A plasma nucleosome releasing factor (NRF) with serine protease activity is instrumental in removal of nucleosomes from secondary necrotic cells.
We observed that interaction of secondary necrotic (sn) cells with human serum or plasma leads to loss of DNA staining. The decrease turned out to be a result of nucleosome release and was specific for apoptotic cells as necrotic cells did not show this phenomenon. We named this activity in plasma nucleosome releasing factor (NRF). NRF activity was completely inhibited by trypsin inhibitors suggesting that a serine protease is involved. Upon testing a number of plasma candidate serine proteases we found that plasmin did have NRF activity. However, plasminogen-deficient plasma still had NRF activity indicating that NRF is not plasmin. We conclude that a yet unidentified plasma serine protease is involved in removal of nucleosomes from sn cells.
Zeerleder
Sacha
S
Department of Immunopathology, Sanquin, Plesmanlaan 125, 1066 CX Amsterdam, The Netherlands.
Zwart
Bas
B
te Velthuis
Henk
H
Manoe
Rishi
R
Bulder
Ingrid
I
Rensink
Irma
I
Aarden
Lucien A
LA
D004789:Enzyme Activation; D005341:Fibrinolysin / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D009336:Necrosis / Q000201:enzymology / Q000473:pathology; D009707:Nucleosomes / Q000187:drug effects / Q000201:enzymology*; D010958:Plasminogen / Q000378:metabolism; D011419:Propidium; D011480:Protease Inhibitors / Q000494:pharmacology; D012697:Serine Endopeptidases / Q000378:metabolism*
D009707:Nucleosomes; D011480:Protease Inhibitors; D011419:Propidium; D010958:Plasminogen; C433550:HABP2 protein, human; D012697:Serine Endopeptidases; D005341:Fibrinolysin