Roger A. Greenberg, MD, PhD
The Perelman School of Medicine at the University of Pennsylvania
421 Curie Boulevard
513 BRB II/III
Philadelphia, PA 19104-6160
Haverford College, 1991.
Ph.D. (Microbiology and Immunology)
Albert Einstein College of Medicine, 2000.
Albert Einstein College of Medicine, 2000.
Description of Research ExpertiseResearch Interests
This laboratory is devoted to understanding basic mechanisms of DNA repair and their impact on genome integrity, cancer etiology and response to targeted therapies. To investigate these interrelationships, we are devoted to elucidating BRCA1- and BRCA2- dependent homologous recombination mechanisms in breast and ovarian cancer, telomere length maintenance mechanisms that rely on a specialized form of homologous recombination, and DNA damage induced activation of immune responses to cancer. We utilize a myriad of approaches to investigate these areas, which include biochemistry, structural biology, cell biology, and genetically engineered mouse models.
Key words: BRCA1, BRCA2, DNA repair, Homologous Recombination, Telomeres, Epigenetics, Breast Cancer, Ovarian Cancer, cytokines, immune therapy.
Description of Research
Germline mutations to the Breast Cancer 1 (BRCA1) or Breast Cancer 2 (BRCA2) genes are the major cause of hereditary breast and ovarian cancer susceptibility. Clinical BRCA1 and BRCA2 mutations render cells deficient in error-free mechanisms of DNA repair known as homologous recombination, implicating these activities in tumor suppression and response to genotoxic therapies.
Our work has revealed a molecular understanding for how BRCA1 recognizes DNA damage and competes with opposing DNA repair proteins to control genome integrity. We have demonstrated that an interaction between the BRCA1 BRCT domain and the RAP80 ubiquitin binding protein targets BRCA1 to K63-linked ubiquitin structures present at DNA damage sites. RAP80 ubiquitin interaction motifs (UIMs) provide a ubiquitin recognition element to target BRCA1 and a K63-ubiquitin specific deubiquitinating enzyme BRCC36 to DNA double strand breaks. Each of these activities is required for appropriate DNA damage checkpoint and repair responses (Sobhian et al. Science 2007; Shao et al. Genes&Dev 2009; Tang et al. Nat Struct & Mol Biol 2013; Jiang et al. Genes Dev 2015; Zeqiraj et al. Mol Cell 2015). Cancer causing BRCA1 BRCT mutants fail to interact with RAP80 and consequently demonstrate inefficient recruitment to DNA damage sites. Moreover, germline mutations in RAP80 and Abraxas are present in familial breast cancer (Nikkila et al. Oncogene 2009; Solyom et al Sci Transl Med 2012) and biallelic BRCA1 mutations cause a new subtype of Fanconi Anemia known as Fanc-S (Domchek et al. Cancer Discov 2013; Sawyer et al Cancer Discov 2015). Thus, a series of ordered events involving ubiquitin recognition, breakdown and synthesis are required for BRCA1-dependent DNA damage responses and tumor suppression.
A second area of interest is the complex relationship between chromatin structure and DNA repair. We have developed several novel systems to investigate interrelationships between chromatin structure and DNA double strand break (DSB) repair. This was instrumental to our discoveries that DSBs silence transcription for multiple kilobases of chromatin in cis to the site of DNA damage (Shanbhag et al. Cell 2010), and that chromatin environment affects DNA repair mechanism choice and sensitivity to PARP inhibitors (Tang et al. Nat Struct Mol Biol 2013). More recently, we have developed methodologies to directly monitor homologous recombination at telomeres, a first for any genomic location in mammalian cells. This enabled our discovery of a novel form of homology directed repair that is responsible for alternative telomere length maintenance mechanisms in approximately 15% of human cancers (Cho et al. Cell 2014; Dilley et al. Nature 2016; Verma et al. Genes Dev 2019).
In addition to these studies involving acute DNA damage responses, we have recently determine the basis for the longstanding observation that DNA damage activates innate and adaptive immune responses (Harding et al. Nature 2017; Walden, Tian et al. Nature 2019). Our findings reveal that mitotic progression in the presence of DNA damage results in micronuclei within the cytoplasm that are recognized by the pattern recognition receptor cGAS. This produces inflammatory cytokine signals that activate anti-tumor immune responses to eradicate cells within the primary tumor and distal metastases. We will continue to use these systems to determine how DNA damage response mechanisms contributes to genome integrity, cancer etiology and response to therapy.
Rotation projects are open to students in each of the areas the lab focuses on. Please see Roger Greenberg to discuss potential rotation projects.
