SELENIUM-DEPENDENT PEROXIDASES SUPPRESS 5-LIPOXYGENASE ACTIVITY IN B-LYMPHOCYTES AND IMMATURE MYELOID CELLS - THE PRESENCE OF PEROXIDASE-INSENSITIVE 5-LIPOXYGENASE ACTIVITY IN DIFFERENTIATED MYELOID CELLS
O. Werz et D. Steinhilber, SELENIUM-DEPENDENT PEROXIDASES SUPPRESS 5-LIPOXYGENASE ACTIVITY IN B-LYMPHOCYTES AND IMMATURE MYELOID CELLS - THE PRESENCE OF PEROXIDASE-INSENSITIVE 5-LIPOXYGENASE ACTIVITY IN DIFFERENTIATED MYELOID CELLS, European journal of biochemistry, 242(1), 1996, pp. 90-97
Differentiation of HL-60 cells by dimethylsulfoxide induces 5-lipoxyge
nase protein expression, but only low cellular 5-lipoxygenase activity
. Similarly, B-lymphocytes express 5-lipoxygenase protein and show act
ivity in cell homogenates but not in intact cells. Hen, we demonstrate
that suppression of cellular 5-lipoxygenase activity in these cell li
nes is serum dependent and that the serum effect can be mimicked by se
lenium. Selenium-dependent inhibition of 5-lipoxygenase activity was a
lso observed in the corresponding cell homogenates or 100000 x g super
natants when dithiothreitol or glutathione (GSH) was added. The proper
ties of the endogenous selenium-dependent inhibitor, i.e. molecular ma
ss, utilization of GSH and dithiothreitol as substrates, sensitivity t
o iodacetate, inhibition of 5-lipoxygenase activity in the presence of
the GPx-1 inhibitor mercaptosuccinate, suggest that a selenoenzyme wi
th properties of the phospholipid hydroperoxide glutathione peroxidase
(GPx-4) is responsible for the 5-lipoxygenase inhibition in BL41-E95-
A and immature HL-60 cells. Differentiation of HL-60 cells in the pres
ence of 1,25-dihydroxyvitamin D-3 and transforming growth factor-beta
(TGF beta) upregulated cellular 5-lipoxygenase activity regardless of
whether the cells were grown with or without serum or selenium. Also,
5-lipoxygenase activity in homogenates or 100000 x g supernatants of 1
,25-dihydroxyvitamin D-3/TGF beta differentiated HL-60 cells and of hu
man granulocytes was not inhibited by dithiothreitol or GSH. Thus, aft
er 1,25-dihydroxyvitamin D-3/TGF beta differentiation HL-60 cells rese
mble normal granulocytes with respect to the high 5-lipoxygenase activ
ity in intact cells and to the dithiothreitol effects in broken cell p
reparations. Combination experiments with 100000 x g supernatants of B
L41-E95-A cells and neutrophils revealed that the high 5-lipoxygenase
activity of granulocytes is due to stability of the 5-lipoxygenase cat
alytic activity against selenium-dependent peroxidases, but not to low
peroxidase activity. Our data suggest that the capability of mature m
yeloid cells to release large amounts of leukotrienes after stimulatio
n is due to a peroxidase-insensitive 5-lipoxygenase catalytic activity
.