1999 Fiscal Year Final Research Report Summary
INVOLVEMENT OF ANNEXIN V IN THE ENDOTHELIAL APOPTOSIS INDUCED BY AUTOANTIBODIES.
| Project/Area Number |
10670441
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
内科学一般
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| Research Institution | RESEARCH INSTITUTE, OSAKAMEDICAL CENTER FOR MATERNAL AND CHILD HEALTH |
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Principal Investigator |
WADA Yoshinao RESEARCH INSTITUTE, OSAKAMEDICAL CENTER FOR MATERNAL AND CHILD HEALTH, DEPARTMENT OF MOLECULAR MEDICINE, DEIRECTOR, 代謝部門, 部長 (00250340)
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| Project Period (FY) |
1998 – 1999
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| Keywords | ANTIPHOSPHOLIPD ANTIVODY / ENDOTHELIAL CELLS / APOPTOSIS / ANNAXIN V / LUPUS ANTICOAGULANT / THROMBOSIS / SYSTEMIC LUPUS ERYTHEMATOSUS / AUTOANTIBODY |
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| Research Abstract |
Lupus anticoagulant (LAC) is associated with arterial and venous thrombosis, thrombocytopenia, and recurrent fetal loss. We have reported previously that plasma with LAC activity induces apoptosis in endothelial cells and binds annexin V. In this study, we separated two IgG antibody fractions, one with and one without affinity for annexin V, from 10 patients with LAC. LAC and apoptotic activities were localized in the annexin V-binding fraction in all 10 patients. DNA fragmentation was dose-dependeub paralleling the amount of IgG added to the human umbilical vein endothelial cell culture medium, and was inhibited by preincubation with annexin V. Removal of the antiphospholipid antibodies from patient IgG with phospholipid liposomes did not abolish the apoptosis-inducing activities or binding to annexin V. These results imply that patients with LAC often have antibodies that do not bind phospholipids and are responsible for the induction of apoptosis in endothelial cells.
Internucleosomal DNA fragmentation is generally perceived as one of the characteristic features of apoptosis, most of which are driven by caspase activation dependent upon ATP. On the other hand, ATP depletion has been reported to induce apoptosis accompanying DNA fragmentation. To address this apparent paradox, we analyzed the DNA: fragmenting activity generated in ATP-depleted cells. In HL-60 promyelocytic leukemia cells cultured in glucose-free medium with oligomycin, internucleosomal DNA fragmentation occurred as an early event. The DNA fragmentation was blocked by serine protease inhibitors but not by caspase inhibitors. Consistently, ICAD/DFF45 could not inhibit the DNA-fragmenting activity of the ATP depleted cytosol in a cell-free system. When ATP was supplied to the cell-free assay, 80% of the DNA-fragmenting activity was lost. The reduced activity was then restored by proteasome inhibitors, suggesting a role of proteasome to protect from a cellular insult derived from ATP-depletion
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