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BIOGRAPHY:
Dr. Göringer received his Ph.D. in 1986 in biochemistry from the Free University of Berlin, and in 1997 he earned his D.Habil. from the University of Munich. He did postdoctoral research in the United States at Brown University and the Seattle Biomedical Research Institute, University of Washington. From 1992 to 1999, he was Principal Investigator at the Gene Center of the Max Planck Institute for Biochemistry in Munich. In 1999 he was appointed a full Professor and Head of the Genetics Department of the Darmstadt University of Technology. His HHMI-funded project focuses on specific aspects of the molecular biology of trypanosomes.
RESEARCH ABSTRACT SUMMARY:
Chemically Substituted RNA Aptamers as Tools for the Development of Novel Therapeutic Measures Against Trypanosome Infections
Trypanosoma brucei is an extracellular blood parasite, which
causes African sleeping sickness in humans and Nagana in cattle.
Sleeping sickness is fatal if untreated. However, the available drugs
are highly toxic and difficult to administer. As a consequence, new
experimental strategies for developing novel therapeutics are needed.
Here we report the use of the SELEX (systematic evolution of ligands by
exponential enrichment) technology to isolate so-called RNA aptamers
that bind with high affinity to the surface of the parasite. One of the
identified aptamers has been found to bind to a specific substructure
of the parasite surface known as the flagellar pocket. The flagellar
pocket represents the main endo- and exocytosis site of the organism.
After binding, the RNAs become rapidly internalized, enter early and
late endosomal compartments, and end up within the lysosome of the
parasite. Binding of the RNA molecules is specific for the infective
life cycle stage of the parasite because the aptamers do not recognize
insect-stage trypanosomes. The RNAs fold into irregular stem/loop
secondary structures with specific sequence motifs within
single-stranded regions. They bind at a fast rate and with nanomolar
affinity. The endocytotic uptake is sequence-specific and does not
occur with randomized RNA sequences or significantly shortened aptamer
fragments. Colocalization experiments with transferrin suggest a
receptor-mediated uptake. The identified internalization and transport
pathway was used to target aptamer-coupled compounds to the lysosome.
We have now synthesized nontoxic components with membrane-disrupting
properties as potential reagents, which become active only within the
acidic environment of the lysosomal organelle. Responsive
hydrophobically associating polymers and pH-responsive pseudo-peptides
are two classes of molecules that possess the required
characteristics. Representatives of the two groups are currently
being tested for their trypanocidal activity when delivered as
aptamer-coupled compounds.
Photo: Kent Kallberg, Kallberg Studios
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