Proteolysis

Proteolysis and its regulation

Research in the area of proteolytic enzymes with an emphasis on explaining their functioning and regulation has largely expanded. Knowledge of the entire human genome has opened up new possibilities in discovering new proteins and their role in normal and pathological processes.

Cysteine proteases, including lysosomal papain-like cathepsins and the caspases, can be found not only in animals and humans, but also in plants and micro organisms. At the moment we know 11 human cysteine cathepsins and 12 human caspases. Generally speaking, cathepsins make an important contribution in processes such as intracellular protein degradation, peptide degradation, antigen presentation, bone growth, and processing other proteins, whereas caspases play a key role in removing damaged, infected or excessive cells (proapoptotic) and in inflammatory processes where they play a key role in processing numerous cytokines (proinflammatory).

Both cathepsins and caspases have a very important role in various pathologies such as cancer, osteoporosis, neurodegenerative disorders, inflammatory processes and autoimmune diseases, which makes them very interesting to the entire pharmaceutical industry as drug targets.

Studies demand preparation of sufficient amount of proteins by means of recombinant DNA technology using heterologous expression systems. To date, we have been able to successfully express cathepsins B, H, L, S, K, F and X and we plan to obtain the other cathepsins as well and to include some mice cathepsins (B, L, S, K) in the programme for use in animal models.

In addition, we intend to increase the number of expressed caspases (caspases-3, -6, -7, -8) and include at least caspase-1 and possibly mouse caspases-1 and -11 for the studies of physiological role.

What’s part of the service

• We will search for new potential cysteine cathepsins and their endogenous protein inhibitors (cystatins, thyropins) in the human genome by bioinformatic methods. New proteins will be biochemically characterised and we will attempt to explain their physiological role.
• With the help of proteomics and classic methods in biochemistry, molecular biology and cell biology we will try to identify new ligands for the individual cathepsins. Our work will also involve using transgenic mice and individual cathepsins knock-out mice and their cells.
• Understanding processing and activation of cathepsins is important in understanding their physiological role, especially in pathology. We will continue our study of activation of cathepsins B and S as model enzymes and the influence of glycosaminoglycans in extracellular conditions as in, for example, osteoarthritis, rheumatoid arthritis and cancer.
• We will continue studies aimed at understanding the molecular mechanism of triggering apoptosis with cathepsins in various in vitro and cellular models. We will primarily study ways to trigger apoptosis directly and through caspase activation. This research will be expanded to the role of lysosomes and cathepsins in neurodegenerative processes and ageing, characterised by excessive dying of neurons.
• We will continue the research of the role of cathepsins and their inhibitors in various types of cancer, with the focus mainly on cathepsins B, H, L, S and X and their inhibitors cystatins and thyropins.

In the area of endogenous inhibitors research will be directed primarily towards new inhibitors of the thyropin family. We will study inhibitory action of some other proteins containing tyroglobulin domains of type 1 (TROP, SMOC), and try to evaluate their physiological role as protease inhibitors. We will also continue the research on cystatins in the area of understanding the fibril formation by stefins A and B as model systems for various amyloidoses.