Prunk Mateja, Perišić Nanut Milica, Jakoš Tanja, Sabotič Jerica, Švajger Urban, Kos Janko
Department of Biotechnology, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia.
Faculty of Pharmacy, University of Ljubljana, Aškerčeva cesta 7, 1000 Ljubljana, Slovenia.
Cancers (Basel). 2020 Dec 6;12(12):3660. doi: 10.3390/cancers12123660.
Cystatin F is a protein inhibitor of cysteine cathepsins, peptidases involved in the activation of the effector molecules of the perforin/granzyme pathway. Cystatin F was previously shown to regulate natural killer cell cytotoxicity. Here, we show that extracellular cystatin F has a role in regulating the killing efficiency of cytotoxic T lymphocytes (CTLs). Extracellular cystatin F was internalised into TALL-104 cells, a cytotoxic T cell line, and decreased their cathepsin C and H activity. Correspondingly, granzyme A and B activity was also decreased and, most importantly, the killing efficiency of TALL-104 cells as well as primary human CTLs was reduced. The N-terminally truncated form of cystatin F, which can directly inhibit cathepsin C (unlike the full-length form), was more effective than the full-length inhibitor. Furthermore, cystatin F decreased cathepsin L activity, which, however, did not affect perforin processing. Cystatin F derived from K-562 target cells could also decrease the cytotoxicity of TALL-104 cells. These results clearly show that, by inhibiting cysteine cathepsin proteolytic activity, extracellular cystatin F can decrease the cytotoxicity of CTLs and thus compromise their function.
胱抑素F是半胱氨酸组织蛋白酶的一种蛋白质抑制剂，半胱氨酸组织蛋白酶是参与穿孔素/颗粒酶途径效应分子激活的肽酶。先前已证明胱抑素F可调节自然杀伤细胞的细胞毒性。在此，我们表明细胞外胱抑素F在调节细胞毒性T淋巴细胞（CTL）的杀伤效率中起作用。细胞外胱抑素F被内化到细胞毒性T细胞系TALL-104细胞中，并降低了它们的组织蛋白酶C和H活性。相应地，颗粒酶A和B的活性也降低，并且最重要的是，TALL-104细胞以及原代人CTL的杀伤效率降低。胱抑素F的N端截短形式（与全长形式不同，它可以直接抑制组织蛋白酶C）比全长抑制剂更有效。此外，胱抑素F降低了组织蛋白酶L的活性，然而，这并不影响穿孔素的加工。源自K-562靶细胞的胱抑素F也可以降低TALL-104细胞的细胞毒性。这些结果清楚地表明，通过抑制半胱氨酸组织蛋白酶的蛋白水解活性，细胞外胱抑素F可以降低CTL的细胞毒性，从而损害其功能。
