(see also the group's page at BTK site)

One of the strongest pieces of evidence for oncogene cooperation has been obtained from transgenic mice overexpressing the c-myc and pim-1 oncogenes. These mice produce lymphomas at a very early stage and often die already in utero. The major aim of our recently initiated studies is to establish a mechanistic model for the cooperation between the c-myc-encoded transcription factor and the pim-1-encoded serine/threonine-specific protein kinase. For this purpose, we have used the yeast two-hybrid system to identify proteins that can physically interact with Pim-1 and which may thereby either regulate or mediate its functions. By this approach, we hope to be able to determine whether Pim-1 is involved in any known signal transduction pathway or in a novel pathway that can more specifically complement c-myc overexpression to induce lymphoid malignancies. Overall, our studies are expected to increase general understanding about signalling mechanisms controlling cell growth, differentiation as well as death both in normal and in transformed hematopoietic cells.

• yeast and mammalian two-hybrid assays and biochemical analyses to identify and confirm protein-protein interactions between Pim-1 and other proteins
• functional assays to investigate the physiological relevance of the observed protein-protein interactions
• transactivation assays to analyze the ability of Pim-1 to activate lymphoid cell transcription factors via phosphorylation
• in vitro and in vivo phosphorylation assays, phosphopeptide mapping and mutagenesis to identify phosphorylation target sites for Pim-1 in its substrates
• immunofluorescence, FACS and FRET assays to visualize protein-protein interactions involving Pim-1 also within living cells
• assays to determine the ability of Pim kinases to protect cells from different types of apoptosis
• production of tetracyclin-regulatable pim-expressing retroviruses

• Rainio, E.M., Sandholm, J. and Koskinen, P.J. Cutting edge: Transcriptional activity of NFATc1 is enhanced by the Pim-1 kinase. J. Immunol., 168, 1524-1527, 2002.
  
  PubMed - abstract

 

• Jalkanen, K.J., Leu, T., Bono, P., Salmi, M., Jalkanen, S. and Smith, D.J. The ligand binding properties of Mac-2-binding protein and mouse cyclophilin C-associated protein. Eur. J. Immunol., 31, 3075-3084, 2001.
  
  PubMed - abstract

 

• Eichmann, A., Yuan, L., Bréant, C., Alitalo, K. & Koskinen, P.J. Developmental expression of Pim kinases suggests functions also outside of the hematopoietic system. Oncogene 19, 1215-1224, 2000.
  
  PubMed - abstract
• Matikainen, S., Sareneva, T., Ronni, T., Lehtonen, A., Koskinen, P.J. & Julkunen, I. IFN-a activates multiple STAT proteins and upregulates proliferation associated IL-2Ra, c-myc and pim-1 genes in human T cells. Blood, 93, 1980-1991, 1999.
  
  PubMed - abstract

 

• Lilly, M., Sandholm, J., Cooper, J.J., Koskinen, P.J. & Kraft, A. The Pim-1 serine kinase prolongs survival and inhibits apoptosis-related mitochondrial dysfunction in part through a bcl-2-dependent pathway. Oncogene, 18, 4022-4031, 1999.
  
  PubMed - abstract

 

• Leverson, J.D., Koskinen, P.J., Orrico, F.C., Rainio, E.M., Jalkanen, K.J., Dash, A.B., Eisenman, R.N. & Ness, S.A. Pim-1 kinase and p100 cooperate to enhance Myb activity. Molecular Cell, 2, 417-425, 1998.
  
  PubMed - abstract

 

• McArthur, G.A., Laherty, C., Quéva, C., Hurlin, P.J., Loo, L., James, L., Grandori, C., Gallant, P., Shiio, Y., Bush, A., Cheng, P.F., Lawrence, Q., Pulverer, B., Koskinen, P.J., Foley, K.P., Ayer, D.E. & Eisenman, R.N. The Mad protein family links transcriptional repression to cell differentiation. Cold Spring Harbor Symp. Quant. Biol., 63, 423-433, 1998.
  
  PubMed - abstract