancy in the paediatric population worldwide. Currently, its diagnosis is clinical, and in nondeveloped countries, where the incidence is higher, it is performed in advanced stages of the disease, compromising the integrity of the eye and the patient's life. Even though new treatments are being continuously developed, enucleation is still a major choice due to the late disease stage diagnosis and treatments costs. Research into biomarkers is our best option to improve the chances of good results in the treatment and hopes of patients' good quality of life. Here, we recapitulated the history of the disease and the first treatments to put the advances in its clinical management into perspective. We also review the different functions of the protein and the progress in the search for biomarkers. It is clear that there is still a long way to go, but we should offer these children and their families a better way to deal with the disease with the community's effort.
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Affiliation(s)
- Mayra Martínez-Sánchez
- Laboratorio de Interacciones Biomoleculares y Cancer, Instituto de Física, Universidad Autónoma de San Luis Potosí, Mexico
| | - Jesús Hernandez-Monge
- Catedra CONACyT - Laboratorio de Biomarcadores Moleculares, Instituto de Física, Universidad Autónoma de San Luis Potosí, Mexico
| | - Martha Rangel
- Departamento de Oftalmología. Hospital Central "Ignacio Morones Prieto", San Luis Potosí, Mexico
| | - Vanesa Olivares-Illana
- Laboratorio de Interacciones Biomoleculares y Cancer, Instituto de Física, Universidad Autónoma de San Luis Potosí, Mexico
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Hülsenbeck I, Frank M, Biewald E, Kanber D, Lohmann DR, Ketteler P. Introduction of a Variant Classification System for Analysis of Genotype-Phenotype Relationships in Heritable Retinoblastoma. Cancers (Basel) 2021; 13:cancers13071605. [PMID: 33807189 PMCID: PMC8037437 DOI: 10.3390/cancers13071605] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 03/26/2021] [Accepted: 03/28/2021] [Indexed: 11/22/2022] Open
Abstract
Simple Summary Heritable retinoblastoma is a genetic disease that predisposes to develop multiple retinoblastomas in childhood and other extraocular tumors later in life. It is caused by genetic variants in the RB1 gene. Here we present a new classification for genetic variants in the RB1 gene (REC) that focuses on the variant’s effect. The different classes, REC-I to -V, correlate with different risks of tumor predisposition. REC correlated with different clinical courses when applied in our study cohort. REC aims to facilitate risk estimation for physicians, patients and their families, and researchers and to improve the definition of the necessity of screening examination. Abstract Constitutional haploinsufficiency of the RB1 gene causes heritable retinoblastoma, a tumor predisposition syndrome. Patients with heritable retinoblastoma develop multiple retinoblastomas early in childhood and other extraocular tumors later in life. Constitutional pathogenic variants in RB1 are heterogeneous, and a few genotype-phenotype correlations have been described. To identify further genotype-phenotype relationships, we developed the retinoblastoma variant effect classification (REC), which considers each variant’s predicted effects on the common causal mediator, RB1 protein pRB. For validation, the RB1 variants of 287 patients were grouped according to REC. Multiple aspects of phenotypic expression were analyzed, known genotype-phenotype associations were revised, and new relationships were explored. Phenotypic expression of patients with REC-I, -II, and -III was distinct. Remarkably, the phenotype of patients with variants causing residual amounts of truncated pRB (REC-I) was more severe than patients with complete loss of RB1 (REC-II). The age of diagnosis of REC-I variants appeared to be distinct depending on truncation’s localization relative to pRB structure domains. REC classes identify genotype-phenotype relationships and, therefore, this classification framework may serve as a tool to develop tailored tumor screening programs depending on the type of RB1 variant.
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Affiliation(s)
- Isabel Hülsenbeck
- Department of Pediatric Hematology and Oncology, University Duisburg-Essen, University Hospital Essen, Hufelandstrasse 55, 45122 Essen, Germany;
- Eye Oncogenetics Research Group, University Hospital Essen, 45122 Essen, Germany; (D.K.); (D.R.L.)
| | - Mirjam Frank
- Institute for Medical Informatics, Biometry and Epidemiology, University Duisburg-Essen, University Hospital Essen, 45122 Essen, Germany;
| | - Eva Biewald
- Department of Ophthalmology, University Duisburg-Essen, University Hospital Essen, 45122 Essen, Germany;
| | - Deniz Kanber
- Eye Oncogenetics Research Group, University Hospital Essen, 45122 Essen, Germany; (D.K.); (D.R.L.)
- Institute of Human Genetics, University Duisburg-Essen, 45122 Essen, Germany
| | - Dietmar R. Lohmann
- Eye Oncogenetics Research Group, University Hospital Essen, 45122 Essen, Germany; (D.K.); (D.R.L.)
- Institute of Human Genetics, University Duisburg-Essen, 45122 Essen, Germany
- German Cancer Consortium (DKTK), Partner Site Essen/Düsseldorf, 69120 Heidelberg, Germany
| | - Petra Ketteler
- Department of Pediatric Hematology and Oncology, University Duisburg-Essen, University Hospital Essen, Hufelandstrasse 55, 45122 Essen, Germany;
- Eye Oncogenetics Research Group, University Hospital Essen, 45122 Essen, Germany; (D.K.); (D.R.L.)
- Institute of Human Genetics, University Duisburg-Essen, 45122 Essen, Germany
- German Cancer Consortium (DKTK), Partner Site Essen/Düsseldorf, 69120 Heidelberg, Germany
- Correspondence:
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Rahaman MM, Islam R, Jewel GMNA, Hoque H. Implementation of computational approaches to explore the deleterious effects of non-synonymous SNPs on pRB protein. J Biomol Struct Dyn 2021; 40:7256-7273. [PMID: 33682629 DOI: 10.1080/07391102.2021.1896385] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Retinoblastoma 1 (RB1) is the first discovered tumor suppressor gene and recognized as the simple model system whose encoded defective protein can cause a pediatric cancer retinoblastoma. It functions as a negative regulator of the cell cycle through the interactions with members of the E2F transcription factors family. The protein of the RB1 gene (pRB) is engaged in various cell cycle processes including apoptosis, cell cycle arrest and chromatin remodeling. Recent studies on Retinoblastoma also exhibited multiple sets of point mutation in the associated protein due to its large polymorphic information in the local database. In this study, we identified the list of disease associated non-synonymous single nucleotide polymorphisms (nsSNPs) in RB1 by incorporating different computational algorithms, web servers, modeling of the mutants and finally superimposing it. Out of 826 nsSNPs, W516G and W563G were predicted to be highly deleterious variants in the conserved regions and found to have an impact on protein structure and protein-protein interaction. Moreover, our study concludes the effect of W516G variant was more detrimental in destabilizing protein's nature as compared to W563G variant. We also found defective binding of pRB having W516G mutation with E2F2 protein. Findings of this study will aid in shortening of the expensive experimental cost of identifying disease associated SNPs in retinoblastoma for which specialized personalized treatment or therapy can be formulated.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Md Mashiur Rahaman
- Department of Genetic Engineering and Biotechnology, School of Life Sciences, Shahjalal University of Science and Technology, Sylhet, Bangladesh
| | - Rahatul Islam
- Department of Genetic Engineering and Biotechnology, School of Life Sciences, Shahjalal University of Science and Technology, Sylhet, Bangladesh
| | - G M Nurnabi Azad Jewel
- Department of Genetic Engineering and Biotechnology, School of Life Sciences, Shahjalal University of Science and Technology, Sylhet, Bangladesh
| | - Hammadul Hoque
- Department of Genetic Engineering and Biotechnology, School of Life Sciences, Shahjalal University of Science and Technology, Sylhet, Bangladesh
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17
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Zhou M, Yang Z, Wang D, Chen P, Zhang Y. The circular RNA circZFR phosphorylates Rb promoting cervical cancer progression by regulating the SSBP1/CDK2/cyclin E1 complex. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2021; 40:48. [PMID: 33516252 PMCID: PMC7846991 DOI: 10.1186/s13046-021-01849-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 01/18/2021] [Indexed: 12/11/2022]
Abstract
Background As a novel type of non-coding RNA, circular RNAs (circRNAs) play a critical role in the initiation and development of various diseases, including cancer. However, the exact function of circRNAs in human cervical cancer remains largely unknown. Methods We identified the circRNA signature of upregulated circRNAs between cervical cancer and paired adjacent normal tissues. Using two different cohorts and GEO database, a total of six upregulated circRNAs were identified with a fold change > 2, and P < 0.05. Among these six circRNAs, hsa_circ_0072088 (circZFR) was the only exonic circRNA significantly overexpressed in cervical cancer. Functional experiments were performed to investigate the biological function of circZFR. CircRNA pull-down, circRNA immunoprecipitation (circRIP) and Co-immunoprecipitation (Co-IP) assays were executed to investigate the molecular mechanism underlying the function of circZFR. Results Functionally, circZFR knockdown represses the proliferation, invasion, and tumor growth. Furthermore, circRNA pull-down experiments combined with mass spectrometry unveil the interactions of circZFR with Single-Stranded DNA Binding Protein 1 (SSBP1). Mechanistically, circZFR bound with SSBP1, thereby promoting the assembly of CDK2/cyclin E1 complexes. The activation of CDK2/cyclin E1 complexes induced p-Rb phosphorylation, thus releasing activated E2F1 leading to cell cycle progression and cell proliferation. Conclusion Our findings provide the first evidence that circZFR is a novel onco-circRNA and might be a potential biomarker and therapeutic target for cervical cancer patients. Supplementary Information The online version contains supplementary material available at 10.1186/s13046-021-01849-2.
