Jørgen Kjems

Research Focus

We are studying alternative splicing in mammalian systems. A primary goal is to uncover the mechanisms involved in regulation of HIV-1 mRNA splicing. In particular, how cellular splicing factors interact with the RNA and direct the spliceosome to the right splice sites. Another aspect is to clarify the role of the HIV-1 proteins Rev and Tat in HIV splicing. We have observed that the recognition event of the viral 5’splice sites by the U1 snRNP plays an important role in transcriptional regulation and we are in the process of characterising the functional mechanism behind this observation.

We are also studying the mechanism for exon skipping in mutated versions of the medium chain acyl-CoA dehydrogenase (MCAD) gene, which leads to deficiency of the MCAD enzyme. We can restore the skipping phenotype by expressing small trans-activating RNAs” (STARs), that contains artificial splicing enhancers. We are currently optimising the design of STARs and hope to progress to mouse models soon, where we recently have established an efficient particulate delivery systems for small RNAs.

Publications

1. Jakobsen, M., Damgaard, C.K. , Andersen, E.S. , Podhajska, A., and Kjems, J. (2004). A genomic SELEX strategy to identify accessible and dimerization sensitive target sites in HIV-1 RNA. Nucleic Acids Research 32:e67.
2. Lund, M. and Kjems, J. (2002). Defining a 5’ splice site by functional selection in the presence and absence of U1 snRNA 5’-end. RNA 8, 166-179.
3. Damgaard, C.K., Tange, T.Ø. and Kjems, J. (2002). hnRNP A1 controls HIV-1 mRNA splicing through cooperative binding to intron and exon splicing silencers in the context of a conserved secondary structure. RNA 8, 1401.
4. Tange, T.Ø. and Kjems, J. (2001). SF2/ASF binds to a splicing enhancer in the third HIV-1 tat exon and stimulates U2AF binding independently of the RS domain. Journal of Molecular Biology 312, 649-662.
5. Tange, T.Ø., Damgaard, C.K., Guth, S., Valcarcel, J., and Kjems, J. (2001). The hnRNP A1 protein regulates HIV-1 tat/rev intron splicing via a novel intronic silencer element. EMBO Journal 20, 5748-5758.

Key lab techniques: in vitro and in vivo RNA processing assays, chemical and enzymatic modification of RNA, single molecule fluorescence microscopy, live cell imaging, RNAi, oligonucleotide delivery in vitro and in vivo (mouse models), flip-in system, small angle X-ray scattering, atomic force microscopy, protein expression.

Key lab reagents: HIV clones for in vitro and in vivo expression, siRNA against key RNA degradation factors.

Lab contact: Suzette Sørensen: ses@mb.au.dk

Lab website: www.rna.dk/jk/index.htm