Uwe Schumacher

Publications of Uwe Schumacher

• Mutations in the M112/M113-coding region facilitate murine cytomegalovirus replication in human cells.

  Authors: Uwe Schumacher, Wiebke Handke, Igor Jurak, Wolfram Brune

  Journal of virology. 08/2010; 84(16):7994-8006.

  Cytomegaloviruses, representatives of the Betaherpesvirinae, cause opportunistic infections in immunocompromised hosts. They infect various cells and tissues in their natural host but are highlyCytomegaloviruses, representatives of the Betaherpesvirinae, cause opportunistic infections in immunocompromised hosts. They infect various cells and tissues in their natural host but are highly species specific. For instance, human cytomegalovirus (HCMV) does not replicate in mouse cells, and human cells are not permissive for murine cytomegalovirus (MCMV) infection. However, the underlying molecular mechanisms are so far poorly understood. In the present study we isolated and characterized a spontaneously occurring MCMV mutant that has gained the capacity to replicate rapidly and to high titers in human cells. Compared to the parental wild-type (wt) virus, this mutant formed larger nuclear replication compartments and replicated viral DNA more efficiently. It also disrupted promyelocytic leukemia (PML) protein nuclear domains with greater efficiency but caused less apoptosis than did wt MCMV. Sequence analysis of the mutant virus genome revealed mutations in the M112/M113-coding region. This region is homologous to the HCMV UL112-113 region and encodes the viral early 1 (E1) proteins, which are known to play an important role in viral DNA replication. By introducing the M112/M113 mutations into wt MCMV, we demonstrated that they are sufficient to facilitate MCMV replication in human cells and are, at least in part, responsible for the efficient replication capability of the spontaneously adapted virus. However, additional mutations probably contribute as well. These results reveal a previously unrecognized role of the viral E1 proteins in regulating viral replication in different cells and provide new insights into the mechanisms of the species specificity of cytomegaloviruses.

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• Deletion of the rat cytomegalovirus immediate early 1 gene results in a virus capable of establishing latency but with lower levels of acute virus replication and latency that compromise reactivation efficiency.

  Authors: Gordon R. Sandford, Uwe Schumacher, Jakob Ettinger, Wolfram Brune, Gary S Hayward, William H Burns, Sebastian Voigt

  The Journal of general virology. 11/2009;

  The IE1 and IE2 proteins encoded by the major immediate-early (MIE) transcription unit of cytomegaloviruses are thought to play key roles in the switch between latent and lytic cycle infection.The IE1 and IE2 proteins encoded by the major immediate-early (MIE) transcription unit of cytomegaloviruses are thought to play key roles in the switch between latent and lytic cycle infection. Whilst IE2 is essential for triggering the lytic cycle, the exact roles of IE1 have not been resolved. An MIE-exon 4 deleted rat cytomegalovirus (DeltaIE1) failed to synthesize the IE1 protein and did not disperse promyelocytic leukemia bodies (PML) early post-infection, but it was still capable of normal replication in fibroblast cell culture. However, DeltaIE1 had diminished ability to infect salivary glands persistently in vivo and to reactivate from spleen explant cultures ex vivo. Quantitation of viral genomes in spleens of infected animals revealed a reduced amount of DeltaIE1 virus produced during acute infection, suggesting a role for IE1 as a regulator in establishing a chronic or persistent infection, rather than in more directly influencing the latency or reactivation processes.

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• Murine cytomegalovirus m38.5 protein inhibits Bax-mediated cell death.

  Authors: Igor Jurak, Uwe Schumacher, Hrvoje Simic, Sebastian Voigt, Wolfram Brune

  Journal of virology. 06/2008; 82(10):4812-22.

  Many viruses encode proteins that inhibit the induction of programmed cell death at the mitochondrial checkpoint. Murine cytomegalovirus (MCMV) encodes the m38.5 protein, which localizes toMany viruses encode proteins that inhibit the induction of programmed cell death at the mitochondrial checkpoint. Murine cytomegalovirus (MCMV) encodes the m38.5 protein, which localizes to mitochondria and protects human HeLa cells and fibroblasts from apoptosis triggered by proteasome inhibitors but not from Fas-induced apoptosis. However, the ability of this protein to suppress the apoptosis of murine cells and its role during MCMV infection have not been investigated previously. Here we show that m38.5 is expressed at early time points during MCMV infection. Cells infected with MCMVs lacking m38.5 showed increased sensitivity to cell death induced by staurosporine, MG132, or the viral infection itself compared to the sensitivity of cells infected with wild-type MCMV. This defect was eliminated when an m38.5 or Bcl-X(L) gene was inserted into the genome of a deletion mutant. Using fibroblasts deficient in the proapoptotic Bcl-2 family proteins Bak and/or Bax, we further demonstrated that m38.5 protected from Bax- but not Bak-mediated apoptosis and interacted with Bax in infected cells. These results consolidate the role of m38.5 as a viral mitochondrion-localized inhibitor of apoptosis and its functional similarity to the human cytomegalovirus UL37x1 gene product. Although the m38.5 gene is not homologous to the UL37x1 gene at the sequence level, m38.5 is conserved among rodent cytomegaloviruses. Moreover, the fact that MCMV-infected cells are protected from both Bak- and Bax-mediated cell death suggests that MCMV possesses an additional, as-yet-unidentified mechanism to block Bak-mediated apoptosis.

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