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Affiliation(s)
- Mingyi Zhou
- Department of Gynecology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital & Institute, Shenyang, 110042, Liaoning Province, People's Republic of China
| | - Zhuo Yang
- Department of Gynecology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital & Institute, Shenyang, 110042, Liaoning Province, People's Republic of China
| | - Danbo Wang
- Department of Gynecology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital & Institute, Shenyang, 110042, Liaoning Province, People's Republic of China.
| | - Peng Chen
- Department of Gynecology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital & Institute, Shenyang, 110042, Liaoning Province, People's Republic of China
| | - Yong Zhang
- Department of Pathology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital & Institute, Shenyang, 110042, China
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18
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The Function of SUMOylation and Its Role in the Development of Cancer Cells under Stress Conditions: A Systematic Review. Stem Cells Int 2020; 2020:8835714. [PMID: 33273928 PMCID: PMC7683158 DOI: 10.1155/2020/8835714] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 10/17/2020] [Accepted: 10/22/2020] [Indexed: 02/06/2023] Open
Abstract
Malignant tumors still pose serious threats to human health due to their high morbidity and mortality. Recurrence and metastasis are the most important factors affecting patient prognosis. Chemotherapeutic drugs and radiation used to treat these tumors mainly interfere with tumor metabolism, destroy DNA integrity, and inhibit protein synthesis. The upregulation of small ubiquitin-like modifier (SUMO) is a prevalent posttranslational modification (PTM) in various cancers and plays a critical role in tumor development. The dysregulation of SUMOylation can protect cancer cells from stresses exerted by external or internal stimuli. SUMOylation is a dynamic process finely regulated by SUMOylation enzymes and proteases to maintain a balance between SUMOylation and deSUMOylation. An increasing number of studies have reported that SUMOylation imbalance may contribute to cancer development, including metastasis, angiogenesis, invasion, and proliferation. High level of SUMOylation is required for cancer cells to survive internal or external stresses. Downregulation of SUMOylation may inhibit the development of cancer, making it an important potential clinical therapeutic target. Some studies have already begun to treat tumors by inhibiting the expression of SUMOylation family members, including SUMO E1 or E2. The tumor cells become more aggressive under internal and external stresses. The prevention of tumor development, metastasis, recurrence, and radiochemotherapy resistance by attenuating SUMOylation requires further exploration. This review focused on SUMOylation in tumor cells to discuss its effects on tumor suppressor proteins and oncoproteins as well as classical tumor pathways to identify new insights for cancer clinical therapy.
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19
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Retinoblastoma Tumor Suppressor Protein Roles in Epigenetic Regulation. Cancers (Basel) 2020; 12:cancers12102807. [PMID: 33003565 PMCID: PMC7600434 DOI: 10.3390/cancers12102807] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 09/19/2020] [Accepted: 09/27/2020] [Indexed: 12/14/2022] Open
Abstract
Simple Summary Loss of function of the retinoblastoma gene (RB1) is the rate-limiting step in the initiation of both the hereditary and sporadic forms of retinoblastoma tumor. Furthermore, loss of function of the retinoblastoma tumor suppressor protein (pRB) is frequently found in most human cancers. In retinoblastoma, tumor progression is driven by epigenetic changes following pRB loss. This review focuses on the diverse functions of pRB in epigenetic regulation. Abstract Mutations that result in the loss of function of pRB were first identified in retinoblastoma and since then have been associated with the propagation of various forms of cancer. pRB is best known for its key role as a transcriptional regulator during cell cycle exit. Beyond the ability of pRB to regulate transcription of cell cycle progression genes, pRB can remodel chromatin to exert several of its other biological roles. In this review, we discuss the diverse functions of pRB in epigenetic regulation including nucleosome mobilization, histone modifications, DNA methylation and non-coding RNAs.
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20
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Moulay Lakhdar I, Ferlazzo ML, Al Choboq J, Berthel E, Sonzogni L, Devic C, Granzotto A, Thariat J, Foray N. Fibroblasts from Retinoblastoma Patients Show Radiosensitivity Linked to Abnormal Localization of the ATM Protein. Curr Eye Res 2020; 46:546-557. [PMID: 32862699 DOI: 10.1080/02713683.2020.1808998] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
PURPOSE/AIM OF THE STUDY Retinoblastoma (Rb) is a rare form of pediatric cancer that develops from retina cells. Bilateral and some unilateral forms of Rb are associated with heterozygous germline mutations of the (retinoblastoma 1) RB1 gene. RB1 mutations are also associated with a significant risk of secondary malignancy like head and neck tumors. Hence, to date, even if Rb patients are less subjected to radiotherapy to treat their primary ocular tumors, their healthy tissues may be exposed to significant doses of ionizing radiation during the treatment against their secondary malignancies with a significant risk of adverse tissue reactions (radiosensitivity) and/or radiation-induced cancer (radiosusceptibility). However, the biological role of the Rb protein in response to radiation remains misunderstood. Since the ataxia telangiectasia mutated (ATM) protein is a key protein of radiation response and since untransformed skin fibroblasts are a current model to quantify cellular radiosensitivity, we investigated here for the first time the functionality of the ATM-dependent signaling and repair pathway of the radiation-induced DNA double-strand breaks (DSB) in irradiated skin fibroblasts derived from Rb patients. MATERIALS AND METHODS The major biomarkers of the DSB repair and signaling, namely clonogenic cell survival, micronuclei, nuclear foci of the phosphorylated forms of the X variant of the H2A histone (γH2AX), the phosphorylated forms of the ATM protein (pATM) and the meiotic recombination 11 nuclease (MRE11) were assessed in untransformed skin fibroblasts derived from three Rb patients. RESULTS Skin fibroblasts from Rb patients showed significant cellular radiosensitivity, incomplete DSB recognition, delay in the ATM nucleo-shuttling and exacerbated MRE11 nuclease activity. Treatment with statin and bisphosphonates led to significant complementation of these impairments. CONCLUSIONS Our findings strongly suggest the involvement of the ATM kinase in the radiosensitivity/radiosusceptibility phenotype observed in Rb cases.
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Affiliation(s)
- Ismahane Moulay Lakhdar
- Institut National De La Santé Et De La Recherche Médicale, UA8 Unit, Radiations, Defense, Health and Environment, Centre Léon-Bérard, Lyon, France
| | - Mélanie L Ferlazzo
- Institut National De La Santé Et De La Recherche Médicale, UA8 Unit, Radiations, Defense, Health and Environment, Centre Léon-Bérard, Lyon, France
| | - Joelle Al Choboq
- Institut National De La Santé Et De La Recherche Médicale, UA8 Unit, Radiations, Defense, Health and Environment, Centre Léon-Bérard, Lyon, France
| | - Elise Berthel
- Institut National De La Santé Et De La Recherche Médicale, UA8 Unit, Radiations, Defense, Health and Environment, Centre Léon-Bérard, Lyon, France
| | - Laurène Sonzogni
- Institut National De La Santé Et De La Recherche Médicale, UA8 Unit, Radiations, Defense, Health and Environment, Centre Léon-Bérard, Lyon, France
| | - Clément Devic
- Institut National De La Santé Et De La Recherche Médicale, UA8 Unit, Radiations, Defense, Health and Environment, Centre Léon-Bérard, Lyon, France.,Fibermetrix, 7 Allée De l'Europe, Entsheim, France
| | - Adeline Granzotto
- Institut National De La Santé Et De La Recherche Médicale, UA8 Unit, Radiations, Defense, Health and Environment, Centre Léon-Bérard, Lyon, France
| | | | - Nicolas Foray
- Institut National De La Santé Et De La Recherche Médicale, UA8 Unit, Radiations, Defense, Health and Environment, Centre Léon-Bérard, Lyon, France
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21
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Nie C, Ma H, Gao Y, Li J, Tang Z, Chen Y, Lu R. RNA Sequencing and Bioinformatic Analysis on Retinoblastoma Revealing that Cell Cycle Deregulation Is a Key Process in Retinoblastoma Tumorigenesis. Ophthalmologica 2020; 244:51-59. [PMID: 32146475 DOI: 10.1159/000506993] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 02/28/2020] [Indexed: 11/19/2022]
Abstract
PURPOSE Retinoblastoma (RB) is a primary pediatric ocular malignancy that can be fatal with inadequate treatment. While multimodal treatments are applied for eye salvage, vision loss and metastasis can occur in some patients. The present study aimed to explore key pathways and factors in RB pathogenesis, which could be potential targets for novel RB treatments. METHODS RNA sequencing was performed on three RB tissues and referenced with three normal retinas. Differentially expressed genes (DEGs) were identified from sequencing data and further analyzed with clustering analysis, function and pathway enrichment, protein-protein interaction (PPI), and data-mining analysis in order to screen for tumorigenic relevancy. RESULTS A total of 331 DEGs were identified by clustering analysis of RB tissues, and the expression patterns were significantly distinguishable from normal retinas. Function and pathway enrichment and PPI analysis together showed that cell cycle was the most prominently upregulated pathway found in RB tissues. Following comprehensive bioinformatic analyses, six key genes relevant to cell cycle regulation were identified, namely BUB1, RRM2, TPX2, UBE2C, NUSAP1, and DTL. CONCLUSIONS Cell cycle pathway and six relevant genes may be potential key factors in RB tumorigenesis and laying the foundation for prospective investigation on development of novel targeted therapies.
