Carboxypeptidases cathepsins X and B display distinct protein profile in human cells and tissues.

Cathepsin X, a recently discovered lysosomal cysteine protease, shares common structural features and activity properties with cysteine protease cathepsin B. Based on its widespread mRNA distribution in primary tumors and tumor cell lines, a redundant function in tumor progression has been proposed. In this study, we have shown that these two related proteases exhibit different profiles with respect to their protein distribution in cells and tissues and to their possible roles in malignancy.

Inhibitory properties of cystatin F and its localization in U937 promonocyte cells.

Cystatin F is a recently discovered type II cystatin expressed almost exclusively in immune cells. It is present intracellularly in lysosome-like vesicles, which suggests a potential role in regulating papain-like cathepsins involved in antigen presentation. Therefore, interactions of cystatin F with several of its potential targets, cathepsins F, K, V, S, H, X and C, were studied in vitro.

Poly(lactide-co-glycolide) nanoparticles as a carrier system for delivering cysteine protease inhibitor cystatin into tumor cells.

Cystatins are able to inhibit the tumor-associated activity of intracellular cysteine proteases cathepsins B and L and have been suggested as potential anticancer drugs. We have incorporated chicken cystatin, a model protein inhibitor of cysteine proteases, in poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) to improve its bioavailability and delivery into tumor cells. Cystatin-loaded NPs, 300-350 nm in diameter, were prepared by the double emulsion solvent diffusion method using low energy emulsification to preserve the biological activity of the protein.

Inhibitory p41 isoform of invariant chain and its potential target enzymes cathepsins L and H in distinct populations of macrophages in human lymph nodes.

Activation of the CD4(+) T-cell mediated immune response relies on the proteolytic capacity of enzymes involved in modulating major histocompatibility complex (MHC) II-associated antigen presentation in antigen-presenting cells (APC). The MHC II-associated chaperone molecule p41 isoform of invariant chain (inhibitory p41 Ii) has been suggested to regulate stability and activity of cathepsin L in these APC. In the present study the human lymph node distribution of non-inhibitory p31 Ii and inhibitory p41 Ii have been compared by differential labelling, using two specific monoclonal antibodies.

Intracellular and extracellular cathepsin B facilitate invasion of MCF-10A neoT cells through reconstituted extracellular matrix in vitro.

Lysosomal cysteine proteinase cathepsin B is implicated in remodeling the extracellular matrix, a crucial step in the process of tumor cell invasion. In this study the contributions of intracellular and extracellular cathepsin B activities in the invasion of ras-transformed human breast epithelial cells, MCF-10A neoT, were assessed using specific cathepsin B neutralizing monoclonal antibody (Mab) 2A2, together with other general and specific cysteine proteinase inhibitors. We showed that the degradation of extracellular matrix by living MCF-10A neoT cells was predominantly intracellular, as imaged by confocal assays using quenched fluorescent substrate DQ-collagen IV.

Amyloid fibril formation by human stefin B in vitro: immunogold labelling and comparison to stefin A.

The mechanism by which proteins form amyloid fibrils is of high interest to the scientific community as its understanding could resolve questions relevant to conformational diseases. The structural and energetic basis of the process is still largely unknown. The main controversial issue is the co-existence of several protein conformations.