Exploiting human immune repertoire transgenic mice for protective monoclonal antibodies against antimicrobial resistant Acinetobacter baumannii.

The use of monoclonal antibodies for the control of drug resistant nosocomial bacteria may alleviate a reliance on broad spectrum antimicrobials for treatment of infection. We identify monoclonal antibodies that may prevent infection caused by carbapenem resistant Acinetobacter baumannii. We use human immune repertoire mice (Kymouse platform mice) as a surrogate for human B cell interrogation to establish an unbiased strategy to probe the antibody-accessible target landscape of clinically relevant A.

Cathepsin L-mediated EGFR cleavage affects intracellular signalling pathways in cancer.

Proteolytic activity in the tumour microenvironment is an important factor in cancer development since it can also affect intracellular signalling pathways via positive feedback loops that result in either increased tumour growth or resistance to anticancer mechanisms. In this study, we demonstrated extracellular cathepsin L-mediated cleavage of epidermal growth factor receptor (EGFR) and identified the cleavage site in the extracellular domain after R224. To further evaluate the relevance of this cleavage, we cloned and expressed a truncated version of EGFR, starting at G225, in HeLa cells.

Intracellular cathepsin C levels determine sensitivity of cells to leucyl-leucine methyl ester-triggered apoptosis.

L-leucyl-leucine methyl ester (LLOMe) is a lysosomotropic detergent, which was evaluated in clinical trials in graft-vs-host disease because it very efficiently killed monocytic cell lines. It was also shown to efficiently trigger apoptosis in cancer cells, suggesting that the drug might have potential in anticancer therapy. Using U-937 and THP-1 promonocytes as models for monocytic cells, U-87-MG and HeLa cells as models for cancer cells, and noncancerous HEK293 cells, we show that the drug triggers rapid cathepsin C-dependent lysosomal membrane permeabilization, followed by the release of other cysteine cathepsins into the cytosol and subsequent apoptosis.

Proteomic Identification of Cysteine Cathepsin Substrates Shed from the Surface of Cancer Cells.

Extracellular cysteine cathepsins are known to drive cancer progression, but besides degradation of extracellular matrix proteins little is known about their physiological substrates and thus the molecular mechanisms they deploy. One of the major mechanisms used by other extracellular proteases to facilitate cancer progression is proteolytic release of the extracellular domains of transmembrane proteins or ectodomain shedding. Here we show using a mass spectrometry-based approach that cathepsins L and S act as sheddases and cleave extracellular domains of CAM adhesion proteins and transmembrane receptors from the surface of cancer cells.

Fast profiling of protease specificity reveals similar substrate specificities for cathepsins K, L and S.

Proteases are important effectors of numerous physiological and pathological processes. Reliable determination of a protease's specificity is crucial to understand protease function and to develop activity-based probes and inhibitors. During the last decade, various proteomic approaches for profiling protease substrate specificities were reported.

Cysteine cathepsins are not critical for TRAIL- and CD95-induced apoptosis in several human cancer cell lines.

The potential role of cysteine cathepsins in tumor necrosis factor-related apoptosis-inducing ligand(TRAIL/Apo2L)- and CD95 (Fas/APO-1)-induced apoptosis was investigated using four different cell lines (HeLa, HuH-7, Jurkat, and U-937). All four cell lines exhibited different levels of cathepsins and responded differently to apoptosis triggering, with Jurkat cells being the most sensitive and the only ones that were sensitive to the agonistic anti-APO-1 antibody. Apoptosis was accompanied by caspase activation, loss of the mitochondria and lysosome integrity, and the release of cysteine cathepsins into the cytosol, as judged based on the hydrolysis of the cysteine cathepsin substrate benzyloxycarbonyl-Phe-Arg-7-amino-4-methylcoumarin and by the immunological detection of cathepsin B.

Influence of sodium nitroprusside on human erythrocyte membrane water permeability: an NMR study.

Sodium nitroprusside (SNP) is a nitric oxide (•NO) donor in vitro and in vivo. In this paper the time variation of the intracellular water proton nuclear magnetic resonance (NMR) effective relaxation time T'(2a) in SNP-treated human erythrocyte suspensions, containing 10 mM membrane impermeable paramagnetic MnCl2, has been measured. The observed T'(2a) time-course was analyzed in terms of the two mechanisms by which released •NO affects T'(2a).