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Affiliation(s)
- Cong Nie
- Department of Orbital Diseases and Ocular Oncology, State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Huan Ma
- Department of Orbital Diseases and Ocular Oncology, State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Yang Gao
- Department of Orbital Diseases and Ocular Oncology, State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Jinmiao Li
- Department of Orbital Diseases and Ocular Oncology, State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Zhixin Tang
- Department of Orbital Diseases and Ocular Oncology, State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Ying Chen
- Department of Orbital Diseases and Ocular Oncology, State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Rong Lu
- Department of Orbital Diseases and Ocular Oncology, State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China,
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22
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Zargar ZU, Kimidi MR, Tyagi S. Dynamic site-specific recruitment of RBP2 by pocket protein p130 modulates H3K4 methylation on E2F-responsive promoters. Nucleic Acids Res 2019; 46:174-188. [PMID: 29059406 PMCID: PMC5758877 DOI: 10.1093/nar/gkx961] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 10/07/2017] [Indexed: 02/01/2023] Open
Abstract
The Histone 3 lysine 4 methylation (H3K4me3) mark closely correlates with active transcription. E2F-responsive promoters display dynamic changes in H3K4 methylation during the course of cell cycle progression. However, how and when these marks are reset, is not known. Here we show that the retinoblastoma binding protein RBP2/KDM5A, capable of removing tri-methylation marks on H3K4, associates with the E2F4 transcription factor via the pocket protein-p130-in a cell-cycle-stage specific manner. The association of RBP2 with p130 is LxCxE motif dependent. RNAi experiments reveal that p130 recruits RBP2 to E2F-responsive promoters in early G1 phase to bring about H3K4 demethylation and gene repression. A point mutation in LxCxE motif of RBP2 renders it incapable of p130-interaction and hence, repression of E2F-regulated gene promoters. We also examine how RBP2 may be recruited to non-E2F responsive promoters. Our studies provide insight into how the chromatin landscape needs to be adjusted rapidly and periodically during cell-cycle progression, concomitantly with temporal transcription, to bring about expression/repression of specific gene sets.
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Affiliation(s)
- Zaffer Ullah Zargar
- Laboratory of Cell Cycle Regulation, Centre for DNA Fingerprinting and Diagnostics (CDFD), Nampally, Hyderabad 500001, India.,Graduate Studies, Manipal University, Manipal, India
| | - Mallikharjuna Rao Kimidi
- Laboratory of Cell Cycle Regulation, Centre for DNA Fingerprinting and Diagnostics (CDFD), Nampally, Hyderabad 500001, India
| | - Shweta Tyagi
- Laboratory of Cell Cycle Regulation, Centre for DNA Fingerprinting and Diagnostics (CDFD), Nampally, Hyderabad 500001, India
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23
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Gerton JL. A transcription factor primes the condensin pump. J Cell Biol 2018; 217:2233-2234. [PMID: 29925630 PMCID: PMC6028535 DOI: 10.1083/jcb.201806043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Gerton introduces new work from Schiklenk et al. identifying the Zas1 transcription factor as a key regulator of chromosome condensation. Chromosome condensation is regulated by the condensin complex but whether this process is subject to transcriptional control is poorly understood. In this issue, Schiklenk et al. (2018. J. Cell Biol.https://doi.org/10.1083/jcb.201711097) reveal that the transcription factor Zas1 mediates timely chromosome condensation and promotes transcription of several genes in Saccharomyces pombe, including the condensin subunit Cnd1.
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Affiliation(s)
- Jennifer L Gerton
- Stowers Institute for Medical Research, Kansas City, MO.,University of Kansas Medical School, Kansas City, KS
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24
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Schiklenk C, Petrova B, Kschonsak M, Hassler M, Klein C, Gibson TJ, Haering CH. Control of mitotic chromosome condensation by the fission yeast transcription factor Zas1. J Cell Biol 2018; 217:2383-2401. [PMID: 29735745 PMCID: PMC6028546 DOI: 10.1083/jcb.201711097] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 03/28/2018] [Accepted: 04/17/2018] [Indexed: 01/05/2023] Open
Abstract
How chromosomes compact into rod-shaped structures is a longstanding unresolved question of cell biology. Schiklenk et al. identify the transcription factor Zas1 as a central regulator of mitotic chromosome condensation in fission yeast and show that it uses a conserved transactivation domain–based mechanism to control gene expression. Although the formation of rod-shaped chromosomes is vital for the correct segregation of eukaryotic genomes during cell divisions, the molecular mechanisms that control the chromosome condensation process have remained largely unknown. Here, we identify the C2H2 zinc-finger transcription factor Zas1 as a key regulator of mitotic condensation dynamics in a quantitative live-cell microscopy screen of the fission yeast Schizosaccharomyces pombe. By binding to specific DNA target sequences in their promoter regions, Zas1 controls expression of the Cnd1 subunit of the condensin protein complex and several other target genes, whose combined misregulation in zas1 mutants results in defects in chromosome condensation and segregation. Genetic and biochemical analysis reveals an evolutionarily conserved transactivation domain motif in Zas1 that is pivotal to its function in gene regulation. Our results suggest that this motif, together with the Zas1 C-terminal helical domain to which it binds, creates a cis/trans switch module for transcriptional regulation of genes that control chromosome condensation.
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Affiliation(s)
- Christoph Schiklenk
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Boryana Petrova
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Marc Kschonsak
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Markus Hassler
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Carlo Klein
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Toby J Gibson
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Christian H Haering
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany .,Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
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25
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Chen L, Huang X, Chen X. miR-365 Suppresses Cholangiocarcinoma Cell Proliferation and Induces Apoptosis by Targeting E2F2. Oncol Res 2018; 26:1375-1382. [PMID: 29471889 PMCID: PMC7844787 DOI: 10.3727/096504018x15188352857437] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cholangiocarcinoma (CCA) is one of the most malignant adenocarcinomas arising from bile duct epithelial cells. However, the molecular mechanism regulating CCA development and progression still needs to be investigated. Here we found that miR-365 was downregulated in CCA tissues compared with adjacent normal tissues. By functional experiments, we found that overexpression of miR-365 significantly inhibited CCA cell proliferation and promoted cellular apoptosis in vitro. Furthermore, administration with miR-365 markedly suppressed the growth of tumor tissues in vivo. Mechanistically, we identified E2F2 as the target gene of miR-365 in CCA cells. We found that overexpression significantly inhibited the expression of E2F2 in CCA cells, and there was an inverse correlation between the expression levels of E2F2 and miR-365 in CCA tissues. We also found that E2F2 was highly expressed in CCA tissues and cell lines. Restoration of E2F2 in miR-365-overexpressing CCA cells promoted cell viability and reduced cellular apoptosis in CCA. Collectively, our study demonstrated the essential role of miR-365 and its functional mechanism in CCA cells, which provided a new insight on the design of therapeutic targets for CCA treatment.
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Affiliation(s)
- Lunjian Chen
- Department of Hepatobiliary Surgery, The Xinjiang Uygur Autonomous Region People's Hospital, Urumqi, P.R. China
| | - Xiaorong Huang
- Otorhinolaryngology Center, The Xinjiang Uygur Autonomous Region People's Hospital, Urumqi, P.R. China
| | - Xinxin Chen
- Department of Preventive Health Care, First Affiliated Hospital of Medical College of Shihezi University, Shihezi, P.R. China
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26
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Palopoli N, González Foutel NS, Gibson TJ, Chemes LB. Short linear motif core and flanking regions modulate retinoblastoma protein binding affinity and specificity. Protein Eng Des Sel 2018; 31:69-77. [DOI: 10.1093/protein/gzx068] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Accepted: 01/10/2018] [Indexed: 12/11/2022] Open
Affiliation(s)
- Nicolás Palopoli
- Department of Science and Technology, Universidad Nacional de Quilmes, CONICET. Roque Sáenz Peña 352. CP (B1876BXD), Bernal, Buenos Aires, Argentina
- Structural Bioinformatics Unit, Fundación Instituto Leloir and IIBBA-CONICET. Av. Patricias Argentinas 435 CP 1405, Buenos Aires, Argentina
| | - Nicolás S González Foutel
- Protein Structure Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA-CONICET. Av. Patricias Argentinas 435 CP 1405, Buenos Aires, Argentina
| | - Toby J Gibson
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117, Heidelberg, Germany
| | - Lucía B Chemes
- Protein Structure Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA-CONICET. Av. Patricias Argentinas 435 CP 1405, Buenos Aires, Argentina
- Instituto de Investigaciones Biotecnológicas IIB-INTECH, Universidad Nacional de San Martín. Av. 25 de Mayo y Francia CP 1650, San Martín, Buenos Aires, Argentina
- Departamento de Fisiología y Biología Molecular y Celular (DFBMC), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Intendente Güiraldes 2160, Ciudad Universitaria, C1428EGA, Argentina
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27
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Betancor-Fernández I, Timson DJ, Salido E, Pey AL. Natural (and Unnatural) Small Molecules as Pharmacological Chaperones and Inhibitors in Cancer. Handb Exp Pharmacol 2018; 245:155-190. [PMID: 28993836 DOI: 10.1007/164_2017_55] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Mutations causing single amino acid exchanges can dramatically affect protein stability and function, leading to disease. In this chapter, we will focus on several representative cases in which such mutations affect protein stability and function leading to cancer. Mutations in BRAF and p53 have been extensively characterized as paradigms of loss-of-function/gain-of-function mechanisms found in a remarkably large fraction of tumours. Loss of RB1 is strongly associated with cancer progression, although the molecular mechanisms by which missense mutations affect protein function and stability are not well known. Polymorphisms in NQO1 represent a remarkable example of the relationships between intracellular destabilization and inactivation due to dynamic alterations in protein ensembles leading to loss of function. We will review the function of these proteins and their dysfunction in cancer and then describe in some detail the effects of the most relevant cancer-associated single amino exchanges using a translational perspective, from the viewpoints of molecular genetics and pathology, protein biochemistry and biophysics, structural, and cell biology. This will allow us to introduce several representative examples of natural and synthetic small molecules applied and developed to overcome functional, stability, and regulatory alterations due to cancer-associated amino acid exchanges, which hold the promise for using them as potential pharmacological cancer therapies.
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Affiliation(s)
- Isabel Betancor-Fernández
- Centre for Biomedical Research on Rare Diseases (CIBERER), Hospital Universitario de Canarias, Tenerife, 38320, Spain
| | - David J Timson
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Huxley Building, Lewes Road, Brighton, BN2 4GJ, UK
| | - Eduardo Salido
- Centre for Biomedical Research on Rare Diseases (CIBERER), Hospital Universitario de Canarias, Tenerife, 38320, Spain
| | - Angel L Pey
- Department of Physical Chemistry, University of Granada, Granada, 18071, Spain.
