Cystatin F has been suggested to regulate the cytotoxicity of NK cells by inhibiting the major granzyme convertases, cathepsins C and H. To test this hypothesis, we prepared variants of cystatin F and analyzed their uptake, subcellular trafficking, peptidase inhibition, and the impact on the cytotoxicity of NK-92 cells and primary NK cells. We found that the glycosylation pattern is responsible for the secretion, uptake, and subcellular sorting of cystatin F. Active, N-terminally truncated, monomeric cystatin F can also be internalized by recipient cells and targeted to endo/lysosomes, affecting also cells lacking the activating peptidase. Cystatin F mutants capable of cell internalization and trafficking through the endo/lysosomal pathway significantly decreased cathepsin C and H activities, both in situ, following transfection and in trans, using conditioned media. Further, incubation of IL-2 stimulated NK-92 and primary NK cells with full-length and N-terminally truncated cystatin F mutants led to suppression of their granule-mediated cytotoxicity.
COBISS.SI-ID: 30930471
We presented that human primary NK cells induce lysis of carcinoma and carcinoma stem cells, while anti-CD16 antibody and monocytes induce functional split anergy by decreasing the cytotoxicfunction of NK cells. In this cell model we demonstrated that the levels of truncated monomeric cystatin F, which is known to inhibit the functions of cathepsins C and H, is significantly elevated in anergized primary NK cells. Furthermore, cystatin F co-localizes with cathepsins C and H in the lysosomal/endosomal vesicles of NK cells. Accordingly, the mature forms of cathepsins C and H, which regulate the activation of effector granzymes in NK cells, are significantly decreased.
COBISS.SI-ID: 3878769
Lectins have been recognized as promising carrier molecules for targeted drug delivery. We tested fungal lectin MpL as potential cystatin delivery carrier. MpL is endocytosed in a clathrin-dependent manner and accumulates initially in the Golgi apparatus and, finally, in the lysosomes. We constructed fusion protein consisting of MpL and the cysteine peptidase inhibitors cystatin C. It impaired both the intracellular degradation of extracellular matrix and the invasiveness of cancer cells due to cystatin's intracellular function. MpL thus enable protein drugs to enter cancer cells, enhance their internalization and sort them to lysosomes and the Golgi apparatus.
COBISS.SI-ID: 30318887
Evidence has previously been demonstrated for the role of NK cells in specific elimination of healthy stem cells (e.g. hMSC, hDPSC, hESC, hiPSC) as well as cancer stem cells, but not their differentiated counterparts. We proposed that CD16+CD56dimCD69 NK cells are important for the selection of stem cells, whereas the CD 16dim/CD56dim/+CD69+anergized NK cells are important for differentiation and eventual regeneration of the tissues and the resolution of inflammation, thus potentially serving as regulatory NK (NKreg) cells. The concept of 'split anergy' in NK cells and the generation of NKreg cells with regard to contributions to cell differentiation, tissue repair and regeneration and in tumor resistance are discussed in paper.
COBISS.SI-ID: 3746673
Cysteine cathepsins are lysosomal peptidases involved at different levels in the processes of the innate and adaptive immune responses. This review is focused on the role of cysteine cathepsins and their inhibitors in the molecular mechanisms leading to the cytotoxic activity of T lymphocytes and NK cells in order to address new possibilities for regulation of their function in pathological processes.
COBISS.SI-ID: 3788913