4 research outputs found
NEUTROPHIL ELASTASE AND PROTEINASE 3 CLEAVAGE SITES ARE ADJACENT TO THE POLYBASIC SEQUENCE WITHIN THE PROTEOLYTIC SENSITIVE ACTIVATION LOOP OF THE SARS-COV-2 SPIKE PROTEIN
Serine proteases neutrophil elastase (NE), protease 3 (PR3), cathepsin G (CatG), and neutrophil serine protease 4 (NSP4) are released by activated neutrophils swarming around the place of pathogen invasion to provoke an immune response. However, uncontrolled proteolytic activity of proteases results in various human diseases, including cardiovascular diseases, thrombosis, and autoimmunity. In addition, proteases can be hijacked by several viruses to prime virus-derived surface proteins and evade immune detection by entering into the host cell. Indeed, porcine elastase increases the suitability of host cells to be infected by SARS-CoV-1. We compared the cleavage sites of human NE, PR3, and CatG as well as porcine-derived trypsin within the amino acid sequence of the proteolytic sensitive activation loop at the interface of S1/S2 of the spike protein (S protein) of SARS-CoV-1 as well as SARS-CoV-2. As a result, NE and PR3, but not CatG, hydrolyze the scissile peptide bond adjacent to the polybasic amino acid sequence of the S1/S2 interface of SARS-CoV-2, which is distinctive from SARS-CoV-1. These findings suggest that neutrophil-derived NE and PR3 participate in priming of the S1/S2 interface during an immune respons
ACTIVITY-BASED PROBES TO UTILIZE THE PROTEOLYTIC ACTIVITY OF CATHEPSIN G IN BIOLOGICAL SAMPLES
Neutrophils, migrating to the site of infection, are able to release serine proteases after being
activated. These serine proteases comprise cathepsin G (CatG), neutrophil elastase
protease 3 (PR3), and neutrophil serine protease 4 (NSP4). A disadvantage of the
uncontrolled proteolytic activity of proteases is the outcome of various human diseases,
including cardiovascular diseases, thrombosis, and autoimmune diseases. Activity-based
probes (ABPs) are used to determine the proteolytic activity of proteases, containing a set of
three essential elements: Warhead, recognition sequence, and the reporter tag for
detection of the covalent enzyme activity–based probe complex. Here, we summarize
the latest findings of ABP-mediated detection of proteases in both locations intracellularly
and on the cell surface of cells, thereby focusing on CatG. Particularly, application of ABPs
in regular flow cytometry, imaging flow cytometry, and mass cytometry by time-of-flight
(CyTOF) approaches is advantageous when distinguishing between immune cell subsets.
ABPs can be included in a vast panel of markers to detect proteolytic activity and determine
whether proteases are properly regulated during medication. The use of ABPs as a
detection tool opens the possibility to interfere with uncontrolled proteolytic activity of
proteases by employing protease inhibitors
REGULATION OF MHC I MOLECULES IN GLIOBLASTOMA CELLS AND THE SENSITIZING OF NK CELLS
Immunotherapy has been established as an important area in the therapy of malignant diseases. Immunogenicity sufficient for immune recognition and subsequent elimination can be bypassed by tumors through altered and/or reduced expression levels of major histocompatibility complex class I (MHC I) molecules. Natural killer (NK) cells can eliminate tumor cells in a MHC I antigen presentation-independent manner by an array of activating and inhibitory receptors, which are promising candidates for immunotherapy. Here we summarize the latest findings in recognizing and regulating MHC I molecules that affect NK cell surveillance of glioblastoma cell
CAMOSTAT DOES NOT INHIBIT THE PROTEOLYTIC ACTIVITY OF NEUTROPHIL SERINE PROTEASES
Coronavirus disease 2019 (COVID-19) can lead to multi-organ failure influenced by co morbidities and age. Binding of the severe acute respiratory syndrome coronavirus 2 spike protein
(SARS-CoV-2 S protein) to angiotensin-converting enzyme 2 (ACE2), along with proteolytic digestion
of the S protein by furin and transmembrane protease serine subtype 2 (TMPRSS2), provokes inter nalization of SARS-CoV-2 into the host cell. Productive infection occurs through viral replication in
the cytosol and cell-to-cell transmission. The catalytic activity of TMPRSS2 can be blocked by the
trypsin-like serine protease inhibitor camostat, which impairs infection by SARS-CoV-2. At the site of
infection, immune cells, such as neutrophils, infiltrate and become activated, releasing neutrophil ser ine proteases (NSPs), including cathepsin G (CatG), neutrophil elastase (NE), and proteinase 3 (PR3),
which promote the mounting of a robust immune response. However, NSPs might be involved in in fection and the severe outcome of COVID-19 since the uncontrolled proteolytic activity is responsible
for many complications, including autoimmunity, chronic inflammatory disorders, cardiovascular
diseases, and thrombosis. Here, we demonstrate that camostat does not inhibit the catalytic activity
of CatG, NE, and PR3, indicating the need for additional selective serine protease inhibitors to reduce
the risk of developing severe COVID-19