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28
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Zhao C, Lasses T, Bako L, Kong D, Zhao B, Chanda B, Bombarely A, Cruz-Ramírez A, Scheres B, Brunner AM, Beers EP. XYLEM NAC DOMAIN1, an angiosperm NAC transcription factor, inhibits xylem differentiation through conserved motifs that interact with RETINOBLASTOMA-RELATED. THE NEW PHYTOLOGIST 2017; 216:76-89. [PMID: 28742236 DOI: 10.1111/nph.14704] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 06/13/2017] [Indexed: 05/19/2023]
Abstract
The Arabidopsis thaliana gene XYLEM NAC DOMAIN1 (XND1) is upregulated in xylem tracheary elements. Yet overexpression of XND1 blocks differentiation of tracheary elements. The molecular mechanism of XND1 action was investigated. Phylogenetic and motif analyses indicated that XND1 and its homologs are present only in angiosperms and possess a highly conserved C-terminal region containing linear motifs (CKII-acidic, LXCXE, E2FTD -like and LXCXE-mimic) predicted to interact with the cell cycle and differentiation regulator RETINOBLASTOMA-RELATED (RBR). Protein-protein interaction and functional analyses of XND1 deletion mutants were used to test the importance of RBR-interaction motifs. Deletion of either the LXCXE or the LXCXE-mimic motif reduced both the XND1-RBR interaction and XND1 efficacy as a repressor of differentiation, with loss of the LXCXE motif having the strongest negative impacts. The function of the XND1 C-terminal domain could be partially replaced by RBR fused to the N-terminal domain of XND1. XND1 also transactivated gene expression in yeast and plants. The properties of XND1, a transactivator that depends on multiple linear RBR-interaction motifs to inhibit differentiation, have not previously been described for a plant protein. XND1 harbors an apparently angiosperm-specific combination of interaction motifs potentially linking the general differentiation regulator RBR with a xylem-specific pathway for inhibition of differentiation.
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Affiliation(s)
- Chengsong Zhao
- Department of Horticulture, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Theres Lasses
- Department of Plant Physiology, Umeå Plant Science Center, Umeå University, S-901 87, Umeå, Sweden
| | - Laszlo Bako
- Department of Plant Physiology, Umeå Plant Science Center, Umeå University, S-901 87, Umeå, Sweden
| | - Danyu Kong
- Department of Horticulture, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Bingyu Zhao
- Department of Horticulture, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Bidisha Chanda
- Department of Horticulture, Virginia Tech, Blacksburg, VA, 24061, USA
| | | | - Alfredo Cruz-Ramírez
- Molecular and Developmental Complexity Group, Unidad de Genómica Avanzada, CINVESTAV, Irapuato, Guanajuato, 36821, México
| | - Ben Scheres
- Plant Developmental Biology, Wageningen University & Research, 6708PB, Wageningen, the Netherlands
| | - Amy M Brunner
- Department of Forest Resources and Environmental Conservation, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Eric P Beers
- Department of Horticulture, Virginia Tech, Blacksburg, VA, 24061, USA
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29
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Miller AK, Munger K, Adler FR. A Mathematical Model of Cell Cycle Dysregulation Due to Human Papillomavirus Infection. Bull Math Biol 2017; 79:1564-1585. [PMID: 28608043 DOI: 10.1007/s11538-017-0299-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 05/17/2017] [Indexed: 12/21/2022]
Abstract
Human papillomaviruses (HPVs) that infect mucosal epithelium can be classified as high risk or low risk based on their propensity to cause lesions that can undergo malignant progression. HPVs produce the E7 protein that binds to cell cycle regulatory proteins including the retinoblastoma tumor suppressor protein (RB) to modulate cell cycle control. Generally, high-risk HPV E7 proteins bind to RB with a higher affinity than low-risk HPV E7s, but both are able to deactivate RB and trigger S phase progression. In uninfected cells, RB inactivation is a tightly controlled process that must coincide with growth factor stimulation to commit cells to division. High-risk HPV E7 proteins short-circuit this control by decreasing growth factor requirement for cell division. We develop a mathematical model to examine the role that RB binding affinity, growth factor concentration, and E7 concentration have on cell cycle progression. Our model predicts that high RB binding affinity and E7 concentration accelerate the [Formula: see text] to S phase transition and weaken the dependence on growth factor. This model thus captures a key step in high-risk HPV oncogenesis.
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Affiliation(s)
- Anna K Miller
- Department of Mathematics, University of Utah, Salt Lake City, UT, USA.
| | - Karl Munger
- Department of Developmental, Molecular and Chemical Biology, Tufts University, Boston, MA, USA
| | - Frederick R Adler
- Departments of Mathematics and Biology, University of Utah, Salt Lake City, UT, USA
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30
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Thwaites MJ, Cecchini MJ, Talluri S, Passos DT, Carnevale J, Dick FA. Multiple molecular interactions redundantly contribute to RB-mediated cell cycle control. Cell Div 2017; 12:3. [PMID: 28293272 PMCID: PMC5348811 DOI: 10.1186/s13008-017-0029-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 02/28/2017] [Indexed: 02/07/2023] Open
Abstract
Background The G1-S phase transition is critical to maintaining proliferative control and preventing carcinogenesis. The retinoblastoma tumor suppressor is a key regulator of this step in the cell cycle. Results Here we use a structure–function approach to evaluate the contributions of multiple protein interaction surfaces on pRB towards cell cycle regulation. SAOS2 cell cycle arrest assays showed that disruption of three separate binding surfaces were necessary to inhibit pRB-mediated cell cycle control. Surprisingly, mutation of some interaction surfaces had no effect on their own. Rather, they only contributed to cell cycle arrest in the absence of other pRB dependent arrest functions. Specifically, our data shows that pRB–E2F interactions are competitive with pRB–CDH1 interactions, implying that interchangeable growth arrest functions underlie pRB’s ability to block proliferation. Additionally, disruption of similar cell cycle control mechanisms in genetically modified mutant mice results in ectopic DNA synthesis in the liver. Conclusions Our work demonstrates that pRB utilizes a network of mechanisms to prevent cell cycle entry. This has important implications for the use of new CDK4/6 inhibitors that aim to activate this proliferative control network.
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Affiliation(s)
- Michael J Thwaites
- London Regional Cancer Program, London, Canada.,Department of Biochemistry, Western University, London, ON Canada
| | - Matthew J Cecchini
- London Regional Cancer Program, London, Canada.,Department of Biochemistry, Western University, London, ON Canada
| | - Srikanth Talluri
- London Regional Cancer Program, London, Canada.,Department of Biochemistry, Western University, London, ON Canada
| | - Daniel T Passos
- London Regional Cancer Program, London, Canada.,Department of Biochemistry, Western University, London, ON Canada
| | - Jasmyne Carnevale
- London Regional Cancer Program, London, Canada.,Department of Biochemistry, Western University, London, ON Canada
| | - Frederick A Dick
- London Regional Cancer Program, London, Canada.,Children's Health Research Institute, London, Canada.,Department of Biochemistry, Western University, London, ON Canada
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31
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Okuda M, Araki K, Ohtani K, Nishimura Y. The Interaction Mode of the Acidic Region of the Cell Cycle Transcription Factor DP1 with TFIIH. J Mol Biol 2016; 428:4993-5006. [DOI: 10.1016/j.jmb.2016.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 10/27/2016] [Accepted: 11/01/2016] [Indexed: 10/20/2022]
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32
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Roesley SNA, Suryadinata R, Morrish E, Tan AR, Issa SMA, Oakhill JS, Bernard O, Welch DR, Šarčević B. Cyclin-dependent kinase-mediated phosphorylation of breast cancer metastasis suppressor 1 (BRMS1) affects cell migration. Cell Cycle 2016; 15:137-51. [PMID: 26771717 DOI: 10.1080/15384101.2015.1121328] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Expression of Breast Cancer Metastasis Suppressor 1 (BRMS1) reduces the incidence of metastasis in many human cancers, without affecting tumorigenesis. BRMS1 carries out this function through several mechanisms, including regulation of gene expression by binding to the mSin3/histone deacetylase (HDAC) transcriptional repressor complex. In the present study, we show that BRMS1 is a novel substrate of Cyclin-Dependent Kinase 2 (CDK2) that is phosphorylated on serine 237 (S237). Although CDKs are known to regulate cell cycle progression, the mutation of BRMS1 on serine 237 did not affect cell cycle progression and proliferation of MDA-MB-231 breast cancer cells; however, their migration was affected. Phosphorylation of BRMS1 does not affect its association with the mSin3/HDAC transcriptional repressor complex or its transcriptional repressor activity. The serine 237 phosphorylation site is immediately proximal to a C-terminal nuclear localization sequence that plays an important role in BRMS1-mediated metastasis suppression but phosphorylation does not control BRMS1 subcellular localization. Our studies demonstrate that CDK-mediated phosphorylation of BRMS1 regulates the migration of tumor cells.
