Increased apoptosis in U937 cells over-expressing lipocortin 1 (annexin I).
The potential involvement of endogenous lipocortin 1 in the process of cellular apoptosis, particularly in cells of the myelo-monocytic lineage, has been investigated. U937 cells were transfected either with an antisense or a sense DNA for lipocortin 1 and the stable clones 36.4AS clone (20-40% lower lipocortin 1 levels) and 15S (30% higher lipocortin 1 levels) were obtained. Cell apoptosis was induced by incubation with tumor necrosis factor-alpha: optimal responses were observed within a 24 h incubation period at a 5 ng/ml concentration. Apoptosis was assessed both morphologically, by annexin V binding and cell cycle analysis with propidium iodide. Whilst no consistent difference was seen between wild type cells and clone 36.4AS, a higher incidence of apoptosis (ranging from +30% to + 60%) was observed in the 15S clone. Release of arachidonic acid from loaded cells was promoted by 24 h incubation with the cytokine, and a higher degree of release was measured in the 15S clone. These data indicate that endogenous intracellular lipocortin 1 is involved in the promotion of apoptosis in cells of the myelo-monocytic derivation.
Canaider
S
S
The William Harvey Research Institute, London, UK.
Solito
E
E
de Coupade
C
C
Flower
R J
RJ
Russo-Marie
F
F
Goulding
N J
NJ
Perretti
M
M
D017305:Annexin A1 / Q000096:biosynthesis*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D016718:Arachidonic Acid / Q000378:metabolism; D002453:Cell Cycle / Q000502:physiology; D002999:Clone Cells / Q000187:drug effects / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D010741:Phospholipases A / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D020298:U937 Cells
D017305:Annexin A1; D014409:Tumor Necrosis Factor-alpha; D016718:Arachidonic Acid; D010741:Phospholipases A