Weihua Li - Research Specialist, Lab Manager
Moniher Deb - Research Specialist, Penn Center for Genome Integrity
Lei Tian - Research Associate
Peter Deraska - Graduate Student
Jie Chen - Postdoctoral Researcher
Eva Hum - Postdoctoral Researcher
Vidhya Krishnamoorthy - Postdoctoral Researcher
Yaroslav Morozov - Postdoctoral Researcher
Jenny Stundon - Postdoctoral Fellow
Priyanka Verma - Postdoctoral Researcher
Xuejiao Yang - Postdoctoral Researcher
Tianpeng Zhang - Postdoctoral Researcher
Yiwen Li – Undergraduate Student
Selected PublicationsWalden M*, Tian L*, Ross R, Sykora UM, Byrne DP, Hesketh EL, Masandi SK, Cassel J, Geirge R, Ault JR, Oualid FE, Pawlowski K, Salvino JM, Eyers PA, Ranson NA, Del Galdo F, Greenberg RA#, Zeqiraj E#: Metabolic control of BRISC-SHMT2 assembly regulates immune signaling. Nature 10.1038/s41586-019-1232-1, May 2019 Notes: * Co-first authors # co-corresponding authors.
Verma P, Dilley RL, Zhang T, Gyparakai MT, Li Y, and Greenberg RA: RAD52 and SLX4 act non-epistatically to ensure telomere stability during alternative telomere lengthening. Genes & Development 33: 221-235, Feb 2019.
Greenberg RA: Assembling a protective shield. Nature Cell Biology 8: 862-863, July 2018.
Li ML, Jiang Q, Bhanu NV, Wu J, Li W, Garcia BA, Greenberg RA.: Phosphorylation of TIP60 suppresses 53BP1 localization at DNA damage sites. Molecular and Cellular Biology [Epub ahead of print], October 2018.
Harding SM, Benci JL, Irianto J, Discher DE, Minn AJ, Greenberg RA: Mitotic progression following DNA damage enables pattern recognition within micronuclei. Nature 548: 466-470, August 2017.
Dilley RL, Verma P, Cho NW, Winters HD, Wondisford AR, and Greenberg RA: Break-Induced Telomere Synthesis Underlies Homology-Directed Telomere Maintenance. Nature 539(7627): 54-58, 2016 Notes: Comment in Nature: Telomere-lengthening mechanism revealed. Roake CM, Artandi SE. Nature. 2016 Oct 19. doi: 10.1038/nature19483.
Cho NW, Dilley RL, Lampson MA, Greenberg RA: Interchromosomal Homology Searches Drive Directional ALT Telomere Movement and Synapsis. Cell 159(1): 108-21, 2014.
Sawyer SL, Tian L, Kahkonen M, Schwartzentruber J, Kircher M, Majewski J, Dyment DA, Innes AM, Boycott KM, Moreau LA, Moilanen JS, Greenberg RA: Biallelic Mutations in BRCA1 Cause a New Fanconi Anemia Subtype. Cancer Discovery 5(2): 135-42, 2015.
Verma P, Greenberg RA: Noncanonical Views of Homology Directed DNA Repair. Genes & Development 30(10): 1138-54, 2016.
Sobhian B, Shao G, Lilli DR, Culhane AC, Moreau LA, Xia B, Livingston DM*, Greenberg RA*: RAP80 targets BRCA1 to specific ubiquitin structures at DNA damage sites. Science 316(5828): 1198-202, 2007 Notes: *co-corresponding authors.
Shao G, Patterson-Fortin J, Messick TE, Feng D, Shanbhag N, Wang Y, Greenberg RA: MERIT40 controls BRCA1-Rap80 complex integrity and recruitment to DNA double-strand breaks. Genes & Development 23(6): 740-54, 2009.
Shanbhag NM, Rafalska-Metcalf IU, Balane-Bolivar C, Janicki SM, and Greenberg RA: ATM dependent chromatin changes silence transcription in cis to DNA Double Strand Breaks. Cell 141: 970-81, 2010.
Greenberg RA: BRCA1, everything but the RING? Science 334(6055): 459-60, 2012
Tang J, Cho NW, Cui G, Manion EM, Shanbhag NM, Botuyan MV, Mer G, Greenberg RA: Acetylation limits 53BP1 association with damaged chromatin to promote homologous recombination. Nature Structural & Molecular Biology 20(3): 317-25, 2013.
Zheng H#, Gupta V#, Patterson-Fortin J#, Bhattacharya S#, Katlinski K, Wu J, Varghese B, Carbone CJ, Aressy B, Fuchs SY*, Greenberg RA*.: A BRISC-SHMT Complex Deubiquitinates IFNAR1 and Regulates Interferon Responses. Cell Reports 5(1): 180-93, 2013 Notes: # co-first author * co-corresponding author.
Cho NW, Greenberg RA: Familiar ends with alternative endings. Nature 518(7538), 2015.
Zeqiraj E, Tian L, Piggott CA, Pillon MC, Duffy NM, Ceccarelli DF, Keszei AF, Lorenzen K, Kurinov I, Orlicky S, Gish G, Heck AJR, Guarné A, Greenberg RA* and Sicheri F*: Higher order assembly of BRCC36–KIAA0157 is required for DUB activity and biological function. Molecular Cell 59(6): 970-83, 2015 Notes: *co-corresponding authorship.
Jiang Q, Paramasivam M, Aressy B, Wu J, Bellani M, Tong W, Seidman MM, Greenberg RA: MERIT40 cooperates with BRCA2 to resolve DNA inter-strand crosslinks. Genes & Development 29(18): 1955-68, 2015.