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Affiliation(s)
- Siti Nur Ain Roesley
- a Cell Cycle and Cancer Unit , St Vincent's Institute of Medical Research , Victoria , Australia.,b Department of Medicine , University of Melbourne , Victoria , Australia
| | | | - Emma Morrish
- a Cell Cycle and Cancer Unit , St Vincent's Institute of Medical Research , Victoria , Australia
| | | | - Samah M A Issa
- e Metabolic Signalling Laboratory, St Vincent's Institute of Medical Research , Victoria , Australia
| | - Jonathan S Oakhill
- e Metabolic Signalling Laboratory, St Vincent's Institute of Medical Research , Victoria , Australia
| | - Ora Bernard
- b Department of Medicine , University of Melbourne , Victoria , Australia
| | - Danny R Welch
- f Department of Cancer Biology and The University of Kansas Cancer Center , University of Kansas Medical Center , Kansas City , KS , USA
| | - Boris Šarčević
- a Cell Cycle and Cancer Unit , St Vincent's Institute of Medical Research , Victoria , Australia.,b Department of Medicine , University of Melbourne , Victoria , Australia
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33
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Hernández-Monge J, Rousset-Roman AB, Medina-Medina I, Olivares-Illana V. Dual function of MDM2 and MDMX toward the tumor suppressors p53 and RB. Genes Cancer 2016; 7:278-287. [PMID: 28050229 PMCID: PMC5115168 DOI: 10.18632/genesandcancer.120] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The orchestrated crosstalk between the retinoblastoma (RB) and p53 pathways contributes to preserving proper homeostasis within the cell. The deregulation of one or both pathways is a common factor in the development of most types of human cancer. The proto-oncoproteins MDMX and MDM2 are the main regulators of the well- known tumor suppressor p53 protein. Under normal conditions, MDM2 and MDMX inhibit p53, either via repression of its transcriptional activity by protein-protein interaction, or via polyubiquitination as a result of MDM2-E3 ubiquitin ligase activity, for which MDM2 needs to dimerize with MDMX. Under genotoxic stress conditions, both become positive regulators of p53. The ATM-dependent phosphorylation of MDM2 and MDMX allow them to bind p53 mRNA, these interactions promote p53 translation. MDM2 and MDMX are also being revealed as effective regulators of the RB protein. MDM2 is able to degrade RB by two different mechanisms, that is, by ubiquitin dependent and independent pathways. MDMX enhances the ability of MDM2 to bind and degrade RB protein. However, MDMX also seems to stabilize RB through interaction and competition with MDM2. Here, we will contextualize the findings that suggest that the MDM2 and MDMX proteins have a dual function on both p53 and RB.
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Affiliation(s)
- Jesús Hernández-Monge
- Instituto de Física, Universidad Autónoma de San Luis Potosí, Av Manuel Nava No 6 Zona Universitaria CP 78290. SLP, México
| | - Adriana Berenice Rousset-Roman
- Instituto de Física, Universidad Autónoma de San Luis Potosí, Av Manuel Nava No 6 Zona Universitaria CP 78290. SLP, México
| | - Ixaura Medina-Medina
- Instituto de Física, Universidad Autónoma de San Luis Potosí, Av Manuel Nava No 6 Zona Universitaria CP 78290. SLP, México
| | - Vanesa Olivares-Illana
- Instituto de Física, Universidad Autónoma de San Luis Potosí, Av Manuel Nava No 6 Zona Universitaria CP 78290. SLP, México
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34
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Gubern A, Joaquin M, Marquès M, Maseres P, Garcia-Garcia J, Amat R, González-Nuñez D, Oliva B, Real FX, de Nadal E, Posas F. The N-Terminal Phosphorylation of RB by p38 Bypasses Its Inactivation by CDKs and Prevents Proliferation in Cancer Cells. Mol Cell 2016; 64:25-36. [PMID: 27642049 DOI: 10.1016/j.molcel.2016.08.015] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 06/21/2016] [Accepted: 08/10/2016] [Indexed: 02/06/2023]
Abstract
Control of the G1/S phase transition by the Retinoblastoma (RB) tumor suppressor is critical for the proliferation of normal cells in tissues, and its inactivation is one of the most fundamental events leading to cancer. Cyclin-dependent kinase (CDK) phosphorylation inactivates RB to promote cell cycle-regulated gene expression. Here we show that, upon stress, the p38 stress-activated protein kinase (SAPK) maximizes cell survival by downregulating E2F gene expression through the targeting of RB. RB undergoes selective phosphorylation by p38 in its N terminus; these phosphorylations render RB insensitive to the inactivation by CDKs. p38 phosphorylation of RB increases its affinity toward the E2F transcription factor, represses gene expression, and delays cell-cycle progression. Remarkably, introduction of a RB phosphomimetic mutant in cancer cells reduces colony formation and decreases their proliferative and tumorigenic potential in mice.
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Affiliation(s)
- Albert Gubern
- Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
| | - Manel Joaquin
- Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
| | - Miriam Marquès
- Epithelial Carcinogenesis Group, Cancer Cell Biology Programme, Spanish National Cancer Research Centre (CNIO), 28029 Madrid, Spain; Departament de Ciències Experimentals i de la Salut, UPF, 08003 Barcelona, Spain
| | - Pedro Maseres
- Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
| | - Javier Garcia-Garcia
- Structural Bioinformatics Group (GRIB), Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
| | - Ramon Amat
- Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
| | - Daniel González-Nuñez
- Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
| | - Baldo Oliva
- Structural Bioinformatics Group (GRIB), Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
| | - Francisco X Real
- Epithelial Carcinogenesis Group, Cancer Cell Biology Programme, Spanish National Cancer Research Centre (CNIO), 28029 Madrid, Spain; Departament de Ciències Experimentals i de la Salut, UPF, 08003 Barcelona, Spain
| | - Eulàlia de Nadal
- Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain.
| | - Francesc Posas
- Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain.
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35
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Liban TJ, Thwaites MJ, Dick FA, Rubin SM. Structural Conservation and E2F Binding Specificity within the Retinoblastoma Pocket Protein Family. J Mol Biol 2016; 428:3960-3971. [PMID: 27567532 DOI: 10.1016/j.jmb.2016.08.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 06/24/2016] [Accepted: 08/17/2016] [Indexed: 11/24/2022]
Abstract
The human pocket proteins retinoblastoma (Rb), p107, and p130 are critical negative regulators of the cell cycle and contribute to tumor suppression. While strong structural conservation within the pocket protein family provides for some functional redundancy, important differences have been observed and may underlie the reason that Rb is a uniquely potent tumor suppressor. It has been proposed that distinct pocket protein activities are mediated by their different E2F transcription factor binding partners. In humans, Rb binds E2F1-E2F5, whereas p107 and p130 almost exclusively associate with E2F4 and E2F5. To identify the molecular determinants of this specificity, we compared the crystal structures of Rb and p107 pocket domains and identified several key residues that contribute to E2F selectivity in the pocket family. Mutation of these residues in p107 to match the analogous residue in Rb results in an increase in affinity for E2F1 and E2F2 and an increase in the ability of p107 to inhibit E2F2 transactivation. Additionally, we investigated how phosphorylation by Cyclin-dependent kinase on distinct residues regulates p107 affinity for the E2F4 transactivation domain. We found that phosphorylation of residues S650 and S975 weakens the E2F4 transactivation domain binding. Our data reveal molecular features of pocket proteins that are responsible for their similarities and differences in function and regulation.
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Affiliation(s)
- Tyler J Liban
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Michael J Thwaites
- Department of Biochemistry, Western University, London Regional Cancer Program and Children's Health Research Institute, London, Ontario, Canada
| | - Frederick A Dick
- Department of Biochemistry, Western University, London Regional Cancer Program and Children's Health Research Institute, London, Ontario, Canada
| | - Seth M Rubin
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA.
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36
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Singh J, Mishra A, Pandian AJ, Mallipatna AC, Khetan V, Sripriya S, Kapoor S, Agarwal S, Sankaran S, Katragadda S, Veeramachaneni V, Hariharan R, Subramanian K, Mannan AU. Next-generation sequencing-based method shows increased mutation detection sensitivity in an Indian retinoblastoma cohort. Mol Vis 2016; 22:1036-47. [PMID: 27582626 PMCID: PMC4985049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 08/14/2016] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Retinoblastoma (Rb) is the most common primary intraocular cancer of childhood and one of the major causes of blindness in children. India has the highest number of patients with Rb in the world. Mutations in the RB1 gene are the primary cause of Rb, and heterogeneous mutations are distributed throughout the entire length of the gene. Therefore, genetic testing requires screening of the entire gene, which by conventional sequencing is time consuming and expensive. METHODS In this study, we screened the RB1 gene in the DNA isolated from blood or saliva samples of 50 unrelated patients with Rb using the TruSight Cancer panel. Next-generation sequencing (NGS) was done on the Illumina MiSeq platform. Genetic variations were identified using the Strand NGS software and interpreted using the StrandOmics platform. RESULTS We were able to detect germline pathogenic mutations in 66% (33/50) of the cases, 12 of which were novel. We were able to detect all types of mutations, including missense, nonsense, splice site, indel, and structural variants. When we considered bilateral Rb cases only, the mutation detection rate increased to 100% (22/22). In unilateral Rb cases, the mutation detection rate was 30% (6/20). CONCLUSIONS Our study suggests that NGS-based approaches increase the sensitivity of mutation detection in the RB1 gene, making it fast and cost-effective compared to the conventional tests performed in a reflex-testing mode.
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Affiliation(s)
- Jaya Singh
- Strand Center for Genomics and Personalized Medicine, Strand Life Sciences, Bangalore, India
| | - Avshesh Mishra
- Strand Center for Genomics and Personalized Medicine, Strand Life Sciences, Bangalore, India
| | | | - Ashwin C. Mallipatna
- Department of Pediatric Ophthalmology and Strabismology, Narayana Nethralaya, Bangalore, India
| | - Vikas Khetan
- Department of Vitreo Retina, Sankara Nethralaya, Chennai, India
| | - S. Sripriya
- Sankara Nethralaya ONGC Department of Genetics and Molecular Biology, Vision Research Foundation, Chennai, India
| | - Suman Kapoor
- Strand Center for Genomics and Personalized Medicine, Strand Life Sciences, Bangalore, India
| | - Smita Agarwal
- Strand Center for Genomics and Personalized Medicine, Strand Life Sciences, Bangalore, India
| | - Satish Sankaran
- Strand Center for Genomics and Personalized Medicine, Strand Life Sciences, Bangalore, India
| | - Shanmukh Katragadda
- Strand Center for Genomics and Personalized Medicine, Strand Life Sciences, Bangalore, India
| | - Vamsi Veeramachaneni
- Strand Center for Genomics and Personalized Medicine, Strand Life Sciences, Bangalore, India
| | - Ramesh Hariharan
- Strand Center for Genomics and Personalized Medicine, Strand Life Sciences, Bangalore, India,Department of Computer Science and Automation, Indian Institute of Science, Bangalore, India
| | | | - Ashraf U. Mannan
- Strand Center for Genomics and Personalized Medicine, Strand Life Sciences, Bangalore, India
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Huang PH, Cook R, Zoumpoulidou G, Luczynski MT, Mittnacht S. Retinoblastoma family proteins: New players in DNA repair by non-homologous end-joining. Mol Cell Oncol 2016; 3:e1053596. [PMID: 27308588 PMCID: PMC4905371 DOI: 10.1080/23723556.2015.1053596] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 05/17/2015] [Accepted: 05/18/2015] [Indexed: 10/23/2022]
Abstract
Loss of retinoblastoma protein (RB1) function is a major driver in cancer development. We have recently reported that, in addition to its well-documented functions in cell cycle and fate control, RB1 and its paralogs have a novel role in regulating DNA repair by non-homologous end joining (NHEJ). Here we summarize our findings and present mechanistic hypotheses on how RB1 may support the DNA repair process and the therapeutic implications for patients who harbor RB1-negative cancers.
