Dirk Lindemann

Molecular- and cell biology of the retroviral replication strategy – Development and application of retroviral vector- and drug screening systems

Previous and current research

My lab is interested in studying molecular- and cell biological aspects of the retroviral replication strategy and the development retroviral vector systems and their potential application for gene transfer. The current research interests of our lab are, (1) the analysis of viral and cellular protein interactions involved in retroviral particle morphogenesis, (2) the functional analysis of viral glycoproteins and their role for entry and particle release processes, and (3) the development and application of retroviral vector systems for gene transfer into different target tissues.

Particle morphogenesis of retroviruses

Our research concentrates on a special type of retrovirus, the foamy viruses (FV). Their replication strategy shows many unique features compared to all other retroviruses. Interestingly some of these bear strong homology to features of the replication strategy of Hepatitis B virus (HBV).
The FV Gag (group specific antigen) polyprotein for example is not processed like orthoretroviral Gag proteins into MA, CA, and NC subunits. In respect to their assembly strategy FV resemble B/D-type retroviruses and preassemble their capsid in the cytoplasm before membrane association can occur. However, unlike as reported for other retroviruses the membrane association of FV capsids is only observed upon coexpression of the cognate viral glycoprotein. This points to a very specific interaction between both proteins during the budding process, which cannot be complemented for by heterologous viral glycoproteins.

Structure and function of viral glycoproteins

Our research interests focus on different viral glycoproteins such as the murine leukemia virus (MLV) Env protein, the vesicular stomatitis virus (VSV) glycoprotein G or the FV Env protein.
For the FV glycoprotein we have discovered several unique features. For example it undergoes a highly unusual biosynthesis. Unlike other retroviral glycoprotein precursor proteins, the cellular signal peptidase complex upon targeting to the ER does not process it. Instead FV Env precursor cleavage occurs late during the intracellular transport and is mediated only by furin-like proteases, leading to the generation of leader peptide (LP), surface- (SU) and transmembrane (TM) subunits. In addition, all three Env subunits are incorporated into the lipid membrane of the viral particle. Furthermore, as one important domain on the viral glycoprotein interacting with the viral capsid during particle release we could identify a 15 amino acids „budding domain“ containing an evolutionary conserved di-tryptophan motive that is located at the cytoplasmic N-terminus of the LP subunit. This represents a very unique function for a viral glycoprotein signal peptide.

Development and application of retroviral vector systems

Retroviral vector systems have been the first viral vectors developed for application in gene therapeutic settings and are today still one of the viral vector systems most frequently used in clinical applications. One advantage of retroviral vectors over other viral vector systems is the stable expression of transgene due to its integration into the host cell genome.
Our lab has developed vector systems based on different retroviruses such as the murine leukemia virus (MLV), the human immunodeficiency virus (HIV), or the prototype foamy virus (PFV). These vector systems allow for an efficient gene transfer into different cell types such as the hematopoetic lineage, leading to constitutive or regulatable expression of various therapeutic gene products.

Electron micrograph of budding foamy virus particles.

Future prospects and goals

• Identification of cellular interaction partners and cellular pathways exploited by FV for particle releas
• Unraveling of the mechanism underlying the regulation of the balance between viral- and subviral particle release of FVs.  
• Characterization of structural motifs of the glycoproteins involved in intracellular localization, intracellular transport, oligomerization or fusion of viral and cellular lipid membranes
• Identification of the currently unknown, ubiquitously expressed, cellular receptor of FVs
• Unraveling of cellular processes involved in FV target cell entry
• Generation of retroviral vector systems for targeted infection or -integration
• Development of drug screening systems employing retroviral components

 

About

Selected publications

K. Stirnnagel, D. Lüftenegger, A. Stange, A. Swiersy, E. Müllers, J. Reh, N. Stanke, A. Große, S. Chiantia, H. Keller, P. Schwille, H. Hanenberg, H. Zentgraf, and D. Lindemann. (2010). Analysis of Prototype Foamy Virus particle-host cell interaction with autofluorescent retroviral particles. Retrovirology. 7 (1): 45.

D. Lindemann and H. Schnittler. (2009). Genetic Manipulation of Endothelial Cells by Viral Vectors. Thrombosis and Haemostasis, 102 (6): 1135-1143.

A. Stange, D. Lüftenegger, J. Reh, and D. Lindemann. (2008). Subviral Particle Release Determinants of Prototype Foamy Virus. Journal of Virology, 82 (20): 9858-9869.

M.W. Yap, D. Lindemann, N. Stanke, J. Reh, D. Westphal, H. Hanenberg, S. Ohkura, and J.P. Stoye. (2008). Restriction of Foamy Viruses by Primate Trim5a. Journal of Virology, 82 (11): 5429-5439.

 I. Mannigel, A. Stange, H. Zentgraf and D. Lindemann. (2007). Correct Capsid Assembly Mediated by a Conserved YXXLGL Motif in Prototype Foamy Virus Gag is Essential for Infectivity and Reverse Transcription of the Viral Genome. Journal of Virology, 81 (7): 3317-3326. .

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