About 1 in 5 adults will experience an ischemic stroke in their lifetime and its incidence is increasing with the ageing population. One of the main causes of ischemic stroke, a sudden stoppage of blood flow in a brain region, is a blood clot in the arteries due to thrombosis. The current treatment modalities are based on lysing the clot with a protease called tissue plasminogen activator (tPA) or removing the clot by surgical procedures (1). In spite of these treatment possibilities, this condition is a major cause of disability and mortality.
To address this unmet need the research team has identified a blood protease called Factor VII activating protease (FSAP) as a possible treatment for ischemic stroke (2). FSAP circulates in the blood as an inactive enzyme in its zymogen form. Exactly how it is activated is not clear, but extracellular free histones released after tissue damage, NETosis or inflammation are likely to be involved. Moreover, the researchers have identified a synthetic cyclic peptide that can also activate this enzyme (3). We hypothesize that activating the zymogen form of FSAP, that is already in the blood, could also be a means of treating ischemic stroke. However, to test this hypothesis we need to understand the detailed mechanism of how the zymogen form of FSAP is converted into an active enzyme and this is the goal of the planned project.
The key questions to answer are: what keeps pro-FSAP in a stable inactive zymogen form at a very high concentrations in the blood? Furthermore, how does an encounter with an activator convert it into an active protease? All the recombinant proteins and complexes for cryo-EM analysis will be prepared at the Kanse-lab in Oslo where the role of FSAP of stroke has been investigated over the last decade. The cryo-EM analysis will be done in Aarhus by the Boesen-Lab, who has more than 16 years’ experience with cryo-EM and other electron microscopy methods.
Striking advances in cryo-EM techniques have been made in the last decade and the accompanying resolution revolution has made cryo-EM the primary method in structural biology for high resolution studies of proteins. Compared to protein crystallography that was the dominating method in structural biology for decades, cryo-EM does not require crystals to determine structures to atomic resolution, which removes a major bottleneck in experimental structure determination and speeds up the process tremendously.
For further information about this HALRIC pilot project, please contact:
University of Oslo
1. Campbell et al, Nature Rev Dis Primers, PMID: 31601801
2. Kim et al, 2022, FASEB J, PMID: 36165219
3. Berge-Seidl, 2022, ACS Chem Biol, PMID: 36070465