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Affiliation(s)
- Paul H. Huang
- The Institute of Cancer Research, Division of Cancer Biology, Chester Beatty Laboratories, London, UK
| | - Rebecca Cook
- The Institute of Cancer Research, Division of Cancer Biology, Chester Beatty Laboratories, London, UK
- Cancer Cell Signalling, UCL Cancer Institute, University College London, London, UK
| | - Georgia Zoumpoulidou
- The Institute of Cancer Research, Division of Cancer Biology, Chester Beatty Laboratories, London, UK
| | - Maciej T. Luczynski
- The Institute of Cancer Research, Division of Cancer Biology, Chester Beatty Laboratories, London, UK
| | - Sibylle Mittnacht
- The Institute of Cancer Research, Division of Cancer Biology, Chester Beatty Laboratories, London, UK
- Cancer Cell Signalling, UCL Cancer Institute, University College London, London, UK
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Mendoza PR, Grossniklaus HE. The Biology of Retinoblastoma. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 134:503-16. [PMID: 26310174 DOI: 10.1016/bs.pmbts.2015.06.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Retinoblastoma, the most common primary intraocular cancer of childhood, is a malignancy arising in the developing retina. Tumor formation usually begins with mutation in both alleles of the retinoblastoma tumor suppressor gene RB1, followed by a series of other genetic alterations that correlate with the clinical stage and pathologic findings of the tumor. Analysis of sporadic and heritable retinoblastoma led to the development of Knudson's Two-Hit Hypothesis. The tumor suppressor RB1 gene codes for the retinoblastoma protein which is a key regulator of cellular replication via its binding to the E2F family of transcription factors and chromatin remodeling proteins. Studies of preclinical models of retinoblastoma in the form of transgenic mice and xenograft animal models have significantly contributed to the development of effective therapies for this disease. Research on retinoblastoma has paved the way toward understanding many of the mechanisms in cancer genetics.
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Affiliation(s)
- Pia R Mendoza
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Hans E Grossniklaus
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, USA.
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Iwahori S, Hakki M, Chou S, Kalejta RF. Molecular Determinants for the Inactivation of the Retinoblastoma Tumor Suppressor by the Viral Cyclin-dependent Kinase UL97. J Biol Chem 2015; 290:19666-80. [PMID: 26100623 DOI: 10.1074/jbc.m115.660043] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2015] [Indexed: 01/10/2023] Open
Abstract
The retinoblastoma (Rb) tumor suppressor restricts cell cycle progression by repressing E2F-responsive transcription. Cellular cyclin-dependent kinase (CDK)-mediated Rb inactivation through phosphorylation disrupts Rb-E2F complexes, stimulating transcription. The human cytomegalovirus (HCMV) UL97 protein is a viral CDK (v-CDK) that phosphorylates Rb. Here we show that UL97 phosphorylates 11 of the 16 consensus CDK sites in Rb. A cleft within Rb accommodates peptides with the amino acid sequence LXCXE. UL97 contains three such motifs. We determined that the first LXCXE motif (L1) of UL97 and the Rb cleft enhance UL97-mediated Rb phosphorylation. A UL97 mutant with a non-functional L1 motif (UL97-L1m) displayed significantly reduced Rb phosphorylation at multiple sites. Curiously, however, it efficiently disrupted Rb-E2F complexes but failed to relieve Rb-mediated repression of E2F reporter constructs. The HCMV immediate early 1 protein cooperated with UL97-L1m to inactivate Rb in transfection assays, likely indicating that cells infected with a UL97-L1m mutant virus show no defects in growth or E2F-responsive gene expression because of redundant viral mechanisms to inactivate Rb. Our data suggest that UL97 possesses a mechanism to elicit E2F-dependent gene expression distinct from disruption of Rb-E2F complexes and dependent upon both the L1 motif of UL97 and the cleft region of Rb.
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Affiliation(s)
- Satoko Iwahori
- From the Institute for Molecular Virology and McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin 53706 and
| | - Morgan Hakki
- the Division of Infectious Diseases, Oregon Health and Science University and
| | - Sunwen Chou
- the Division of Infectious Diseases, Oregon Health and Science University and Veterans Affairs Portland Health Care System, Portland, Oregon 97239
| | - Robert F Kalejta
- From the Institute for Molecular Virology and McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin 53706 and
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40
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Guiley KZ, Liban TJ, Felthousen JG, Ramanan P, Litovchick L, Rubin SM. Structural mechanisms of DREAM complex assembly and regulation. Genes Dev 2015; 29:961-74. [PMID: 25917549 PMCID: PMC4421984 DOI: 10.1101/gad.257568.114] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Indexed: 01/01/2023]
Abstract
To understand the biochemical mechanisms underpinning DREAM function and regulation, Guiley et al. investigated the structural basis for DREAM assembly. Together, the data inform a novel target interface for studying MuvB and p130 function and the design of inhibitors that prevent tumor escape in quiescence. The DREAM complex represses cell cycle genes during quiescence through scaffolding MuvB proteins with E2F4/5 and the Rb tumor suppressor paralog p107 or p130. Upon cell cycle entry, MuvB dissociates from p107/p130 and recruits B-Myb and FoxM1 for up-regulating mitotic gene expression. To understand the biochemical mechanisms underpinning DREAM function and regulation, we investigated the structural basis for DREAM assembly. We identified a sequence in the MuvB component LIN52 that binds directly to the pocket domains of p107 and p130 when phosphorylated on the DYRK1A kinase site S28. A crystal structure of the LIN52–p107 complex reveals that LIN52 uses a suboptimal LxSxExL sequence together with the phosphate at nearby S28 to bind the LxCxE cleft of the pocket domain with high affinity. The structure explains the specificity for p107/p130 over Rb in the DREAM complex and how the complex is disrupted by viral oncoproteins. Based on insights from the structure, we addressed how DREAM is disassembled upon cell cycle entry. We found that p130 and B-Myb can both bind the core MuvB complex simultaneously but that cyclin-dependent kinase phosphorylation of p130 weakens its association. Together, our data inform a novel target interface for studying MuvB and p130 function and the design of inhibitors that prevent tumor escape in quiescence.
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Affiliation(s)
- Keelan Z Guiley
- Department of Chemistry and Biochemistry, University of California at Santa Cruz, Santa Cruz, California 95064, USA
| | - Tyler J Liban
- Department of Chemistry and Biochemistry, University of California at Santa Cruz, Santa Cruz, California 95064, USA
| | - Jessica G Felthousen
- Division of Hematology, Oncology, and Palliative Care, Richmond, Virginia 23298, USA; Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia 23298, USA
| | - Parameshwaran Ramanan
- Department of Chemistry and Biochemistry, University of California at Santa Cruz, Santa Cruz, California 95064, USA
| | - Larisa Litovchick
- Division of Hematology, Oncology, and Palliative Care, Richmond, Virginia 23298, USA; Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia 23298, USA
| | - Seth M Rubin
- Department of Chemistry and Biochemistry, University of California at Santa Cruz, Santa Cruz, California 95064, USA;
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Cook R, Zoumpoulidou G, Luczynski MT, Rieger S, Moquet J, Spanswick VJ, Hartley JA, Rothkamm K, Huang PH, Mittnacht S. Direct involvement of retinoblastoma family proteins in DNA repair by non-homologous end-joining. Cell Rep 2015; 10:2006-18. [PMID: 25818292 PMCID: PMC4386026 DOI: 10.1016/j.celrep.2015.02.059] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2014] [Revised: 01/02/2015] [Accepted: 02/24/2015] [Indexed: 12/31/2022] Open
Abstract
Deficiencies in DNA double-strand break (DSB) repair lead to genetic instability, a recognized cause of cancer initiation and evolution. We report that the retinoblastoma tumor suppressor protein (RB1) is required for DNA DSB repair by canonical non-homologous end-joining (cNHEJ). Support of cNHEJ involves a mechanism independent of RB1's cell-cycle function and depends on its amino terminal domain with which it binds to NHEJ components XRCC5 and XRCC6. Cells with engineered loss of RB family function as well as cancer-derived cells with mutational RB1 loss show substantially reduced levels of cNHEJ. RB1 variants disabled for the interaction with XRCC5 and XRCC6, including a cancer-associated variant, are unable to support cNHEJ despite being able to confer cell-cycle control. Our data identify RB1 loss as a candidate driver of structural genomic instability and a causative factor for cancer somatic heterogeneity and evolution.
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Affiliation(s)
- Rebecca Cook
- Division of Cancer Biology, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK; Cancer Cell Signalling, UCL Cancer Institute, University College London, 72 Huntley Street, London WC1E 6DD, UK
| | - Georgia Zoumpoulidou
- Cancer Cell Signalling, UCL Cancer Institute, University College London, 72 Huntley Street, London WC1E 6DD, UK
| | - Maciej T Luczynski
- Division of Cancer Biology, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - Simone Rieger
- Cancer Cell Signalling, UCL Cancer Institute, University College London, 72 Huntley Street, London WC1E 6DD, UK
| | - Jayne Moquet
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot OX11 0RQ, UK
| | - Victoria J Spanswick
- Cancer Research UK Drug-DNA Interactions Research Group, UCL Cancer Institute, University College London, 72 Huntley Street, London WC1E 6DD, UK
| | - John A Hartley
- Cancer Research UK Drug-DNA Interactions Research Group, UCL Cancer Institute, University College London, 72 Huntley Street, London WC1E 6DD, UK
| | - Kai Rothkamm
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot OX11 0RQ, UK
| | - Paul H Huang
- Division of Cancer Biology, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK.
| | - Sibylle Mittnacht
- Division of Cancer Biology, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK; Cancer Cell Signalling, UCL Cancer Institute, University College London, 72 Huntley Street, London WC1E 6DD, UK.
