The role of cellular chromatin modulators and DNA repair factors during the establishment and maintenance of gammaherpesvirus latency
Nuclear Structures formed by KSHV LANA (‘LANA speckles’)
Kaposi Sarcoma is a tumor derived from the inner layer of blood or lymphatic vessels. It often emerges on the skin and in internal organs of AIDS patients. In the film Philadelphia HIV-infected Andrew is startled when he detects a dark spot in his face. However, Kaposi Sarcoma can also occur in people who are not infected with HIV, especially in Mediterranean countries and in East/Central Africa. The cause of this tumor is Kaposi Sarcoma-associated herpesvirus (KSHV), which is also called human herpesvirus 8 (HHV 8). Kaposi Sarcoma may manifest itself not only as dark spots or lumps on the skin, but can also cause life-threatening bleeding if it affects internal organs. In sub-Saharan Africa, Kaposi Sarcoma is the commonest tumor in men. After infecting exposed individuals, KSHV persists for the lifetime of the infected person. However, in most individuals with an intact immune system, KSHV is innocuous, because a functioning immune system is able to control this virus.
The group led by T. F. Schulz wants to understand how KSHV manages to establish such a long-lasting infection. Scientists in this group focus on how this virus manages to maintain its genetic information in the infected cell in a manner that allows it to escape the detection by the immune system and yet to be transferred from mother to daughter cell during cell division. In doing so, they concentrate on a particular viral protein, the latency-associated nuclear antigen LANA, which mediates many of these functions and can also reprogram the infected cell for the benefit of the virus. An important aspect of their work is to understand the structure of LANA and the nature of tiny ‘territories’ in the nucleus of the infected cell in which the virus resides in a latent form. Their long term aim is to find ‘weak spots’ in this interaction between the virus and the infected cell that could perhaps one day be targeted by new treatments
The cancer-causing (oncogenic) lymphotropic gamma herpesviruses Epstein-Barr virus (EBV) and Kaposi Sarcoma herpesvirus (KSHV) persist in a latent form – i.e. without producing new viral particles – in dividing cells, most importantly B-lymphocytes. They therefore need mechanisms that guarantee the replication of the circular viral genome during the S-phase of the latently infected cell and the distribution of replicated genomes to daughter cells during mitosis. In addition, latency involves a restricted viral gene expression pattern.
The aim of project C1 is to understand the persistence of latent KSHV genomes at the molecular level as a basis of perhaps identifying new targets for therapeutic intervention. The KSHV latency-associated nuclear antigen LANA plays an essential role during latent viral persistence: it is required for the replication of the latent KSHV episome during the S-phase of the cell cycle, tethers viral episomes to mitotic chromatin, and thereby ensures that replicated viral genomes are passed onto daughter cells as if they were additional chromosomes. Work in project C1 has solved the molecular structure of a LANA domain that interacts with viral latent DNA and has thereby allowed investigators to build a model of how LANA assembles complexes of viral DNA and associated chromatin (Hellert et al., PLoS Pathogens 2013; Proc. Natl. Acad. Sci. USA 2015).
Currently ongoing work aims to resolve the role of cellular Brd2 and Brd4 proteins during the interaction of complexes of LANA and viral DNA with ‘active’ regions in the cellular chromatin and the ability of LANA to influence cellular gene expression. We also made the surprising discovery that cytoplasmic variants of LANA play an important role in antagonizing the innate immune response in order to ensure that viral DNA is not detected by the cellular sensor of cytoplasmic DNA, cGAS. This prevents cGAS from activating the interferon pathway and thereby inhibiting productive viral replication (Zhang et al., PNAS 2016). Furthermore, cytoplasmic LANA also antagonizes Mre11 and RAD50, two components of the double strand DNA repair complex, which have recently been shown to activate another innate response pathway, NFkB, and this also helps the reactivation of KSHV from latency (Mariggiò et al., PLoS Pathogens 2017). Taken together, our results show how LANA functions during the assembly, replication and shielding from the innate immune system of latent viral DNA.
Thomas Schulz is talking about his research at CRC 900
Thomas Schulz is the founder and speaker of the CRC 900. His project C1 focuses on the persistence of Kaposi’s sarcoma herpesvirus. He and his research group want to understand how the viruses can remain in the body for long periods during the latent phase and how they are then reactivated.
Publications of the project C1
Kaposi’s Sarcoma Herpesvirus Latency-Associated Nuclear Antigen (LANA): Replicating and Shielding Viral DNA during Viral Persistence. Weidner-Glunde M, Mariggiò G, Schulz TF. J Virol. 2017 Jun 26;91(14).
