Research Projects Brix – Intestine

We demonstrated that a non-regulated release of proteolytic enzymes as a result of tissue damage due to surgical trauma has dramatic consequences for the affected tissue. Our studies on intestine trauma focus on the possible contribution of cathepsins to onset of inflammatory responses, ultimately leading to dysfunction of intestinal smooth muscles and post-operative ileus, which is a severe and potentially life-threatening complication common in the clinics. To assess the role of cathepsins during trauma at the molecular level, we established an in vitro model that allows simulating surgical trauma through mechanical compression of cultured intestinal epithelial cells. Furthermore, we established a model with intestine-specific expression of GFP-tagged cathepsin B under the control of the A33-antigen promotor that allows us to investigate cysteine peptidase trafficking in intestine epithelial cells. Using standardized models of intestine trauma in mice and rats, we observed a local cathepsin B release concomitant with extracellular matrix damage during initial post-operative phases. Interestingly, cathepsin B-deficient animals showed an increased deposition of extracellular matrix components in the intestine. We concluded that the observed massive degradation of extracellular matrix in traumatized intestine might be a result of direct proteolytic action of released cysteine peptidases such as cathepsin B, or be driven by a more indirect activation of proteolytic cascades. As a possible consequence of the alterations of proteolytic activities due to trauma, impairment of the mucosal barrier function can occur which in turn severely affects homeostasis of the intestine.

In addition, activity and distribution patterns of the cysteine cathepsins, extracellular matrix components, lateral and tight junction constituents, and brush border enzymes were investigated along the length of the gastro-intestinal tract of wild type and cathepsin-deficient mice. The results highlight for the first time major differences of protease distribution among various parts of the mouse intestine, and demonstrate the significance of a delicate balance of proteolytic activities in intact gastro-intestinal tissue. Furthermore, the outcomes of cysteine cathepsin-deficiencies depend on specific regions of the small and large intestine, pointing to the importance of further studies aiming at more detailed and improved assessments of drug safety when cathepsin inhibitors are thought to be orally administered.

Recently, immunofluorescence and immunoblotting investigations revealed the presence of cathepsin L and legumain/AEP in the nuclear compartment in addition to the expected endo-lysosomal localization in colorectal carcinoma cells. It was also found that the activity of cathepsin L, in particular, is high in the nucleus of colorectal carcinoma cells because of lacking stefin B inhibitory control. We propose nuclear cathepsin L accelerates cell cycle progression of HCT116 cells thereby supporting the notion that cysteine cathepsins may play significant roles in carcinogenesis due to deregulated trafficking.


Collaboration with KFO 115, Prof. J. Kalff & Prof. A. Hirner, Bonn, Germany; supported by DFG BR1308 / 7-1, 7-2, 7-3.
Supported by DFG BR1308 / 10-1.
Collaboration with Dr. Gunhild Maelandsmo & Dr. Mads Haugen, Oslo Radiumshospitalet, Norway.



  • Tamhane, T., R. Illukkumbura, S. Lu, G.M. Maelandsmo, M.H. Haugen, and K. Brix (2016). Nuclear cathepsin L activity is required for cell cycle progression of colorectal carcinoma cells. Biochimie 122, 208-218. doi: 10.1016/j.biochi.2015.09.003
  • Tamhane, T., B.K. Wolters, R. Illukkumbura, G.M. Maelandsmo, M.H. Haugen, and K. Brix (2015). Construction of a plasmid coding for green fluorescent protein tagged cathepsin L and data on expression in colorectal carcinoma cells. Data in Brief 5, 468-475. doi: 10.1016/j.dib.2015.09.022
  • Brix, K., J. McInnes, A. Al-Hashimi, M. Rehders, T. Tamhane, M.H. Haugen (2015). Proteolysis mediated by cysteine cathepsins and legumain – recent advances and cell biological challenges. Protoplasma 252, 755-774. doi: 10.1007/s00709-014-0730-0.
  • Haugen, M.H., K. Boye, J.M. Nesland, S.J. Pettersen, E.V. Egeland, T. Tamhane, K. Brix, G.M. Maelandsmo, and K. Flatmark (2015). High expression of the cysteine proteinase legumain in colorectal cancer – Implications for therapeutic targeting. Eur. J. Cancer 51, 9-17. doi: 10.1016/j.ejca.2014.10.020.
  • Tamhane, T. / M. Arampatzidou, V. Gerganova, M. Tacke, R. Illukkumbura, S. Dauth, N. Schaschke, C. Peters, T. Reinheckel, and K. Brix (2014). The activity and localization patterns of cathepsins B and X in cells of the mouse gastrointestinal tract differ along its length. Biol. Chem. 395, 1201-1219. doi:10.1515/hsz-2014-0151.
  • Haugen, M.H., H.T. Johansen, S.J. Pettersen, R. Solberg, K. Brix, K. Flatmark, and G.M. Maelandsmo (2013). Nuclear legumain activity in colorectal cancer. PLoS One 8(1), e52980. doi: 10.1371/journal.pone.0052980
  • Arampatzidou, M., A. Schütte, G.C. Hansson, P. Saftig, and K. Brix (2012). Effects of cathepsin K deficiency on intercellular junction proteins, luminal mucus layers, and extracellular matrix constituents in the mouse colon. Biol. Chem. 393, 1391-1403. doi:10.1515/hsz-2012-0204
  • Arampatzidou, M., K. Mayer, M.E. Iolyeva, S. Gebre Asrat, M. Ravichandran, T. Günther, R. Schüle, T. Reinheckel, and K. Brix (2011). Studies of intestinal morphology and cathepsin B expressing in a transgenic mouse aiming at intestine-specific expression of Cath B-EGFP. Biol. Chem. 392, 983-993. doi:10.1515/BC.2011.096.
  • Dauth, S., M. Arampatzidou, M. Rehders, D.M.T. Yu, D. Führer, and K. Brix (2011). Thyroid cathepsin K – roles in physiology and thyroid disease. Clin. Rev. Bone Miner. Metab. 9, 94-106. doi:10.1007/s12018-011-9093-7
  • Arampatzidou, M., M. Rehders, S. Dauth, D.M.T. Yu, S. Tedelind, and K. Brix (2011). Imaging of protease functions – current guide to spotting cysteine cathepsins in classical and novel scenes of action in mammalian epithelial cells and tissues. It. J. Anat. Embryol. 116, 1-19.
  • Vreemann, A., H. Qu, K. Mayer, L. Bjorkholt Andersen, M.I. Stefana, S. Wehner, M. Lysson, A.M. Farcas, C. Peters, T. Reinheckel, J. Kalff, and K. Brix (2009). Cathepsin B release from rodent intestine mucosa due to mechanical injury results in extracellular matrix damage in early post-traumatic phases. Biol. Chem. 390, 481-492. doi:10.1515/BC.2009.055
  • Mayer, K., A. Vreemann, H. Qu, and K. Brix (2009). Release of endo-lysosomal cathepsins B, D, and L from IEC6 cells in a cell culture model mimicking intestinal manipulation. Biol. Chem. 390, 471-480. doi:10.1515/BC.2009.047
  • Mayer, K., M.E. Iolyeva, U. Meyer-Grahle, and K. Brix (2008). Intestine-specific expression of green fluorescent protein-tagged cathepsin B: proof-of-principle experiments. Biol. Chem. 389, 1085-1096. doi 10.1515/BC.2008.360
  • Brix, K., A. Dunkhorst, K. Mayer, and S. Jordans (2008). Cysteine cathepsins: Cellular roadmap to different functions. Biochimie 90, 194-207. doi:10.1016/j.biochi.2007.07.024