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42
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MDMX exerts its oncogenic activity via suppression of retinoblastoma protein. Oncogene 2015; 34:5560-9. [PMID: 25703327 DOI: 10.1038/onc.2015.11] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 12/12/2014] [Accepted: 01/14/2015] [Indexed: 12/15/2022]
Abstract
Inactivation of the retinoblastoma protein (RB) has a major role in the development of human malignancies. We have previously shown that MDM2, an ubiquitin E3 ligase and major negative regulator of p53, binds to and promotes proteasome-mediated degradation of RB. MDMX, a homolog of MDM2, also binds to and inhibits p53 transactivation activity, yet it does not possess intrinsic ubiquitin ligase activity. Here, we show that MDMX binds to and promotes RB degradation in an MDM2-dependent manner. Specifically, the MDMX C-terminal ring domain binds to the RB C-pocket and enhances MDM2-RB interaction. Silencing MDMX induces RB accumulation, cell cycle arrest and senescence-like phenotypes, which are reverted by simultaneous RB knockdown. Furthermore, MDMX ablation leads to significant retardation of xenograft tumor growth, concomitant with RB accumulation. These results demonstrate that MDMX exerts oncogenic activity via suppression of RB, and suggest that both MDM2 and MDMX could be chemotherapeutic targets.
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43
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Sun Y, Stine JM, Atwater DZ, Sharmin A, Ross JBA, Briknarová K. Structural and functional characterization of the acidic region from the RIZ tumor suppressor. Biochemistry 2015; 54:1390-400. [PMID: 25640033 DOI: 10.1021/bi501398w] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
RIZ (retinoblastoma protein-interacting zinc finger protein), also denoted PRDM2, is a transcriptional regulator and tumor suppressor. It was initially identified because of its ability to interact with another well-established tumor suppressor, the retinoblastoma protein (Rb). A short motif, IRCDE, in the acidic region (AR) of RIZ was reported to play an important role in the interaction with the pocket domain of Rb. The IRCDE motif is similar to a consensus Rb-binding sequence LXCXE (where X denotes any amino acid) that is found in several viral Rb-inactivating oncoproteins. To improve our understanding of the molecular basis of binding of Rb to RIZ, we investigated the interaction between purified recombinant AR and the pocket domain of Rb using nuclear magnetic resonance spectroscopy, isothermal titration calorimetry, and fluorescence anisotropy experiments. We show that AR is intrinsically disordered and that it binds the pocket domain with submicromolar affinity. We also demonstrate that the interaction between AR and the pocket domain is mediated primarily by the short stretch of residues containing the IRCDE motif and that the contribution of other parts of AR to the interaction with the pocket domain is minimal. Overall, our data provide clear evidence that RIZ is one of the few cellular proteins that can interact directly with the LXCXE-binding cleft on Rb.
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Affiliation(s)
- Yizhi Sun
- Department of Chemistry and Biochemistry, University of Montana , Missoula, Montana 59812, United States
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44
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Mayrhofer M, Kultima HG, Birgisson H, Sundström M, Mathot L, Edlund K, Viklund B, Sjöblom T, Botling J, Micke P, Påhlman L, Glimelius B, Isaksson A. 1p36 deletion is a marker for tumour dissemination in microsatellite stable stage II-III colon cancer. BMC Cancer 2014; 14:872. [PMID: 25420937 PMCID: PMC4251789 DOI: 10.1186/1471-2407-14-872] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 11/13/2014] [Indexed: 12/15/2022] Open
Abstract
Background The clinical behaviour of colon cancer is heterogeneous. Five-year overall survival is 50-65% with all stages included. Recurring somatic chromosomal alterations have been identified and some have shown potential as markers for dissemination of the tumour, which is responsible for most colon cancer deaths. We investigated 115 selected stage II-IV primary colon cancers for associations between chromosomal alterations and tumour dissemination. Methods Follow-up was at least 5 years for stage II-III patients without distant recurrence. Affymetrix SNP 6.0 microarrays and allele-specific copy number analysis were used to identify chromosomal alterations. Fisher’s exact test was used to associate alterations with tumour dissemination, detected at diagnosis (stage IV) or later as recurrent disease (stage II-III). Results Loss of 1p36.11-21 was associated with tumour dissemination in microsatellite stable tumours of stage II-IV (odds ratio = 5.5). It was enriched to a similar extent in tumours with distant recurrence within stage II and stage III subgroups, and may therefore be used as a prognostic marker at diagnosis. Loss of 1p36.11-21 relative to average copy number of the genome showed similar prognostic value compared to absolute loss of copies. Therefore, the use of relative loss as a prognostic marker would benefit more patients by applying also to hyperploid cancer genomes. The association with tumour dissemination was supported by independent data from the The Cancer Genome Atlas. Conclusion Deletions on 1p36 may be used to guide adjuvant treatment decisions in microsatellite stable colon cancer of stages II and III. Electronic supplementary material The online version of this article (doi:10.1186/1471-2407-14-872) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | - Anders Isaksson
- Science for Life Laboratory, Department of Medical Sciences, Uppsala University, Box 3056, Uppsala 750 03, Sweden.
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Ferrari R, Gou D, Jawdekar G, Johnson SA, Nava M, Su T, Yousef AF, Zemke NR, Pellegrini M, Kurdistani SK, Berk AJ. Adenovirus small E1A employs the lysine acetylases p300/CBP and tumor suppressor Rb to repress select host genes and promote productive virus infection. Cell Host Microbe 2014; 16:663-76. [PMID: 25525796 DOI: 10.1016/j.chom.2014.10.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 07/25/2014] [Accepted: 09/07/2014] [Indexed: 12/27/2022]
Abstract
Oncogenic transformation by adenovirus small e1a depends on simultaneous interactions with the host lysine acetylases p300/CBP and the tumor suppressor RB. How these interactions influence cellular gene expression remains unclear. We find that e1a displaces RBs from E2F transcription factors and promotes p300 acetylation of RB1 K873/K874 to lock it into a repressing conformation that interacts with repressive chromatin-modifying enzymes. These repressing p300-e1a-RB1 complexes specifically interact with host genes that have unusually high p300 association within the gene body. The TGF-β, TNF-, and interleukin-signaling pathway components are enriched among such p300-targeted genes. The p300-e1a-RB1 complex condenses chromatin in a manner dependent on HDAC activity, p300 lysine acetylase activity, the p300 bromodomain, and RB K873/K874 and e1a K239 acetylation to repress host genes that would otherwise inhibit productive virus infection. Thus, adenovirus employs e1a to repress host genes that interfere with viral replication.
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Affiliation(s)
- Roberto Ferrari
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA
| | - Dawei Gou
- Molecular Biology Institute, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA; Department of Microbiology, Immunology and Molecular Genetics, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA
| | - Gauri Jawdekar
- Molecular Biology Institute, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA
| | - Sarah A Johnson
- Molecular Biology Institute, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA
| | - Miguel Nava
- Department of Microbiology, Immunology and Molecular Genetics, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA
| | - Trent Su
- Department of Biological Chemistry, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA
| | - Ahmed F Yousef
- Molecular Biology Institute, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA
| | - Nathan R Zemke
- Molecular Biology Institute, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA
| | - Matteo Pellegrini
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA; Molecular Biology Institute, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA; Department of Molecular, Cellular, and Developmental Biology, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA
| | - Siavash K Kurdistani
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA; Molecular Biology Institute, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA; Department of Biological Chemistry, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA; Department of Pathology and Laboratory of Medicine, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA
| | - Arnold J Berk
- Molecular Biology Institute, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA; Department of Microbiology, Immunology and Molecular Genetics, UCLA David Geffen School of Medicine, Los Angeles, CA 90095-1570, USA.
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Grossniklaus HE. Retinoblastoma. Fifty years of progress. The LXXI Edward Jackson Memorial Lecture. Am J Ophthalmol 2014; 158:875-91. [PMID: 25065496 PMCID: PMC4250440 DOI: 10.1016/j.ajo.2014.07.025] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 07/14/2014] [Accepted: 07/14/2014] [Indexed: 12/12/2022]
Abstract
PURPOSE To review the progress made in understanding the genetic basis, molecular pathology, and treatment of retinoblastoma since the previous Jackson lecture on the topic was published 50 years ago. DESIGN Perspective based on personal experience and the literature. METHODS The literature regarding retinoblastoma was reviewed since 1963. Advances in understanding the biology and treatment of retinoblastoma provided context through the author's clinical, pathologic, and research experiences. RESULTS Retinoblastoma was first identified in the 1500s and defined as a unique clinicopathologic entity in 1809. Until the mid-1900s, knowledge advanced sporadically, with technological developments of ophthalmoscopy and light microscopy, and with the introduction of surgical enucleation, chemotherapy, and radiation therapy. During the last 50 years, research and treatment have progressed at an unprecedented rate owing to innovations in molecular biology and the development of targeted therapies. During this time period, the retinoblastoma gene was discovered; techniques for genetic testing for retinoblastoma were developed; and plaque brachytherapy, chemoreduction, intra-arterial chemotherapy, and intraocular injections of chemotherapeutic agents were successfully introduced. CONCLUSIONS Nearly all patients with retinoblastoma in developed countries can now be cured of their primary cancer--a remarkable achievement for a childhood cancer that once was uniformly fatal. Much of this success is owed to deciphering the role of the Rb gene, and the benefits of targeted therapies, such as chemoreduction with consolidation as well as intra-arterial and intravitreal chemotherapies. Going forward, the main challenge will be ensuring that access to care is available for all children, particularly those in developing countries.
