Human cystatin C (HCC) is a small protein with a flexible structure. It undergoes conformational changes, including domain swapping, induced by physical and chemical parameters such as pH, temperature, irradiation, and shear forces. This protein is responsible for inhibiting cysteine proteases; however, it is also involved in the formation of amyloid structures. The pathogenic mutant Leu68Gln is observed in patients with hereditary cystatin C amyloid angiopathy, a disease related to the formation of protein deposits in brain blood vessels. Our studies aimed to analyze the physical factors influencing the conformational changes and misfolding of HCC, as well as the formation of amyloid fibers. The process of cystatin amyloidogenesis was induced by microfluidic flow in channels with a cross-section similar to that of brain blood vessels. A second approach involved high-pressure experiments (up to 350 MPa). The kinetics of this process was characterized using small-angle synchrotron radiation scattering at ESRF, DESY, and CHESS. Combined techniques such as circular dichroism spectroscopy, atomic force microscopy, microfluidics, and spectrofluorimetry were also employed for a more in-depth analysis. As a result, amyloid aggregation processes were observed under both microfluidic flow and high-pressure conditions. The research was supported by grant 2021/41/B/ST4/03807 from the National Science Centre (Poland).
Kozak et al. (Sun,) studied this question.