Kaposi Sarcoma Herpesvirus (KSHV) Latency-Associated Nuclear Antigen (LANA) recruits components of the MRN (Mre11-Rad50-NBS1) repair complex to modulate an innate immune signaling pathway and viral latency. Mariggiò G, Koch S, Zhang G, Weidner-Glunde M, Rückert J, Kati S, Santag S, Schulz TF. PLoS Pathog. 2017 Apr 21;13(4):e1006335.
Proliferation status defines functional properties of endothelial cells. Lipps C, Badar M, Butueva M, Dubich T, Singh VV, Rau S, Weber A, Kracht M, Köster M, May T, Schulz TF, Hauser H, Wirth D. Cell Mol Life Sci. 2016 Nov 16.
Genome-wide analysis of chromosomal import patterns after natural transformation of Helicobacter pylori. Bubendorfer S, Krebes J, Yang I, Hage E, Schulz TF, Bahlawane C, Didelot X, Suerbaum S. Nat Commun. 2016 Jun 22;7:11995.
Cytoplasmic isoforms of Kaposi sarcoma herpesvirus LANA recruit and antagonize the innate immune DNA sensor cGAS. Zhang G, Chan B, Samarina N, Abere B, Weidner-Glunde M, Buch A, Pich A, Brinkmann MM, Schulz TF. Proc Natl Acad Sci U S A. 2016 Jan 25. pii: 201516812.
Genome-wide Profiling Reveals Remarkable Parallels Between Insertion Site Selection Properties of the MLV Retrovirus and the piggyBac Transposon in Primary Human CD4+ T Cells. Gogol-Döring A, Ammar I, Gupta S, Bunse M, Miskey C, Chen W, Uckert W, Schulz TF, Izsvák Z, Ivics Z. Mol Ther. 2016 Jan 12.
Generation of high-titre virus stocks using BrK.219, a B-cell line infected stably with recombinant Kaposi’s sarcoma-associated herpesvirus. Kati S, Hage E, Mynarek M, Ganzenmueller T, Indenbirken D, Grundhoff A, Schulz TF. J Virol Methods. 2015 Jun 1;217:79-86.
The 3D structure of Kaposi sarcoma herpesvirus LANA C-terminal domain bound to DNA. Hellert J, Weidner-Glunde M, Krausze J, Lünsdorf H, Ritter C, Schulz TF, Lührs T. Proc Natl Acad Sci U S A. 2015 May 26;112(21):6694-9.
The role of Kaposi sarcoma-associated herpesvirus in the pathogenesis of Kaposi sarcoma. Gramolelli S, Schulz TF. J Pathol. 2015 Jan;235(2):368-80. Review.
Bromo- and extraterminal domain chromatin regulators serve as cofactors for murine leukemia virus integration. Gupta SS, Maetzig T, Maertens GN, Sharif A, Rothe M, Weidner-Glunde M, Galla M, Schambach A, Cherepanov P, Schulz TF. J Virol. 2013 Dec;87(23):12721-36.
A structural basis for BRD2/4-mediated host chromatin interaction and oligomer assembly of Kaposi sarcoma-associated herpesvirus and murine gammaherpesvirus LANA proteins. Hellert J, Weidner-Glunde M, Krausze J, Richter U, Adler H, Fedorov R, Pietrek M, Rückert J, Ritter C, Schulz TF, Lührs T. PLoS Pathog. 2013;9(10):e1003640.
Activation of the B cell antigen receptor triggers reactivation of latent Kaposi’s sarcoma-associated herpesvirus in B cells. Kati S, Tsao EH, Günther T, Weidner-Glunde M, Rothämel T, Grundhoff A, Kellam P, Schulz TF. J Virol. 2013 Jul;87(14):8004-16.
The ubiquitin-specific protease USP7 modulates the replication of Kaposi’s sarcoma-associated herpesvirus latent episomal DNA. Jäger W, Santag S, Weidner-Glunde M, Gellermann E, Kati S, Pietrek M, Viejo-Borbolla A, Schulz TF. J Virol. 2012 Jun;86(12):6745-57.
Recruitment of the tumour suppressor protein p73 by Kaposi Sarcoma Herpesvirus latent nuclear antigen contributes to the survival of primary effusion lymphoma cells. Santag S, Jäger W, Karsten CB, Kati S, Pietrek M, Steinemann D, Sarek G, Ojala PM, Schulz TF. Oncogene, 2012, 1-10.
A role for the internal repeat of the Kaposi’s sarcoma-associated herpesvirus latent nuclear antigen in the persistence of an episomal viral genome. Alkharsah KR, Schulz TF. J Virol. 2012 Feb;86(3):1883-7.
Prof. Thomas F. Schulz
Institute of Virology
Hannover Medical School
+49 511 532-6737