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Affiliation(s)
- Hans E Grossniklaus
- Departments of Ophthalmology and Pathology, Emory University School of Medicine, Atlanta, Georgia.
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47
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PRMT4-mediated arginine methylation negatively regulates retinoblastoma tumor suppressor protein and promotes E2F-1 dissociation. Mol Cell Biol 2014; 35:238-48. [PMID: 25348716 DOI: 10.1128/mcb.00945-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The retinoblastoma protein (pRb/p105) tumor suppressor plays a pivotal role in cell cycle regulation by blockage of the G1-to-S-phase transition. pRb tumor suppressor activity is governed by a variety of posttranslational modifications, most notably phosphorylation by cyclin-dependent kinase (Cdk) complexes. Here we report a novel regulation of pRb through protein arginine methyltransferase 4 (PRMT4)-mediated arginine methylation, which parallels phosphorylation. PRMT4 specifically methylates pRb at the pRb C-terminal domain (pRb C(term)) on arginine (R) residues R775, R787, and R798 in vitro and R787 in vivo. Arginine methylation is important for efficient pRb C(term) phosphorylation, as manifested by the reduced phosphorylation of a methylation-impaired mutant, pRb (R3K). A methylmimetic form of pRb, pRb (R3F), disrupts the formation of the E2F-1/DP1-pRb complex in cells as well as in an isolated system. Finally, studies using a Gal4-E2F-1 reporter system show that pRb (R3F) expression reduces the ability of pRb to repress E2F-1 transcriptional activation, while pRb (R3K) expression further represses E2F-1 transcriptional activation relative to that for cells expressing wild-type pRb. Together, our results suggest that arginine methylation negatively regulates the tumor suppressor function of pRb during cell cycle control, in part by creating a better substrate for Cdk complex phosphorylation and disrupting the interaction of pRb with E2F-1.
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48
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Carloni S, Albertini MC, Galluzzi L, Buonocore G, Proietti F, Balduini W. Increased autophagy reduces endoplasmic reticulum stress after neonatal hypoxia-ischemia: role of protein synthesis and autophagic pathways. Exp Neurol 2014; 255:103-12. [PMID: 24631374 DOI: 10.1016/j.expneurol.2014.03.002] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 03/04/2014] [Indexed: 01/25/2023]
Abstract
The endoplasmic reticulum (ER) stress can result from several pathological conditions that perturb ER homeostasis and is characterized by accumulation of unfolded proteins in the ER lumen. To cope with ER stress, cells activate the unfolded protein response (UPR), a protein quality control mechanism aimed at restoring homeostasis. The present study was undertaken to characterize the UPR after neonatal hypoxia/ischemia (HI) and its crosstalk with autophagy. After HI, there was a significant increase of GRP78 and Hsp70 expression, phosphorylation of eIF2α, Xbp-1 mRNA splicing and CHOP expression, revealing severe ER stress and UPR. Increasing autophagy with rapamycin (Rap) significantly reduced the UPR. Rap did not further increase the eIF2α phosphorylation and p70S6 kinase (p70S6K) inactivation induced by HI. After autophagy activation, however, there was a clear co-localization between monodansylcadaverine (MDC)-positive autophagosome-like structures and the ribosomal protein S6 (RPS6), indicating the presence of ribosomes in autophagosomes (ribophagy). We found that the autophagy inhibitor 3-methyladenine administered after Rap treatment completely reverted the increased phosphorylation of eIF2α and p70S6K inactivation, and blocked the formation of autophagosome-like structures restoring the UPR. These results demonstrate that the UPR is strongly activated after neonatal HI. Over-activation of autophagy significantly reduces this response, highlighting the relevance of the cross-talk between ER and the autophagy machinery in this important pathological condition. Furthermore, the presence of ribosome subunits in autophagosome-like structures suggests that increased ribosome turnover through autophagy (ribophagy) may represent an additional mechanism involved in the neuroprotective effect observed after autophagy over-activation.
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Affiliation(s)
- Silvia Carloni
- Department of Biomolecular Sciences, University of Urbino "Carlo Bo", Via S. Chiara 27, 61029 Urbino, Italy.
| | - Maria Cristina Albertini
- Department of Biomolecular Sciences, University of Urbino "Carlo Bo", Via S. Chiara 27, 61029 Urbino, Italy
| | - Luca Galluzzi
- Department of Biomolecular Sciences, University of Urbino "Carlo Bo", Via S. Chiara 27, 61029 Urbino, Italy
| | - Giuseppe Buonocore
- Department of Paediatrics, Obstetrics and Reproductive Medicine, Policlinico Le Scotte, University of Siena, Viale M. Bracci 16, 53100, Siena, Italy
| | - Fabrizio Proietti
- Department of Paediatrics, Obstetrics and Reproductive Medicine, Policlinico Le Scotte, University of Siena, Viale M. Bracci 16, 53100, Siena, Italy
| | - Walter Balduini
- Department of Biomolecular Sciences, University of Urbino "Carlo Bo", Via S. Chiara 27, 61029 Urbino, Italy.
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49
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Hasan MM, Brocca S, Sacco E, Spinelli M, Papaleo E, Lambrughi M, Alberghina L, Vanoni M. A comparative study of Whi5 and retinoblastoma proteins: from sequence and structure analysis to intracellular networks. Front Physiol 2014; 4:315. [PMID: 24478706 PMCID: PMC3897220 DOI: 10.3389/fphys.2013.00315] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 10/13/2013] [Indexed: 11/18/2022] Open
Abstract
Cell growth and proliferation require a complex series of tight-regulated and well-orchestrated events. Accordingly, proteins governing such events are evolutionary conserved, even among distant organisms. By contrast, it is more singular the case of “core functions” exerted by functional analogous proteins that are not homologous and do not share any kind of structural similarity. This is the case of proteins regulating the G1/S transition in higher eukaryotes–i.e., the retinoblastoma (Rb) tumor suppressor Rb—and budding yeast, i.e., Whi5. The interaction landscape of Rb and Whi5 is quite large, with more than one hundred proteins interacting either genetically or physically with each protein. The Whi5 interactome has been used to construct a concept map of Whi5 function and regulation. Comparison of physical and genetic interactors of Rb and Whi5 allows highlighting a significant core of conserved, common functionalities associated with the interactors indicating that structure and function of the network—rather than individual proteins—are conserved during evolution. A combined bioinformatics and biochemical approach has shown that the whole Whi5 protein is highly disordered, except for a small region containing the protein family signature. The comparison with Whi5 homologs from Saccharomycetales has prompted the hypothesis of a modular organization of structural disorder, with most evolutionary conserved regions alternating with highly variable ones. The finding of a consensus sequence points to the conservation of a specific phosphorylation rhythm along with two disordered sequence motifs, probably acting as phosphorylation-dependent seeds in Whi5 folding/unfolding. Thus, the widely disordered Whi5 appears to act as a hierarchical, “date hub” that has evolutionary assayed an original way of modular organization before being supplanted by the globular, multi-domain structured Rb, more suitable to cover the role of a “party hub”.
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Affiliation(s)
- Md Mehedi Hasan
- SYSBIO Centre for Systems Biology Milano, Italy ; Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
| | - Stefania Brocca
- SYSBIO Centre for Systems Biology Milano, Italy ; Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
| | - Elena Sacco
- SYSBIO Centre for Systems Biology Milano, Italy ; Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
| | - Michela Spinelli
- SYSBIO Centre for Systems Biology Milano, Italy ; Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
| | - Elena Papaleo
- Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
| | - Matteo Lambrughi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
| | - Lilia Alberghina
- SYSBIO Centre for Systems Biology Milano, Italy ; Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
| | - Marco Vanoni
- SYSBIO Centre for Systems Biology Milano, Italy ; Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
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50
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Burke JR, Liban TJ, Restrepo T, Lee HW, Rubin SM. Multiple mechanisms for E2F binding inhibition by phosphorylation of the retinoblastoma protein C-terminal domain. J Mol Biol 2013; 426:245-55. [PMID: 24103329 DOI: 10.1016/j.jmb.2013.09.031] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 09/20/2013] [Indexed: 12/22/2022]
Abstract
The retinoblastoma protein C-terminal domain (RbC) is necessary for the tumor suppressor protein's activities in growth suppression and E2F transcription factor inhibition. Cyclin-dependent kinase phosphorylation of RbC contributes to Rb inactivation and weakens the Rb-E2F inhibitory complex. Here we demonstrate two mechanisms for how RbC phosphorylation inhibits E2F binding. We find that phosphorylation of S788 and S795 weakens the direct association between the N-terminal portion of RbC (RbC(N)) and the marked-box domains of E2F and its heterodimerization partner DP. Phosphorylation of these sites and S807/S811 also induces an intramolecular association between RbC and the pocket domain, which overlaps with the site of E2F transactivation domain binding. A reduction in E2F binding affinity occurs with S788/S795 phosphorylation that is additive with the effects of phosphorylation at other sites, and we propose a structural mechanism that explains this additivity. We find that different Rb phosphorylation events have distinct effects on activating E2F family members, which suggests a novel mechanism for how Rb may differentially regulate E2F activities.
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Affiliation(s)
- Jason R Burke
- Department of Chemistry and Biochemistry, University of California Santa Cruz, CA 95064, USA
| | - Tyler J Liban
- Department of Chemistry and Biochemistry, University of California Santa Cruz, CA 95064, USA
| | - Tamara Restrepo
- Department of Chemistry and Biochemistry, University of California Santa Cruz, CA 95064, USA
| | - Hsiau-Wei Lee
- Department of Chemistry and Biochemistry, University of California Santa Cruz, CA 95064, USA
| | - Seth M Rubin
- Department of Chemistry and Biochemistry, University of California Santa Cruz, CA 95064, USA.
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